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  • 2000-2004
  • 1995-1999
  • 1990-1994  (287)
  • 1992  (287)
  • Rat  (193)
  • Human
  • Industrial Chemistry
  • 1
    Electronic Resource
    Electronic Resource
    Precise anorectal sphincter dilatation—Its role in the therapy of anal fissures (1992)
    Springer
    Diseases of the colon & rectum 35 (1992), S. 322-327 
    Details
    ISSN: 1530-0358
    Keywords: Fissure-in-ano ; Therapy ; Surgery ; Dilatation ; Adult ; Female ; Male ; Human ; Methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract For the past 20 years, internal anal sphincterotomy has generally been considered to be the standard operation for an anal fissure. We sought an alternative form of treatment because of the wound complications inherent in this operation. Anal dilatation, precisely performed with a Parks' retractor opened to 4.8 cm or with a 40mm rectosigmoid balloon, has been found to cure successfully the fissure in 93 percent and 94 percent, respectively, of each group and to be associated with fewer complications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02048108
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  • 2
    Electronic Resource
    Electronic Resource
    Healing of ischemic colonic anastomosis: Fibrin sealant does not improve wound healing (1992)
    Springer
    Diseases of the colon & rectum 35 (1992), S. 884-891 
    Details
    ISSN: 1530-0358
    Keywords: Rat ; Colon ; Anastomosis ; Wound healing ; Tissue adhesive ; Ischemia ; Bursting pressure ; Collagen ; Adhesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fibrin adhesives have been advocated as a protective sealant in high-risk colonic anastomoses to prevent leakage. To assess the effect of fibrin glue sealing on the healing ischemic anastomosis, we compared the healing of sutured colonic anastomoses in the rat, with and without fibrin adhesive (Groups IA and IB), and ischemic anastomoses with and without fibrin adhesive (Groups IIA and IIB). On days two, four, and seven, 10 animals in each group were sacrificed. Adhesion formation was scored, and the in situ bursting pressure was measured. The collagen concentration and degradation were estimated by measuring hydroxyproline. Adhesion formation was more prominent in Groups IB, IIA, and IIB on day four only; abscesses were noted in the ischemic group in four rats. Anastomotic bursting pressure was significantly lower in sealed (IB) and ischemic anastomoses (IIA) than in normal anastomoses (IA) on day four. Sealing of ischemic anastomoses did not change bursting pressures on days two, four, and seven. The relative decrease of collagen in the sealed anastomoses is significantly higher on day four only. It is concluded that sealing of normal colonic anastomoses in the rat has a negative effect on wound healing. Ischemia at the anastomotic site results in weaker anastomotic strength on day four postoperatively. Also in ischemic anastomoses, fibrin sealant does not improve wound healing during the first seven days. Adhesion formation on ischemic intestinal anastomoses was not prevented by fibrin sealing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02047878
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  • 3
    Electronic Resource
    Electronic Resource
    Dehydroepiandrosterone sulfate-binding sites in plasma membrane from human uterine cervical fibroblasts (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 999-1002 
    Details
    ISSN: 1420-9071
    Keywords: Human ; uterine cervix ; fibroblasts ; dehydroepiandrosterone sulfate ; ripening ; labor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Dehydroepiandrosterone sulfate (DHA-S) plays a critical role in cervical dilation at labor. Incubation of cervical fibroblasts with [3H]DHA-S caused a rapid and saturable increase in cellular radioactivity: an apparent equilibrium was reached by 2 min. There was no detectable conversion of DHA-S into DHA or oestradiol. When the fibroblasts loaded with [3H]DHA-S were homogenized and fractionated, the specific radioactivity in the plasma membrane fraction was enriched approximately 8- to 9-fold compared with the whole homogenate; only low amounts of radioactivity were observed in the other subcellular fractions. The binding of DHA-S to plasma membrane preparations showed saturation kinetics with an apparent equilibrium dissociation constant (K d) of 12 nM, and the binding capacity (B max) was calculated to be 1.25 fmol/mg protein. Neither DHA nor oestrone sulfate affected [3H]DHA-S binding to the plasma membrane. The plasma membranes of skin fibroblasts did not show specific binding sites for DHA-S. These findings demonstrate the presence of specific binding sites for DHA-S in the plasma membrane of cervical stroma cells. The fetal adrenal steroid may exert its action on cervical ripening at least in part through membrane-associated binding sites, or receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01919152
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  • 4
    Electronic Resource
    Electronic Resource
    Amino acids as well as polyols and methylamines accumulated in rat kidney during dehydration (1992)
    Springer
    Amino acids 3 (1992), S. 131-138 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Osmolytes ; Dehydration ; Rat ; Taurine ; Myoinositol ; Sorbitol ; Betaine ; Glycerophosphorylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During antidiuresis cells in the renal inner medulla contain large amounts of sorbitol, myo-inositol, glycerophosphorylcholine and betaine to adjust the intracellular osmolality to the extracellular hyperosmolality. Although the accumulation of these four major organic osmolytes in the inner medulla of the dehydrated animal has been a consistent finding, the role of another class of organic osmolytes, amino acids, in osmoregulation in the kidney remains controversial. In the present study, renal responses of four major osmolytes and amino acids to dehydration were investigated using two HPLC systems. Taurine levels were significantly higher in the inner medulla of the dehydrated rats as compared with the control rats, and increased monotonically from the cortex to the inner medulla along the corticopapillary axis in the dehydrated rats. As for four major osmolytes, we confirm previously reported patterns in antidiuresis in greater detail. In conclusion, not only the four major osmolytes but taurine also plays a salient role in the osmoregulation in the kidney.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806778
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  • 5
    Electronic Resource
    Electronic Resource
    Induction of the fed pattern of human exocrine pancreatic secretion by nutrients: role of cholecystokinin and neurotensin (1992)
    Springer
    Journal of molecular medicine 70 (1992), S. 902-908 
    Details
    ISSN: 1432-1440
    Keywords: Cholecystokinin ; Gastrointestinal hormones ; Human ; Interdigestive pattern ; Fed pattern ; Pancreatic secretion ; Neurotensin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of the present study was to assess the role of cholecystokinin and neurotensin in converting the cyclical interdigestive pattern of pancreatic secretion into the non-cyclical fed pattern. Six healthy male volunteers were studied on 4 separate days. During each experiment a mixed liquid meal or solutions of individual nutrients were perfused intraduodenally for 180 min at 2 ml/min. The mixed meal contained 4.3 g glucose, 2.0 g fractionated soya oil, and 1.7 g casein hydrolysate per 100 ml, which delivered a caloric load of 0.9 kcal/min into the duodenum. The isocaloric and isotonic solutions of individual nutrients contained 44.5 g glucose, 17.8 g fractionated soya oil, or 44.5 g hydrolysed serum bovine albumin per liter and delivered 0.36 kcal/min into the duodenum. Duodenal aspirates and blood samples were collected at regular intervals for determination of pancreatic enzyme outputs and plasma levels of cholecystokinin and neurotensin, respectively. The mixed meal converted the cyclical interdigestive secretory pattern into the noncyclical fed pattern whereas none of the three individual nutrients abolished the interdigestive pattern. Not only the mixed meal but also lipid and protein perfusion consistently stimulated cholecystokinin release. Integrated incremental cholecystokinin release amounted to 32.3±9.9 pg/ml × 180 min with the mixed meal, 23.2±6.5 with lipid perfusion (P〈 0.05 versus mixed meal) and 13.4±3.8 with protein perfusion (P〈0.05 versus mixed meal). The carbohydrate solution did not significantly release cholecystokinin. None of the duodenal perfusates raised neurotensin plasma levels. We conclude that (a) intraduodenal delivery of a mixed meal at 0.9 kcal/min converts the interdigestive pattern of pancreatic secretion, (b) cholecystokinin but not neurotensin is involved in converting this pattern in response to low-caloric meals, and (c) a threshold amount of CCK release must be exceeded to convert the secretory pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180436
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  • 6
    Electronic Resource
    Electronic Resource
    Comparison of the effects of losigamone and its isomers on maximal electroshock induced convulsions in mice and on three different patterns of low magnesium induced epileptiform activity in slices of the rat temporal cortex (1992)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 345 (1992), S. 85-92 
    Details
    ISSN: 1432-1912
    Keywords: Entorhinal cortex ; Isomers ; Low magnesium epilepsy ; Losigamone ; Maximal electroshock test ; Mice ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Losigamone (AO-33) is a recemate of a tetronic acid derivative. The effects of losigamone and its three isomers (AO-242, AO-294 and AO-23) were compared on maximal electroshock (MES) induced convulsions in mice and on different patterns of extracellularly recorded, low Mg 2+ induced epileptiform activity in slices of the rat temporal cortex. Lowering Mg 2+ induced recurrent short discharges in areas CA3 and CA1 while ictaform events that lasted for many seconds were induced in the entorhinal cortex. In the hippocampus the activity stayed stable over a number of hours. In contrast, the ictaform events in the entorhinal cortex changed their characteristics after one to two hours to recurrent discharges of 0.8 to 10 s. Afterdischarges and interictal events were absent. 50 μM AO-242 showed a similar efficacy to 50 μM AO-33 in reducing and blocking epileptiform discharges in areas CA1 and CA3 while 50 μM AO-294 and 50 μM AO-23 had weaker effects than 50 μM AO-33. Concentrations of 50 μM and 100 μM AO-242 showed a similar efficacy to AO-33 on ictaform events in the entorhinal cortex. Late recurrent discharges were also blocked by AO-33 and AO-242 although at higher concentrations (300 μM). The in vitro observations are with respect to order of efficacy in accordance with the in vivo data obtained in the maximal electroshock test in mice. The order of potency in the MES test was AO-242〉AO-33≫AO-294≫ AO-23. The results show that the erythro-isomer AO-23, although active, is much less potent than AO-33. Of the two optical isomers of losigamone the (+) isomer AO-242 is more active than the (−) form AO-294.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175474
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  • 7
    Electronic Resource
    Electronic Resource
    Verapamil induces increased bone volume and osteopenia in female rats but has the opposite effect in male rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 524-526 
    Details
    ISSN: 1432-0827
    Keywords: Verapamil ; Bone ; Osteopenia ; Rat ; Female ; Intestinal calcium absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Verapamil inhibits the intestinal absorption of calcium (Ca) and increases serum parathyroid hormone in rats. The effects of verapamil on bone tissue after long-term treatment is, however, not well described. Adult female and male Sprague-Dawley rats received verapamil in their drinking water at a dosage of 0.075 mg/ml (low dose) or 0.75 mg/ml (high dose) for 12 weeks; control rats received only drinking water. All rats were fed a diet containing 0.1% Ca and 0.5% P. In female rats, the amount of bone ash per volume was significantly reduced from 0.742 g/ml in controls to 0.713 g/ml after low-dose treatment of verapamil, and to 0.667 g/ml following high-dose treatment (P〈0.01). The tibial length was increased from 39.7 mm in controls to 40.3 mm or to 40.7 mm after low or high doses (P〈0.01). The tibial volume increased from 0.385 ml in controls to 0.397 ml after low doses and to 0.429 ml after high doses (P〈0.01). In contrast, in male rats the amount of bone ash per volume was significantly increased from 0.578 g/ml in controls to 0.580 g/ml after low doses and to 0.620 g/ml after high doses of verapamil (P〈0.01). The tibial bone volume in males as decreased from 0.633 ml in controls to 0.641 ml after low doses and to 0.583 ml after high doses (P〈0.05). The tibial length in the males was not changed by verapamil. The intestinal absorption of Ca was reduced in male rats from 5.28 in controls to 4.03 (serosa/mucosa) after low-dose treatment and to 2.46 after high-dose treatment with verapamil (P〈0.05). In female rats, the intestinal absorption of Ca did not change after verapamil treatment. Thus, chronic treatment with verapamil in female rats induced osteopenia whereas in male rats bone growth was inhibited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582167
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  • 8
    Electronic Resource
    Electronic Resource
    Bone blood flow and In vitro proliferation of bone marrow and trabecular bone osteoblast-like cells in ovariectomized rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 336-341 
    Details
    ISSN: 1432-0827
    Keywords: Rat ; Osteoblast-like culture ; Ovariectomy ; Estrogens ; Bone blood supply
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Ovariectomy in the rat induces a rapid osteopenia associated with an elevated bone turnover. One hundred and twenty-day-old rats were ovariectomized (OVX) or sham-operated (n=6–8 per group and per time period studied). 45Ca accretion rate and bone blood flow (microspheres trapping technique) in the femurs were determined at 28, 42, 84, and 119 days after ovariectomy. Both parameters were markedly increased by 84 days and subsided thereafter. At the 42nd day, when bone turnover was maximal, bone marrow and trabecular bone cultures were obtained from shamoperated and ovariectomized animals (n=10/group). Proliferation rate of bone marrow cells and trabecular osteoblast-like cells estimated by fibroblast colony-forming units (FCFU) efficiency and cell counting was markedly increased in primary and secondary cultures in ovariectomy. These data fitted well with the enhanced number of osteoblasts observed in situ in the long bone metaphyses of estrogen-depleted animals. As estrogens were shown in the literature to inhibit proliferation of the red cell line and of other hemopoietic lines, it is possible that estrogens, through a general mechanism, inhibit hemopoietic and stromal lines and also the proliferation of bone marrow-derived trabecular bone cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301631
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  • 9
    Electronic Resource
    Electronic Resource
    Statistical analysis and prediction of the exonic structure of human genes (1992)
    Springer
    Journal of molecular evolution 35 (1992), S. 239-252 
    Details
    ISSN: 1432-1432
    Keywords: Computer analysis ; Exons ; Introns ; Exon-intron structure ; Exon-exon junctions ; Splicing ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nonhomologous fully sequenced human protein-coding genes were studied. Three sets of exon-exon junctions were formed defined by the intron (shadow) position relative to the reading frame. For the analysis of intron shadow signals in exons, information content and discrimination energy approaches were used with the correction allowing one to ignore the influence of a protein-coding message. The corrected formulas allow one to define the consensuses for the three types of intron shadow signals as aAG/guwn, cAG/GUnn, and cAG/gunU, and provide better recognition than the original formulas. The analysis of the codon usage in the signal positions leads to the conclusion that the prevalence of some amino acids in corresponding protein sites is caused by the signal requirements and not vice versa. The distribution of potential intron shadow signals in exons contradicts the hypothesis of intron insertion into suitable preexisting sites. There exists a correlation between the intron types and/or the exon length modulo 3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178600
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of tactile stimulation of nipples on the milk ejection reflex in the rat (1992)
    Springer
    Journal of comparative physiology 170 (1992), S. 645-650 
    Details
    ISSN: 1432-1351
    Keywords: Milk ejection reflex ; Positive pressure oscillations ; Motor activity of pups ; Tactile stimulation of nipples ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes of positive pressure exerted by pups on nipples during sucking were investigated using anesthetized, lactating dams. It was found that, every 50–60 s, individual pups performed bouts of pressure oscillations (3/s) of high amplitude which lasted about 10–12 s and coincided with periods of increased motor activity. During the intervals, when pups were quiet, series of low-amplitude oscillations (3/s) were also observed. Using a strain measuring method to record the activity of sucking pups, synchronization of activity of two or more pups was found to occur periodically every 25–30 s and, most frequently, 10–30 s before the reflex increase of milk pressure. In further experiments, artificial tactile stimulation was applied to the dam's nipples using the joint action of suction and positive pressure. Following a short-term (10–20 s) increase in frequency and amplitude of artificial nipple stimulation, 60%–80% of all reflexive peaks of milk pressure were elicited with a latency of 19 ± 5 s. This suggests that there are specific conditions under which the stimulation of nipples by pups may trigger the formation of the milk ejection reflex in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199340
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  • 11
    Electronic Resource
    Electronic Resource
    Effects of lesion of the inferior olivary complex by 3-acetylpyridine on learning and memory in the rat (1992)
    Springer
    Journal of comparative physiology 171 (1992), S. 657-664 
    Details
    ISSN: 1432-1351
    Keywords: Inferior olivary complex ; Cerebellum ; 3-acetylpyridine ; Harmaline ; Learning ; Memory ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary DA/HAN-strained male rats (pigmented rats) were submitted to two experimental tasks consisting of spatial learning (water-escape) and a passive avoidance conditioning. Both these tasks were performed by different animals. In order to destroy the inferior olivary complex, the animals were injected with 3-acetylpyridine either 9 days prior to the initial learning session or 24 h after completion of the learning task. They were retested (retrieval test) 10 days after the initial learning was achieved. Learning and retention were compared to those noted in control rats. Administration of 3-acetylpyridine before the initial learning did not prevent the spatial learning but the scores were greatly altered and the number of trials needed to reach the fixed learning criterion was much greater than in controls. However, 10 days later the animals had memorized their initial experience. Injection of 3-acetylpyridine after the initial learning session impaired memory: the animals had completely forgotten their initial learning. It can therefore be concluded that lesion of the afferent climbing fibres to the cerebellar cortex alters learning and retention of a spatial task. Such a lesion does not interfere with learning and retention of a passive avoidance conditioning, since in this condition the experimental animals injected with 3-acetylpyridine either before or after the initial learning behave similarly to controls. The effects of the inferior olivary complex lesion are obviously different according to the task to be learnt, suggesting that these two tasks do not require the integrity of the same nervous structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194113
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  • 12
    Electronic Resource
    Electronic Resource
    Analytical aspects of FRCS (Fluorescence Activated Cell Sorter) identification of rat T and B peripheral lymphocytes in toxicity studies (1992)
    Springer
    Comparative clinical pathology 2 (1992), S. 220-226 
    Details
    ISSN: 1433-2981
    Keywords: FACS ; Rat ; T and B lymphocytes ; FITCand PE-conjugated MoAbs ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There is a strong need for generation and publication of reference values of immunotoxicity parameters within experimental and toxicological areas. This is particularly true where the type of distribution of reference values and thus the statistical method to be employed is often unknown and will become necessary if current official proposals to implement immune parameters into regulatory toxicity studies are adopted. T and B lymphocytes were identified and quantitated by Fluorescence Activated Cell Sorter Analysis (FACS, using either one or two colours) after labelling of lymphocytes in suspension with fluorescent monoclonal antibodies (MoAbs). For single labelling of T and B lymphocytes, fluorescein isothiocyanate (FITC)-conjugated monoclonal antibody (MoAb) Ox-19 and Mark-1 were used respectively. In double labelling, T and B lymphocytes were identified with phycoerythrin (PE)-conjugated Ox-19 and FITC-conjugated Mark-1 MoAbs respectively. The physicochemical stability shelf-life of labelled T lymphocytes was at least 24 h at 2–8°C permitting overnight storage before FACS analysis, whereas enumeration of B lymphocytes should preferably be done directly after labelling. The sum of the percentages of T and B lymphocytes obtained in the combined T+B lymphocyte analysis with FITC-conjugated Ox-19 and Mark-1 were compared with the sum of values obtained in separate experiments after single labelling, yielding an inaccuracy of 0.3%. The precision of B and T cell analysis after double labelling was found to be 8.2% and 0.5% respectively. Baseline data (reference/normal values) were obtained for rat T lymphocytes (63%–90%) and for B lymphocytes (7.5%–28%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216098
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  • 13
    Electronic Resource
    Electronic Resource
    Histological reactivity of a monoclonal antibody against rat colon cancer cells on human and rat normal gut and colonic tumours (1992)
    Springer
    Virchows Archiv 420 (1992), S. 233-242 
    Details
    ISSN: 1432-2307
    Keywords: Monoclonal antibody ; Digestive tract ; Colon cancer ; Rat ; Golgi apparatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A monoclonal antibody, F11C, was raised against rat colon cancer cells. Its immunoreactivity on normal human and rat gut as well as human and rat colonic tumours was studied by the avidin-biotin-peroxidase complex technique. In both normal rat and human gastrointestinal tract, F11C stained surface epithelial cells from the fundus to distal colon, mainly as supranuclear vesicles. These vesicles appeared to be part of the Golgi apparatus on electron microscopy with immunogold labelling. Twenty primary rat colon tumours and 28 of 43 human colon tumours were also stained, with a heterogeneous pattern but much more strongly than the normal colonic mucosa. Biochemical purification suggested that in rat tumours F11C epitope was carried by a high molecular weight glycoprotein. Absorption experiments with synthetic oligosaccharides showed that F11C monoclonal antibody reacted with blood group A-related oligosaccharides. Nevertheless, F11C reactivity on human tissues was not related to the individual ABO or Lewis phenotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01600276
