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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of anesthesia 2 (1988), S. 113-114 
    ISSN: 1438-8359
    Schlagwort(e): Sevoflurane ; Minimum alveolar concentration ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Eight adult cats of either sex were studied. The minimal alveolar concentration (MAC) for sevoflurane in the cats was found to be 2.58 ± 0.30% (mean ± SD). The ratios of MAC values between sevoflurane and halothane, enflurane and isoflurane in cats were very similar to those ratios found in humans and dogs. This observation suggests that the results of this study are correct and allows us to estimate unknown MAC values for sevoflurane in other species using known MAC values for other anesthetic agents. (Doi M, Yunoki H, Ikeda K: The minimum alveolar concentration of sevoflurane in cats. J Anesth 2: 113–114, 1988)
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Neurosurgical review 11 (1988), S. 87-94 
    ISSN: 1437-2320
    Schlagwort(e): Cat ; CSF ; CT scans ; experimental hydrocephalus ; syringomyelia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Two methods were used to induce a model of experimental hydrocephalus and hydrosyringomyelia in the cat: a) injection of kaolin into the cisterna magna and b) closure of the lateral apertures of the fourth ventricle with cotton swabs. The pathological changes in the brain ventricles and the central canal of the spinal cord were monitored and documented at regular intervals by computed tomography (CT). The CT method is particularly advantageous for studies of this kind because the animals can be examined frequently without risking disturbances in cerebro-spinal fluid dynamics or tissue damage that would result from introduction of contrast media into the ventricular system. Our results and others reported earlier suggest that the dilated central canal acts as a kind of spontaneous CSF deviation route from the ventricles to the subarachnoid space. In spite of the tendency of the animals to recover in a clinical sense, the internal CSF space continued to expand; in cats the disease is progressive, a fact that is readily evident in follow-up CTs. This characteristic indicates that the spontaneous “shunt system” from the fourth ventricle through the dilated central canal to the spinal CSF spaces does not function well enough. Possible explanations for hydrocephalus compensation and the development of hydrosyringomyelia in experimental animals are discussed.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 337 (1988), S. 53-57 
    ISSN: 1432-1912
    Schlagwort(e): Endogenous histamine release ; Mamillary body ; Medial amygdaloid nucleus ; Ultradian rhythm ; Suprachiasmatic nucleus ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The mamillary body and the medial amygdaloid nucleus of cats anaesthetized with sodium pentobarbital were bilaterally and simultaneously superfused through push-pull cannulae with CSF and the release of endogenous histamine was determined in the superfusates. Collection of the superfusates in 10 min time periods revealed that histamine was rhythmically released in the two areas with frequencies of one cycle/90 min (mamillary body) or one cycle/135 min (medial amygdaloid nucleus). Collection of the superfusates in time periods of 2 min revealed the existence of an additional ultradian rhythm with a frequency of approximately one cycle/19 min in both areas. Bilateral lesions of the suprachiasmatic nucleus did not seem to influence the pattern of histamine release in the mamillary body and the medial amygdaloid nucleus, but the rate of histamine release was decreased in the mamillary body. It is concluded that the ultradian rhythms of histamine release in the mamillary body and the medial amygdaloid nucleus are not dependent on the integrity of the suprachiasmatic nucleus. The rate of histamine release in the mamillary body seems to be under the influence of excitatory neurons which originate from the suprachiasmatic nucleus.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 177 (1988), S. 277-283 
    ISSN: 1432-0568
    Schlagwort(e): Lateral reticular nucleus ; Oculomotor region ; Retrograde transport of WGA-HRP ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary By means of retrograde transport of the wheat germ agglutinin-horseradish peroxidase complex, afferent fibres to the lateral reticular nucleus from the oculomotor and accessory oculomotor nuclei were demonstrated in the cat. Small iontophoretic ejections were made into the main part of the lateral reticular nucleus from a ventral approach. Significant numbers of retrogradely labelled neurons were found bilaterally in all parts of the oculomotor nucleus. The majority was of small size and distributed along the dorsal and lateral boundaries of the nucleus. Some labelled neurons were located just outside these boundaries, in the periaqueductal gray and the adjacent mesencephalic reticular formation. Retrogradely labelled neurons were also found in the accessory oculomotor nuclei: The interstitial nucleus of Cajal featured a substantial number of labelled neurons. Some labelled neurons were consistently found also in the nucleus of the posterior commissure, but no labelled neurons were found in the nucleus of Darkschewitch. The labelled neurons in the interstitial nucleus of Cajal were of different sizes and located bilaterally, mainly in its rostral part. Caudal as well as rostral parts of the main lateral reticular nucleus appear to receive the descending afferents from the oculomotor region, but higher numbers of labelled neurons were found subsequent to ejections in the rostral part. The findings are discussed and some comments are made concerning the lateral reticular nucleus as a possible relay nucleus for oculomotor input to the cerebellum.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 177 (1988), S. 285-295 
    ISSN: 1432-0568
    Schlagwort(e): Accessory optic system ; Rabbit ; Cat ; Dog Monkey
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The three-dimensional fiber pathways of the accessory optic system in the rabbit, cat, dog and monkey were studied in whole-mounted preparations of the diencephalon and the midbrain, without sectioning, by anterograde labeling of retinal axons with horseradish peroxidase (HRP). HRP histochemical studies on alternate serial coronal sections were also performed. The rabbit accessory optic system exhibited two fasciculi (the inferior fasciculus, and the superior fasciculus consisting of the anterior fibers and the posterior fibers) and three terminal nuclei (the medial terminal nucleus, and the anterior and posterior porcions of the lateral terminal nucleus), but lacked the dorsal terminal nucleus. In the cat and dog, only the posterior fibers of the superior fasciculus were detected. The inferior fasciculus and the anterior fibers of the superior fasciculus were absent. The medial terminal nucleus and the posterior portion of the lateral terminal nucleus were commonly observed in the cat and dog. The cat accessory optic system possessed the dorsal terminal nucleus, and the dog accessory optic system possessed the anterior portion of the lateral terminal nucleus. The monkey (Macaca fuscata) accessory optic system consisted of the posterior fibers of the superior fasciculus, but blacked the inferior fasciculus and the anterior fibers of the superior fasciculus. Most of the posterior fibers terminated in the well-developed posterior portion of the lateral terminal nucleus located on the upper surface of the cerebral peduncle. A small number of posterior fibers projected to the poorly-developed medial terminal nucleus. Based on these findings, species differences in the mammalian accessory optic system were discussed.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 178 (1988), S. 67-75 
    ISSN: 1432-0568
