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  • 2000-2004
  • 1965-1969  (12)
  • 1967  (8)
  • 1966  (4)
  • Cat  (12)
  • Engineering General
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 117-134 
    ISSN: 1432-1106
    Keywords: Supraspinal effects ; Extrapyramidal pathways ; Spinal activity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of stimulation of the sensorimotor cortex on activity of the lumbosacral cord were studied in pyramidotomized cats. The following actions initiated by corticofugal volleys were found: 1. postsynaptic effects on motoneurones, mainly excitatory in flexor motoneurones and inhibitory or excitatory in extensor motoneurones, 2. facilitation of spinal reflexes to motoneurones at an interneuronal level, 3. depolarization of presynaptic terminals of group Ib and cutaneous fibres. The latencies of the earliest cortical effects on motoneurones as indicated by modification of monosynaptic reflexes or PSPs were 9–12 msec. Experiments with lesions of different spinal tracts suggest that the effects on motoneurones are mediated mainly by pathways in the ventral part of the lateral funiculus (probably reticulospinal), the facilitation of reflex transmission by pathways in the dorsal part of the lateral funiculus (probably rubrospinal) and primary afferent depolarization by both the former and the latter pathways. The strongest cortical effects were evoked by stimulation of an area around the postcruciate dimple.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 372-381 
    ISSN: 1432-1106
    Keywords: Red nucleus ; Inferior olive ; Muscle spindles ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cats anesthetized with halothane the influence of central stimulation upon the dynamic sensitivity of muscle spindles in the flexor digitorum longus muscle was studied. One mesencephalic and one medullary region were found which caused an increase in dynamic spindle sensitivity when stimulated electrically. Histological identification of stimulating points showed these regions to be the caudal pole of the red nucleus and the inferior olivary nucleus respectively. Lesions in the olive decreased rubral effects on the spindles, indicating that the red nucleus and the olive are parts of the same system descending to dynamic fusimotor neurones. Further evidence for this point are given in a following paper (APPELBERG 1967).
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 382-390 
    ISSN: 1432-1106
    Keywords: Red nucleus ; Inferior olive ; Cerebellum ; Muscle spindles ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the preceding paper (Appelberg and Molander 1967) the caudal part of the red nucleus and parts of the inferior olivary nucleus were shown to cause increased dynamic sensitivity of muscle spindles when stimulated repetitively. The results to be presented will show that single shock electrical stimulation in the caudal part of the red nucleus evoked a field potential in the inferior olivary nucleus. This response seemed to be monosynaptically evoked and was observed only in parts of the olive where repetitive stimulation caused increased dynamic sensitivity of muscle spindles. Stimulation in the red nucleus as well as single shock stimulation in the actual part of the inferior olive also caused a potential in the vermis of the posterior cerebellar lobe. In conditioning — test experiments with the two stimuli the conditioning shock was seen to cause alternating periods of decreased and increased responsiveness in the pathway concerned. The same type of interaction was seen between two responses caused by double shock stimulation in the red nucleus. It is concluded that information from the caudal part of the red nucleus reaches dynamic fusimotor neurones in the spinal cord via a relay in the inferior olivary nucleus; an additional relay in the pathway is also predicted. The cerebellum seems to receive information about ongoing activity in the pathway but mesencephalic stimulation was seen to cause spindle effects also in decerebellated animals.