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  • 14
    Electronic Resource
    Electronic Resource
    The effect of acute distension on vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) and substance P (SP) immunoreactive nerves in the female rat urinary bladder (1992)
    Springer
    Urological research 20 (1992), S. 259-263 
    Details
    ISSN: 1434-0879
    Keywords: Neuropeptide Y ; Vasoactive intestinal polypeptide ; Substance P ; Bladder distension ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of acute distension on vasoactive polypeptide (VIP)-, neuropeptide Y (NPY)- and substance P (SP)-immunoreactive nerves in the wall of the urinary bladder was investigated. At the age of 3 months, 25 female albino rats underwent forced diuresis combined with balloon obstruction to achieve maximal distension for 3 h. A modified, indirect immunofluorescence detection method was applied 2 days, 7 days and 21 days after distension. A marked, extensive depletion of VIP, NPY-and SP-immunoreactive nerves was observed after distension. This disturbance was reversible, and increased fluorescence of VIP-, NPY- and SP-immunoreactive nerve fibres compared with control specimens was seen in bladder specimens taken even as soon as 21 days after distension. This transient depletion of peptidergic innervation may partly explain the prolonged voiding problems that often occur after acute urinary retention. The depletion of sensory nerves containing SP shortly after distension may explain the transient benefit obtained from distension therapy in patients with painful bladder disease. It is suggested that the increased SP activity during the recovery phase may be related to neurogenic inflammation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300255
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  • 15
    Electronic Resource
    Electronic Resource
    Effect of acute distension on cholinergic innervation of the rat urinary bladder (1992)
    Springer
    Urological research 20 (1992), S. 59-62 
    Details
    ISSN: 1434-0879
    Keywords: Urinary bladder ; Overdistension ; Cholinergic Hypoinnervation ; Acetylcholinesterase ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of short-term urinary bladder distension on its cholinergic innervation was studied in Sprague-Dawley rats. Distension was induced for 3 h by forced diuresis and balloon outlet obstruction, and whole thick biopsy specimens were taken from the dome and lateral side of the anterior body 2, 7 and 21 days afterwards. The acetylcholinesterase (AChE) method was used to demonstrate the cholinergic nerves in the distended bladder wall. Cholinergic hypoinnervation was observed 7 days after the distension, persisting up to 21 days, although AChE-reactive nerves were then observed to be more numerous. The distribution of hypoinnervation was uneven, being more marked in the lateral side of the anterior body than in the dome. The distribution of AChE-reactive nerves varied even in the same biopsies, with areas of total hypoinnervation occurring next to areas of slightly diminished innervation. This was especially true 21 days after cholinergic innervation, which may in turn explain the prolonged voiding difficulties often seen after catheterization of an overdistended bladder in a patient with urinary retention. The short-lasting effect of bladder dilatation therapy used to treat detrusor instability or interstitial cystitis may be due to the fairly rapid regeneration of cholinergic innervation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294337
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  • 16
    Electronic Resource
    Electronic Resource
    Interleukin-2-induced growth inhibition of prostatic adenocarcinoma (Dunning R 3327) in rats (1992)
    Springer
    Urological research 20 (1992), S. 189-191 
    Details
    ISSN: 1434-0879
    Keywords: Interleukin-2 ; Prostatic carcinoma ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study was designed to evaluate the effect of a biological response modifier, interleukin-2 (IL-2), on the growth in rats of Dunning (R3327, androgen sensitive) prostatic adenocarcinoma. IL-2 was given to one group of tumour-bearing rats by subcutaneous infusion (Alzet micro-osmotic pump 2002, 14 days) of 424,286 IU/kg per day during 4 weeks. Another group was shamoperated and served as control. Tumour growth was calculated by weekly measurement of tumour volume. IL-2 treatment caused a significant growth delay without any significant toxicity. Plasma testosterone concentrations were similar in both groups and ventral prostatic weights did not differ. Morphometric analyses of epithelial cells, stroma, luminal compartment in tumour tissue and calculation of the number of intratumoral lymphocytes did not show any differences between the two groups. It is suggested that IL-2 treatment can decrease prostatic tumour growth without apparently affecting the testosterone metabolism. Further studies with special interest on the mechanism of action are justified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299715
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  • 17
    Electronic Resource
    Electronic Resource
    Receptor function studies in specimens from the proximal human urethra obtained by transurethral resection (1992)
    Springer
    Urological research 20 (1992), S. 55-58 
    Details
    ISSN: 1434-0879
    Keywords: Adrenergic receptors ; α-Adrenergic agonists ; α1-Adrenergic antagonists ; Urethra ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During transurethral resection (TUR) for prostatic hyperplasia, specimens were taken from the proximal urethra. Muscle strips thus obtained were mounted in an organ bath and muscle contraction was induced by adding increasing concentrations of noradrenaline (NA), methoxamine (α1-agonist) and clonidine (α2-agonist). NA and methoxamine induced a dose-dependent muscle contraction, but clonidine had no effect. The influence of prazosin (α1-antagonist) and yohimbine (α2-antagonist) on the NA-induced muscle contraction was also evaluated. Both antagonists had an inhibitory effect,which was much more potent with prazosin. The specimens taken during TUR were found to be suitable for in vitro receptor function studies. The α-adrenergic receptor function in the proximal human urethra was found to be mainly of the α-type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294336
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  • 18
    Electronic Resource
    Electronic Resource
    α-Adrenoceptor function before and after chemical sympathectomy in human and feline detrusor muscles (1992)
    Springer
    Urological research 20 (1992), S. 265-269 
    Details
    ISSN: 1434-0879
    Keywords: 6-Hydroxydopamine ; α-Adrenoceptors ; Bladder ; Human ; Animal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Isolated bladder segments from man and cat were treated with 6-hydroxydopamine (6-OHDA) in vitro. Chemical sympathectomy was evaluated with fluorescence microscopy and found to be very similar to the effect of 6-OHDA administered in vivo to cats. Isometric smooth muscle contractile responses were induced by field stimulation (FS). The amplitude of the responses increased after denervation. The effects of α-adrenoceptor agonists and antagonists on the FS-induced contractile responses were compared before and after treatment with 6-OHDA. The reduction in the contractile responses after the addition of noradrenaline to the feline bladder strips was more pronounced after treatment. Phentolamine induced an increase in contractile responses before treatment, an effect not seen afterwards in human bladder strips but which persisted in feline bladder strips. Selective α-adrenoceptor agonists did not alter the contractile responses in denervated strips. It is suggested that the function of the α-adrenoceptors in the detrusor is to inhibit neuronally mediated contractile responses of smooth muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300256
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  • 19
    Electronic Resource
    Electronic Resource
    Morphometric study of the sensory neuron and peripheral nerve changes induced by chronic cisplatin (DDP) administration in rats (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 364-371 
    Details
    ISSN: 1432-0533
    Keywords: Cisplatin ; Spinal ganglia ; Peripheral neuropathy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We performed a morphological, morphometric and toxicological study on the spinal ganglia and peripheral nerves of the rat after chronic administration of cisplatin (cis-dichlorodiammineplatinum II; DDP) with two different schedules. Severe damage of the spinal ganglia neurons was demonstrated with predominant involvement of the nucleus and nucleolus associated with a decrease in the cell size. Morphological and morphometric changes also occurred in the sciatic and peroneal nerves with the features of axonopathy. All these changes were more marked in the group of rats which underwent the most intense DDP treatment and the tissue platinum concentrations were also higher in this group. This experimental model is the first available for chronic DDP administration in which concomitant spinal ganglia and peripheral nerve damage has been confirmed pathologically. Our study supports the hypothesis that DDP-induced peripheral nerve fiber degeneration may result from nuclear and nucleolar changes in the sensory ganglion cell perikaryon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227662
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  • 20
    Electronic Resource
    Electronic Resource
    Computer-assisted 3D-reconstruction and statistics of the limbic system (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 137-143 
    Details
    ISSN: 1432-0568
    Keywords: Human ; Hippocampus ; Limbic system ; Computer graphics ; Stereotactic surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A statistical method is described to show the distribution of neuroanatomical structures within a Cartesian coordinate system from any given number of examinations. The algorithm is based on polygons derived from the outlines of neuroanatomical structures in parallel canthomeatal-orientated cutting planes. These polygons are transformed in virtual voxels, rotated into the bicommissural coordinate system, and projected onto the three main planes of this coordinate system. Areas with the same probability for the structures examined are given in these planes. As an example this method is applied to the hippocampal formation and the results attained are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174951
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  • 21
    Electronic Resource
    Electronic Resource
    Enhancement of muscle regeneration in the rat gastrocnemius muscle by low energy laser irradiation (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 497-503 
    Details
    ISSN: 1432-0568
    Keywords: Skeletal muscle ; Regeneration ; Morphometry ; Histology ; Rat ; Laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of low-energy laser (He-Ne) irradiation on the rate of skeletal muscle regeneration after partial excision of the rat gastrocnemius muscle was studied using quantitative histological morphometric methods. The injured zones of the experimental rats were subjected to direct He-Ne laser (632.8 nm wavelength) irradiation (6.0 mW for 2.3 min) immediately following injury and once daily thereafter for 5 days. Muscles that were injured as above and subjected to red or room light irradiation served as a control group. The volume fraction (percent of total volume of injured zone) of the mononucleated cells in the injured zone decreased gradually with time after injury, but more rapidly in the laser irradiated muscles than in the control. At 3 days post-injury the myotubes in the laser-irradiated muscles populated a significantly higher percentage (13.9 ± 1.1%) of the injured area than in the control muscles (7.8 ± 1.0%). The volume fraction of the young myofibers in the laser irradiated muscles exceeded 30.6 ± 2.2% and 49.6 ± 5.6% at 8 and 11 days post-injury, respectively, while in control muscles these structures comprised only 9.6 ± 1.0% and 27.2 ± 3.8% of the injured zone at 8 and 11 days after injury, respectively. It is concluded that He-Ne laser irradiation during the regeneration process promotes muscle maturation in the injured zone following partial excision of the rat gastro-cnemius muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185463
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  • 22
    Electronic Resource
    Electronic Resource
    Postnatal development of the rat organ of Corti (1992)
    Springer
    Anatomy and embryology 185 (1992), S. 559-569 
    Details
    ISSN: 1432-0568
    Keywords: Cochlea ; Organ of Corti ; Development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of the rat organ of Corti was studied during the first postnatal weeks. The temporal and the spatial patterns of cochlear development were investigated between 4 and 24 days after birth by means of semi-thin sections at approx. ten equidistant positions along the entire cochlear duct. At all examined positions width, thickness and cross sectional area of basilar membrane, cross-sectional area of tectorial membrane, of cells of Hensen, Claudius and Boettcher and of the organ of Corti were quantitatively analyzed. The most conspicuous maturational changes occur between 8 and 12 days after birth. These are the detachment of the tectorial membrane, the first appearance of filaments within the basilar membrane, the formation of the tunnel of Corti and the opening of the inner spiral sulcus. Quantitative analysis revealed that structures of a given position along the cochlear duct do not develop synchronously. Width of the basilar membrane and cross-sectional area of the tectorial membrane are already mature at the onset of hearing (10–12 days after birth). Length, thickness and cross-sectional area of the basilar membrane as well as cross-sectional area of the organ of Corti and of the cells of Hensen, Claudius and Boettcher still develop after the onset of hearing (up to 20–24 days after birth). We suggest that basic cochlear function is established by structures which are mature before the onset of hearing. Cochlear structures which develop after the onset of hearing might be involved in this improvement during this period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185615
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  • 23
    Electronic Resource
    Electronic Resource
    Postnatal development of the rat organ of Corti (1992)
    Springer
    Anatomy and embryology 185 (1992), S. 571-581 
    Details
    ISSN: 1432-0568
    Keywords: Cochlea ; Development ; Rat ; Hair cells ; Stereocilia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of cochlear receptor cells and their supporting elements was studied by means of semi-thin and ultra-thin sections during the first postnatal weeks in the rat. The temporal and spatial patterns of the receptor cell development were investigated between the 4th and 24th days after birth. At approx. ten equidistant positions along the entire cochlear duct length of inner and outer hair cells, width of outer hair cell triad and stereocilia-length of the outer hair cells were quantitatively analyzed. Striking maturational changes take place before the 12th day after birth, that is, when the onset of hearing occurs. These changes are the formation of the tunnel of Corti, of the Nuel spaces, the appearance of filaments within the supporting elements and the change in cell shape of the hair cells. Between 4 days and 20 days after birth the maturation of outer hair cells is characterized by a decrease of organelles in the cytoplasm and establishment of the subsurface cistern. The quantitative analysis revealed a unique developmental pattern of the length of the outer hair cells, the width of the outer hair cell triad and the stereocilia length of the outer hair cells. Shortly after birth these structures have an almost constant size along the whole cochlear duct, but with increasing age the structures shorten at the cochlear base and enlarge at the apex. This pattern results in the establishment of a basoapical gradient of the above mentioned structures. We assume that this baso-apical gradient is of central importance for the frequency representation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185616
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  • 24
    Electronic Resource
    Electronic Resource
    Progressive expression of immunomolecules on microglial cells in rat dorsal hippocampus following transient forebrain ischemia (1992)
    Springer
    Acta neuropathologica 83 (1992), S. 149-157 
    Details
    ISSN: 1432-0533
    Keywords: Microglia ; Hippocampus ; Ischemia ; Rat ; Major histocompatibility complex antigens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We show a differential up-regulation of immunomolecules in the rat dorsal hippocampus accompanying neuronal cell death as a consequence of transient forebrain ischemia (four-vessel occlusion model). Using a panel of monoclonal antibodies (mAbs), we have examined the time course of expression of major histocompatibility complex (MHC) antigens class I (OX-18) and class II (OX-6), leukocyte common antigen (OX-1), CD4 (W3/25) and CD8 (OX-8) antigens, CR3 complement receptor (OX-42), as well as brain macrophage antigen (ED2). The study was performed at time intervals ranging from 1 to 28 days after reperfusion. Throughout all post-ischemic time periods, strongly enhanced immunoreactivity on microglial cells in the CA1 region and dentate hilus and, to a lesser extent, in CA3 was demonstrated with mAb OX-42. MHC class I-positive cells (OX-18) appeared on day 2, whereas cells immunoreactive with OX-1 and W3/25 became evident in the CA1 and hilar regions on post-ischemic day 6. In contrast, MHC class II (Ia) antigen was first detected on indigenous microglia by day 13. In some animals, the OX-8 antibody resulted in the labelling of scattered CD8-positive lymphocytes, but perivascular inflammatory infiltrates were absent. No changes in the expression of ED2 immunoreactivity on perivascular cells could be observed. The results show that following ischemic injury, microglial cells demonstrate a timedependent up-regulation and de novo expression of certain immunomolecules, indicative of their immunocompetence. The findings are compared with those obtained in other models of brain injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308474
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  • 25
    Electronic Resource
    Electronic Resource
    Different effects of physical training on the morphology of motor nerve terminals in the rat extensor digitorum longus and soleus muscles (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 125-128 
    Details
    ISSN: 1432-0568
    Keywords: Training ; Motor nerve terminals ; Neuromuscular junction ; Extensor digitorum longus muscle ; Soleus muscle ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of nerve terminals in the rat extensor digitorum longus and soleus muscles was studied with light microscopy in 13-week-old male animals after 6 weeks of treadmill running and compared with data from untrained controls. The terminals were stained with methylene blue. Physical training tended to increase the area and length of the nerve terminals in relation to the corresponding muscle fiber diameter, and to reduce the density of nerve terminal varicosities, but significant differences between the trained group and the control group were obtained only in the extensor digitorum longus muscle. The different degrees of effect on the nerve terminals in the two muscles may be due to different abilities to respond to the training, but may also be due to differences in work load caused by the training. The effect of training on extensor digitorum longus junctions may reflect some transformation from fast to slow morphological characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174949
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  • 26
    Electronic Resource
    Electronic Resource
    Normal colon of Sprague-Dawley rats (1992)
    Springer
    Anatomy and embryology 185 (1992), S. 69-76 
    Details
    ISSN: 1432-0568
    Keywords: Human-tumor-associated antigens ; Rat ; Colon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The patterns of expression of the human-tumor-associated antigens, CO17-1A, GA73-3, BR55-2, GICA19-9, CA50 and carcino-embryonic antigen (CEA) were studied in the normal colonic mucosa (the last three also in the serum) of Sprague-Dawley rats. Four immunohistochemically different segments were identified: caecum, ascending colon, transverse colon and descending colon. The immunohistochemical reactions of the cells at the lower part of the crypt were essential for the distinction of the four segments. In the caecum, the MAbs 17-1A, 73-3 and 19-9 stained the glycocalyx of the cells of the lower part of the crypts and the Golgi apparatus of the intercalated cells (IC). MAb55-2 stained very weakly the goblet-like cells (GLC) of the lower part of the crypt of transverse colon, in addition to a nearly complete lack of reaction in the upper part of the crypts. In the ascending colon, the lower part of the crypts showed a characteristic diffuse staining of the intercalated cells with MAb55-2. The perinuclear and mucosal staining observed in the GLC of the transverse colon with MAbs 17-1A, 73-3 and 19-9 as against the supranuclear and Golgi zone staining observed in the GLC/goblet cells (GC)/columnar cells (CC) of the lower part of crypts of the descending colon with the same MAbs, distinguished the former segment from the latter. The IC demonstrated by immunohistochemistry in the lower parts of the crypts of caecum and ascending colon appear to correspond to the replicating cells of the colonic crypts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213602
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  • 27
    Electronic Resource
    Electronic Resource
    A direct projection from the medial vestibular nucleus to the cervical spinal dorsal horn of the rat, as demonstrated by anterograde and retrograde tracing (1992)
    Springer
    Anatomy and embryology 185 (1992), S. 77-85 
    Details
    ISSN: 1432-0568
    Keywords: Vestibular nuclei ; Spinal cord ; Dorsal horn ; Tracing study ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Phaseolus vulgaris leucoagglutinin and wheat germ agglutinin-horseradish peroxidase were iontophoretically injected into different parts of the vestibular nuclear complex (VNC) of the rat. Injections centered into the caudal part of the medial vestibular nucleus revealed a vestibulospinal projection predominantly to the dorsal horn of the cervical spinal cord, besides the expected projection to the intermediate zone (IZ) and ventral horn (VH). While most of the anterogradely labelled fibres could be localized in laminae III to V, some scattered fibres were also seen in laminae I and VI. Lamina II remained free of labelling. The dorsal horn (DH) area with detectable anterograde labelling showed a rostrocaudal extension from C1-C6. Injections into other parts of the VNC labelled fibres and terminals in the IZ and VH while the DH remained almost free of labelling. Additionally, fluorogold and wheat germ agglutininhorseradish peroxidase were pressure- or iontophoretically injected at different levels into the spinal cord to confirm the projection to the dorsal horn by means of retrograde tracing. Labelled neurons in the area of the medial vestibular nucleus (MVN), from which anterograde labelling in the DH was obtained, were only detectable after fluorogold and wheat germ agglutinin-horseradish peroxidase injections into the cervical spinal cord, in particular its DH. This projection from the caudal medial vestibular nucleus to the dorsal horn of the cervical spinal cord probably enables the VNC to influence sensory processing in the DH, in addition to its well-established influence on posture and locomotion via projections to the intermediate zone and ventral horn.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213603