    Schlagwort(e): Retrograde transport of WGA-HRP ; Oculomotor nucleus ; Cerebellar nuclei ; Cerebellar cortex ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The cytoarchitecture of the feline oculomotor nucleus was examined in sections stained with thionin and neutral red. Five different subdivisions (caudal central, paramedian, ventral, dorsomedial and dorsolateral divisions) can be identified on each side of the midline. This observation is discussed, and our findings are compared to previous studies of the cytoarchitecture or central muscular representation of the oculomotor nucleus in which different subgroups have been distinguished. Implants or injections of the wheat germ agglutinin-horseradish peroxidase complex have revealed that all five subdivisions project to different parts of the cerebellar cortex and nuclei. Retrogradely labelled cells were found in the oculomotor nucleus in 18 cases following deposition of tracer in the fastigial and interposed nuclei and certain regions of the anterior, posterior and flocculonodular lobes. The projection is bilateral and appears to have its main termination in flocculus. It originates from small neurons, especially from those located along the dorsal border of the oculomotor nucleus.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-0568
    Schlagwort(e): Motoneurons ; Infrahyoid muscles ; Spinal cord ; HRP ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The distribution of cell bodies and the peripheral course of axons of infrahyoid motoneurons were examined in the cat by the retrograde horseradish peroxidase method after application of the enzyme to the peripheral nerve branches supplying the infrahyoid muscles. Infrahyoid motoneurons were observed to constitute a slender cell column, which extended from a level of the caudal part of the hypoglossal nucleus usually to the most caudal level of the C1 cord segment, or occasionally to the lower levels of the C2 cord segment. The cell column was located immediately lateral to that of motoneurons of the spinal accessory nerve. In the cell column, thyrohyoid motoneurons were distributed in the medulla oblongata; sternohyoid motoneurons were located somewhat more cranially than sternothyroid motoneurons in the medulla oblongata and cervical cord. However, the level of craniocaudal distribution of thyrohyoid, sternohyoid or sternothyroid motoneurons highly overlapped. The experiments involving severance of the hypoglossal and/or cervical nerves indicated that axons of thyrohyoid and sternohyoid motoneurons passed via the roots of both hypoglossal and C1 nerves, that axons of sternohyoid motoneurons passed via the C1 nerve roots, and that axons of infrahyoid motoneurons innervating the conjugated part of the sternohyoid and sternothyroid muscles passed usually via the C1 nerve roots, or occasionally via the roots of both C1 and C2 nerves.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 178 (1988), S. 59-65 
    ISSN: 1432-0568
    Schlagwort(e): Retrograde transport of WGA-HRP ; Edinger-Westphal nucleus ; Cerebellar nuclei ; Cerebellar cortex ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The cerebellar projection from the Edinger-Westphal nucleus was studied in the cat by means of retrograde transport of the wheat germ agglutinin-horseradish peroxidase complex. The present findings give evidence that the flocculus is the main terminal area. However, small tracer implants and injections into various parts of the cerebellar nuclei and cortex revealed projections also to the fastigial and interposed nuclei and to most parts of the anterior and posterior lobe cortices. The projecting neurons are small and located bilaterally throughout the Edinger-Westphal nucleus. No topical differences between the projections to different parts of the cerebellum were found.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 72 (1988), S. 543-561 
    ISSN: 1432-1106
    Schlagwort(e): Spinocerebellar neurons ; Cerebellar peduncles ; Axonal course ; Horseradish peroxidase ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Among the newly discovered spinocerebellar cell groups, those at lumbar and more caudal levels of the cat's spinal cord were studied with regard to which of the two cerebellar peduncles, the restiform body or the superior cerebellar peduncle, is used by their axons. Bilateral injections with horseradish peroxidase were made into either of the anterior lobe or the posterior cerebellar termination area for spinocerebellar fibers, following unilateral transections of either the superior cerebellar peduncle or the restiform body, combined with low contralateral transections of the lateral and ventral funiculi. Following transection of the superior cerebellar peduncle, labeled neurons were found ipsilateral to the transection in the column of Clarke and in laminae IV–VI at L 3–L 7. Contralaterally, labeled neurons were found in the ventromedial nucleus and lamina VIII of the ventral horn in the sacro-coccygeal segments and in the medial part of lamina VII at L 6 and more caudal levels. All these neurons were regarded as sending their axons through the restiform body. Following transection of the restiform body, labeled neurons were found in the following areas contralateral to the transection: the dorsolateral nucleus of the L 3–L 6 segments, the lateral part of lamina VII at L 3–L 5/6, the medial part of lamina VII in L 6 and more caudal segments, and the ventrolateral nucleus of L 4–L 5. Ipsilaterally, labeled neurons were found in lamina VIII at L 4–L 6. All these neurons were regarded as sending their axons through the superior cerebellar peduncle. In addition to new information about the peduncular routes of spinocerebellar neurons, the study has given confirming evidence as to the crossing conditions for different spinocerebellar cell groups. The findings should be useful in future studies on the organization of the spinocerebellar systems.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 72 (1988), S. 562-576 
    ISSN: 1432-1106
    Schlagwort(e): Spinocerebellar neurons ; Cerebellar cortex ; Fluorescent tracers ; Double labeling ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The collateral projections of spinocerebellar neurons located in the L 2 to Ca 1 spinal segments in the cat were investigated by retrograde fluorescent double labeling technique. Rhodamine labeled latex microspheres (Rm) and Fast Blue (FB) were used for injections into the cerebellum in 8 cats. Two additional cats, with injections of Fluoro-Gold (FG) combined with Rm were excluded because lipofuchsin autofluorescence obscured the labeling. After injections with one tracer unilaterally in the paramedian lobule and another tracer bilaterally in the anterior lobe, double labeled neurons were found on the side of the paramedian lobule injection in the column of Clarke at L 2–L 4, laminae IV–VI at L 2–L 5 and the dorsolateral nucleus at L 2–L 6. After bilateral injections of one tracer in lobule VIII B and another in the anterior lobe, double labeled neurons were found bilaterally in the column of Clarke at L 2–L 4, laminae IV–VI at L 2–L 5, the medial part of lamina VII at L 6–L 7 and in certain cell groups at sacro-coccygeal levels. Neurons in the lateral part of lamina VII at L 3–L 5 and the ventrolateral nucleus of L 4–L 5 were labeled exclusively from injections in the anterior lobe. The findings indicate that spinocerebellar neurons at lumbar and more caudal levels of the cat spinal cord have different projection patterns in the cerebellum. A certain number of neurons which project to the anterior lobe have divergent axon collaterals supplying also the posterior vermis and/or the paramedian lobule. Other neurons project to the anterior or to the posterior lobe only.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 71 (1988), S. 345-352 
    ISSN: 1432-1106
    Schlagwort(e): Anterior semicircular canal ; Vestibular nuclei ; Vestibulo-collic ; Neck motoneuron ; Unitary EPSP ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Unit activites of secondary vestibular neurons that selectively responded to stimulation of the anterior semicircular canal nerve (ACN) were recorded extracellularly in the anesthetized cat. Axonal pathways and projections in the spinal cord of the ACN-activated neurons were examined by recording their antidromic responses to stimulation of the lateral and medial vestibulospinal tracts (LVST and MVST), and the bilateral neck extensor motoneuron pools in the C1segment (C1dorsal rami [DR] motoneuron pools). In order to determine whether the neurons had ascending axon collaterals to the extraocular motoneurons, the contralateral (c-) inferior oblique (IO) motoneuron pool was also stimulated. Twenty-seven neurons sent their axons to the ipsilateral (i-) C1DR motoneuron pool via the LVST without any projection to the extraocular motoneuron pool. All the cells except one were located in the ventral part of the lateral vestibular nucleus. This pathway produced monosynaptic EPSPs with short time-to-peak and short half-width in C1DR motoneurons (16/16 motoneurons). Eight neurons sent axons to the i-C1DR motoneuron pool via the MVST without any to the extraocular motoneuron pool. Cell somata were located in the descending nucleus or in the ventral part of the lateral nucleus. These neurons did not produce postsynaptic potentials (PSPs) in any C1DR motoneurons. All thirty-five neurons sending axons to the c-C1DR motoneuron pool have ascending axon collaterals to the c-IO motoneuron pool.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1432-1106