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  • 4
    ISSN: 1432-1106
    Keywords: Monosynaptic reflex ; Presynaptic inhibition ; Extensor nerve ; Spinal cord ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Electrical stimulation of extensor nerves of the ankle has been used to investigate the presynaptic inhibition in a synergic monosynaptic reflex arc. 2. Depression of monosynaptic reflex response as well as increase in excitability of Ia afferent terminals in the MG (medial gastrocnemius) reflex arc is found following the conditioning stimulation of LGS (lateral gastrocnemius-soleus) nerve at Group I strength. 3. Excitability increase of the Ia terminals of the LGS nerve is also found following the conditioning stimulation of either a group of fibres of the same nerve or the MG nerve. 4. Conditioning by Group I afferent volleys from either the LGS or the PBST (posterior biceps-semitendinosus) muscles produces comparable changes in excitability of the Ia terminals from MG muscle. 5. The hypothesis is advanced that the depression of the monosynaptic reflex discharge during repetitive stimulation is mainly caused by the depolarization of the Ia afferent terminals, i.e. by presynaptic inhibition.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 3 (1967), S. 249-265 
    ISSN: 1432-0428
    Keywords: Spontaneous Diabetes ; Dog ; Cat ; Diabetes in dogs and cats ; Pancreas ; Islets of Langerhans ; B cells ; Insulitis ; Hyalin ; Capillaries ; Kidney ; Retina ; Microaneurysms ; Pituitary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs présentent une étude histopathologique de 30 chiens et de 5 chats spontanément diabétiques. — Les îlots de Langerhans et les cellules B étaient fortement diminués en nombre chez la grande majorité des chiens. Les cellules B étaient souvent dégranulées et hydropiques. Chez les chiens dont le diabète avait évolué pendant longtemps, les îlots étaient très rares et les cellules B absentes. — Chez les 5 chats spontanément diabétiques par contre, les îlots et les cellules B étaient nombreuses. Les cellules B étaient dégranulées et hydropiques chez 4 chats. Chez 1 des chats, les cellules B paraissaient normales. De nombreux îlots présentaient des dépôts de substance hyaline dans le stroma. Chez un chat, il existait une infiltration lymphocytaire très dense dans un îlot. — Ni chez les chiens, ni chez les chats, il n'a été vu de lésions glomérulaires identiques à celles de glomérulosclérose diabétique humaine. Les lésions les plus fréquentes consistaient en un épaississement des axes membraneux des touffes glomérulaires et une hypertrophie de la paroi des artérioles afférentes.— Dans les rétines des chiens diabétiques il existait une acellularité focale ou généralisée de la paroi des capillaires. Un petit nombre de microanévrysmes ont été trouvés chez 3 chiens diabétiques. L'incidence plus faible des lésions de rétinopathie vasculaire, comparativement aux diabétiques humains, s'explique probablement par la durée de vie plus courte du chien et du chat. Il est possible aussi que les capillaires rétiniens de ces animaux soient moins susceptibles de développer des lésions dégénératives. — Un degré marqué de stéatose hépatique a été observé chez beaucoup de chiens et de chats. Les surrénales étaient souvent hypertrophiées et contenaient des adénomes, mais ces lésions ne paraissent pas différentes de celles que l'on peut trouver chez des chiens et des chats non diabétiques de même âge. L'hypophyse a été prélevée chez 7 chiens. Dans 2 cas, elle contenait un adénome. Une étude cytologique plus complète des hypophyses sera publiée ultérieurement.
    Abstract: Zusammenfassung Die Autoren berichten über die Ergebnisse von Untersuchungen an 30 spontan-diabetischen Hunden und 5 spontan-diabetischen Katzen. Bei der großen Mehrzahl der diabetischen Hunde war die Zahl der Langerhansschen Inseln und der B-Zellen stark herabgesetzt. Die B-Zellen waren oft degranuliert und hydropisch. Bei Hunden mit schon lang anhaltender Krankheit waren die Inseln nur noch vereinzelt und B-Zellen überhaupt nicht mehr nachweisbar. — Im Gegensatz zu diesen Ergebnissen fanden sich bei allen 5 Katzen zahlreiche Inseln und B-Zellen. Bei 4 dieser Katzen jedoch waren die B-Zellen, wie bei den Hunden, degranuliert und hydropisch entartet. Bei einer Katze war das Aussehen der B-Zellen normal. Im Stroma der Inseln von 2 Katzen konnten starke Hyalinablagerungen nachgewiesen werden. In einem Falle zeigten die Inseln eine starke lymphocytäre Infiltration. — Weder bei den Hunden noch bei den Katzen waren typische Läsionen der Glomeruli, wie sie bei der Glomerulosklerose des menschlichen Diabetes auftreten, nachweisbar. Die häufigsten Veränderungen bestanden aus einer mehr oder weniger ausgeprägten Verdickung des mesangialen Teils der Kapillaren der Glomeruli und aus einer Hypertrophie der Wand der zuführenden Arteriolen. Bei einigen Hunden und Katzen bestanden auf chronische Pyelonephritis zurückführende Narben. — In der Retina der diabetischen Hunde waren zellenlose und funktionslose Kapillaren vorhanden, und degenerierte Pericyten (“ghostcells”) waren häufiger als bei normalen Hunden. In drei Hunden wurden einige Mikroaneurismen beobachtet. Daß diese für die Retinopathie des Diabetes typischen Läsionen beim Hund verhältnismäßig selten auftreten könnte mit der kürzeren Lebensdauer der Krankheit bei diesen Tieren zusammenhängen. Es ist jedoch nicht ausgeschlossen, daß die Retina von Hunden und Katzen weniger zu degenerativen Veränderungen neigt. — In der Leber vieler Hunde und Katzen wurde eine schwere Steatose beobachtet. In vier Hunden zeigte sich beginnende Lebercirrhose. In diabetischen Hunden und Katzen waren die Nebennieren oft hypertrophisch und enthielten Adenome, die allerdings auch bei nichtdiabetischen alternden Hunden beobachtet wurden. In 2 von 7 Hypophysen diabetischer Hunde fanden sich Adenome, über deren cytologische Untersuchung in einer späteren Veröffentlichung berichtet wird.