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  • 28
    Electronic Resource
    Electronic Resource
    Differential Ca2+ binding properties in the human cerebellar cortex: distribution of parvalbumin and calbindin D-28k immunoreactivity (1992)
    Springer
    Anatomy and embryology 185 (1992), S. 163-167 
    Details
    ISSN: 1432-0568
    Keywords: Cerebellum ; Human ; Ca2+-binding proteins ; Parvalbumin ; Calbindin D-28k
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The distribution of the Ca2+-binding proteins parvalbumin (PV) and calbindin D-28k (CaBP) was investigated in the human cerebellar cortex. Purkinje cells contain both PV and CaBP. PV but not CaBP stains stellate and basket cells in the molecular layer. In the granular layer Golgi neurons can be subdivided into a majority, devoid of both Ca2+-binding proteins, and a scanty population which appears to be PV- and CaBP-immunoreactive. Thus GABAergic neurons in the human cerebellar cortex show selective differences in their Ca2+-binding properties, and these differences might reflect a heterogeneity in the processing of Ca2-mediated events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185917
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  • 29
    Electronic Resource
    Electronic Resource
    The influence of hypothermia on hypoglycemia-induced brain damage in the rat (1992)
    Springer
    Acta neuropathologica 83 (1992), S. 379-385 
    Details
    ISSN: 1432-0533
    Keywords: Hypoglycemia ; Hypothermia ; Neuronal damage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of hypothermia on hypoglycemic brain damage were studied in rats after a 30-min period of hypoglycemic coma, defined as cessation of spontaneous EEG activity. The rats were either normothermic (37°C) or moderately hypothermic (33°C). Morphological brain damage was evaluated after various periods of recovery. Hypothermic animals with halothane anesthesia never resumed spontaneous respiration, thus requiring artificial ventilation during recovery (maximally 8h). In contrast, when isoflurane was used as the anesthetic agent, all animals survived and were examined after 1 week of recovery. There was a tendency towards gradually higher arterial plasma glucose levels during hypoglycemia with lower body temperature. The time period from insulin injection until isoelectric EEG appeared was gradually prolonged by hypothermia, and was shorter when isoflurane was used for anesthesia. Brain damage was examined within the neocortex, caudoputamen and hippocampus (CA1, subiculum and the tip of the dentate gyrus). Damage to neurons was found to be of two types, namely condensed dark purple neurons (pre-acidophilic) and shrunken bright red-staining neurons (acidophilic). In the neocortex, no clear influence of temperature on the degree of injury was seen. In the caudoputamen, the number of injured neurons clearly decreased at lower temperature (33°C,P〈0.001) when halothane was used, while no such difference was seen when isoflurane was used as the anesthetic agent. Likewise, a protective effect of hypothermia was seen in subiculum (P〈0.01) when halothane, but not isoflurane was used. Damage to CA1 neurons was mild in both groups with halothane, but slightly less frequent (P〈 0.05) in the hypothermic group, in which the majority of animals showed no damage. No protection of hypothermia was seen in the animals with isoflurane anesthesia. Furthermore, with isoflurane, more damaged CA1 cells were seen in the normothermic situation as compared to when halothane was used (P〈0.01). In contrast, damage to the tip of the dentate gyrus was remarkedely resistant to hypothermia, with the majority of animals showing the same degree of damage as the normothermic ones irrespective of the anesthetic agent used. In summary, hypothermia seemed to have only a partial protective effect on the development of hypoglycemic brain damage, the effects differing between regions previously described to be selectively vulnerable to hypoglycemia, and also differing when halothane or isoflurane were used as anesthetic agents. While long-term survival was achieved with the use of isoflurane, the protective effect of hypothermia seemed to be lost.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713529
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  • 30
    Electronic Resource
    Electronic Resource
    Moderate hypothermia reduces blood-brain barrier disruption following traumatic brain injury in the rat (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 495-500 
    Details
    ISSN: 1432-0533
    Keywords: Traumatic brain injury ; Hypothermia ; Blood-brain barrier ; Hypertension ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of moderate hypothermia on blood-brain barrier (BBB) permeability and the acute hypertensive response after moderate traumatic brain injury (TBI) in rats were examined. TBI produced increased vascular permeability to endogenous serum albumin (IgG) in normothermic rats (37.5°C) throughout the dorsal cortical gray and white matter as well as in the underlying hippocampi as visualized by immunocytochemical techniques. Vascular permeability was greatly reduced in hypothermic rats cooled to 30°C (brain temperature) prior to injury. In hypothermic rats, albumin immunoreactivity was confined to the gray-white interface between cortex and hippocampi with no involvement of the overlying cortices and greatly reduced involvement of the underlying hippocampi. The acute hypertensive response in normothermic rats peaked at 10 s after TBI (187.3 mm Hg) and returned to baseline within 50 s. In contrast, the peak acute hypertensive response was significantly (P〈0.05) reduced in hypothermic rats (154.8 mm Hg, 10 s after TBI) and returned to baseline at 30 s after injury. These results demonstrate that moderate hypothermia greatly reduces endogenous vascular protein-tracer passage into and perhaps through the brain. This reduction may, in part, be related to hypothermia-induced modulation of the systemic blood pressure response to TBI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304468
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  • 31
    Electronic Resource
    Electronic Resource
    Ibotenic acid-induced calcium deposits in rat substantia nigra (1992)
    Springer
    Acta neuropathologica 85 (1992), S. 55-70 
    Details
    ISSN: 1432-0533
    Keywords: Excitotoxin ; Substantia nigra ; Neuronal degeneration ; Calcification ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The excitotoxin ibotenic acid (IBO) induces local calcium deposits upon injection into rat substantia nigra. Their formation has been investigated at the ultrastructural level in a time course study from 2 days to 8 weeks survival. Potassium bichromate stain was used to visualize pathological calcium accumulation. Two days after IBO application, reaction product for calcium was observed in mitochondria of degenerating perikarya and dendrites, but not in axons, boutons or glia. Four days after the lesion, calcium stain was found, in addition, in a seemingly free form in a few dendrites, especially those still contacted by intact boutons and not sequestrated by invading glia. Two days later, most of these calcium-accumulating dendrites were separated by astroglia from their synaptic partners. At the border between glia and dendrite a fibrillar matrix was formed which further accumulated calcium. During the following weeks this matrix enlarged stepwise and was infiltrated with calcium, thus giving a picture resembling the annual growth rings of trees. The evolving bodies incorporated smaller deposits in their vicinity, finally representing the large concretions seen at the light microscopic level from the 4th postoperative week onward. Similarities and dissimilarities of these observations with the results from other ultrastructural studies on excitotoxin lesions are detailed. It is suggested that the different outfit of neuronal subpopulations and of glia with ligand-gated and metabotropic glutamate receptors in the single brain region, as well as the local response repertoire of glial cells towards the excitotoxic injury with the subsequent formation of a calcium-accumulating matrix provide the molecular basis for the formation of calcium deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304634
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  • 32
    Electronic Resource
    Electronic Resource
    Computer-assisted 3D-reconstruction and statistics of the limbic system (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 129-136 
    Details
    ISSN: 1432-0568
    Keywords: Human ; Hippocampus ; Limbic system ; Computer graphics ; Neuroimaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The hippocampal formation of eight perfusion-fixed human brains was examined using new methods according to stereotactic and morphometric principles (macrovibratome and computer-aided 3D reconstruction). The reconstructions form part of a neuroanatomical reference system (NeuRef). This reference system allows for 3D visualisation of the brain and its components on a computer graphic workstation, as well as for the presentation of the union set based on a neuroanatomical structure taken from this sample of brains. This retrievable knowledge of neurofunctional systems is important for the preoperative planning of neurosurgeons and the adjustment of radiotherapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174950
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  • 33
    Electronic Resource
    Electronic Resource
    Laminar distribution and morphology of NADPH-diaphorase containing neurons in the superior colliculus and underlying periaqueductal gray of the rat (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 245-250 
    Details
    ISSN: 1432-0568
    Keywords: Superior colliculus ; Periaqueductal gray ; NADPH-diaphorase ; Golgi method ; Neuronal types ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the laminar distribution of reduced nicotinamide dinucleotide phosphate diaphorase (NADPH-d) activity and the morphology of positive neurons in the superior colliculus (SC) and the underlying periaqueductal gray (PAG) of the rat. The morphology of NADPH-d-positive neurons has been compared to that of Golgi-impregnated cells. The highest activity occurs in the stratum zonale and stratum griseum superficiale, contrasting with the pale neuropil in the stratum opticum, where only a few positive neurons are found. In the stratum griseum intermedium positive neurons are grouped in patches separated by narrow, NADPH-d-negative bands. In the deeper layers, the neuropil is NADPH-d-negative, and few neurons show enzymatic activity. In contrast, numerous neurons in the dorsolateral part of the PAG are intensely positive. They are continuous with the positive neurons in the stratum album profundum, with no clear border between the two centers. In both SC and PAG, only small and medium sized neurons are NADPH-d-positive. In comparison with Golgi material, all types of small neurons in the superficial layers show NADPH-d activity; NADPH-d histochemistry, however, does not visualize the characteristic dendritic appendages of these neurons. The large neurons of the SC and PAG, probably representing the long-projecting neurons of these centers, do not contain the enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174146
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  • 34
    Electronic Resource
    Electronic Resource
    Inhibition of cephalic neural tube closure by 5-azacytidine in neurulating rat embryos in vitro (1992)
    Springer
    Anatomy and embryology 185 (1992), S. 217-223 
    Details
    ISSN: 1432-0568
    Keywords: Rat ; Embryo culture ; Cephalic neurulation ; 5-Azacytidine ; Methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Head-fold stage rat embryos (9.5 days of gestation) were cultured for 48 h in rat serum with or without 0.8 μM 5-azacytidine. Incomplete closure of the cephalic neural tube was observed in 5-azacytidine-treated embryos cultured for 48 h (25-somite stage). Control embryos showed complete fusion of cephalic neural folds at 33 h (16-somite stage) in culture. Drug administration or removal experiments revealed that embryos were sensitive to 5-azacytidine during 6–12 h of culture (three to five somite stages). Electron microscopical studies indicated that the arrangement and fine structure of cephalic neuroepithelial cells were almost the same in control and treated embryos. There was no significant difference in DNA and protein contents between control and treated embryos cultured for 36 h. Immunocytochemical observations using 5-methylcytosine-specific antibody revealed that the staining of neuroepithelial cells in the median part of the transversely sectioned cephalic neural plate, and of mesenchymal cells near the apices of the plate, was suppressed by 5-azacytidine. These results suggest that DNA methylation of these cells plays an important role in closure of the cephalic neural tube.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00211820
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  • 35
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    Electronic Resource
    Regionally disturbed production of cartilage proteoglycans in malformed fetuses from diabetic rats (1992)
    Springer
    Diabetologia 35 (1992), S. 517-521 
    Details
    ISSN: 1432-0428
    Keywords: Rat ; teratology ; diabetic pregnancy ; mandible ; congenital malformation ; proteoglycans ; proteoglycan synthesis ; chondroitin sulphate ; costal cartilage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fetuses from normal and manifestly diabetic rats were obtained on pregnancy day 20. The fetuses from the diabetic rats were of normal or malformed morphology. Three tissue groups were dissected free; costal cartilage, the hard tissue of the rear, and of the frontal portion of the mandible. These tissues were maintained in vitro for 24 h during which time they were labelled with [35S]sulphate. After the culture period the tissues were extracted with guanidine HCl and the resulting residues were further extracted with alkali. The culture medium was saved and its macromolecular content was compared to that of the extracts. The proteoglycans recovered in all extracts eluted at two distinct positions after chromatography on a Sepharose CL-2B column (peak I: Kav ∼0.4, and peak II: Kav ∼0.8), but the elution patterns were markedly different in extracts from various tissues. Thus, in rib cartilage, the majority of the labelled proteoglycans were located in peak I (∼90%) with no difference between extracts of fetuses from normal and diabetic pregnancies. In extracts of mandibular cartilaginous tissue from normal rat off-spring the peak I percentage (60–80 %) was lower than in the rib cartilage extracts. In the extracts from the frontal portion of malformed mandibles of fetuses of diabetic rats, the peak I percentage (35±21%) was the lowest of all recorded and the only one to significantly differ from the other percentages in its (the frontal mandible) group. The results show an association between a congenital malformation, micrognathia, and a disturbance in the production of chondroitin sulphate proteoglycans in the malformed region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400478
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  • 36
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    Electronic Resource
    Insulin action and determinants of glycaemia in a rat model of Type 2 (non-insulin-dependent) diabetes mellitus (1992)
    Springer
    Diabetologia 35 (1992), S. 208-215 
    Details
    ISSN: 1432-0428
    Keywords: Rat ; basal hyperglycaemia ; insulin action ; Type 2 (non-insulin-dependent) diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We aimed to assess prandial responses, basal glucose turnover and insulin action (euglycaemic clamp) in a very low-dose neonatal streptozotocin model of Type 2 (noninsulin-dependent) diabetes mellitus. Male Wistar rats were injected at 2 days of age with 45 mg/kg streptozotocin or vehicle (control). At 8 weeks, the groups were subdivided and fed either a high-fat or high-starch diet for 3 weeks. Both the fat diet and streptozotocin treatments had independent hyperglycaemic effects (streptozotocin/fat 9.3±0.3 mmol/l; streptozotocin/starch 7.5±0.3 mmol/l; control/fat 7.4±0.1 mmol/l; all p〈0.01 vs control/starch 6.4±0.1 mmol/l). The fat diet effect was associated with both a reduction in basal glucose clearance (p〈0.001) and in basal hepatic glucose output (p〈0.05). Streptozotocin increased basal hepatic glucose output. Significantly higher prandial glycaemia in the streptozotocin/starch group occurred despite similar insulin levels and appeared to be related to an impaired early insulin response. Whole-body and tissue-specific insulin sensitivity were significantly depressed in fat-fed animals compared to starch-fed animals, however there were no significant effects of streptozotocin treatment. We conclude that fasting hyperglycaemia associated with abnormalities in both glucose production and clearance can exist in the presence of a basal hepatic glucose output which is reduced compared to control animals. Furthermore, dietary-fat-induced insulin resistance is not exacerbated by the relative insulin deficiency and/or mild hyper glycaemia observed when dietary fat and neonatal streptozotocin-treatments are combined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400919
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  • 37
    Electronic Resource
    Electronic Resource
    Maternal insulin treatment improves pre-implantation embryo development in diabetic rats (1992)
    Springer
    Diabetologia 35 (1992), S. 406-408 
    Details
    ISSN: 1432-0428
    Keywords: Rat ; diabetes mellitus ; insulin ; blastocyst ; pre-implantation development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pre-implantation embryos were recovered from control, diabetic and insulin-treated diabetic rats on day 5 of pregnancy. Compared to control animals, diabetic rats had a 20 % reduction in the number of embryos per rat and blastocysts recovered from diabetic rats showed a 19 % decrease in total cell number. The cellular decrease observed in blastocysts was mainly at the expense of the inner cell mass. Insulin replacement therapy was started on day 1 of pregnancy and normalized the glycaemia of diabetic rats but failed to raise the number of embryos per rat toward the control value. Insulin treatment, however, fully restored the normal cell number in both the inner cell mass and trophectoderm of blastocysts. The dead cell index, which was significantly elevated in the inner cell mass of blastocysts from diabetic rats, also returned to the control value following insulin treatment. Our data suggest that diabetes-induced impairment of pre-implantation development can be partly prevented by insulin treatment started shortly after conception.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02342434
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  • 38
    Electronic Resource
    Electronic Resource
    Effect of a five-week swimming program on rat bone: A histomorphometric study (1992)
    Springer
    Calcified tissue international 51 (1992), S. 137-142 
    Details
    ISSN: 1432-0827
    Keywords: Swimming exercise ; Bone histomorphometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To specify the exercise-induced changes on different skeletal sites, the effect of a 5-week endurance swin training was studied in rats. Eighteen Lyon strain (Sprague-Dawley) 5-week old female rats were divided into nine sedentary and nine swimming rats. Each swim training session was increased by 15 minutes from 2–6 hours per day. A histomorphometric study was performed at the primary and secondary spongiosa of the distal femur and at the secondary spongiosa of lumbar and thoracic vertebral bodies. After training, bone loss was observed in the secondary spongiosa of lumbar vertebral bodies (24.7%) and in the primary spongiosa of distal femur (15.2%). A tendency to bone loss was also detected in the secondary spongiosa of distal femur (10.8%), whereas no change was detected in thoracic vertebral bodies. In secondary spongiosa, bone loss was accompanied with a thinning of trabeculae. Total eroded surfaces and osteoid surfaces were significantly decreased in the three studied skeletal sites, suggesting a decreased bone turnover. The decreased thickness of osteoid seams in both lumbar vertebrae and distal femur could mean that the osteoblastic activity has also been altered at the cell level, leading to thinning of trabeculae. Five-week swim training with such duration and intensity of exercise appears unable to increase bone volume in rats and, therefore, causes adverse effects. The three studied bones seemed to adapt differently to experimental conditions. The lack of ground reaction forces induced by water immersion might have contributed to the observed bone loss. “Normal” gravity would be an important cofactor in the osteogenic effects of exercise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298502
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  • 39
    Electronic Resource
    Electronic Resource
    Biphasic dose-response curves of cortisol effects on rat diaphyseal bone biomechanics (1992)
    Springer
    Calcified tissue international 50 (1992), S. 49-54 
    Details
    ISSN: 1432-0827
    Keywords: Cortisol ; Cortical bone ; Bone biomechanics ; Rat ; Femur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Doses of 8, 16 (low), 32, 48, 64 (medium), and 150 (high) mg/kg/day of cortisol were administered to groups of 8 growing rats each during 16 days, and their femurs were then submitted to 3-point bending tests at low strain rate. Low doses had no effect. Medium doses, previously shown to improve calcium (Ca) balance and weight gain in the species, augmented diaphyseal elastic and ultimate strength, stiffness, and plastic-to-elastic deformation ratio with respect to untreated controls. This effect was achieved either by enhancing bone mass (volume, sectional moment of inertia, wall/lumen ratio) without changes in material quality parameters (32 mg/kg/day) or, conversely, by increasing bone tissue mechanical properties (stress, modulus of elasticity) not affecting bone geometry (48 and 64 mg/kg/day). The highest dose, known to depress Ca balance and weight gain, impaired diaphyseal mechanical performance in controls by substantially reducing bone mass without major variation in bone material properties, that is, developing a true osteopenic state in mechanical terms. The energy elastically absorbed per unit volume (proportional to the risk of comminute fractures) was greater with the highest dose because of enhanced deformability and diminished bone mass. The biphasic dose-response curves obtained, grossly parallel to those previously demonstrated for metabolic actions of cortisol in the same species, showed that biomechanical repercussion of this treatment on bone depends on different, dose-dependent effects which vary independently in temporal course, intensity, and sign.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297297
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  • 40
    Electronic Resource
    Electronic Resource
    Different forms of alkaline phosphatase in adult rat femur. Effect of a Vitamin D3-deficient diet and of a sorbitol-enriched diet (1992)
    Springer
    Calcified tissue international 50 (1992), S. 433-438 
    Details
    ISSN: 1432-0827