    Schlagwort(e): Area 18 ; Receptive field ; Velocity ; Spatial frequency ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The spatial frequency tuning curves of neurones of area 18 depend upon the velocity of the visual stimulus. The higher the velocity the lower the spatial frequencies to which the cell is tuned. Since in area 17 the size of the cell receptive field is inversely related with the optimal spatial frequency to which the cell responds, we have investigated whether the shift of the optimal spatial frequency with the velocity corresponds to a “change” in the receptive field size. We recorded extracellularly from neurones in area 18; for each cell we selected two gratings, one of high spatial frequency drifting at low velocity and another of low spatial frequency drifting at high velocity to which the cell gave comparable responses. The results show that the masking of the cells receptive field which abolishes the response to the high frequency low velocity grating does not prevent the cell from responding to the low frequency high velocity grating. We conclude that the size of the receptive field of neurones in area 18 depends upon the characteristics (spatial frequency and velocity) of the visual stimulus.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 71 (1988), S. 33-46 
    ISSN: 1432-1106
    Schlagwort(e): Columns ; Visual cortex ; Orientation ; Ocular dominance ; Maps ; Cat ; Development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In the visual cortex of four adult cats ocular dominance and orientation columns were visualized with (3H)proline and (14C)deoxyglucose autoradiography. The two columnar systems were reconstructed from serial horizontal sections or from flat-mount preparations and graphically superimposed. They share a number of characteristic features: In both systems the columns have a tendency to form regularly spaced parallel bands whose main trajectory is perpendicular to the border between areas 17 and 18. These bands frequently bifurcate or terminate in blind endings. The resulting irregularities are much more pronounced in the ocular dominance than in the orientation system. The periodicity of the columnar patterns was assessed along trajectories perpendicular to the main orientation of the bands and differed in the two columnar systems. The spacing of the ocular dominance stripes was significantly narrower than the spacing of orientation bands. The mean periodicity of a particular columnar system was virtually identical in the two hemispheres of the same animal but it differed substantially in different animals. However, the spacing of orientation columns covaried with that of the ocular dominance columns, the ratios of the mean spacings of the two columnar systems being similar in the four cats. The superposition of the two columnar systems revealed no obvious topographic relation between any of the organizational details such as the location of bifurcations, blind endings and intersections. We suggest the following conclusions: 1. The developmental processes generating the two columnar systems seem to obey the same algorithms but they act independently of each other. 2. The space constants of the two systems are rigorously specified and appear to depend on a common variable. 3. The main orientation of the bands in both columnar systems is related to a) the representation of the vertical meridian, b) the anisotropy of the cortical magnification factor, and c) the tangential spread of intracortical connections.
    Materialart: Digitale Medien
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  • 14
    ISSN: 1432-1106
    Schlagwort(e): Postural reflexes ; Unexpected postural perturbations ; Electromyographic activity ; Muscle synergies ; Motor control ; Hindlimb muscles ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of the direction of unexpected horizontal perturbations of stance on the organization of automatic postural responses was studied in cats. We recorded EMG activity in eight proximal and distal muscles of the hindlimb along with vertical forces imposed by the limbs in awake behaving cats while they stood on an hydraulic platform. Postural responses to motion of the platform in 16 different horizontal directions were recorded. Vertical force changes were consistent with passive shifts of the center of mass and active correction of stance by the animals. When the perturbation was in the sagittal plane, vertical force changes began about 65 ms following initial platform movement. When the perturbation contained a component in the lateral direction, latency for vertical force changes was about 25 ms and an inflection in the vertical force trace was observed at 65 ms. No EMG responses were observed with latencies that were short enough to account for the early force component and it was concluded that this force change was due to passive shifts of the center of mass. The amplitude of the EMG responses of each muscle recorded varied systematically as perturbation direction changed. The directions for which an individual muscle showed measurable EMG activity were termed the muscle's “angular range of activation.” No angular range of activation was oriented strictly in the A-P or lateral directions. Most muscles displayed angular ranges of activation that encompassed a range of less than 180°. Onset latencies of EMG responses also varied systematically with perturbation direction. The amplitude and latency relationships between muscles, which made up the organization of postural responses, also varied systematically as perturbation direction was changed. This result suggests that direction of perturbation determines organizational makeup of postural responses, and for displacements in the horizontal plane, is considered a continuous variable by the nervous system.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 73 (1988), S. 329-342 
    ISSN: 1432-1106
    Schlagwort(e): Dorsal roots ; Locomotion ; Sprouting ; Cat ; Plasticity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Previous studies showed that after complete hindlimb deafferentation in cats, the ipsilateral descending pathways mediated recovery of overground, goal-directed locomotion and accurate placement of the deafferented limb. In the present study deafferentations sparing one dorsal root (L6) were performed to see if the descending systems would still be responsible for the recovery. The partially deafferented hindlimb is initially impaired in postural reflexes and accurate placement during locomotion but considerable recovery occurs. A similar pattern of severe impairment and subsequent recovery is observed in cats in which the only lesion is L1 hemisection. When a hemisection is added 6 months later to chronic spared-root deafferentation the recovery (from the latter lesion) is temporarily reversed but the animals recover again in a fashion similar to that after hemisection alone. Since there is no recovery of overground locomotion when hemisection is added to complete deafferentation but there is when deafferentation is incomplete, the descending pathways apparently are not responsible for maintaining the recovery when one dorsal root is spared as they are when all are cut. The results suggest that a competitive or hierarchical control over residual systems may regulate recovery of motor function.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1432-1106