    Notes: Summary A histological study of 30 spontaneously diabetic dogs and 5 spontaneously diabetic cats is presented. — The islets of Langerhans and the B cells were strongly reduced in number in a large majority of the diabetic dogs. The B cells were often degranulated and hydropic. In cases of longer duration, the islets were scarce and B cells could no longer be found. — In contrast to the findings in diabetic dogs, all five cats showed numerous islets and B cells. However in 4 cats, the B cells showed complete degranulation and hydropic changes, as in the dogs. In one cat, the B cells had a normal appearance. Extensive hyalin deposits were found in the stroma of the islets in 2 cats. In one cat, an islet showed a dense lymphocytic infiltration. — No lesions identical to human diabetic glomerulosclerosis were found in any of the dogs or cats. The changes most frequently observed were a variable degree of thickening of the mesangial stalk of the glomerular capillaries, and an hypertrophy of the wall of the afferent arteriole. Scars resulting from chronic pyelonephritis, were found in a few dogs and cats. — Acellular, non-functional capillaries, with degeneration of pericytes (“ghost-cells”) were found in larger numbers in the retinas of the diabetic dogs than in non-diabetic control dogs. A very few microaneurysms could be found in 3 dogs. The lower incidence of the most typical lesions of diabetic retinopathy in dogs, as compared with the human diabetic, is probably related to the shorter duration of the disease in these animals. However, a lower susceptibility of the retina of dogs and cats to develop degenerative changes cannot be excluded. — A severe steatosis was observed in the liver of many dogs and cats. In 4 dogs, the liver showed early cirrhosis. In diabetic dogs and cats, the adrenal cortex often showed hypertrophy and contained adenomas; however, these changes have also been reported in non-diabetic aging dogs. An adenoma was found in 2 of the 7 pituitaries obtained from diabetic dogs; the cytological aspect of these adenomas and of the pituitaries will be reported in a later publication.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 95-110 
    ISSN: 1432-1106
    Keywords: Mossy fibre pathways ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Field potentials in the vermal cerebellar cortex generated by a mossy fibre volley along reticulo-, cuneo- and spino-cerebellar tracts were recorded with microelectrodes and analysed by the same procedures as was done for the mossy fibre responses in the cortex by juxta-fastigial (J.F.) and trans-folial (T.F.) stimulations in the previous paper (Eccles, Sasaki and Strata 1967a). li 3. All these results corroborate the analyses and the interpretations of the field potentials in the cerebellar cortex produced by T.F.- and J.F.-evoked mossy fibre volleys in the previous paper. 4. There have not been found electrophysiologically significant differences, as Szentágothai (1964) has suggested, between the modes of mossy fibre terminations of the reticulo-cerebellar and the spino-cerebellar systems.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 353-367 
    ISSN: 1432-1106
    Keywords: Tectum opticum ; Movement detecting neurons ; Directional sensitive neurons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden 80 Einheiten des Tectum opticum der Katze abgeleitet und ihre Reaktionen auf stationäre und bewegte optische Reize geprüft. Neben den Neuronen, die in ihrer Reaktionsweise retinalen Einheiten vergleichbar waren, fanden sich überwiegend (89%) Neurone, die auf bewegte optische Reize reagierten. Unter den letzteren zeigte die Mehrheit (70%) richtungsspezifisches Verhalten. Bei einigen Neuronen war in einem beschränkten Bereich von 1–7.5∘/sec die Reaktion gesetzmäßig abhängig von der Winkelgeschwindigkeit des Bewegungsreizes (Potenzfunktion mit dem Exponenten 0.67). Die rezeptiven Felder waren meist rund mit einem durchschnittlichen Durchmesser von 8.1∘ (3–22∘). 68% der Einheiten reagierten nicht auf diffusen Lichtreiz. Die Reaktionen auf nicht bewegte Punktlichtreize waren rasch adaptierend und inkonstant in ihrer Art und Stärke. In kurzen Abständen mehrfach wiederholte Bewegungsreize bewirkten bei einem Teil der Bewegungsneurone rasche Adaptation. Zwei kurz aufeinander folgende Punktlichtreize ergaben eine Reaktion, die niedriger als die Summe der Erregungen der jeweils einzeln gegebenen Lichtreize war, wenn die zeitliche Folge der beiden Reize der Vorzugsrichtung des Neurons entgegengesetzt war. Bei Reizfolgen entsprechend der Vorzugsrichtung entsprach die Gesamtreaktion der Summe der Einzelreizantworten. Dies läßt vermuten, daß die Richtungsspezifität durch unilaterale Hemmung bedingt ist.