    Keywords: Bone alkaline phosphatase ; Rat ; Vitamin D ; Sorbitol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In the femoral extremities of the adult rat containing the metaphysis, the epiphyseal cartilage, and the epiphysis, four alkaline phosphatase (AP) forms were distinguished on polyacrylamide gel electrophoresis. Two soluble forms were present in the 160,000 g supernatant: one of Mr 165 kDa and another of Mr 110–115 kDa, which exhibited a strong catalytical activity. Moreover, from the pellet, three membrane-bound forms of Mr 130, 110–115, and 100 kDa could be extacted with sodium deoxycholate. When denaturated AP was visualized by postelectrophoretic autoradiography of the phosphorylated intermediates, subunits always appeared as three monomers of Mr 75–80, 60–70, and 50–60 kDa. As four native forms but only three types of subunits were found to be present in the femur, it seems that, apart from homodimers, some heterodimers could also occur. Three types of diets were administered to three groups of rats for 5 weeks. Two are known to disturb bone mineralization: (1) a vitamin D3-deficient diet, and (2) the same as (1) but enriched with 12% sorbitol. The third was a normal diet containing vitamin D3. Concerning the effects on AP of dietary sorbitol and the vitamin D3-deficient diet, it was found that rats receiving the diet supplemented with sorbitol showed a substantial rise in the activity of the Mr 165 kDa form with the concomitant appearance of a new monomer of Mr 100 kDa. In contrast, rats fed the vitamin D3-deficient diet always displayed an increase in enzyme activity, principally of the Mr 100 and 110 kDa forms. In conclusion, the femur extracts of normal rats contained different forms of AP: either soluble 110–115 and 165 kDa forms or membrane-bound 130, 110–115, and 100 kDa forms. The administration of sorbitol-enriched diet induced a marked increase of the 165 kDa form whereas the administration of vitamin D3-deficient diet increased the 100 and 110 kDa forms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296774
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  • 41
    Electronic Resource
    Electronic Resource
    Synthetic parathyroid hormone-like protein (1–74) is anabolic for bone in vivo (1992)
    Springer
    Calcified tissue international 51 (1992), S. 30-34 
    Details
    ISSN: 1432-0827
    Keywords: PTHRP ; Anabolic ; Rat ; Bone ; Potency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parathyroid hormone-related protein (PTHRP) has recently been purified from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The gene encoding PTHRP has been cloned, and based on predicted amino acid sequence, polypeptides comprising the first 36 [36Tyr(1–36) PTHRP amide] and 74 [(1–74)PTHRP] amino acids have been synthesized. Human (h) PTHRP (1–36) and (1–74) are potent bone-resorbing agents, and are catabolic for bone in vivo when given continuously at high doses. Bovine parathyroid hormone (bPTH) (1–34) is also catabolic for bone at high dose levels, but when given in low doses for weeks to months, it is anabolic. Although PTHRP possess several PTH-like properties in bone, hPTHRP (1–34) is reported to be only weakly anabolic in vivo. As polypeptide length influences PTHRP action, we evaluated hPTHRP(1–74) as an anabolic agent for bone in vivo. Twenty-four 4-week-old male Sprague-Dawley rats were given daily subcutaneous injections of hPTHRP(1–74) (1 and 2 nmol/100 g body weight, bw), bPTH(1–34) (4 nmol/100 g bw) or vehicle. Rats were sacrificed on day 12, and serum calcium, phosphorus, and 1,25 dihydroxyvitamin D and femoral bone dry weight, calcium content, and hydroxyproline content were measured. Serum calcium and phosphorus were equivalent in all groups. A significant increase in dry bone weight was observed in both PTHRP-treated groups compared with controls. PTHRP also caused a significant, dose-dependent increase in bone calcium and hydroxypro-line content. Results of these studies indicate that PTHRP (1–74) is anabolic for bone in vivo when administered at low-dosage levels for a prolonged period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296214
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  • 42
    Electronic Resource
    Electronic Resource
    The carcinogenic effect of 2,2-dioxopropylnitrosamine on the renal pelvic epithelium of Sprague-Dawley rats, after chronic subcutaneous injections (1992)
    Springer
    Journal of cancer research and clinical oncology 118 (1992), S. 222-227 
    Details
    ISSN: 1432-1335
    Keywords: Renal pelvis ; Carcinogenesis ; 2,2-Dioxopropylnitrosamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The carcinogenicity of 2,2-dioxopropylnitrosamine on the urinary tract was investigated in three experimental groups of Sprague-Dawley rats (15 males, 15 females/group) by weekly subcutaneous administration for the life of the carcinogen at dose levels 1/5, 1/10 and 1/20 of the LD50, and compared with that in a similar group of untreated controls. It resulted in the induction of urinary tract tumours in 42 out of 79 effective animals (53%). Of these animals, 38 developed tumours within the renal pelvis. In the high-dose group, females had a 100% incidence of renal pelvic tumours, and males 73%. In all experimental groups, renal pelvic tumours were more frequent than ureteral and vesical ones. Histologically, the tumours were transitional cell papillomas and carcinomas, except for one squamous carcinoma. Out of 66 tumours, 42 (64%) were low-grade. High-grade tumours arose mainly in the renal pelvis of animals belonging to the highest-dose group. This experiment offers a useful model for the study of mechanisms involved in renal pelvic carcinogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410138
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  • 43
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    Electronic Resource
    Involvement of local ischemia in endothelin-1 induced lesions of the neostriatum of the anaesthetized rat (1992)
    Springer
    Experimental brain research 88 (1992), S. 131-139 
    Details
    ISSN: 1432-1106
    Keywords: Endothelin ; Ischemia ; Striatum ; Microdialysis ; Cerebral blood flow ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study examines the possibility that lesions induced by intrastriatal injections of endothelin-1 (ET-1, 0.43 nmol/0.5 µl) are ischemic in nature due to a vasoconstriction of the cerebral microvessels. In time course and dose-response experiments with ET-1 and in comparisons with ET-3, the volume of the lesions has been determined based mainly on the disappearance of striatal nerve cells, using a computer assisted morphometrical analysis. The blood flow in the neostriatum close to the site of injection of ET-1 was determined acutely by Laser-Doppler flowmetry. The acute metabolic effects of ET-1 were also studied on striatal superfusate levels of lactate, pyruvate, dopamine and its metabolites DOPAC (3,4-dihydroxyphenylacetic acid) and homovanilic acid (HVA) using an instrastriatal microdialysis probe. Dose related striatal lesions were observed with ET-1 (0.043–0.43 nmol) with a peak lesion volume after 24–48 h and the possible existence of a penumbra area. ET-3 showed a reduced potency to produce striatal lesions compared to ET-1. The lesions induced by ET-1 were prevented by coinjection with dihydralazine, a vasodilator drug. Acutely ET-1 (0.43 nmol/0.5 µl) produced a prolonged reduction of the cerebral blood flow down to 40% of control values and temporary increases of striatal lactate and DA efflux, the latter change being very marked. Also a significant reduction of DOPAC and HVA was observed. These neurochemical changes were all prevented by treatment with dihydralazine. These results indicate that ET-1 injected in the neostriatum may produce lesions by causing local ischemia, related to its vasoconstrictor activity and possibly also to an activation of ET-1 receptors in the astroglial-endothelial complex. Based on the present results it seems possible that ET-1 may participate in the multifactorial pathogenesis of cerebral ischemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259134
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  • 44
    Electronic Resource
    Electronic Resource
    Morphology of neurons in the white matter of the adult human neocortex (1992)
    Springer
    Experimental brain research 88 (1992), S. 204-212 
    Details
    ISSN: 1432-1106
    Keywords: Cerebral cortex of man ; Morphology of white matter neurons ; Subplate cells ; Golgi method ; Immunohistochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurons in the human cerebral cortical white matter below motor, visual, auditory and prefrontal orbital areas have been studied with the Golgi method, immunohistochemistry and diaphorase histochemistry. The majority of white matter neurons are pyramidal cells displaying the typical polarized, spiny dendritic system. The morphological variety includes stellate forms as well as bipolar pyramidal cells, and the expression of a certain morphological phenotype seems to depend on the position of the neuron. Spineless nonpyramidal neurons with multipolar to bitufted dendritic fields constitute less than 10% of the nuerons stained for microtubule associated protein (MAP-2). Only 3% of the MAP-2 immunoreactive neurons display nicotine adenine dinucleotide-diaphorase activity. The white matter pyramidal neurons are arranged in radial rows continuous with the columns of layer VI neurons. Neuron density is highest below layer VI, and decreases with increasing distance from the gray matter. White matter neurons are especially abundant below the primary motor cortex, and are least frequent below the visual cortex area 17. In contrast to other mammalian species, the white matter neurons in man are not only present during development, but persist throughout life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259143
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  • 45
    Electronic Resource
    Electronic Resource
    Inhibitory action of a conditioning procedure on visual responsive neurons of the nucleus reticularis thalami in rats (1992)
    Springer
    Experimental brain research 88 (1992), S. 199-203 
    Details
    ISSN: 1432-1106
    Keywords: Visual part of nucleus reticularis thalami ; Unit activity ; Conditioning ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In urethane anesthetized rats neuronal responses of the visual part of nucleus reticularis thalami (vTR) to light were compared with those during pairing light as a conditioned stimulus (CS) with the electrical stimulation of the rat's tail (US). The intensity of the US was adjusted to the minimum required to evoke a slight freezing behavior in the awake rat. The firing rate of most vTR neurons decreased in the period between light and US application (P 〈 0.01). Significant response modulations to light were observed in 39% of the units, in most of them they persisted over an extinction period of 15 min. In addition, neurons which were predominantly inhibited by conditioning sometimes changed from regular spiking to a burst pattern. The results support the hypothesis that conditioning related facilitation of geniculate neurons observed in previous experiments can be explained at least partly by disinhibition of geniculate units from vTR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259142
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  • 46
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    Electronic Resource
    Synthesis and secretion of α2-macroglobulin by human glioma established cell lines (1992)
    Springer
    Experimental brain research 88 (1992), S. 213-218 
    Details
    ISSN: 1432-1106
    Keywords: Glial cultures ; Gliomas ; Tumor cells ; Proteinase inhibitors ; α2-macroglobulin ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Human α2-macroglobulin (α2M) is a high molecular weight plasma proteinase inhibitor exhibiting a broad specificity; in fact it is capable of binding endopeptidases from all known classes of proteases (Barret 1981). Two human glioma cell lines, namely an astrocytoma and a glioblastoma, were found to synthesize and secrete in the culture medium a protein which resembles the serum α2M for immunological, biochemical and biological features. Using polyclonal antibodies to serum α2M, an α2M-like factor could be detected in the cytoplasm and in the culture medium of the tumor cells. Furthermore this factor accumulated in cytoplasmic granules if cells were incubated with monensin and its production was dramatically reduced following a treatment with cycloheximide. This protein behaved like the serum α2M in immunoblotting analysis and exhibited the same antiproteolytic activity. Its role in human brain is unknown at present. Since interactions of proteinases and proteinase-inhibitors appear to influence the hosttumor immune response and to play a crucial role during the migration of metastasizing tumor cells, α2M expression observed in these glioma cells could be involved in tumor cell proliferation and invasion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259144
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  • 47
    Electronic Resource
    Electronic Resource
    Human tactile discrimination of curvature when contact area with the skin remains constant (1992)
    Springer
    Experimental brain research 88 (1992), S. 447-450 
    Details
    ISSN: 1432-1106
    Keywords: Tactile ; Finger ; Cutaneous ; Shape ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A forced choice paradigm was used to measure the capacity of human subjects to discriminate the curvature of stimuli applied passively to the skin of an immobilized finger. The stimuli consisted of spherically curved segments with a base radius of 2.5 mm; thus the area of contact with the fingerpad skin was approximately 19.6 mm2 for all stimuli. There were 2 series of experiments. In series 1, the standard surface had a curvature of 286 m−1 (radius of curvature 3.5 mm); subjects were able to discriminate an increase in curvature of about 13%. In series 2, the standard had a curvature of 154 m−1 (radius 6.5 mm); subjects were able to discriminate an increase in curvature of about 18%. Thus, even when the contact area between the surface and the skin was invariant, humans were able to discriminate small changes in curvature using only information from the cutaneous receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259120
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  • 48
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    Electronic Resource
    A novel member to the family of perineuronal antigens associated with subpopulatios of central neurons in the rat (1992)
    Springer
    Experimental brain research 88 (1992), S. 345-354 
    Details
    ISSN: 1432-1106
    Keywords: Neuronal subsets ; Pericellular antigen ; Monoclonal antibody ; Cat ; 301 ; VC1.1 ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We reported earlier that monoclonal antibodies (MAbs) 473 and 376 gave perineuronal staining of different subsets of central neurons, and that both immunoreactivities were labile to treatment with chondroitinase ABC. On the other hand, MAb 1B5, the immunoreactivity to which is uncovered by chondroitinase ABC, stained a neuronal subset that included neurons positive to MAbs 473 and 376 (Fujita et al. 1989). We now report a new antibody, MAb 374, that stained perimeter of neurons of a subset different from those stained by MAbs 473, 376 and 1B5. In the rat central nervous system MAb 374-positive cells were found in the neocortex, thalamic reticular nucleus, hippocampus, cerebellar cortex and nuclei, and in the brain stem. MAb 374-immunoreactive neuropil was found in the medial habenular, arcuate, dorsal endopiriform nuclei, and the two plexiform layers of the retina. The immunoreactivity was not affected by treatment with chondroitinase ABC. Immunoblot experiments using a rat brain homogenate revealed a specific band at a position corresponding to a molecular weight of 600 kD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259110
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  • 49
    Electronic Resource
    Electronic Resource
    Time-varying stiffness of human elbow joint during cyclic voluntary movement (1992)
    Springer
    Experimental brain research 88 (1992), S. 433-442 
    Details
    ISSN: 1432-1106
    Keywords: Movement ; Neuromuscular control ; Time-varying ; Stiffness ; Elbow ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The objective of this study was to determine the extent to which subjects modulate their elbow joint mechanical properties during ongoing arm movement. Small pseudo-random force disturbances were applied to the wrist with an airjet actuator while subjects executed large (1 rad) elbow joint movements. Using a lumped parameter model of the muscle, tendom and proprioceptive feedback dynamics, a time-varying system identification technique was developed to analyze the phasic changes in the elbow joint's mechanical response. The mechanical properties were found to be time-varying, and well approximated by a quasi-linear second-order model. The stiffness of the arm was found to drop during movement. The arm was always underdamped, with the damping ratio changing during movement. Inertia estimates were constant and consistent with previous measurements. Overall, the moving arm was found to be very compliant, with a peak stiffness value less than the lowest value measured during posture, and a natural frequency of less than 3 Hz. Changing the speed of movement, or the load from gravity, changed the stiffness measured, but not in strict proportion to the change in net muscle torque.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259118
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  • 50
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    Electronic Resource
    Substance P-, vasoactive intestinal polypeptide-, and cholecystokinin-like immunoreactive fiber projections from the superior colliculus to the dorsal lateral geniculate nucleus in the rat (1992)
    Springer
    Experimental brain research 89 (1992), S. 59-66 
    Details
    ISSN: 1432-1106
    Keywords: Tectogeniculate projections ; SP ; VIP ; CCK ; WGA-HRP ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Substance P (SP)-, vasoactive intestinal polypeptide (VIP)-, and cholecystokinin (CCK)-like immunoreactive (LI) neurons were found in the superior colliculus (SC) of the rat, and examined to ascertain whether they sent projection fibers to the dorsal lateral geniculate nucleus (LGNd). Immunocytochemical staining with antisera against SP, VIP, and CCK showed that many immunoreactive neuronal cell bodies were located in the superficial layers of the SC, especially in the stratum griseum superficiale. The pattern of distribution of these immunoreactive neuronal cell bodies in the SC was similar to that of neuronal cell bodies which were retrogradely labeled with WGA-HRP (wheat germ agglutinin-horseradish peroxidase conjugate) injected ipsilaterally into the LGNd. On the other hand, SP-, VIP- and CCK-LI axons were seen most densely in the lateral part of the LGNd, especially in the small-celled LGNd zone adjacent to the optic tract, where anterograde labeling was also observed after injection of WGA-HRP ipsilaterally into the superficial layers of the SC. When a lesion was produced by kainic acid injection into the superficial layers of the SC, axons showing SP-, VIP-, or CCK-LI in the LGNd ipsilateral to the lesion were markedly depleted. The results indicate that SC-LGNd projection neurons contain SP, VIP, and/or CCK in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229001
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    Evidence that non-NMDA receptors are involved in the excitatory pathway from the pedunculopontine region to nigrostriatal dopaminergic neurons (1992)
    Springer
    Experimental brain research 89 (1992), S. 79-86 
    Details
    ISSN: 1432-1106
    Keywords: Basal ganglia ; Pedunculopontine nucleus ; Substantia nigra pars compacta ; Excitatory amino acids ; Acetylcholine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Extracellular single-neuron recordings were obtained from electrophysiologically identified nigrostriatal neurons in chloral hydrate anesthetized rats, in order to test the hypothesis that excitatory amino acid receptors are involved in responses of these neurons to electrical stimulation of the pontine region where the pedunculopontine nucleus (PPN) is located. The effects of iontophoretic application of excitatory amino acids and their antagonists as well as of cholinergic antagonists were tested on the fast orthodromic excitation of nigrostriatal neurons evoked by stimulation of the PPN region. The N-methyl-D-aspartate (NMDA) receptor antagonist D-a-aminoadipic acid as well as the cholinergic receptor antagonists mecamylamine and atropine failed to suppress the synaptic excitation of nigral neurons. The NMDA receptor antagonist DL-2-amino-5-phosphonovalerate exerted a weak depressant action on the synaptic response in a few neurons only. On the contrary, the broad spectrum antagonists of excitatory amino acid receptors kynurenic acid and gamma-Dglutamyl-amino-methyl-sulphonate were found to block simultaneously both the synaptic excitation and the neuronal responses to iontophoretic pulses of glutamate while leaving unaffected the neuronal responses to local application of acetylcholine or carbachol. The competitive antagonist of non-NMDA receptors 6-cyano-2,3-dihy-droxy-7-nitro-quinoxaline suppressed the synaptic excitation at ejection currents which antagonized neuronal responses to quisqualate and kainate. These results suggest that PPN excitatory fibers synapsing onto pars compacta nigrostriatal neurons utilize an excitatory amino acid as a synaptic transmitter acting preferentially on non-NMDA receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229003
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    Three-dimensional drawings in isometric conditions: relation between geometry and kinematics (1992)
    Springer
    Experimental brain research 88 (1992), S. 685-690 
    Details
    ISSN: 1432-1106
    Keywords: Force ; Trajectory ; Kinematics ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Normal human subjects grasped a 3-D isometric handle with an otherwise unrestrained, pronated hand and exerted forces continuously to draw circles, ellipses and lemniscates (figure-eights) in specified planes in the presence or absence of a 3-D visual force-feedback cursor and a visual template. Under any of these conditions and in all subjects, a significant positive correlation was observed between the instantaneous curvature and angular velocity, and between the instantaneous radius of curvature and tangential velocity; that is, when the force trajectory was most curved, the tangential velocity was lowest. This finding is similar to that obtained by Viviani and Terzuolo (1982) for 2-D drawing arm movements and supports the notion that central constraints give rise to the relation between geometric and kinematic parameters of the trajectory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228198
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    Cerebral blood flow and histopathological changes following permanent bilateral carotid artery ligation in Wistar rats (1992)
    Springer
    Experimental brain research 89 (1992), S. 87-92 
    Details
    ISSN: 1432-1106
    Keywords: Autoradiography ; Cerebral blood flow ; Cerebral ischemia ; Iodoantipyrine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cerebral blood flow and histopathological changes after bilateral carotid artery ligation (BCAL) in Wistar rats were studied. Eight of the 38 rats (21%) died within one week. In the 30 survivors, the incidence of histopathological change was 90% in the caudate nucleus, 23% in the cortex, 30% in the hippocampus, and 0% in the other structures. Local cerebral blood flow (LCBF) was measured using the quantitative autoradiographic 14C-iodoantipyrine technique in 24 anatomically discrete regions of the brain. BCAL induced ischemia in the entire forebrain. The percent reduction of LCBF was between 25–94% of the control at 2.5 h after BCAL. LCBF tended to recover 1 week after BCAL except for the regions of neuronal damage. These results suggest that neuronal damage does not correlate with the flow rate. In the present study, selective neuronal damage was also observed in rats with chronic cerebral ischemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229004