    Schlagwort(e): Axonal branching ; Vestibulo-ocular ; Vestibulo-collic ; Neck motoneurons ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Unit activities of 148 secondary vestibular neurons related to the posterior semicircular canal were recorded extracellularly in anesthetized cats. Axonal projections of these neurons were examined by their antidromic responses to stimulation of the excitatory target motoneurons of the contralateral (c-) inferior rectus muscle (IR) and bilateral (bi-) motoneuron pools of longus capitis muscles, neck flexors, in the C1 segment (C1LC). The neurons were classified into 4 groups according to their axonal projections. The first group of neurons, termed vestibulo-oculo-collic (VOC) neurons, sent axon collaterals both to the c-IR motoneuron pool and to the c-C1LC motoneuron pool. The majority of them (72%) were located in the descending nucleus. The second group of neurons were termed vestibuloocular (VO) neurons and sent their axons to the c-IR motoneuron pool but not to the cervical cord. Most of them (86%) were located in the medial nucleus. The third group of neurons, termed vestibulo-collic (contralateral) (VCc) neurons, sent axons to the cC 1LC motoneuron pool via the contralateral ventral funiculus but not to the oculomotor nuclei. They were mostly (75%) found in the descending nucleus. The last group of neurons were vestibulo-collic (ipsilateral) (VCi) neurons, which gave off axons to the ipsilateral (i-) C1LC motoneuron pool via the ipsilateral ventral funiculus but not to the oculomotor nuclei. One of them also sent an axon collateral to the c-C1LC motoneuron pool. The majority of them (74%) were located in the ventral part of the lateral nucleus. It was also observed in some of the VOC and VCi neurons that they produced unitary EPSPs in the c-C1LC and i-C1LC motoneurons, respectively. Their synaptic sites were estimated to be on the cell somata and/or proximal dendrites of the motoneurons.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 72 (1988), S. 191-194 
    ISSN: 1432-1106
    Schlagwort(e): Visual cortex ; Ablation ; Orientation discrimination ; Contrast ; Redundancy ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Intact animals can make fine orientation discriminations over a wide range of contrasts. After ablation of area 17 deficits in orientation discrimination are observed only at low contrast. The relevance of this finding for the design of sensitive ablation experiments is discussed.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 70 (1988), S. 449-454 
    ISSN: 1432-1106
    Schlagwort(e): Preoptic area ; Amygdala ; Medial forebrain bundle ; Medial basal hypothalamus ; LH ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Neuronal responses were recorded extracellularly in the preoptic region of 11 male castrate cats following stimulation in the ‘medial’ group of amygdalar nuclei (medial, basomedial, basolateral). The latency of responses varied with the site of stimulation and could be explained if connections to the preoptic region were made through both the stria terminalis and the ventral amygdalofugal pathway. Projection of 13% of orthodromically excited preoptic units to the medial basal hypothalamus was established by collision tests following stimulation in these regions. The amygdalar excitation was probably exerted through the amygdalofugal pathway. In 5/6 cats the amygdalar stimulation was successfully used to raise plasma LH levels. In one cat no preoptic units projecting to the medial basal hypothalamus were found and in the cat which failed to increase plasma LH in response to amygdala stimulation, 5 such units were found. We conclude the pathway from the amygdala through the preoptic region to the hypothalamus may not be the way in which amygdalar stimulation affects LH release in the cat. Projection of 10% of orthodromically excited preoptic units in the medial forebrain bundle was established by collision tests in 3 cats. These identified units were driven from amygdalar sites thought to project to the preoptic region by ventral amygalofugal pathways.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 71 (1988), S. 231-240 
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Retinal electrophysiology ; Electroretinogram ; Neurotransmitters ; Dopamine ; Serotonin ; Aminophosphonobutyric acid (APB)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Anatomical structures of the cat retina were related to functional changes induced by the application of dopaminergic and serotonergic substances. We report on the contribution of dopaminergic and serotonin accumulating retinal neurones to retinal activity as reflected by the electroretinogram. The effect of dopaminergic neurones was investigated by the application of the neurotoxin 6-hydroxydopamine (6-OHDA) which is known to destroy dopaminergic neurones, and injections of either serotonin (5-HT) or the analogue 5,6-dihydroxytryptamine (5,6-DHT) were used to monitor the effects of indoleamines. In control experiments aminophosphonobutyric acid (APB), an agonist of glutamate transmission, was injected. Conventional immunohistochemical methods identified dopaminergic and serotonin accumulating neurones, and the electrophysiological data obtained from the same animals were related to the anatomical structures influenced by the respective substances. Destruction of dopaminergic amacrine cells by 6-OHDA increased the ERG b-wave amplitude. Accumulation of indoleamines by certain amacrine cells also caused an increase of the ERG b-wave. However, intravitreal injection of APB completely blocked the bwave. The data show that ERG mass responses can be used to monitor transmitter-specific effects on retinal circuitry.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 73 (1988), S. 523-532 
    ISSN: 1432-1106
    Schlagwort(e): Opiate ; Receptor ; Vision ; Cat ; Mu ; Kappa ; Delta
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The distributions of μ, δ, and χ opiate receptors within visual regions in the cat cortex, thalamus and midbrain were determined by in vitro autoradiography. The overall distribution of receptors was examined using [3H]-etorphine, a ligand that nonselectively labels all types of opiate receptors. [3H]-[D-Ala2, N-Me-Phe4, Gly(ol)5]-enkephalin (DAGO) was used to selectively label μ receptors, [3H]-[D-Pen2,5]-enkephalin (DPDPE) for δ receptors, and [3H]-bremazocine for χ receptors. Each of the areas examined showed clear opiate receptor binding with [3H]-etorphine and a differential distribution of μ, δ, and χ receptors. Compared to other cortical regions, opiate binding in layers 3 and 4 of areas 17 and 18 was sparse. In the adjacent areas a more uniform distribution across layers was observed. The density of χ opiate receptors was greater in cortex than in subcortical structures, whereas the reverse was the case for μ receptors. Nevertheless, all three types of opiate receptors were found in the ventral and dorsal subdivisions of the lateral geniculate (LGN), the pulvinar complex, and the suprageniculate nucleus. In the midbrain, the superficial layers of the superior colliculus were heavily labelled with the μ, receptor ligand, and modestly with the χ ligand. Compared with other midbrain and diencephalic areas, δ binding was low in the superior colliculus. These results suggest that the diverse effects of opiates on visual perception are mediated by the unique distributions of opiate receptor types throughout the visual areas in the brain.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 69 (1988), S. 497-508 
    ISSN: 1432-1106
    Schlagwort(e): Binocular interaction ; Perigeniculate nucleus ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We have recorded from single cells in the perigeniculate nucleus (PGN) of the cat to determine their response properties. Quantitative tests have been conducted with sinusoidal gratings. Using optimal stimulus parameters, determined monocularly, we explored binocular interaction by varying the relative phase between dichoptically presented gratings. Monocularly, cells exhibit varying degrees of response specificities with respect to stimulus orientation and spatial frequency. Binocularly, we have identified six types of response. The most prominent, type 1, found for half the cells, is phase-specific binocular interaction at the fundamental frequency component of the drifting grating. For these cells, mean response rate is independent of interocular phase. The remaining types of binocular responses involve varying degrees of interaction at different harmonic components. For a quarter of the sample, no binocular interaction was observed. To investigate the role of cortical input to PGN, visual cortex was removed from some cats. Subsequent study of PGN cells indicated that response properties were generally similar to those found in intact animals. We conclude that PGN response properties are determined primarily by subcortical inputs.