    Notes: Summary Recordings were made from 80 single units in cat's Tectum opticum during visual stimulation with moving and stationary optic stimuli. The majority of units (89%) showed movement specific reactions, the rest behaved functionally similar to retinal or geniculate neurons. 70% of the movement specific units showed directional selective reactions. The receptive fields, as determined with stationary and moving stimuli were mostly circular with an average diameter of 8.1° (range 3–22°). Stimuli passing through the periphery of the field led to less pronounced reactions than those going through the center. In 10 out of 30 units, the relation between discharge rate and angular velocity in a restricted range from 1°–7.5°/sec could be approximated by a power function with an exponent of 0.67. Above 10°/sec irregular and unsystematic alterations of reactivity were observed. 68% of the tectal units recorded did not respond to diffuse light stimuli. The reactions to localized intermittent stationary light stimuli were mostly off (42%) or on-off-responses (19%) and were characterized by fast adaptation, change of reaction type during successive intermittent stimulation and by the absence of an antagonistic field-structure. Stimulation of adjacent points in a temporal sequence corresponding to movement opposite to the most sensitive direction of a directional specific neuron led to a reaction which was below the sum of the reaction of the two stimuli given alone. At a temporal sequence of the two stimuli such as to simulate the most sensitive direction, the resulting reaction corresponded to the sum of the reactions of both stimuli given alone. This suggests a mechanism of unilateral inhibition to be responsible for directional selectivity.
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  • 8
    ISSN: 1432-1912
    Keywords: Dopa formation ; Tyrosine hydroxylase ; Dopa decarboxylase ; Adrenal gland ; Cat ; Dopa-Bildung ; Tyrosin-Hydroxylase ; Dopa-Decarboxylase ; Nebenniere ; Katze
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Injektion von H-3-Tyrosin wurde die Bildung von H-3-Dopa in verschiedenen Organen (Nebenniere, Hirnstamm, Herz, Leber, Niere, Milz, Pankreas und Blut) des Huhnes und der Katze gemessen. Die Isolierung von H-3-Dopa wurde wie folgt durchgeführt: 1. Die säurelösliche Fraktion wurde durch Papierhochspannungselektrophorese im Pyridin-Eisessig-Puffer vorgetrennt. 2. Die Tyrosin-Dopa-Bande wurde eluiert und papierchromatographisch aufgetrennt. 3. Die Dopa-Bande wurde erneut eluiert und Dopa wurde als Borat-Komplex durch Papierhochspannungselektrophorese in einem Borat-Puffer charakterisiert. Nach Hemmung der Dopa-Decarboxylase mit NSD-1034 [N-Methyl-N-(3-hydroxybenzyl)hydrazin-dihydrogenphosphat] betrug der Anteil des H-3-Dopa an der Gesamtaktivität der säurelöslichen Fraktion der Nebenniere beim Huhn 4% und bei der Katze 5%. Unter diesen Bedingungen konnte H-3-Dopa in allen anderen untersuchten Organen nicht nachgewiesen werden. Ohne NSD-1034 fand sich auch in der Nebenniere kein H-3-Dopa. Bei Versuchen an Katzen wurde die H-3-Dopa-Konzentration im venösen Blut der Nebenniere gemessen. In einigen Blutproben betrug die H-3-Dopa-Aktivität bis zu 3% der Gesamtaktivität. Nahezu die gesamte von der Nebenniere gebildete Menge an H-3-Dopa wurde an das venöse Blut abgegeben. Nur 5% des neugebildeten Dopa waren am Ende des Versuches in der Nebenniere nachweisbar. Das zeigt, daß Dopa von der Nebenniere nicht gespeichert wird. Im Blut anderer Organe fand sich hingegen kein Dopa. Die Dopa-Konzentration der Nebenniere betrug nach Blockierung der Dopa-Decarboxylase ca. 1 μg/g Naßgewebe und war ohne Hemmung 〈0,2 μg/g. Die Dopa-Neubildungsrate der Nebenniere wurde abgeschätzt aus dem H-3-Dopa-Gehalt der Nebenniere sowie aus dem zeitlichen Verlauf der H-3-Dopa-Aktivität und der spezifischen Aktivität des freien H-3-Tyrosins. Bei der Katze werden von einer einzelnen Nebenniere etwa $$\frac{{0,02{{\mu}}g}}{{\min /kg}}$$ Dopa gebildet $$\left( { = \frac{{1,2{{m\mu Mol}}}}{{\min /1{{gNebenniere}}}}} \right)$$ .