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    Monoclonal antibody 473 selectively stains a population of GABAergic neurons containing the calcium-binding protein parvalbumin in the rat cerebral cortex (1992)
    Springer
    Experimental brain research 89 (1992), S. 109-114 
    Details
    ISSN: 1432-1106
    Keywords: Parvalbumin ; GABA ; Nonpyramidal cell ; Monoclonal antibody ; Lectin ; Cerebral cortex ; Proteoglycan ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Monoclonal antibody (MAb) 473 is shown to outline selectively a subpopulation of GABAergic neurons containing a specific calcium-binding protein parvalbumin (PV) in the adult rat parietal cortex, using preembedding immunocytochemistry at the light microscopic level. About 90% of MAb 473 stained cells in the rat parietal cortex were PV immunoreactive. Thus we compared MAb 473 staining with that of three chemical probes, previously shown to stain selectively a subpopulation of PV-containing GABAergic neurons in this brain region, namely, a lectin, Vicia villosa agglutinin (VVA), with a specific affinity for terminal N-acetylgalactosamine, MAb 3B3 which is specific for chondroitin sulfate proteoglycan and MAb HNK-1 which is specific for some types of carbohydrate epitope containing a sulfated derivative of glucuronic acid. About 85% of MAb 473 immunoreactive cells were shown to be stained with VVA. Furthermore about 90% of MAb 473 immunoreactive cells were also stained with MAb 3B3. Thus MAb 473 positive cells were almost included into VVA and/or MAb 3B3 positive cells. On the other hand only about 34% of MAb 473 positive cells were HNK-1 positive, whereas about 44% of HNK-1 positive cells were MAb 473 positive. Thus these two MAbs defined different, though partially overlapping, subsets of PV-containing GABAergic neurons in the rat parietal cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229007
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    Noradrenergic hyperactivity after partial fornix section: role in cholinergic dependent memory performance (1992)
    Springer
    Experimental brain research 89 (1992), S. 125-132 
    Details
    ISSN: 1432-1106
    Keywords: Noradrenergic hyperactivity ; NE ; ACh ; Fornix section ; DSP4 ; Spatial memory ; Alzheimer's disease ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rats with unilateral or bilateral partial section of the fornix were impaired on an eight arm radial maze task. Neurochemical analysis of hippocampal tissue four weeks after the lesions revealed a 50% reduction of choline acetyltransferase (ChAT) activity. The cholinergic marker was correlated negatively with the number of errors in the maze; the lower the ChAT activity, the higher the error score. The fornix lesion also induced a 50% reduction in norepinephrine (NE), but no change in the noradrenergic metabolite methylhydroxyphenylglycol (MHPG), suggesting a net increase in turnover of NE in these animals. Additional lesion of the noradrenergic system with the neurotoxin DSP4 reduced both MHPG and NE levels by more than 90%, compared to nonlesioned controls, and reversed the behavioral deficit. This treatment had no further effect on cholinergic markers. There was a significant negative correlation between ChAT activity and the index of NE turnover, suggesting that hyperactivity in the noradrenergic system after fornix section inhibits the spared cholinergic function and thus exacerbates the cognitive deficit. The pattern of neurochemical results bear a striking resemblance to those seen in some Alzheimer's patients and suggest that an equilibrium among neurotransmitters is important to cognitive function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229009
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    Dead zone for express saccades (1992)
    Springer
    Experimental brain research 89 (1992), S. 214-222 
    Details
    ISSN: 1432-1106
    Keywords: Express saccade ; Reaction time ; Attention ; Fixation ; Rhesus monkey ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The saccadic eye movements of three humans and one non-human primate (a male rhesus monkey) have been measured for target eccentricities between 0.3 and 15 deg. With a gap task (fixation point offset precedes target onset by 200 ms) and a target at 4 deg, all subjects produced reasonable amounts of express saccades as indicated by a clear peak in the distribution of their saccadic reaction times (SRT): about 100 ms in human subjects and 70 ms in the monkey. This peak disappeared with decreasing target eccentricity below 2 deg, but saccades of longer (regular) reaction times were still present. Thus it was found that there exists a dead zone for express saccades. In addition, small saccades have a much stronger tendency to overshoot the target and their velocity falls above the main sequence as defined by the least square fit of an exponential v=vo(1-exp(-a/ao)) to the maximal velocity (v) versus amplitude (a) relationship (vo and ao are constants fitted). It is concluded that for small saccades the express way is blocked functionally or does not exist anatomically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229018
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    Somatosensory control of precision grip during unpredictable pulling loads (1992)
    Springer
    Experimental brain research 89 (1992), S. 204-213 
    Details
    ISSN: 1432-1106
    Keywords: Motor control ; Precision grip ; Hand -Grasp force ; Mechanoreceptors ; Tactile sensibility ; Kinesthesia ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During manipulation involving restraint of ‘active’ (mechanically unpredictable) objects, it is presumed that the control of the grip and other reaction forces more regularly relies on somatosensory input than during manipulation of ‘passive’ (mechanically predictable) objects. In companion studies we have shown that grip forces are automatically adjusted to the amplitude and the rate of distal pulling loads imposed through an ‘active’ object held in a precision grip. In this study anesthesia of either one or both digits holding the manipulandum was used to examine whether the grip force regulation was dependent on afferent signals from the digits. Five types of trapezoidal load force profiles of various rate and amplitude combinations were given in an unpredictable sequence while the subject was prevented from seeing the hand. Grip forces, load forces and position of the manipulandum in the pulling direction were recorded. With both digits anesthetized the load amplitude changes yielded considerably less grip force modulation and in many trials obvious grip force responses were absent. Moreover, the latencies between the onset of the load changes and the observed grip force responses were much prolonged. However, there was pronounced inter-individual variation. Subjects exhibiting a lower stiffness in the pulling direction, probably due to more flexed fingers when holding the manipulandum, showed a higher force modulation, higher responsiveness to the load ramps and shorter latencies. Hence, under certain conditions afferent input from receptors proximal to the digits could be utilized to provide some grip regulation. The evoked grip force responses showed an initial response similar to the normally occurring ‘catch-up’ response, but it was not graded by the load force rate. Also, there was no ‘tracking’ response, suggesting that the latter was contingent upon a momentto-moment control using afferent input from the digits. With only one digit anesthetized (thumb) the handicap was less severe. Thus, the grip force regulation was impaired under any condition of digital anesthesia, i.e., afferent input from both index finger and thumb was required for the adequate operation of the grip force regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229017
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    The role of predictive visual temporal information in the coordination of muscle activity in catching (1992)
    Springer
    Experimental brain research 89 (1992), S. 223-228 
    Details
    ISSN: 1432-1106
    Keywords: Time-to-contact ; Catching ; Muscle activity ; Coordination ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study addresses the question as to the nature of the information on which the preactivation of the appropriate muscles in the grasping of the ball in a onehanded catching task is initiated and coordinated. High speed film and electromyograms were recorded while experiences subjects (N = 4) caught balls — projected towards them by a ball-machine at different speeds (11.9, 13.9 and 16.2 m/s — resulting in significantly different flight times of 508, 443 and 355 ms, respectively). Tau-margins (times to contact) values were calculated at the time of the initiation of the grasp movement for each subject at each speed. No significant differences were found between taumargins at different speeds. Further, the onset of the muscle activity for the initiation of the grasp movement was shown to be independent of ball speed. These findings lend support to the contention that the initiation of the grasp movement in catching is controlled and coordinated by the optical variable tau which specifies (directly) this time-to-contact. Given that the muscle group selected includes both flexors and extensors, co-activation on the basis of tau information is evidenced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229019
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    Widely distributed GABA-mediated afferent inhibition processes within the ventrobasal thalamus of rat and their possible relevance to pathological pain states and somatotopic plasticity (1992)
    Springer
    Experimental brain research 89 (1992), S. 363-372 
    Details
    ISSN: 1432-1106
    Keywords: GABA ; Iontophoresis ; Somatotopy ; SR95531 ; Ventrobasal thalamus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have recently described extensive inhibitory interactions between inputs to the ventroposterolateral (VPL) (Roberts and Wells 1990, 1991) and ventropos-teromedial (VPM) (Salt 1989) portions of the ventrobasal nucleus of the thalamus (VB). We wished to determine whether (i) the inhibition observed in the VPL was operating at the thalamic level, (ii) was dependant on GABA receptors, (iii) was demonstrable on neurons of the ventro-posteromedial nucleus of the thalamus (VPM) and (iv) was operant on test responses evoked by natural stimuli. Conditioning stimulation of sciatic nerve afferents caused inhibition of air jet evoked test responses of single VB neurons in urethane-anaesthetized rats. Both VPM and VPL neurons were subject to inhibition by conditioning stimulation of hindlimb afferents, indicating the widespread nature of the inhibitory process. This inhibition was reduced by the iontophoretic application of SR95531, a GABAA receptor antagonist. We conclude that there is a widely distributed inhibitory system operating in the somatic thalamus which involves both the medial and lateral portions of the nucleus and is, at least in part, mediated by GABAA receptors. The possible involvement of inhibitory processes and intrinsic membrane properties of thalamic neurones in the somatotopic plasticity of the sensory thalamus following deafferentation and in deaf-ferentation pain is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228252
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    Characteristics of “anti” saccades in man (1992)
    Springer
    Experimental brain research 89 (1992), S. 415-424 
    Details
    ISSN: 1432-1106
    Keywords: Anti saccades ; Saccadic reaction time ; Express saccades ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four subjects — all made large numbers of Express saccades in the normal gap task — were instructed to make saccades in the direction opposite to the side where a visual stimulus appeared (“anti” task). Gap and overlap trials were used. Saccadic reaction time (SRT), velocity and amplitude of the corresponding eye movements were analysed and compared to those of saccades made in the normal task. The velocity of “anti saccades” was found to be slightly (up to 15%) but significantly slower in two subjects. The distributions of SRTs in normal gap tasks show a small group of anticipatory saccades (with SRT below 80 ms and slower velocities) followed by a group of saccades with fast reaction times between 80 ms and 120 ms (Express saccades) followed by another large group ranging up to 180 ms (regular saccades). In the gap anti task there are anticipatory saccades and saccades with SRTs above 100 ms; Express saccades are missing. The distribution of SRTs obtained in the overlap anti task was unimodal with a mean value of 231 ms as compared to 216 ms in the normal task. The introduction of the gap therefore clearly decreases the reaction times of the anti saccades. Control experiments show that the delay of anti saccades is not due to an interhemispheric transfer time but must be attributed to the saccade generating system taking more time to program a saccade to a position where no visual stimulus appears. These data are discussed as providing further evidence for the existence of a reflex-like pathway connecting the retina to the oculomotor nuclei mediating the Express saccade.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228257
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    Changes of cortical activity when executing learned motor sequences (1992)
    Springer
    Experimental brain research 89 (1992), S. 435-440 
    Details
    ISSN: 1432-1106
    Keywords: Supplementary motor area ; Sensorimotor cortex ; Bereitschaftspotential ; Movement-related potentials ; Cortical DC potentials ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fifteen right-handed subjects performed a learned sequence of four movements (flex index finger, extend hand, extend index finger, flex hand) either with their left or their right hand. The sequence of movements had to be continuously repeated for 20 s (period of execution). In the beginning of each period of execution large negative DC potentials were recorded in positions located above the mesial fronto-central cortex (Cz) and the sensorimotor hand areas of either hemisphere (C3 and C4). In contrast, DC potentials were absent in Cz at the end of the period of execution. In recordings from a position above the sensorimotor hand area contralateral to the performing side, negative DC potentials declined to some extent during task execution but were still present at the end of the period. Variations of both the amplitude and topography of negative cortical DC potentials during task-execution indicate changes of both the size and pattern of cortical activity. These findings were consistently found at both the beginning and end of the experiment. Motor performance as quantified by movement times and inter-onset latencies of movements showed no change, either during the periods of execution or when comparing the beginning of the experiment with the end. Conclusions are: (1) the execution of a learned motor sequence task cannot be associated with a particular size and pattern of cortical activity. (2) A pronounced decline of neural activity in the mesial, fronto-central area constitutes the predominant feature of the changes of cortical activity during the period of execution. (3) Since motor programs and plans are pre-established, changes of cortical activity reflect changing levels or modes of motor control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228259
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    In vitro study of central respiratory-like activity of the fetal rat (1992)
    Springer
    Experimental brain research 89 (1992), S. 459-464 
    Details
    ISSN: 1432-1106
    Keywords: Fetal breathing ; Respiratory centers ; Development ; Ontogeny ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A fetal rat brain stem-spinal cord in vitro preparation (15–20 days) which retains for several hours respiratory-like discharges on cervical and cranial ventral roots has been developed for analysing fetal central respiratory activity. Two different patterns of easily distinguishable rhythmic activity were recorded. The first, of spinal origin, appeared every 2–10 min as long bursts of potentials (3–30 s) on cervical, but not hypoglossal, roots. The second pattern corresponded to brief bursts (1 s) of potentials occurring on both cervical and hypoglossal roots at a frequency ranging from 3–4 cycles min-1. The second type of activity was likely to be respiratory since it originated from the medulla, and behaved similarly to the respiratory activity recorded in vitro from newborn rats. The fetal respiratory-like activity was never observed at day 15, appeared at day 16 in 30% of the preparations with fluctuating frequency and amplitude bursts, and stabilised at day 20 where it was usually present and resembled newborn rat respiratory activity: its frequency was stable but was reduced by withdrawal of CO2 and pH stimuli and modulated by a pontine noradrenergic influence. This fetal preparation offers many advantages for studying the ontogeny of the central respiratory activity because of the background knowledge available on the adult and newborn rat respiratory centers and the possibility of performing electrophysiological, morphological and pharmacological fetal studies directly at the central level without any feedback from the periphery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228263
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    The morphology and connectivity of dissociated and reaggregated fetal tectal tissue transplanted to the midbrain of newborn rats (1992)
    Springer
    Experimental brain research 89 (1992), S. 560-570 
    Details
    ISSN: 1432-1106
    Keywords: Visual system ; Superior colliculus ; Transplantation ; Retinotectal specificity ; Development ; Neuronal phenotype ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Tectal tissue from E15 or E16 Wistar rat embryos was dissociated and reaggregated (DR) prior to transplantation on to the midbrain of newborn host rats. We wished to determine how complete disruption of the donor tissue (i) affected the subsequent morphological development of the grafts in the host brain, and (ii) whether this procedure affected the selectivity with which host retinal axons innervated target regions in the tectal transplants. Forty-three to 135 days after transplantation, host rats received binocular injections of wheatgerm agglutinin-conjugated horseradish peroxidase. After perfusion, frozen sections of the grafts and underlying host brainstem were cut and reacted with tetramethylbenzidine to identify retinal projections, or stained for either acetylcholinesterase (AChE), Nissl or neurofibrils. All host brains contained identifiable DR grafts. Each brain contained at least one large transplant and numerous smaller pieces of graft tissue. The fragmentation of DR grafts was greater than that seen in direct, undissociated tectal transplants; however the morphology of individual DR grafts was markedly similar to direct grafts. Of particular interest was the presence in DR grafts of localized, often oval or circular regions, that possessed high AChE activity and contained mostly small (5 to 10 μm) close-packed neurons. AChE-dense patches were found both superficially and deep within DR grafts and appeared identical to those seen in direct transplants. These regions are thought to be homologous to the superficial, retinorecipient layers of normal superior colliculus (SC) and it is likely that the formation of these localized areas resulted from the selective association of presumptive SGS neurons within the reaggregating neuropil. In almost all cases, host retinal input to DR grafts was confined to the localized AChE-dense patches, suggesting that despite the dissociation procedure, specific retinal innervation of regions containing at least some of the appropriate target cells was maintained in DR tectal grafts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229881
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    Attentional functions of the forebrain cholinergic systems: effects of intraventricular hemicholinium, physostigmine, basal forebrain lesions and intracortical grafts on a multiple-choice serial reaction time task (1992)
    Springer
    Experimental brain research 89 (1992), S. 611-622 
    Details
    ISSN: 1432-1106
    Keywords: Basal forebrain ; Acetylcholine ; Attention ; Transplantation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Degeneration of the cholinergic magnocellular neurons in the basal forebrain and their cortical projections is a major feature of the neuropathology of Alzheimer's disease. In the present study, two experiments examined the disruptive effects on visual attentional performance of two different manipulations that reduce central cholinergic function. In Expt. I, pharmacological manipulation of the cholinergic system was investigated using icv administration of hemicholinium (HC-3), a 9high affinity choline uptake blocker, administered either alone or in conjunction with the anticholinesterase, physostigmine. The results revealed impairments in the ability of the rats to localize brief visual targets in a serial reaction time task, as shown in particular by a reduction in choice accuracy and lengthening of the latency to respond correctly to the visual stimulus. Cholinergic specificity was supported by the reversal of these behavioural impairments by pre-treatment with the anticholinesterase, physostigmine. In Expt. II, quisqualateinduced lesions of the basal forebrain produced behavioural deficits at 3 weeks post-lesion surgery similar to those observed following icv infusion of HC-3. In an attempt to restore the extrinsic cortical cholinergic innervation by reinnervation of the deafferented cortex, embryonic basal forebrain cholinergic cells were transplanted into the cortex of lesioned animals. After three months recovery, impairments in performance on the baseline schedule of the task were no longer apparent in lesioned animals. However, behavioural deficits, observed predominantly as a lengthening of correct response latency, could be reinstated in the lesioned animals by interpolation of distracting bursts of white noise during each trial, and this deficit was ameliorated by the cholinergic grafts. Furthermore, a non-specific effect of both cholinergic and non-cholinergic grafts in controlling the increase in perseverative time-out responses which occurred as a result of the basal forebrain lesion was consistently observed. These results suggest that cholinergic dysfunction can produce deficits in visual attention which can be ameliorated by cholinergic treatments such as physostigmine or cholinergic-rich cortical grafts. These data provide support for a role for the basal forebrain-neocortical cholinergic projection in attentional function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229886
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    Role of vestibular and neck inputs for the perception of object motion in space (1992)
    Springer
    Experimental brain research 89 (1992), S. 655-668 
    Details
    ISSN: 1432-1106