    Materialart: Digitale Medien
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  • 22
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Nucleus medialis dorsalis ; Ventral tegmental area ; Nucleus accumbens ; Pericruciate cortex ; Attentional mechanisms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In anaesthetized cats, single units were recorded from the ventrolateral part of n. medialis dorsalis (MD) of the thalamus. Cells were tested for their ortho- or antidromic short latency responses to single electrical shocks applied to the pericruciate cortex (PCx) and to either the mesencephalic ventral tegmental area (VTA) or the nucleus accumbens (ACC). Some reciprocal direct connections were thus shown to exist between MD and PCx, i.e. a cortical area posterior to the main classical MD “prefrontal” projection zone. Reciprocal direct connections were also identified physiologically between MD and VTA and between MD and ACC. Coupled stimulations showed that some MD cells could serve as a relay for a pathway from VTA to cortex, others for a reciprocal pathway from PCx to VTA, and still others, for a pathway from PCx to ACC. These findings are compared to previous — mostly anatomical — data obtained in other species, mainly rat. Their functional meaning is also discussed, in the light of previous results on the roles of MD, VTA and ACC in the control of immobility during focused attentive behaviour in cat.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 73 (1988), S. 553-568 
    ISSN: 1432-1106
    Schlagwort(e): Cat ; Visual cortex ; Acetylcholine ; Nicotinic receptors ; Iontophoresis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Radioligand binding assays, receptor autoradiography and iontophoresis have been used to look for evidence of a nicotinic component to the actions of acetylcholine in cat visual cortex. [3H]Nicotine bound to a uniform population of high affinity binding sites in cat primary visual cortex. This binding was inhibited by nicotine agonists and antagonists but not muscarinic antagonists. The concentration of nicotinic binding sites was about 10% of that of muscarinic binding sites measured with [3H]N-methylscopolamine. The muscarinic sites were resolved into M1 and M2 subtypes. Quantitative receptor autoradiography showed that there were muscarinic sites in all layers, although they were least abundant in layer IV of area 17. In contrast, the nicotinic sites were most concentrated in layer IV in area 17. The concentration of this labelling was reduced at the 17/18 border and also at the 18/19 border. Layer I of the cingulate and suprasylvian gyri were also labelled. Electrolytic lesions of the lateral geniculate nucleus (LGN) led to a loss of nicotinic binding sites in layer IV of area 17, indicating that these sites are most likely located on the LGN terminals. Iontophoresis of mecamylamine, a nicotinic antagonist, decreased evoked responses in visual cortex, providing evidence that the [3H]nicotine binding sites are functional receptors and suggesting that the release of acetylcholine onto these receptors on the LGN terminals facilitates the input of visual information into visual cortex.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 69 (1988), S. 509-521 
    ISSN: 1432-1106
    Schlagwort(e): Vestibulo-ocular reflex ; Cat ; Norepinephrine ; Neuronal adaptation ; 6-hydroxydopamine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The vestibulo-ocular reflex (VOR) operates to stabilize the eyes in space during movements of the head. The system has been described as having a gain of approximately -1 since stimulation of the semi-circular canals brought about by head movements will have the effect of causing the eyes to rotate an equal amount in the opposite direction. Change in the gain of the VOR has been put forth as a model to study plasticity in the central nervous system. Since numerous studies have implicated norepinephrine (NE) in neuroplasticity and modifiability of neural circuits, we attempted to determine the effect of NE depletion (via 6-hydroxydopamine (6-OHDA) intra-cisternal injection) on the modifiability of the VOR. We have found that cats increase the gain of their VOR over a four hour period when rotated in the horizontal plane in a manner equal but opposite to the rotation of a surrounding opto-kinetic drum. The entire group of animals manifests a statistically significant decrement in their ability to increase VOR gain when central stores of norepinephrine are depleted via intra-cisternal injection of 6-OHDA. Individual animals manifest a wide variety of gain changes (0.98 to 1.62). We have found that there were two groups of cats — high and low gain modifiers. The greatest reduction in VOR gain increase after NE depletion was observed in the high gain modifiers. No difference was observed in the low gain modifiers. These same animals tested for VOR modification after amphetamine injection, produced similar results. Alertness during the VOR modification task, as estimated by saccadic eye movement counts, was unchanged after NE depletion. NE levels, measured by HPLC-EC, after depletion were reduced to the greatest extent in the cerebellum. There was also a substantial reduction of NE in the visual cortex with less of a reduction in the brain stem.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 71 (1988), S. 21-32 
    ISSN: 1432-1106
    Schlagwort(e): Voiced vocalization ; Hypothalamic stimulation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Voiced vocalizations evoked by hypothalamic stimulation were studied in a series of six awake adult cats. Electrical stimulation was found to evoke vocalizations at numerous sites within the hypothalamus, ranging from A+8 to A+16. Regions showing the largest number of responsive sites were the preoptic region, the ventromedial area, the perifornical region, the lateral and the dorso-medial hypothalamus. The form of the evoked calls was generally similar to the spontaneous calls of the same animal. Call latency, duration, and intensity were not significantly affected by changes in stimulus intensity or duration but all three of these call parameters were significantly affected by changes in stimulus frequency. In general, call latency was longest at sites in the rostral hypothalamus and shortest at sites in the caudal hypothalamus. This study is the first to investigate systematically voiced call producing areas in the hypothalamus of awake cats and to document similarities between these calls and spontaneously produced voiced calls.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 72 (1988), S. 264-278 
    ISSN: 1432-1106
    Schlagwort(e): Convergent strabismus ; Cat ; Area 18 ; Temporal properties ; Contrast sensitivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Single-cell recording experiments were carried out to determine whether rearing kittens with surgically induced convergent strabismus (esotropia) alters the development of receptive field (RF) properties of neurons in area 18. In agreement with previous work on kittens with divergent strabismus (exotropia), there was a marked loss of binocularly driven cells in area 18 of esotropic cats. In contrast to the striate cortex of strabismic cats, the spatial properties of area 18 neurons, including receptive-field size and spatial frequency tuning, did not differ from those in normal controls. On the other hand, we found that contrast thresholds, measured at an optimal spatial frequency, were significantly elevated, and that the contrast gain in many cells was reduced in strabismic cats. These deficits were observed in both eyes, though the cells dominated by the deviating eye had a lower response amplitude at all contrasts. Furthermore, temporal frequency tuning curves were abnormal in strabismic cats in that the optimal frequencies and temporal resolutions were shifted to lower values. These effects were also bilateral. Velocity tuning, measured with a high-contrast bar stimulus, revealed that area 18 neurons in strabismic cats were unable to respond to very high velocities compared to normals. This reduced response was more severe when measured with the deviating eye in spite of the bilateral nature of the deficit. Finally, latencies to electrical stimulation of the optic chiasm or the optic radiation were significantly longer in strabismic cats. The magnitude of these effects was virtually the same for both eyes. From these observations, we conclude that the temporal properties of area 18 neurons, particularly the cells abilities to follow fast temporal modulations, are affected by raising kittens with surgically induced convergent strabismus.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 72 (1988), S. 503-509 