    Notes: Summary After injection of H-3-tyrosine the synthesis of H-3-dopa was measured in various organs (adrenal glands, brain stem, heart, liver, kidney, spleen, pancreas and blood) of fowl and cat. The isolation of H-3-dopa was carried out in the following way: 1. The acid soluble fraction was fractionated by high voltage paper electrophoresis in a pyridine-acetic acid-buffer. 2. The tyrosine-dopa-spot was eluated and descending paper chromatography was carried out. This system separated tyrosine from dopa. 3. The dopa-spot was eluated again, and dopa was characterized by its complex with boric acid in paper high voltage electrophoresis in a boric acid-sodium hydroxide-buffer. After inhibition of the dopa decarboxylase by NSD-1034 [N-methyl-N-(3-hydroxybenzyl)hydrazine dihydrogen phosphate] H-3-dopa represented in adrenal glands of domestic fowl 4% and in those of cats 5% of the total radioactivity. Under these conditions in all the other organs investigated H-3-dopa could not be detected. Without NSD-1034 H-3-dopa was undetectable in the adrenals, too. In experiments with cats the H-3-dopa concentration in the venous blood of the adrenals was measured. In some samples H-3-dopa represented up to 3% of the total radioactivity. Nearly the total amount of H-3-dopa formed in the adrenals was secreted into the venous blood, and only 5% of the total amount were detected in the gland at the end of the experiments. This demonstrates that dopa cannot be stored by the adrenals. We failed to detect H-3-dopa in blood from any other organ. The concentration of dopa in the adrenals was about 1 μg/g wet weight after inhibition of dopa decarboxylase and without inhibition it was 〈0.2 μg/g wet weight. The dopa synthesis rate in adrenals was calculated from the H-3-dopa activity in the gland and in the venous blood and from the specific activity of its precursor H-3-tyrosine. One adrenal of the cat synthetized 0.02 μg dopa/min·kg body weight (=1.2 mμMol/min·1 g adrenal).
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 2 (1966), S. 247-260 
    ISSN: 1432-1106
    Keywords: Synaptic excitation ; Hippocampus ; Pyramidal cells ; Dendritic activation ; Cat ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following selective activation of four afferent paths that terminate exclusively on dendrites, only a small proportion of pyramidal cells in the hippocampal fields CA1 and CA3 discharged impulses. Following a single afferent volley, an EPSP was never observed even in cells synaptically excited. On tetanic stimulation (about 10/sec), a large EPSP developed, but this was not a prerequisite for an action potential. Studies of the extracellular field potentials corresponding to the EPSP and the population spike potential, indicated that the EPSP was generated across the dendritic membrane and that the spike was initiated in the neighbouring part of the dendritic tree, propagating from there along the thicker dendrites towards the soma. This conduction had an average velocity of 0.4m/sec, and, presumably, a relatively low safety factor. In certain cases, the intrasomatic electrode recorded small all-or-nothing spikes which presumably were generated in the dendritic tree. These small spikes (D-spikes) invaded the soma only if assisted by some additional depolarization, for example by frequency potentiation of excitatory synapses. The results indicate two functional types of pyramidal dendrites, the conducting and the synaptic type.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 1 (1966), S. 1-16 
    ISSN: 1432-1106
    Keywords: Inhibitory interneurones ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Extracellular microelectrode recording has been employed to study the responses of three types of interneurones in the cat cerebellar cortex: basket cells, superficial stellate cells and Golgi cells. The large unitary spike potentials of single cells were sharply localized and presumably were generated by impulse discharges from the cell somata. The characteristics of their responses described below sharply distinguished them from Purkinje cells. 