    Keywords: Perception ; Visual object motion ; Vestibular-neck interaction ; Coordinate systems ; Oculogyral illusion ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The contribution of vestibular and neck inputs to the perception of visual object motion in space was studied in the absence of a visual background (in the dark) in normal human subjects (Ss). Measures of these contributions were obtained by means of a closed loop nulling procedure; Ss fixed their eyes on a luminous spot (object) and nulled its actual or apparent motion in space during head rotation in space (vestibular stimulus) and/ or trunk rotation relative to the head (neck stimulus) with the help of a joystick. Vestibular and neck contributions were expressed in terms of gain and phase with respect to the visuo-oculomotor/joystick feedback loop which was assumed to have almost ideal transfer characteristics. The stimuli were applied as sinusoidal rotations in the horizontal plane (f= 0.025–0.8 Hz; peak angular displacements, 1–16°). Results: (1) During vestibular stimulation, Ss perceived the object, when kept in fixed alignment with the moving body, as moving in space. However, they underestimated the object motion; the gain was only about 0.7 at 0.2–0.8 Hz and clearly decreased at lower stimulus frequencies, while the phase exhibited a small lead. (2) During pure neck stimulation (trunk rotating relative to the stationary head), the object, when stationary, appeared to move in space counter to the trunk excursion. This neck-contingent object motion illusion was small at 0.2–0.8 Hz, but increased considerably with decreasing frequency, while its phase developed a small lag. (3) Vestibular, neck, and visuo-oculomotor effects summed linearly during combined stimulations. (4) The erroneous vestibular and neck contributions to the object motion perception were complementary to each other, and the perception became about veridical (G≈1, φ≈0°), when both inputs were combined during head rotation with the trunk stationary. The results are simulated by an extended version of a computer model that previously had been developed to describe vestibular and neck effects on human perception of head motion in space. In the model, the perception of object motion in space is derived from the superposition of three signals, representing “object to head”, (visuo-oculomotor; head coordinates), “head on trunk” (neck; trunk coordinates), and “trunk in space” (vestibular-neck interaction; space coordinates).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229890
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    Cryopreservation, survival and function of intrastriatal fetal mesencephalic grafts in a rat model of Parkinson's disease (1992)
    Springer
    Experimental brain research 90 (1992), S. 54-62 
    Details
    ISSN: 1432-1106
    Keywords: Neural grafting ; Neural transplantation ; Parkinson's disease ; Cryopreservation ; Fetal mesencephalon ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the present study we quantitatively assessed to what extent freeze-storage at liquid nitrogen temperature influences the survival and function of fetal mesencephalic grafts in the dopamine-depleted rat striatum. Ventral mesencephalic (VM) tissue was dissected from rat fetuses and stored overnight in a preservative medium at 4 °C (hibernation). It was grafted intrastriatally either as a fresh cell suspension or was frozen as tissue fragments or as a cell suspension after stepwise incubation in ascending concentrations of dimethyl-sulphoxide. Following a cryopreservation interval of 80 days in liquid nitrogen, the frozen samples were rapidly thawed, rinsed, and grafted. Cellular viabilities of graft cell suspensions, as assessed by ethidium bromide/acridine orange staining, were decreased from 90% in fresh tissue to 38-35% in frozen and thawed tissue. Amphetamine-induced turning behavior at 6 weeks post-grafting was significantly attenuated in hosts that had received fresh grafts or grafts that were frozen as tissue fragments. Tyrosine hydroxylase-(TH-) immunocytochemistry of recipient brains revealed significant decreases in TH-positive graft cell numbers in rats grafted with cryopreserved tissue (38–42% of fresh tissue). Moreover, the dye exclusion viability of thawed VM tissue was found to accurately predict the subsequent graft survival. There was no difference with respect to graft cell numbers between the two freezing methods employed, though block storage seems to be more simple from a practical point of view. The present study indicates that freezing in liquid nitrogen may be a feasible method for long-term storage of fetal neural tissue for grafting, although a marked decrease in graft survival and function of cryopreserved tissue must be taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229256
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    Postnatal X-ray irradiation effects on glomerular layer of rat olfactory bulb: quantitative and immunocytochemical analysis (1992)
    Springer
    Experimental brain research 90 (1992), S. 103-115 
    Details
    ISSN: 1432-1106
    Keywords: X-ray irradiation ; GABA ; Catecholamine ; Calcium binding proteins ; Olfactory bulb ; Development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the rat olfactory bulb, the majority of interneurons in the glomerular layer (GL) are supposed to be generated during first postnatal week. Low and repeated doses of X-rays (200 rad x 4 and 200 rad x 6) were used during this period to impair the development of interneurons. The resulting effects on olfactory bulb neurons were examined stereologically and immunocytochemically in animals of 4 and 12 weeks of age. Quantitative analysis showed that, 1) the volume of the GL decreased to 55% (1200 rad) – 70% (800 rad) of control, 2) numerical cell densities in GL decreased to 40% (1200 rad) – 60% (800 rad) of control, thus resulting in 3) a decrease of the total cell number in GL to 20% (1200 rad) – 40% (800 rad) of control in irradiated olfactory bulbs of animals 4 weeks old. In comparison, mitral cells, which are generated prenatally, were much less affected (total cell number: 70–80% of control), indicating a selective loss of cells generated during the first postnatal week in GL. Effects on somata and processes immunoreactive for GABA, tyrosine hydroxylase (TH), calbindin D-28K and parvalbumin (PV) were examined in irradiated bulbs of both 4 and 12 week-old rats. All of these immunoreactive elements showed a drastic decrease in all layers. Semiquantitative analysis showed that in the GL, calbindin D-28K immunoreactive (calbindin D-28K(+)) neurons decreased more extensively than TH immunoreactive (TH(+)) and GABA-like immunoreactive (GABA(+)) neurons; that is, TH(+) and GABA(+) neurons decreased to 20% (1200 rad) – 40% (800 rad) of control, whereas calbindin D-28K(+) neurons decreased to 10% (1200 rad) – 30% (800 rad) of control in the GL of irradiated bulbs. These findings indicated that larger proportions of calbindin D-28K(+) neurons might be generated during the first postnatal week than those of GABA(+) and TH(+) neurons. Furthermore, in irradiated bulbs the proportion of GABA(-)TH(+) cells in TH(+) cells increased to about twice of control, and the estimated total numbers of GABA(-)TH(+) cells in irradiated rats were 95% (800 rad) and 40% (1200 rad) of control. These observations suggest that the majority of GABA(-)TH(+) neurons were less affected by X-ray irradiation during the first postnatal week and thus that they might be generated in the prenatal period. Since during the first 2 postnatal weeks, neurons showing GABA(-)TH(+) were not seen in GL (Kosaka et al. 1987a), the majority of GABA(-)TH(+) neurons in adult olfactory bulb were assumed to change their phenotype at some postnatal developmental period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229261
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    The effects of wrist muscle vibration on human voluntary elbow flexion-extension movements (1992)
    Springer
    Experimental brain research 90 (1992), S. 217-220 
    Details
    ISSN: 1432-1106
    Keywords: Muscle vibration ; Spindle afferents ; Elbow movement ; Forearm muscle ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of forearm muscle tendon vibration during alternating step flexion-extension movements about the elbow was studied in normal humans. In one experiment, a vibrator was mounted over either the forearm flexor or the extensor muscle. In a second experiment, a vibrator was mounted over either the forearm muscle or the biceps muscle. In both experiments, vibration was applied either to a single muscle or simultaneously to both muscles during elbow flexion-extension movements. After a period of practice, subjects learned the required movements and were able to make them with their eyes closed. Application of vibration to the forearm and the biceps muscle during extension movements produced an undershoot of the required end movement position. Moreover, application of high frequency vibration (100 Hz) to the forearm extensor and flexor muscle produced an overshoot of the required end-movement position. The observed results are consistent with vibration induced activation of muscle spindle receptors not only in the lengthening muscle during movement but also in the forearm muscles. It is suggested that the pattern of distribution of muscle spindle afferent from the forearm muscle onto α-motoneurons of muscles acting at the elbow has played an important role of alternating step flexion-extension movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229274
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    Midbrain influences on ventrolateral medullo-spinal neurones in the rat (1992)
    Springer
    Experimental brain research 90 (1992), S. 147-152 
    Details
    ISSN: 1432-1106
    Keywords: Periaqueductal grey matter ; Rostral ventrolateral medulla ; Cardiovascular control ; Medullo-spinal neurones ; Defence reaction ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A study has been carried out to investigate the influence of the periaqueductal grey matter (PAG) on spinally-projecting neurones in the rostral ventrolateral medulla (RVLM) in rats anaesthetised with urethane. Microinjection of D,L-homocysteic acid was used to selectively activate nerve cell bodies in the PAG. Stimulation throughout the rostral half of the PAG and in the caudal PAG on a level with and dorsolateral to the level of the aqueduct evoked excitatory responses in 21 medullospinal cells in the RVLM. The neuronal excitation was associated with a rise in blood pressure. In contrast, stimulation within a restricted area of the ventrolateral PAG at the level of the dorsal raphe nucleus inhibited 10 medullo-spinal neurones in the RVLM, and produced variable changes in blood pressure. Convergence of excitatory and inhibitory influences from dorsolateral and ventrolateral stimulating sites in the PAG on to individual cells was also demonstrated. The results are discussed with respect to the role of the ventrolateral PAG in modulating the cardiovascular components of the “defence” response which is integrated by the dorsal PAG.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229266
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    Anatomical and functional compartmentalization of the subparafascicular thalamic nucleus in the rat (1992)
    Springer
    Experimental brain research 90 (1992), S. 175-179 
    Details
    ISSN: 1432-1106
    Keywords: Inferior colliculus ; Spinal cord ; Retrograde transport ; Tyrosine hydroxylase ; Glutamate decarboxylase ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The localization and the transmitter phenotype of subparafascicular thalamic nucleus (Spf) neurons projecting to the inferior colliculus (IC) and to the spinal cord (Sp) were studied by using a retrograde fluorescent double labeling technique, and a combined technique of retrograde tracing and immunohistochemistry for tyrosine hydroxylase (TH) and glutamate decarboxylase (GAD). The cell population of Spf-IC neurons was totally differentiated from that of Spf-Sp neurons which have been reported to be dopaminergic. The former were densely distributed, small to medium sized cells and localized in the central portion of the Spf, while the latter were sparsely distributed, large cells and localized in the marginal portion of the Spf. Spf-IC neurons were completely devoid of TH immunoreactivity and, instead, approximately half of them showed GAD immunoreactivity. From these findings, it is concluded that the Spf is distinctly compartmentalized by the presence at least two separate neuronal subpopulations, which are distinguishable in terms of their cell size, distribution patterns, transmitter phenotypes and trajectories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229269
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    Human ocular torsion during parabolic flights: an analysis with scleral search coil (1992)
    Springer
    Experimental brain research 90 (1992), S. 180-188 
    Details
    ISSN: 1432-1106
    Keywords: Ocular torsion ; Parabolic flights ; Eye movements ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rotation of the eyes about the visual axis is known as ocular torsion. A lateral inclination (a “roll”) of the head induces ocular torsion in the opposite direction, a response known as ocular counterrolling. For six subjects, we recorded the static (head still) and dynamic (head in oscillatory roll motion) ocular torsion in normal 1 g condition and also during the microgravity and hypergravity periods of parabolic flight, using the electromagnetic scleral search coil technique. With the head still, the direction and magnitude of torsion that occured in response to microgravity and hypergravity differed substantially from one individual to another, but there was a significant difference in torsional magnitude between the microgravity and hypergravity periods, for all static head positions including the upright position. Under normal 1 g conditions, counterrolling compensated for about 16% of (voluntary) static head roll, while dynamic counterroll was much larger, up to 36% of head roll at 0.55 Hz. With increasing frequency of head oscillation between 0.33 Hz and 0.55 Hz, the gain of counter rolling increased and there was no change in the phase relationship. The gain of dynamic counterroll (in response to voluntary head rolling) was not significantly less in hypogravity, suggesting that on the ground at these frequencies the contribution of gravity and gravity receptors to this reflex is redundant: this reflex is probably driven by the semicircular canals. In some subjects, the torsional displacement in microgravity is accompanied by micro-torsional oscillatory motion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229270
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    Motor control prior to movement onset: preparatory mechanisms for pointing at visual targets (1992)
    Springer
    Experimental brain research 90 (1992), S. 209-216 
    Details
    ISSN: 1432-1106
    Keywords: Sensorimotor integration ; Arm movements ; Preparation ; Precues ; Reaction time ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study investigated the mechanisms involved in the preparation of pointing movements in humans. We provided visual precues on the location of the upcoming target, and registered the effect of these precues on the reaction time (RT = interval between target appearance and movement onset). Generally, precues were found to reduce RT, suggesting that some aspects of the preparatory process have been advanced in time. In Exp. 1, precues fully specified the direction required for the upcoming movement while indicating only a range of movement amplitudes; in Exp. 2, precues fully specified the amplitude and indicated a range of directions. In both experiments, RT was shorter than in control trials without precues, and gradually increased with the size of the precued amplitude or direction range. This result suggests that the preparation of either parameter is possible without knowing the precise value of the other, i.e. amplitude and direction are not prepared in a fixed order. Furthermore, our results are consistent with the view that movement preparation includes a progressive contraction of the precued range towards the final value. The speed of this process can be estimated as 0.31 cm/ms for amplitude, and 1.7 deg/ms for direction ranges. In Exp. 3 and 4, precues indicated both amplitude and direction as ranges only. The size of the amplitude range was held constant while the size of the direction range was varied (Exp. 3), or vice versa (Exp. 4). Under these conditions, RT increased with the size of the varied range. For all range sizes tested, RT when precuing both amplitude and direction as ranges corresponded to the longer of the two RTs obtained in control trials where only one parameter was precued as range (like in Exp. 1 and 2), This outcome supports the hypothesis that amplitude and direction are prepared in parallel. The contraction speeds of amplitude and direction ranges estimated from Exp. 3 and 4 were comparable to those estimated from Exp. 1 and 2, indicating that processing speed is not reduced if both parameters rather than just one have to be prepared. In Exp. 5, the precued amplitude and direction range was held constant while precue area, and thus the range of possible final arm positions, was varied. RT was independent of precue area, which argues against a major contribution of position control mechanisms. Taken together, the present data support the hypothesis that amplitude and direction are the two most predominant parameters of movement preparation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229273
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    The area postrema is not involved in osmotic activation of neurosecretory cells in the supraoptic nucleus (1992)
    Springer
    Experimental brain research 90 (1992), S. 271-274 
    Details
    ISSN: 1432-1106
    Keywords: Area postrema ; Lesion ; Supraoptic nucleus ; Oxytocin ; Osmotic stimulation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were performed to examine whether or not the area postrema (AP) is involved in the osmotic control of neurohypophysial hormone release. In control rats and in rats bearing extensive lesions of AP, extracellular action potentials were recorded from neurosecretory cells in the supraoptic nucleus (SON) and firing rates determined before and after the intraperitoneal (i.p.) injection of 1.5 M-NaCl solution. Lesion of the AP significantly (p≦0.05, Mann-Whitney's U-test) lowered firing rate of putative vasopressin (phasic) cells but not that of oxytocin (non-phasic) cells. In lesioned animals, i.p. injection of hypertonic saline, however, caused similar changes in plasma osmotic pressure, plasma oxytocin concentration and mean firing rates of both putative oxytocin and vasopressin cells to those in control rats. The results suggest that the osmotic control of SON neurosecretory cell activity in the rat can take place in the absence of the AP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227238
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    Longitudinal neuronal organization of defensive reactions in the midbrain periaqueductal gray region of the rat (1992)
    Springer
    Experimental brain research 90 (1992), S. 307-318 
    Details
    ISSN: 1432-1106
    Keywords: Periaqueductal gray matter ; Defensive behavior ; Excitatory amino acids ; Freezing ; Hypertensive reaction ; Ultrasonic vocalization ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a previous study we investigated the intraspecific defensive reactions evoked by excitation of neurons in the intermediate third of the midbrain periaqueductal gray matter (PAG) of the rat. Experiments revealed that activation of neurons in this region of the PAG mediated: (i) backward defensive behavior, characterized by upright postures and backward movements, and (ii) reactive immobility (“freezing”), in which the rat remained immobile, but reacted with backward defensive behavior to investigative, non-aggressive contact initiated by the partner. In the present study, we aimed to extend our understanding of PAG mediation of defensive behavior by observing: (i) in a non-aggressive social interaction test, the behavioral effects of microinjections of low doses of kainic acid (40 pmol in 200 nl) made in the caudal third of the PAG; and (ii) the behavioral and cardiovascular effects of microinjections of d, l-homocysteic acid (5–10 nmol in 50–100 nl) made in the PAG of the unanesthetized decerebrate rat. Kainic acid injections into the area lateral to the midbrain aqueduct in the caudal third of the PAG evoked: (i) forward avoidance behavior, characterized by forward locomotion and occasional hop/jumps; (ii) reactive immobility (“freezing”), in which the rat remained immobile, but reacted with forward avoidance behavior to investigative, non-aggressive contact initiated by the partner; and (iii) 22–28 kHz ultrasonic vocalizations. These injections also evoked a dramatic increase in defensive responsiveness to tactile stimuli on the half of the body contralateral, but not ipsilateral, to the site of injection. Electroencephalographic measurements indicated that none of these effects were secondary to seizure activity. In the decerebrate rat, d, l-homocysteic acid injections in the caudal third of the PAG evoked forward running movements along with increased blood pressure and heart rate, the strongest effects being evoked from the region lateral to the midbrain aqueduct. More rostrally, sites in the intermediate PAG evoked backward “defensive” movements, which were also associated with increased blood pressure and heart rate. These data, along with those from our previous study in the rat indicate that: (i) defensive reactions are integrated within a longitudinal neuronal column which spans the caudal two thirds of the lateral PAG; (ii) the lateral PAG “defensive behavior” column contains two distinct populations of neurons, one within the intermediate lateral PAG which integrates defensive behavior characterized by facing towards and backing away from a “threatening” stimulus, and a second in the caudal lateral PAG which integrates defensive behavior characterized by forward avoidance behavior; and (iii) neurons within the lateral PAG couple strong cardiovascular changes with each distinctive defensive behavior pattern. The emerging view from this and recent studies of this midbrain region in other species, suggests that similar rostrocaudal differences within a longitudinally oriented lateral PAG neuronal column represent a fundamental principle underlying the PAG organization of defensive behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227243
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    Development of human precision grip (1992)
    Springer
    Experimental brain research 90 (1992), S. 393-398 
    Details
    ISSN: 1432-1106
    Keywords: Precision grip ; Motor programming ; Motor development ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of anticipatory control during lifts with the precision grip was examined in 100 children aged 1 to 15 years and in 15 adults. The children were instructed to lift an instrumented test object by using the precision grip between the thumb and index finger. The employed grip force, load force (vertical lifting force), vertical position and their corresponding time derivatives (i.e., grip and load force rates and acceleration) were recorded. The weight of the object was varied between trials to access the influence of the object's weight in the previous trial on the isometric force output. Already by the second year, children began to use information pertaining to the object's weight in the previous lift, i.e., they began to use an anticipatory control strategy. This occurred concomitant to the development of mainly bell shaped force rate profiles (Forssberg et al. 1991). The succeeding development of a more mature anticipatory control was gradual and adult-like capacity was not reached until 8–11 years of age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227253
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    Phase-dependent reversal of reflexly induced movements during human gait (1992)
    Springer
    Experimental brain research 90 (1992), S. 404-414 
    Details
    ISSN: 1432-1106