    ISSN: 1432-1106
    Schlagwort(e): Strabismic amblyopia ; Cat ; Lateral geniculate nucleus ; Acuity ; X-cell ; VEP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The acuities of X-cells from the dorsal lateral geniculate nucleus (LGN) were measured in five cats raised with a convergent strabismus, surgically induced by tenotomy. The acuities of cells driven by the strabismic eye were not significantly different from the acuities of cells driven by the non-deviating eye over the range of eccentricities in the visual field studied (from the area centralis to over 20°). The data were also similar to X-cell acuities in the LGN of 3 normal cats. Lowered acuities of LGN X-cells driven by the deviating eye of an esotropic cat in which the strabismus was created by myectomy confirm a previous finding of a retinal locus of amblyopia associated with that preparation. In contrast, the results here implicate the visual cortex as the initial site of the deficit in spatial processing in amblyopia arising from tenotomy strabismus.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 71 (1988), S. 147-152 
    ISSN: 1432-1106
    Schlagwort(e): Eye movements ; Vestibulo-ocular reflex ; Otoliths ; Off-vertical-axis rotation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The response to off-vertical-axis rotation (OVAR) was measured in cats under circumstances in which the signals from the horizontal semicircular canals and otoliths were opposed. Opposition was achieved by sudden acceleration or deceleration during constant velocity OVAR. The degree of opposition was expressed as a canal/otolith ratio where a ratio of unity indicated agreement. For a canal/otolith ratio of 1, the OVAR gain (eye velocity/ stimulus velocity) was 0.73 (±0.13). The steady-state OVAR response was, however, reduced if the canals and otoliths were opposed. The reduction depended on the degree of opposition with a fall-off of 0.15 gain/(unit of canal/otolith ratio). These findings are discussed with respect to the central velocity store and the mechanism underlying the generation of the OVAR response.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 71 (1988), S. 262-272 
    ISSN: 1432-1106
    Schlagwort(e): Swallowing ; Synaptic potential ; Hypoglossal motoneuron ; Extrinsic tongue muscle ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The postsynaptic potentials produced in cat genioglossus and styloglossus motoneurons (GG- and SG-Mns) during swallowing were studied. During swallowing elicited by placing water on the dorsum of the tongue, the GG-muscle discharged for 80–210 ms (mean±S. D. 123±31 ms, N=59) and was abruptly suppressed, and the SG-muscle began discharging in synchrony with the GG-muscle and discharged for 200–360 ms (mean+ S. D. 247±36 ms, N=59). The GG and the SG-Mns were identified if unitary muscle activity followed the induced spike of the motoneuron one-for-one. During swallowing, excitatory postsynaptic potentials (EPSPs) were evoked in the SG-Mns regardless of the respiratory drive on the SG-Mns, and inhibitory postsynaptic potential (IPSP) or EPSP-IPSP was evoked on the GG-Mns regardless of the respiratory drive on the GG-Mns. By increasing the intracellular concentration of chloride ions, the IPSP elicited in the GG-Mn during swallowing was turned into a depolarizing potential. In immobilized cats, a depolarizing potential and a depolarizing-hyperpolarizing potential sequence was evoked successively on a tongue retractor motoneuron and a tongue protruder motoneuron by repetitive electrical stimulation of the superior laryngeal nerve.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 73 (1988), S. 78-90 
    ISSN: 1432-1106
    Schlagwort(e): Otoliths ; Nystagmus ; Labyrinth ; Eye movements ; Velocity storage mechanism ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1) In the alert cat, nystagmus induced by off-vertical axis rotation (OVAR) was recorded following steps in head velocity or ramps of velocity at constant acceleration below canal threshold. Dependence of nystagmus characteristics on tilt angle of rotation axis and head velocity was studied. Similar results were obtained with both types of stimulation. 2) Mean and modulation amplitude of horizontal eye velocity increased with tilt angle in the range 0–30 degrees. 3) Both variables increased also with head velocity, but with different trends, probably because they are set by different mechanisms. When head rotational velocity was increased above 80°/s, mean eye velocity progressively decreased to zero. 4) In spite of variations from one animal to another, some regularity was observed in the phase of eye velocity modulation. In several cases, a reduction in phase lead of eye velocity with respect to conventional origin of phases (nose-down position) was observed when head velocity increased. 5) Time constant of post-OVAR nystagmus decreased with the tilt angle of the rotation axis from gravity, but not with the orientation of the head with respect to rotation axis. 6) The results could be accounted for by a general equation describing the vestibulo-ocular reflex, provided that estimates of kinematic variables of head movement (head rotational and translational velocities), and visual target distance could be computed by the Central Nervous System.
    Materialart: Digitale Medien
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  • 31
    ISSN: 1432-2013
    Schlagwort(e): Peripheral chemoreceptors ; Central chemoreceptors ; Control of respiration ; Dopamine ; Haloperidol ; Domperidone ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We investigated the effects of the dopamine antagonists haloperidol and domperidone on the ventilatory response following square-wave changes in end-tidal CO2 during normoxia in chloralose-urethane anaesthetized cats. In 7 cats these responses were measured before (control, 28 runs) and after the administration of 1 mg/kg haloperidol i.v. (26 runs) and in 8 other cats before (39 runs) and after 0.5 mg/kg domperidone i.v. (34 runs). Each response was separated into a slow central and a fast peripheral part by fitting two exponential functions to the measured ventilation. These functions have as parameters a CO2 sensitivity, a time constant, a time delay and an apnoeic threshold B (extrapolated PETCO2 of the steady-state response curve at zero ventilation). Haloperidol significantly diminished the peripheral (Sp) and the central (Sc) ventilatory sensitivity to CO2 and the B-value (P〈0.001). The ratio Sp/Sc, the time constants and the time delays were not significantly changed. Domperidone only diminished the B-value significantly (P〈0.001). Since domperidone does not readily cross the blood-brain barrier, its effect was a CO2 independent increase of the ventilation mediated by the peripheral chemoreceptors. Haloperidol exhibited, besides the peripheral stimulatory effect a depressant central effect due to an action on the central integrative structure, resulting in a proportional decrease of Sp and Sc.