2. The parallel fibre volleys generated by surface stimulation of a folium evoked brief repetitive discharges that were graded in respect of frequency and number. Maximum responses had as many as 10 impulses at an initial frequency of 500/sec. 3. At brief test intervals there was facilitation of the response to a second parallel fibre volley; at about 50 msec it passed over to depression for over 500 msec. 4. Stimulation deep in the cerebellum in the region of the fastigial nucleus (juxta-fastigial, J.F.) evoked by synaptic action a single or double discharge, presumably by the mossy fibre-granule cell-parallel fibre path, but climbing fibre stimulation from the inferior olive also usually had a weak excitatory action evoking never more than one impulse. 5. J.F. stimulation also had an inhibitory action on the repetitive discharge evoked by a parallel fibre volley. Possibly this is due to the inhibitory action of impulses in Purkinje cell axon collaterals. 6. There was a slow (7–30/sec) and rather irregular background discharge from all interneurones. The inhibitory actions of parallel fibre and J.F. stimulation silenced this discharge for some hundreds of milliseconds, probably by Golgi cell inhibition of a background mossy fibre input into granule cells. 7. All these various features were displayed by cells at depths from 180 to 500 μ; hence it was concluded that superficial stellate, basket and Golgi cells have similar properties, discrimination being possible only by depth, the respective depth ranges being superficial to 250μ, 250μ to 400μ, and deeper than 400μ.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 1 (1966), S. 17-39 
    ISSN: 1432-1106
    Keywords: Parallel fibres ; Purkinje cells ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. When electrical stimuli were applied to the surface of a cerebellar folium by a local electrode (LOC), there was a propagated potential wave along the folium with a triphasic (positive-negative-positive) configuration. 2. Investigations by microelectrode recording established that this wave is produced by impulses propagating for at least 3 mm and at about 0.3 m/sec along a narrow superficial band or “beam” of parallel fibres. As expected from this interpretation, there was an absolutely refractory period of less than 1 msec and impulse annihilation by collision. 3. Complications occurred from the potential wave forms resulting from the excitation of mossy fibres by spreading of the applied LOC stimulus. These complications have been eliminated by chronically deafferenting the cerebellum. 4. When recording within the beam of excited parallel fibres there was a slow negative wave of about 20 msec duration, and deep and lateral thereto, there was a slow positive wave of approximately the same time course. 5. These potential fields were expressed in serial profile plots and in potential contour diagrams and shown to be explicable by the excitatory and inhibitory synaptic action on Purkinje cells: excitatory depolarizing synapses of parallel fibre impulses on the dendrites; and hyperpolarizing inhibitory synapses of stellate and basket cells respectively on the dendrites and somata. The active excitatory synapses would be strictly on the parallel fibre beam and the inhibitory concentrated deep and lateral thereto, which is in conformity with the axonal distributions of those basket and stellate cells that would be excited by the parallel fibre beam. 6. Complex problems were involved in interpretation of slow potentials produced by a second LOC stimulus at brief stimulus intervals and up to 50 msec: there was a potentiation of the slow negative wave, and often depression of the positive wave deep and lateral to the excited beam of parallel fibres. 7. Often the LOC stimulus evoked impulse discharge from the Purkinje cells, these discharges being inhibited by a preceding LOC stimulus.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 1 (1966), S. 48-64 
    ISSN: 1432-1106