    Keywords: Human gait ; Sural nerve ; Ankle angle ; Reflex reversal ; Phase-dependent modulation ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To investigate whether phase-dependent reversals in reflex responses on electromyography (EMG) are accompanied by movement reversals, a series of human volunteers were studied for their behavioural responses to sural nerve stimulation during running or walking on a treadmill. Low-intensity stimulation (〈 2.5 x perception threshold, T) of the sural nerve yielded facilitatory responses in the tibialis anterior muscle (TA), correlated with an induced ankle dorsiflexion (mean maximum 4°) in early swing. The same stimuli yielded primarily TA suppression and weak ankle plantar flexion (mean maximum 1°) at end swing. The correlated induced knee angle changes did not precede the ankle changes, and they were relatively small. Mean maximum flexion in early swing was 6.2°, while mean maximum extension was 3.7°. High-intensity stimulation of the sural nerve (〉 2.5 x T) always gave rise to suppression of the ongoing activity. This resulted in a second type of movement reversal. During late stance and early swing the responses in TA were suppressive (i.e. below background activity) and related to ankle plantar flexion. In contrast, the responses during early and middle stance consisted of suppression in extensor activity (gastrocnemius medialis and soleus) and ankle dorsiflexion. The data are discussed in terms of a new hypothesis, which states that the responses to electrical stimulation of cutaneous nerves during locomotion do not correspond directly to corrections for stumbling following mechanical perturbations during the step cycle. Instead, the data invite a reinterpretation in terms of the opening and closing of reflex pathways, presumably by a central pattern generator for locomotion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227255
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    Functional organization of the nociceptive withdrawal reflexes (1992)
    Springer
    Experimental brain research 90 (1992), S. 469-478 
    Details
    ISSN: 1432-1106
    Keywords: Pain ; Nociception ; Spinal cord ; Withdrawal reflexes ; Spinal cord injury ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spatial organization of the cutaneous input to hindlimb withdrawal reflexes was studied in spinalized, decerebrated, unanesthetized rats. Reflex activity in plantar flexors of the digits, pronators of the foot, dorsiflexors of the digits, and/or the ankle and flexors of the knee was recorded with electromyographic techniques for up to 12 h after spinalization. Graded mechanical (pinch) and thermal stimulation (CO2 laser) of the skin were used. Reflexes were absent (“spinal shock”) during approximately 10–20 min after spinalization. The reflex thresholds for pinch and CO2 laser stimulation then decreased considerably during the following 5–8 h. After this time, even mild pressure (less than 0.1 N/mm2) on the skin was sufficient to evoke a reflex in most muscles. During the period from about 0.5–3 h after spinalization, the nociceptive receptive field of each muscle usually corresponded to the area of the skin withdrawn by the muscle. Maximal responses were evoked from the area of the receptive field maximally withdrawn. During this period, responses to innocuous pinch were evoked mainly from the most sensitive area of the receptive fields. Concomitant with the decrease in reflex thresholds, the nociceptive receptive fields expanded for all muscles, often to include areas of the skin not withdrawn by the muscles. For most muscles, reflexes on tactile stimuli were eventually elicited from the entire receptive fields. The receptive fields for thermonociceptive and mechanonociceptive inputs were similar in most muscles. The interossei muscles were exceptional in that they responded very weakly to thermal stimulation. It is concluded that there are neuronal networks in the spinal cord that translate cutaneous nociceptive and tactile input into a withdrawal. However, the control exerted by descending pathways is necessary to maintain a functionally adequate excitability in these reflex pathways and an appropriate size for their receptive fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230929
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    Axonal and dendritic arborization of an intracellularly labeled chandelier cell in the CA1 region of rat hippocampus (1992)
    Springer
    Experimental brain research 90 (1992), S. 519-525 
    Details
    ISSN: 1432-1106
    Keywords: Interneuron ; Axo-axonic cell ; Pyramidal cell ; Inhibition ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During the course of an in vivo intracellular labeling study, a chandelier (axo-axonic) cell was completely filled with biocytin in the CA1 region of the hippocampus. Chandelier cells are known to provide GABAergic terminals exclusively to the axon initial segment of pyramidal cells. The lateral extent and laminar distribution of the dendritic arborization of the chandelier cell was very similar to that of pyramidal cells; the numerous basal and apical dendrites reached the ventricular surface and the hippocampal fissure, respectively. The dendrites, however, had very few spines. The neuron had an asymmetric axonal arbor occupying an elliptical area of 600 by 850 μm in the pyramidal cell layer and stratum oriens, with over three-quarters of the axon projecting to the fimbrial side of the neuron. Counting all clusters of terminals, representing individually innervated axon initial segments, the chandelier cell was estimated to contact 1214 pyramidal cells, a number that exceeds previous estimations, based on Golgi studies, by several-fold. The findings support the view that chandelier cells may control the threshold and/or synchronize large populations of principal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230934
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    Intracellular calcium and hormone release from nerve endings of the neurohypophysis in the presence of opioid agonists and antagonists (1992)
    Springer
    Experimental brain research 90 (1992), S. 539-545 
    Details
    ISSN: 1432-1106
    Keywords: Opioid peptides ; Neurohypophysis ; Nerve endings ; Vasopressin ; Oxytocin ; Calcium ; Release ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rat neural lobes and isolated nerve terminals from the neurohypophysis were stimulated in the presence of different opioid agonists and antagonists. The secretion of arginine vasopressin and oxytocin and rise in cytoplasmic calcium induced by depolarization were analyzed by radioimmunoassay and the fluorescent probe fura-2, respectively. The kappa-agonists dynorphin A1 -13 and dynorphin A1 -8 did not affect electrically evoked release of vasopressin, although oxytocin release was slightly reduced. U-50 488, a relatively specific kappa-receptor agonist, had no effect on the amount of vasopressin or oxytocin secreted, although it significantly reduced K+-evoked changes in [Ca2+]i in isolated nerve endings. Two kappa-receptor antagonists, MR 2266 and diprenorphin, alone had no effect on vasopressin and oxytocin secretion from isolated nerve endings depolarized with potassium. Opioid agonists less selective for the kappa receptors, etorphin and ethylketocyclazocin, were found to inhibit the release of both vasopressin and oxytocin significantly. Naloxone, a nonselective opiate receptor antagonist, alone had no effect on vasopressin release but potentiated the electrically evoked release of oxytocin. Naloxone also could overcome the inhibitory effect of etorphin on oxytocin and vasopressin release observed after electrical stimulation of the neural lobe. A number of inconsistencies therefore exist between the effects of opioid agonists and antagonists on neuropeptide release and on the evoked changes in [Ca2+]i. In view of these inconsistencies and the high concentrations of opioid agonists and antagonists necessary to modify release, we conclude that it is doubtful that opioid molecules have a physiological role in controlling neurohypophysial secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230936
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    Distribution of heteronymous Ia facilitation and recurrent inhibition in the human deltoid motor nucleus (1992)
    Springer
    Experimental brain research 90 (1992), S. 620-624 
    Details
    ISSN: 1432-1106
    Keywords: Ia afferents ; Recurrent inhibition ; Upper limb ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Distribution of heteronymous Ia facilitation and of heteronymous recurrent inhibition in motoneurones innervating the anterior part of the deltoid muscle were investigated in normal human subjects following electrical stimulation of the nerves innervating the main muscles of the upper limb. Activation of group I afferents originating from deltoid, biceps, triceps and extensor carpi radialis (ECR) muscles resulted in an early increase in firing probability of voluntarily activated motor units belonging to the anterior part of the deltoid muscle whereas activation of motor axons supplying deltoid, triceps, ECR and flexor carpi radialis (FCR) muscles resulted in an early and long-lasting decrease in firing probability. No effect was seen following activation of group I afferents and motor axons contained in the ulnar nerve. The characteristics of the early facilitation suggest that it is at least partly due to heteronymous Ia monosynaptic connections while these of the long-lasting inhibition suggest that it is at least partly due to heteronymous recurrent inhibition. Their patterns of distribution are discussed with regards to the functional role of the human deltoid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230946
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    Effects of sensory deprivation upon a single cortical vibrissal column: a 2DG study (1992)
    Springer
    Experimental brain research 90 (1992), S. 639-642 
    Details
    ISSN: 1432-1106
    Keywords: Vibrissae ; Barrels ; Somatosensory cortex ; 2-deoxyglucose ; Neuronal plasticity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of sensory deprivation upon ability of a vibrissa to activate a functional column in the barrel field of somatosensory cortex were examined with 2 deoxyglucose (2DG) autoradiography in the rat. After six weeks of whisker plucking started at birth, and one week of recovery, the cortical column activated by the deprived whisker and labeled with 2DG had a reduced diameter but higher labeling density than the normal vibrissal column. Loss of a peri-barrel labeling zone, possibly due to loss of intracortical activation, is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230950
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  • 82
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    Brain stem projections of rat lumbar dorsal root ganglia studied with choleragenoid conjugated horseradish peroxidase (1992)
    Springer
    Experimental brain research 91 (1992), S. 12-20 
    Details
    ISSN: 1432-1106
    Keywords: Choleragenoid ; Horseradish peroxidase ; Lumbar spinal ganglia ; Brainstem nuclei ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brain stem projections from each of the L1–L6 lumbar dorsal root ganglia (DRGs) were investigated in adult rats following DRG injections of choleragenoid-horseradish peroxidase. All these DRGs projected throughout the rostrocaudal extent of the gracile nucleus (Gr). Labeling from L1–L6 DRGs was transported to successively more dorsomedial areas of Gr. Investigation of the Gr projections from the DRGs revealed a somatotopic organization which was most prominent in the middle part of Gr. The cuneate nucleus showed smaller projections from all investigated DRGs. Minor projections to the internal basilar nucleus, external cuneate nucleus, medial vestibular nucleus, ventral cochlear nucleus and trigeminal sensory nuclei were also found from some of the DRGs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230009
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  • 83
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    Distribution of glutamate-like and glutamine-like immunoreactivities in the rat organ of Corti: a light microscopic and semiquantitative electron microscopic analysis with a note on the localization of aspartate (1992)
    Springer
    Experimental brain research 91 (1992), S. 1-11 
    Details
    ISSN: 1432-1106
    Keywords: Glutamate ; Glutamine ; Cochlea ; Neurotransmitter ; Immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The light- and electron microscopic localization of glutamate and glutamine in the rat organ of Corti was studied by means of antisera raised against the respective amino acids coupled to carrier proteins. The light microscopic analysis was performed in semithin sections treated according to the peroxidase-antiperoxidase procedure. The two amino acids were visualized in the same ultrathin sections by use of postembedding immunocytochemistry with two different gold particle sizes. The distribution of aspartate-like immunoreactivity was also recorded, but only at the light microscopic level. In the hair cells, the level of glutamate-like immunoreactivity was higher than that in supporting cells but lower than that in the presumed glutamatergic terminals of cerebellar parallel and mossy fibres. The latter types of terminal were sampled from ultrathin sections that had been incubated under the same conditions as the cochlear sections. Within the hair cells, gold particles signalling glutamate were enriched on mitochondria but not on clusters of synaptic vesicles. Glutamine-like immunoreactivity was present in hair cells as well as supporting cells. The glutamate/glutamine ratio, expressed as the ratio between the respective gold particle densities, was considerably lower for hair cells compared with the cerebellar excitatory terminals. No consistent difference was found between outer and inner hair cells in relation to the levels and subcellular distribution of glutamate and glutamine immunoreactivities. Aspartate-like immunoreactivity was accumulated in outer hair cells, with some labelling also of border cells and Böttcher cells. While the present study confirmed the presence of glutamate in hair cells and demonstrated that these cells are also endowed with the important glutamate precursor glutamine, it revealed notable differences between hair cells and presumed glutamatergic terminals in the CNS. These could reflect differences in the synthesis and compartmentation of transmitter glutamate. Methodological factors could also contribute. Alternatively, the differences could be interpreted to suggest that the hair cell transmitter is not glutamate, but a similar compound. Aspartate could be a candidate in the case of the outer hair cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230008
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  • 84
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    Further evidence for myelinated as well as unmyelinated fibre damage in a rat model of neuropathic pain (1992)
    Springer
    Experimental brain research 91 (1992), S. 73-78 
    Details
    ISSN: 1432-1106
    Keywords: Hyperalgesia ; Peripheral neuropathy ; Nerve histopathology ; Neuropathic pain ; Unmyelinated fibre ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A mononeuropathy, produced by ligation of the sciatic nerve in rats, has recently been proposed as an animal model of experimental pain and pain-related disorders (hyperalgesia and allodynia). We investigated quantitatively the morphological changes in myelinated and unmyelinated fibres of the sciatic nerves 2 weeks after ligation in rats exhibiting allodynia to thermal stimulation. There was a marked reduction in the number of large myelinated fibres distal to the ligature (711 ± 34 compared with 5315 ± 230 in normal nerves). We also found a significant loss of small myelinated fibres (2429 ± 109 compared with 3197 ± 308 in normal nerves), the remaining fibres of this type showing pathological properties. Finally, ultrastructural evidence of damage to unmyelinated fibres was found. The typical pattern of large clusters of normal unmyelinated axons was no longer present within most regions of the nerve. There was a significant reduction in the size of the unmyelinated fibres (0.41 μm ± 0.15 compared with 0.71 μm ± 0.08 in normal nerves), together with a twofold increase in their number per cluster. Hypotheses about the mechanism of thermal allodynia in this pain model therefore must take into account the fact that all fibre classes show pathological changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230014
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  • 85
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    Effects of practice on final position reproduction (1992)
    Springer
    Experimental brain research 91 (1992), S. 129-134 
    Details
    ISSN: 1432-1106
    Keywords: Voluntary movement ; Motor control ; Location programming ; Distance programming ; Equilibrium-point hypothesis ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three subjects practiced fast, accurate 36° elbow flexion movements to a 2.5° target for 14 sessions of 100 trials (total, 1400 trials). Subjects then returned for a 15th experimental session in which they were asked to perform 15 movements under identical conditions to the practice condition. They were then tested under three experimental conditions without visual feedback: (1) identical to the practice conditions, (2) with small shifts in starting position (± 3° of the practiced starting position), that were insufficient for subjective discrimination and, therefore, subjects were instructed to repeat the practiced movements; and (3) with a large shift in starting position (range, ± 15° of the practiced starting position), under the instruction to move to the same target. Experimental conditions 2 and 3 demonstrated that shifts in starting position were partially correlated with shifts in final position. These results are interpreted from the point of view of the equilibrium-point hypothesis of motor control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230021
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  • 86
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    Does limb proprioception drift? (1992)
    Springer
    Experimental brain research 91 (1992), S. 162-166 
    Details
    ISSN: 1432-1106
    Keywords: Motor control ; Vision ; Proprioception ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The hypothesis that proprioceptively perceived limb position drifts during visual occlusion was re-examined by combining some of the protocols used in previous experiments. Sixteen adult subjects made judgements of static limb position during visual occlusion lasting up to 2 min. In addition, the effect of brief 250 ms “glimpses” of the limb, occasional proprioceptive stimulation and directed attention were examined. Despite, conflicting evidence from earlier experiments, there was clear evidence of a drift in perceived limb position, towards the body, during visual occlusion. This drift was halted if brief glimpses of the limb were provided, or minor re-positioning (without vision) was allowed. In neither case, however, did the supplementary cues reset limb position to its originally perceived position. Drift was amplified when subjects attempted to attend to limb position rather than perform a secondary tracking task. The results are not easily accounted for if drift is considered purely as an effect of peripheral sensor adaptation. A notion of central-drift between visual and proprioceptive maps is suggested as an alternative hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230024
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  • 87
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    Observations on the development of transplanted embryonic ventral horn neurones grafted into adult rat spinal cord and connected to skeletal muscle implants via a peripheral nerve (1992)
    Springer
    Experimental brain research 91 (1992), S. 249-258 
    Details
    ISSN: 1432-1106
    Keywords: Transplantation ; Developmental neurobiology ; Retrograde labelling ; Immunocytochemistry ; Acetylcholinesterase histochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Embryonic spinal cord grafts from 12-day-old rat embryos were placed into the lumbar spinal cord of adult rats depleted of sciatic motoneurones by a neonatal nerve injury. A soleus muscle was removed from the leg and implanted paravertebrally, the proximal end of its nerve connected to the graft site. Fluorescent retrograde tracers injected into the soleus implant, 37–64 days postoperatively, labelled neurones that had grown axons to the muscle. Approximately one-fifth of retrogradely labelled neurones were within the graft; however, the majority were found within the host spinal cord close to the graft. These included large neurones within the motoneurone-depleted dorsolateral ventral horn. In control experiments a muscle and nerve were implanted but no embryonic tissue grafted. Significantly fewer neurones were labelled. In some animals, one tracer was injected into the soleus muscle whilst another was applied to the cut sciatic nerve ipsilateral to the graft site. No neurones were found to project axons to both targets. In animals that received grafts prelabelled with bromodeoxyuridine (BrDU) some neurones were found to be both BrDU positive and retrogradely labelled from the soleus implant. These were most frequently within the motoneuronedepleted ventral horn ipsilateral to the graft. Thus, grafted neurones may migrate to an appropriate location within the host neuropil. Acetylcholinesterase (AChE) histochemistry showed the graft site contained immature but AChE-positive neurones. Some regions of host ventral horn contained unusually few AChE-positive nerve fibres and occasional large AChE-positive neurones, some of which were also retrogradely labelled from the implanted muscle. Studies of implanted soleus 21–90 days after transplantation showed that muscle fibres, after initial degeneration, regenerated displaying differing phenotypes, presumably under the influence of new motor innervation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231658
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  • 88
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    The transcortical nature of the late reflex responses in human small hand muscle to digital nerve stimulation (1992)
    Springer
    Experimental brain research 91 (1992), S. 320-326 
    Details
    ISSN: 1432-1106
    Keywords: Long-latency reflex ; Cortex ; Magnetic stimulation ; Cutaneous reflexes ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The hypothesis that long-latency reflex activity in human small hand muscles in response to stimulation of digital nerves involves a transcortical pathway was tested by combining digital nerve stimulation and magnetic stimulation over the motor cortex in 12 studies on nine normal subjects. Postsynaptic events in human single first dorsal interosseous (FDI) motoneurones were derived from changes in the firing probability of voluntarily activated single motor units. Electromagnetic stimulation over the contralateral motor cortex resulted in a short-latency, brief facilitation of FDI motor units considered to be due to the activation of “fast” corticospinal neurones making monosynaptic projections to motoneurones. Stimulation of the digital nerves of the index finger produced a period of reduced firing probability (I1), a period of increased firing probability (E2) and a further period of reduced firing probability (I2) in FDI motor units. When the two stimuli were given separately and then together, timed so that the magnetic stimulus occurred at the predicted transit time of the E2 through the cortex, the facilitation of FDI motoneurones by the combined stimulation was often less than the algebraic sum of the facilitations from each stimulus alone. Thus, in contrast to the results of similar studies on the late response to muscle stretch, there is no confirmation that the E2 from digital nerve stimulation is due to a transcortical reflex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231665
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  • 89
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    Difference in taste quality coding between two cortical taste areas, granular and dysgranular insular areas, in rats (1992)