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 95 (1988), S. 268-270 
    ISSN: 1432-2072
    Schlagwort(e): Aminotetralin ; Apomorphine ; Cat ; Emesis ; Limb flicks
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Apomorphine-induced limb flicks in cats have been ascribed to a central dopamino-mimetic action of the drug. In these experiments we investigated the role of receptors located outside the blood-brain barrier (BBB) in the induction of limb flicking. Domperidone, a dopamine-receptor blocker which does not readily pass through the BBB, antagonised the induction of limb-flicks induced by apomorphine. This suggests that limb flicking behaviour may involve interactions with receptors located before the BBB. In contrast, 6-amino-5,6,7,8-tetrahydro-1,2-naphtalenediol HBr (6-ATN), a dopamine-agonist which does not penetrate the BBB, did not induce limb flicks, indicating that receptor stimulation outside the BBB alone is not sufficient to induce limb flicks. We suggest that limb flicks in cats is a behaviour which can be elicited by combined activation of centrally located dopamine receptors and dopamine receptors in the area postrema.
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  • 33
    ISSN: 1432-0878
    Schlagwort(e): Neurokinin A ; Substance P ; Dental pulp ; Immunohistochemistry ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distribution and origin of neurokinin A (NKA)-like immunoreactivity were investigated in feline dental pulp by an indirect immunofluorescence method. NKA-containing nerve fibres with varicosities, which entered the dental pulp via apical foramen, were distributed throughout this tissue. Many NKA-containing nerve fibres were localized around blood vessels, but some were observed apart therefrom. At the odontoblastic layer, thin NKA-containing nerve fibres were observed running straight toward the pulp-predentinal border between odontoblasts. After inferior alveolar nerve section, all NKA-containing nerve fibres disappeared in the dental pulp, while the removal of the superior cervial ganglion resulted in no change in the distribution of these fibres. The correlation of NKA-like immunoreactivity and substance P (SP)-like immunoreactivity was also investigated by double-immunofluorescence technique. The distribution of NKA-containing nerve fibres was very similar to that of SP-containing nerve fibres; it appeared that all NKA-containing nerve fibres contained SP.
    Materialart: Digitale Medien
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  • 34
    ISSN: 1432-0878
    Schlagwort(e): Calcitonin gene-related peptide (CGRP) ; Vasoactive intestinal polypeptide (VIP) ; Merkel cells ; Free nerve endings ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Calcitonin gene-related peptide (CGRP)-and vasoactive intestinal polypeptide (VIP)-immunoreactivity were observed to coexist in Merkel cells of cats. No differences in peptide content were found between Merkel cells located in epithelia of the hard palate, in hairy and glabrous skin of the upper lip, and in vibrissae follicles. CGRP-and VIP-immunoreactive nerve fibres were also found near CGRP/VIP-immunoreactive Merkel cells. In the vibrissae follicles some CGRP-and VIP-immunoreactive nerve terminals end abutting on the glassy membrane. Other CGRP immunoreactive nerve fibres penetrate the epithelium of the skin and end within it. Electron microscopy of vibrissae follicles revealed that Merkel cell neuntes are not immunostained and that immunostained nerve fibres form unmyelinated bundles before ending freely. Thus, CGRP-and VIP immunoreactive nerve fibres in cat skin do not end as Merkel cell neuntes but as different kinds of free nerve endings.
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  • 35
    ISSN: 1432-0878
    Schlagwort(e): Corticotropin-releasing factor (CRF) ; Medulla oblongata ; Inferior olive ; Immunohistochemistry ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Corticotropin releasing factor (CRF)-immunoreactive (IR) perikarya, visualized by the indirect immunoperoxidase method in colchicine-pretreated cats, were localized in many discrete regions of the medulla oblongata. They were found mainly in the dorsal aspect and midline of the medulla oblongata, and more rostrally in the ventrolateral portion. Our results also demonstrated CRF-IR neurons in the rostrocaudal extent of the inferior olive, probably projecting to the cerebellar cortex via thick axons visualized along the lateral edge of the medulla. CRF-IR olivary cells were also found in the pontine cat from which the forebrain was removed, but neither in hypophysectomized nor adrenalectomized cats.
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  • 36
    ISSN: 1432-0878
    Schlagwort(e): Calcitonin gene-related peptide ; Regulatory peptides ; Paravertebral ganglia ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Paraffin sections of cervical and upper thoracic paravertebral ganglia of the cat were investigated by immunohistochemistry using antisera directed against calcitonin gene-related peptide (CGRP). The relationships of CGRP-immunoreactive structures to those exhibiting immunoreactivity to antisera against other regulatory peptides and dopamine-β-hydroxylase (DBH), respectively, were studied in consecutive sections. Singly scattered CGRP-immunoreactive neuronal perikarya were observed in the superior and middle cervical ganglia as well as in the stellate ganglion. These neurons also displayed immunoreactivity to vasoactive intestinal polypeptide (VIP), and some additionally exhibited faint substance-P immunoreactivity. DBH- and neuropeptide Y-immunoreactive ganglion cells were not identical with CGRP-immunoreactive neuronal cell bodies. According to the immunoreactive properties of varicosities, which abut on CGRP/VIP-immunoreactive perikarya, three types of CGRP/VIP-immunoreactive ganglion cells could be distinguished: (1) CGRP/VIP-immunoreactive neurons being surrounded by somatostatin-immunoreactive nerve fibers, (2) neurons being approached by both DBH- and met-enkephalin-immunoreactive varicosities, and (3) neurons receiving both DBH- and neurotensin-immunoreactive fibers. The stellate and upper thoracic ganglia harbored clusters of intensely VIP-immunoreactive somata, which lacked CGRP-immunoreactivity. Fine somatostatin-immunoreactive and coarse CGRP-immunoreactive fibers were distributed within these clusters, whereas patches of neurotensin-immunoreactive fibers were complementarily arranged. At all segmental levels investigated, a few postganglionic neurons were approached by both CGRP-immunoreactive and substance P-immunoreactive varicosities, but lacked a VIP-immunoreactive innervation. Therefore, CGRP/substance P-immunoreactive fiber baskets appeared rather to be of extraganglionic origin than to emerge from intraganglionic CGRP/VIP/SP neurons. CGRP-immunoreactive cell bodies or fibers were absent in clusters of small paraganglionic cells, but some of the solitary paraganglionic cells displayed CGRP-immunoreactivity. Our findings establish the presence of CGRP-immunoreactivity in a population of sympathetic neurons in the cat. A highly differentiated, segment-dependent organizational pattern of neuropeptides in cervico-thoracic paravertebral ganglia was demonstrated.