    Keywords: Spontaneous post-synaptic potentials (EPSPs, IPSPs) ; Motor cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Im motorischen Cortex von ausgewachsenen Katzen (mittlere Nembutalnarkose) wurden spontane postsynaptische Potentiale (PSP) mit intrazellulären Mikroelektroden untersucht. Die spontanen EPSP wurden mit ausgelösten EPSP nach schwachen Reizen in spezifischen (VL) und unspezifischen (CM) Thalamuskernen verglichen. 2. Spontane EPSP treten entweder einzeln oder gruppiert auf. spontane IPSP sind seltener und machen nur 3–10% aller spontanen PSP aus. Die kleinsten EPSP haben eine Amplitude von 150–200 μV, daneben kommen kleinere, flache Schwankungen des Membranpotentials vor. Die mittlere Amplitude von spontanen EPSP liegt bei 0.7 mV. Amplitudenhistogramme spontaner EPSP unterscheiden sich nicht wesentlich von solchen, die durch schwache CM- oder VL-Reize ausgelöst sind. 3. Die Anstiegssteilheit von spontanen EPSP liegt zwischen 2 und 15 msec. Es besteht keine konstante Beziehung zwischen Amplitude und Anstiegssteilheit. Der Potentialabfall ist annähernd exponentiell, die Zeitkonstante liegt zwischen 8 und 12 msec und ist damit etwas länger als die passive Neuronzeitkonstante (8.5±2.2 msec nach Creutzfeldt u. Mitarb., 1964b). Es bestehen keine konstanten Unterschiede der Zeitverläufe von spontanen, durch VL- oder CM-Reiz ausgelösten EPSP-Einheiten. 4. Die Intervallhistogramme von spontanen EPSP sind verschieden je nach dem, ob alle Intervalle oder nur Perioden mit sporadischer, nicht-gruppierter Aktivität ausgezählt werden. Nicht gruppierte EPSP haben längere mittlere Intervalle (70–80 msec). 5. Nach überschwelligen Thalamusreizserien ist sowohl die spontane als auch die reizinduzierte PSP-aktivität vermindert. Es kann jedoch nicht entschieden werden, inwieweit corticale und inwieweit thalamische Mechanismen für diese post-tetanische Depression verantwortlich sind. 6. Während reversibler Deafferentierung des Cortex durch K+-depolarisation afferenter Fasern und im chronisch isolierten Cortex finden sich keine spontanen PSP mehr, obwohl EPSP und IPSP am isolierten Cortex durch epicorticale Reize noch ausgelöst werden können. 7. Aus den Befunden wird geschlossen, daß die beobachteten PSP durch afferente und collaterale Faseraktivität ausgelöst sind. Für echte „Miniaturpotentiale” entsprechend Beobachtungen an Muskelendplatten findet sich kein Anhalt. Insofern repräsentiert das „synaptische Rauschen” corticaler Zellen die konvergierende Afferenz dieser Zellen und kann nicht als echtes „spontanes Rauschen” angesehen werden.
    Notes: Summary Spontaneous post-synaptic potentials (PSP's) of neurones of the motor cortex are analysed (intracellular recording, Nembutal anesthesia, cats). Distinct EPSP's either appear grouped or more sporadically distributed. Spontaneous EPSP's only represent about 3–10% of all spontaneous PSP's. The mean amplitude of EPSP's is about 0.7 mV. The smallest EPSP's have an amplitude of 150–200 μV, smaller slow fluctuations of the membrane potential (MP) are seen occasionally. Amplitude histograms of spontaneous EPSP's are similar to those of evoked EPSP units following weak thalamic stimulation. — The rising time of spontaneous EPSP's varies between 2 and 15 msec. and is not correlated with the peak amplitude. The decay is almost exponential, the time constant is between 8 and 12msec., thus being slightly higher than the neurone time constant of cortical pyramidal cells (8.5±2.2 msec. Creutzfeldt et al., 1964b). No consistant differences in time course and amplitude of “EPSP units” after VL and CM thalamic stimulation and of spontaneous EPSP's was found. Cortical and thalamic components of post-tetanic depression of spontaneous and evoked PSP activity cannot be distinguished. Interval histograms are different whether all EPSP's during sporadic and grouped activity or whether only sporadically appearing EPSP's are counted. Non-grouped EPSP's show longer mean intervals (between 70 and 80 msec.). — During reversible deafferentation with K+-depolarization of afferent fibers and in the chronically isolated cortex no spontaneous EPSP's or IPSP's are found eventhough membrane fluctuations of cells in the latter preparation may sometimes be difficult to distinguish from real EPSP's. In the chronically isolated cortex, EPSP's and IPSP's can still be elicited by epicortical stimulation. — From these findings it is concluded that the observed spontaneous PSP's represent “unit” EPSP's and IPSP's due to afferent and collateral fiber activity and that no true miniature potentials due to spontaneous liberation of transmitter substance can be recorded. Thus, the “synaptic noise” of cortical neurones represents convergent activity on these cells and consequently cannot be considered as true “spontaneous noise”.
    Type of Medium: Electronic Resource
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