    Springer
    Experimental brain research 91 (1992), S. 415-424 
    Details
    ISSN: 1432-1106
    Keywords: Taste ; Insular cortex ; Response profile ; Inhibitory response ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The responses of 84 taste neurons to stimulation of the oral cavity in rats were examined; most taste neurons were found in either a granular insular area (area GI; n = 55) or dysgranular insular area (DI; n = 25), and the others (n = 4) were in an agranular insular area (area AI). The fraction of neurons responding to only one of the four basic stimuli was significantly larger in area GI than in area DI. When neurons were classified by the stimulus which most excited the neuron among the four basic stimuli, every “best-stimulus category” of neurons was found in both GI and DI areas. Quinine-best and “multistimulus-type” neurons, whose responses to some non-best stimulus exceeded 90% of the maximum, were more numerous in the cortex than in the thalamocortical relay neurons. When responses were plotted against taste stimuli arranged in the order of sucrose, NaCl, HCl, and quinine along the abscissa (taste coordinate), response profiles of taste neurons often showed two peaks. The double-peaked type of response profiles were found in every best-stimulus category of neurons in both areas; though, a significantly large fraction of quinine-best neurons in area GI were of the double-peaked type. Some taste neurons in area GI (n = 21) and in area DI (n = 7) were inhibited by one to two taste stimuli, particularly by the stimuli present next to the best one along the taste coordinate. In correlation profiles — correlation coefficients between sucrose and NaCl and between HCl and quinine — pairs of stimuli which were located next to each other on the taste coordinate were significantly smaller in area GI than in area DI. It is thus highly probable that area GI plays an important role in fine taste discrimination and area DI in integration of taste information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227838
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  • 90
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    Experimental study and modeling of vestibulo-ocular reflex modulation during large shifts of gaze in humans (1992)
    Springer
    Experimental brain research 91 (1992), S. 496-508 
    Details
    ISSN: 1432-1106
    Keywords: Vestibulo-ocular reflex ; Eye-head coordination ; Eye movements ; Gaze movements ; Model simulation ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An experimental study of head-free and headfixed gaze shifts explores the role of the vestibulo-ocular reflex (VOR) during saccadic and slow phase components of the gaze shifts. A systematic comparison of head-free and head-fixed gaze shifts in humans revealed that while the VOR is switched off as soon as the saccade starts, its function is progressively restored during the terminal phase of the saccade. The duration of this restoration period is fairly constant; therefore, the faster the gaze saccade, the sooner the VOR function starts to be restored. On the basis of these experimental data, a new eye-head coordination model is proposed. This model is an extension of the one proposed by Laurutis and Robinson (1986) where VOR gain is a function of both the dynamic gaze error signal and head velocity. This extension has also been added to another eye-head coordination model (Guitton et al. 1990). Both modified models yield simulation results comparable to experimental data. This study pinpoints the high efficiency of the gaze control system. Indeed, a fixed period of time (≈40 ms) is needed to restore the inhibited VOR; the gaze control system thus must have a knowledge of its own dynamics in order to be able to anticipate the end of the saccadic movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227846
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  • 91
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    Human ocular following responses are plastic: evidence for control by temporal frequency-dependent cortical adaptation (1992)
    Springer
    Experimental brain research 91 (1992), S. 525-538 
    Details
    ISSN: 1432-1106
    Keywords: Ocular following ; Eye movements ; Optokinetic nystagmus ; Visual stabilization ; Smooth pursuit ; Motion adaptation ; Motion aftereffects ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Optokinetic nystagmus (OKN) induced by wide-field visual stimulation was measured with and without prior adaptation to moving sinusoidal gratings. Under unadapted conditions the mean gains of the slow phases of OKN in the first 500 ms were 0.5–0.8, and the eye velocities and amplitudes had rise times with time constants of 0.1–0.2 s. By contrast, following adaptation to as little as 1 s of image motion, the magnitude of the initial gains fell and the rise times of the velocities and amplitudes increased markedly. The degree of adaptation depended on the adapting temporal frequency, the optimum adaptive frequencies being 1.7–3.4 Hz. In this range of temporal frequencies, the initial gains fell to 0.1–0.3 and the rise times for velocity and amplitude ranged from 0.4 to 7.0 s, depending on the length of the adapting period. Thus the observed changes in the time constant were up to 70-fold. Neither spatial frequency or image velocity had any marked influence on the level of adaptation. The dependence on temporal frequency rather than image velocity suggests that the motion detectors feeding the adaptive system respond to local motion-related changes in luminance. The adaptive effects were direction-selective, showing that this must also be the case for the motion detectors. The adaptive effects were observed both when the drift temporal frequency on the retina was established by artificially maintaining a fixed gaze or when the adapting temporal frequency was induced by retinal slip during OKN. Time constants for recovery from adaptation were similar to motion aftereffects measured by psychophysical and physiological methods. The results suggest a link between cortical motion adaptation and adaptive mechanisms effecting the oculomotor system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227849
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  • 92
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    Effects of weak antagonist on fast elbow flexion movements in man (1992)
    Springer
    Experimental brain research 91 (1992), S. 509-519 
    Details
    ISSN: 1432-1106
    Keywords: Voluntary movements ; Antagonist muscle ; Quadriplegia ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary By using a mathematical model and experiments involving electrical simulation of antagonistic muscles, we have formed the hypothesis (Wierzbicka et al. 1986) that in one-joint movements the antagonist muscle not only provides braking torque but also controls movement time. To get additional experimental support for this hypothesis, we studied elbow flexion movements performed by patients with spinal cord injury at the C 5–6 level who had relatively normal strength in their biceps muscle and little or no voluntary control of the triceps. Seven quadriplegic patients and six control subjects performed elbow flexion movements of 10°, 20°, and 30° “as fast and accurately as possible”. Despite the lack of antagonist, patients used the same “pulse height” strategy as control subjects to scale their responses with movement amplitude. However, patients' movement time was on average twice that of control subjects, and durations of both accelerative and decelerative phases of movement were increased. Movement speed and acceleration were reduced to 20–50% of the corresponding values of control subjects. Patients tended to overshoot the target to a larger extent than control subjects, particularly 10° targets, with nearly twice the error. We performed the same experiments using an external torque motor to assist the weak triceps. When a constant extensor torque of 2.5 or 5 Nm was provided by the motor, patients were able to move faster, and movement accuracy improved to within the normal range. These results provide direct evidence that the lack of an antagonist has an important effect on completion time and accuracy of fast goal-directed movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227847
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  • 93
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    Independent control of the digits: changes in perceived heaviness over a wide range of force (1992)
    Springer
    Experimental brain research 91 (1992), S. 539-542 
    Details
    ISSN: 1432-1106
    Keywords: Motor commands ; Hand function ; Perceived heaviness ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Perceived heaviness of a weight lifted by flexion of the distal joint of one digit increases when an adjacent digit concurrently lifts a weight. The present study confirmed this finding for relatively low weights (representing 3–5% maximal voluntary force) and a method was adapted to show that this effect occurs for much larger weights (20–25% maximal force). Thus, the increase in perceived heaviness is likely to operate over a wide range of muscle force generated by the hand. As perceived heaviness is biased by the magnitude of the central motor commands, these findings may reflect a lack of complete independence of motor commands to the long flexor muscles acting on the digits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227850
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  • 94
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    Spinothalamic and propriospinal neurones in the upper cervical cord of the rat: terminations of primary afferent fibres on soma and primary dendrites (1992)
    Springer
    Experimental brain research 92 (1992), S. 59-68 
    Details
    ISSN: 1432-1106
    Keywords: Cervical ; Cuneate ; Trigeminal ; Primary afferents ; Somatosensory ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were performed on rats to determine whether primary afferents from the upper cervical region terminate directly on Spinothalamic and propriospinal neurones. The central terminations of primary afferents from the upper cervical region were identified by diffusely filling their axons with horseradish peroxidase. Spinothalamic neurones or propriospinal neurones were identified in the same experimental animals by using retrograde transport of wheat germ agglutinin conjugated to horseradish peroxidase. Approximately 3–11 % of Spinothalamic cells in laminae 4–6 of spinal segments C2–4 received apparent synaptic contacts from primary afferents on the soma or primary dendrites. Approximately 18–36% of propriospinal neurones with axons descending to lower thoracic or lumbar levels received apparent synaptic contacts on the soma or primary dendrites. These data provide anatomical evidence that Spinothalamic and long propriospinal neurones in the upper cervical cord are excited directly by primary afferents. The data also help to clarify the neural circuitry underlying somatic sensation and reflex movements evoked by neck receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230383
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  • 95
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    Receptor subtypes involved in callosally-induced postsynaptic potentials in rat frontal agranular cortex in vitro (1992)
    Springer
    Experimental brain research 88 (1992), S. 33-40 
    Details
    ISSN: 1432-1106
    Keywords: Corpus callosum ; Frontal agranular cortex ; GABA receptor ; NMDA receptor ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A slice preparation of rat frontal agranular cortex preserving commissural inputs has been used for intracellular recording from layer V pyramidal cells, in order to characterize the synaptic potentials induced by stimulation of the corpus callosum and to reveal the subtypes of amino acid receptors involved. Stimulation of the corpus callosum induced EPSPs followed by early IPSPs with a peak latency of 30 ± 2 ms and late IPSPs with a peak latency of 185 ± 18 ms. Reversal potentials for early and late IPSPs were −75 ± 5 mV (early) and −96 ± 5 mV (late). Late IPSPs were more dependent on extracellular K+ concentration. The early IPSPs were blocked by GABAA antagonists, bicuculline and picrotoxin, whereas the late IPSPs were reduced by the GABAB antagonist, phaclofen. CNQX (6-cyano-7-nitroquinoxaline-2,3-dione), an antagonist of non-NMDA (N-methyl-D-aspartate) receptors, suppressed both EPSPs and late IPSPs at 5 µM. Early IPSPs remained at this concentration but were suppressed by 20 µM CNQX. In Mg2+-free solution, EPSPs were larger and more prolonged than in control solution. These enhanced EPSPs persisted after 5 to 20 µM CNQX, but were reduced in amplitude, and their onset was delayed by 3.6 ± 0.8 ms. The remaining EPSPs were suppressed by 50 µM APV (DL-2-amino-5-phosphono-valeric acid), an antagonist of NMDA receptors. In Mg2+-free solution containing 5 to 20 µM CNQX, the late IPSPs were not diminished. The remaining late IPSPs were suppressed by APV or by phaclofen. By contrast, the amplitude of early IPSPs was not affected by APV in Mg2+-free solution containing 5 µM CNQX. These results show that stimulation of the corpus callosum can induce GABAA and GABAB dependent IPSPs and NMDA and non-NMDA dependent excitation. It is suggested that these four types of amino acid-based transmission are conveyed by intracortical pathways with different characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259126
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  • 96
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    Ultrastructural changes in the hippocampal CA1 region following transient cerebral ischemia: evidence against programmed cell death (1992)
    Springer
    Experimental brain research 88 (1992), S. 91-105 
    Details
    ISSN: 1432-1106
    Keywords: Cerebral ischemia ; Glutamate ; Heat shock protein ; Hippocampus ; Programmed cell death ; Rat ; Ubiquitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructural changes in the pyramidal neurons of the CA1 region of the hippocampus were studied 6 h, 24 h, 48 h, and 72 h following a transient 10 min period of cerebral ischemia induced by common carotid occlusion combined with hypotension. The pyramidal neurons showed delayed neuronal death (DND), i.e. at 24 h and 48 h postischemia few structural alterations were noted in the light microscope, while at 72 h extensive neuronal degeneration was apparent. The most prominent early ultrastructural changes were polysome disaggregation, and the appearance of electron-dense fluffy dark material associated with tubular saccules. Mitochondria and nuclear elements appeared intact until frank neuronal degeneration. The dark material accumulated with extended periods of recirculation in soma and in the main trunks of proximal dendrites, often beneath the plasma membrane, less frequently in the distal dendrites and seldom in spines. Protein synthesis inhibitors (anisomycin, cycloheximide) and an RNA synthesis inhibitor (actinomycin D), administered by intrahippocampal injections or subcutanously, did not mitigate neuronal damage. Therefore, DND is probably not apoptosis or a form of programmed cell death. We propose that the dark material accumulating in the postischemic period represents protein complexes, possibly aggregates of proteins or internalized plasma membrane fragments, which may disrupt vital cellular structure and functions, leading to cell death.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259131
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  • 97
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    Motor function, graft survival and gliosis in rats with 6-OHDA lesions and foetal ventral mesencephalic grafts chronically treated with L-DOPA and carbidopa (1992)
    Springer
    Experimental brain research 88 (1992), S. 326-340 
    Details
    ISSN: 1432-1106
    Keywords: 6-OHDA lesion ; Foetal ventral mesencephalic graft ; L-DOPA and carbidopa ; Parkinson's disease ; Circling behaviour ; Neural grafting ; Gliosis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In rats with a unilateral 6-OHDA lesion of the nigrostriatal pathway, foetal ventral mesencephalic grafts implanted into the 6-OHDA-lesioned striatum produced a reduction in apomorphine-induced contralateral rotation, and complete abolition of (+)-amphetamine-induced ipsilateral rotation. The graft-induced reduction of apomorphine and (+)-amphetamine-induced rotation was not affected by chronic 27 week administration of L-DOPA and carbidopa to rats receiving foetal grafts. TH-immunohistochemistry revealed 〉96% loss of dopamine cells in the substantia nigra ipsilateral to the 6-OHDA lesion in all animals, but cell loss in the ipsilateral ventral tegmental area was more variable (21–46% of the intact side). TH-positive cells in the intact substantia nigra and ventral tegmental area were not affected by chronic treatment with L-DOPA and carbidopa. In the lesioned striatum of rats receiving sham grafts, no TH-positive cells or fibres were seen. In the 6-OHDA-lesioned striatum of animals receiving foetal grafts, many TH-positive cells were seen in the grafts and chronic treatment with L-DOPA and carbidopa did not reduce cell survival. GFA-P immunohistochemistry revealed that a unilateral 6-OHDA lesion followed by a sham graft was not associated with a reactive gliosis reaction in the striatum at the time of study (38 weeks after lesion surgery and 30 weeks after sham-graft), and treatment of such rats with L-DOPA and carbidopa was also without effect on glia. In contrast there was a marked gliosis in the striatum surrounding foetal grafts which was unaffected by chronic treatment with L-DOPA and carbidopa. The grafts themselves were surrounded by a rim of glial cells, and the glial density within the grafts was higher in animals receiving chronic L-DOPA and carbidopa treatment. However, there was no obvious relationship between the number of TH-positive cells within the grafts, or graft volume, and glial cell density within the grafts. These results suggest that long-term treatment with L-DOPA and carbidopa does not impair either the behavioural recovery produced by foetal ventral mesencephalic grafts in rats or the long-term survival of grafts as revealed by TH-immunohistochemistry. The presence of a foetal graft is associated with a reactive gliosis in the implanted striatum, which was not altered by long-term treatment with L-DOPA and carbidopa. However such treatment did result in an increase in glial density within the grafts themselves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259108
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  • 98
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    Electronic Resource
    Is there a dopaminergic projection from the A11 catecholamine cell group to the amygdala? (1992)
    Springer
    Experimental brain research 88 (1992), S. 451-454 
    Details
    ISSN: 1432-1106
    Keywords: Subparafascicular area ; Amygdala ; Striatum ; Fluorescent tracer ; Tyrosine hydroxylase immunohistochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The dopaminergic nature of the pathway from the subparafascicular thalamic nucleus and its adjacent region to the amygdala was reexamined by means of retrograde fluorescent tracers coupled with tyrosine hydroxylase (TH) immunofluorescence. After injecting a small amount of tracer into the amygdala, retrogradely labeled cells were found in the subparafascicular thalamic nucleus and its adjacent periventricular region. TH immunofluorescence showed that these labeled cells completely lacked TH immunoreactivity. Similar results were obtained when a larger amount of tracer was applied to the amygdala. The present study, in contrast to the previous report describing the dopaminergic innervation of the amygdala by the cells in and around the subparafascicular area (A11 catecholamine cell group), indicates that the A11 cell group does not contribute to a dopaminergic input to the amygdala.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259121
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  • 99
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    Electronic Resource
    Glutamate-induced action potentials are preceded by regenerative prepotentials in rat hippocampal pyramidal cells in vitro (1992)
    Springer
    Experimental brain research 88 (1992), S. 485-494 
    Details
    ISSN: 1432-1106
    Keywords: Glutamate ; Hippocampal pyramidal cells ; Action potentials ; Prepotentials ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary (1) The responses of CA1 pyramidal cells to short glutamate pulses (10–50 ms) delivered at sensitive spots in the apical dendrites have been analysed by intracellular recording. (2) The glutamate pulses elicited stable depolarizing responses in a dose- and frequencydependent manner. (3) When a single action potential with a firing probability around 0.5 was elicited, a subtraction procedure showed that a slow depolarizing ramp preceded each spike. We call this ramp the glutamate-induced prepotential (GluPP). (4) In contrast to the upward convex subthreshold depolarization the GluPP was upward concave. (5) The GluPP amplitude and time course increased with depolarization of the membrane, a phenomenon which appears to be connected to the elevation of action potential threshold. (6) The GluPP was regenerative since once started, it ended in an action potential. (7) A specific N-methyl-D-aspartate receptor antagonist, DL-2-amino-5-phosphonovaleric acid (50 μM) reduced the glutamateinduced depolarization, but did not affect the form or amplitude of GluPP, once the latter was induced. (8) It is concluded that short glutamate pulses elicited action potentials through a prepotential mechanism, similar to the slow prepotentials induced by long depolarizing current pulses across the soma membrane. (9) A possible physiological role for the GluPP is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228178
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  • 100
    Electronic Resource
    Electronic Resource
    Somatosensory evoked potential correlates of psychophysical magnitude estimations for air-puff stimulation of the face in man (1992)
    Springer
    Experimental brain research 88 (1992), S. 639-644 
    Details
    ISSN: 1432-1106
    Keywords: Tactile air-puff stimulation ; Face ; Stimulus intensity ; Somatosensory evoked potentials ; Psycho-physical magnitude estimations ; Mechanical properties of the skin ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Air-puff stimuli were applied to the skin of the face to obtain psychophysical and neurophysiological responses. Six levels of stimulus intensity above threshold were adopted for numerical magnitude estimation and for recording somatosensory evoked potentials (SEPs). A power function with an exponent of 0.71 provided an adequate description of the magnitude estimation values as a function of stimulus intensity, as was verified by the high correlation coefficient (r=0.86, P 〈 0.001). Six SEP components (N15, P20, N30, P40, N50 and P65) were recorded during the 100 ms following stimulation. Stimulus-amplitude functions of the various SEP components were well represented by power functions. The P20-N30 component had the highest power exponent (0.66) and also the highest correlation coefficient (r=0.55, P 〈 0.001). The SEP latencies as a function of stimulus intensity had negative power functions. The latency function of the P20 component had the largest negative power exponent (-0.10) and showed the highest negative correlation (r = — 0.62) with the stimulus intensity. These results suggest that processing of intensity information occurs at a relatively early stage within the central nervous system, and that both the amplitude and latency information encoded in the SEPs may contribute to stimulus processing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228192
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