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 253 (1988), S. 83-93 
    ISSN: 1432-0878
    Schlagwort(e): Pacinian corpuscle ; Axonal spines ; Inner core lamella ; Inner core cleft ; Elastica ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of cat mesenteric Pacinian corpuscles in cross and longitudinal sections has been examined. The terminal ends of lamellar cells of the inner core have been identified in longitudinal sections through the proximal portion of the inner core. These terminal bulbous expansions contain characteristic concentric membranes of rough endoplasmic reticulum and in some cases masses of oval membranous inclusions. The central axon as seen in cross section is oval in profile, having X-(short) and Y-(long) axes, and each axonal face is characterized by specializations of the axolemma. At the X-axis, the inner lamellae of the inner core tightly abut a smooth axolemma, with no intervening connective tissue matrix, in a manner reminiscent of a neuroepithelium. The axolemma of the Y-axis has numerous axonal spines (microspikes) that project into the cleft in the inner core. The extent of the axolemma having axonal spines can only be appreciated in longitudinal sections. The clefts contain a specialized connective tissue with elastic and collagen fibrils. The connective tissue compartment of fibers and matrix separating individual inner core lamellae is unique, in that it contains extremely thin collagen fibrils measuring approximately 15 nm in diameter. The diameter of collagen fibrils increases as the cleft is approached. Here the fibrils resemble typical endoneural collagen.
    Materialart: Digitale Medien
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 253 (1988), S. 95-103 
    ISSN: 1432-0878
    Schlagwort(e): Pacinian corpuscle ; Axonal spines ; Axonal extreme tip ; Inner core lamella ; Basal lamina-like material ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present report is the second of two studies re-evaluating the cytological characteristics of Pacinian corpuscles. The extreme tip of the axon of a Pacinian corpuscle has been identified and is quite different from the previously described ultraterminal region. The latter is the site where the inner core lamellae begin to terminate and is characterized by a smooth axolemma. The extreme tip lacks inner core lamellae directly abutting the axolemma and is instead characterized by the presence of many axonal spines projecting into a matrix of basal lamina-like material. The extreme tip of the axon thus resembles the organization of the axolemma facing the clefts of the inner core. The axonal spines at the cleft and extreme tip are proposed as a site of restricted current flow due to the tight apposition of inner core lamellae to the axolemma of X-axis. The hemiinner cores thus could restrict current flow to the cleft. These anatomical specializations could represent both a source and a sink for K+ ions during mechano-electric transduction and account in part for the exquisite sensitivity of Pacinian corpuscles to complex pressure waves.
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 245 (1988), S. 321-324 
    ISSN: 1434-4726
    Schlagwort(e): Otoliths ; Middle ear pressure ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The influence of varying middle ear pressure on the otolith system was investigated in anesthetized cats. Extra-axonal recordings of action potentials were performed in the vestibular nerve fibers and in the neurons in the lateral vestibular nucleus that responded to lateral or anteroposterior steadystate tilt. Positive or negative pressure was applied to the ipsilateral middle ear during the recordings. Seventy-three percent of the fibers and 63% of the neurons responded to changes in the middle ear pressure. These response rates were higher than those previously reported on the units innervating semicircular canals. Findings suggest that the otolith organs are more sensitive to changes in the middle ear pressure than are the semicircular canals. The units responding to lateral tilt were more sensitive to middle ear pressure than those that responded to anteroposterior tilt. Displacement of endolymph caused by pressure changes in the middle ear was considered to have affected the activities of hair cells in otolith organs.
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Annals of biomedical engineering 16 (1988), S. 65-77 
    ISSN: 1573-9686
    Schlagwort(e): Receptive field ; Ganglion cells ; Nonlinear analysis ; X-Cells ; Y-Cells ; Wiener kernel ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract Originally, modeling of ganglion-cell responses in cat was based mainly on linear analysis. This is satisfactory for those cells in which spatial summation of excitation is approximately linear (X-cells) but it fails for Y-cells, where summation has strong nonlinear components. Others have shown the utility of using sinusoidal analysis to study harmonic and intermodulation nonlinearities in the temporal frequency domain. We have used Wiener-kernel analysis to obtain directly both temporal and spatial impulse responses and their nonlinear interactions. From these, we were able to predict accurately the responses that a counterphase modulated grating elicited in both X-cells and Y-cells. In addition, we show that the first-order responses can measure the two-dimensional spatial features of the receptive field with high resolution. Thus, nonlinear analysis of responses to white-noise stimuli may be sufficient to both classify and measure the receptive fields of many different types of ganglion cells.
    Materialart: Digitale Medien
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 264 (1969), S. 406-419 
    ISSN: 1432-1912
    Schlagwort(e): Intestinal Absorption ; Cardiac Glycosides ; Blood of Portal Vein ; Intestinal Lymph ; Cat ; Intestinale Resorption ; Herzglykoside ; Portalvenenblut ; Darmlymphe ; Katze
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. The cardiac glyoosides digitoxin, ouabain, digoxin and peruvosid labelled with3H were injected into tied intestinal loops of anaesthetized cats in situ. The absorbed glycosides were measured in the blood of the portal vein and in the intestinal lymph. At the same time the3H-activity was measured in the blood of the peripheral circulation, in the bile and in the urine. 2. Calculation of the amount of glycosides totally absorbed from the3H-concentration in the blood of the portal vein and the circulation volume (bubble-flow-meter) gave the following absorption rates as a percentage of the administered dose per hour: digitoxin 56%, digoxin 42%, peruvosid 26% and ouabain 10%. 3. The amount of glycosides passing into the lymph during 1 hour was found to be only 0.006 to 0.02% of the amount offered. In lymph3H-activity cannot be measured earlier than 5 min after the administration of the labelled glycosides. The3H-concentration in the lymph did not equal that measured in the blood of the peripheral circulation until at least 1 hour after the administration and always remained below the3H-concentration of the blood in the portal vein. This proportion remained unchanged even if digitoxin was administered as an emulsion in oil instead of an aqueous solution. From the time course of3H-concentration it might be concluded that the glycosides do not pass directly to the lymph after absorption but indirectly by way of the blood. 4. The amount of glycoside excreted in the bile is for peruvosid 15,5% of the amount absorbed, for ouabain 1,9%, for digoxin 1,4% and for digitoxin 0,8%. The3H-activity excreted in urine is very small and can be disregarded. 5. Chromatographic analyses of the bile revealed, that in the case of digoxin, 4/5 of the amount excreted were unchanged, in the case of digitoxin and ouabain 2/3 and in the case of peruvosid only 1/4. In the lumen of the tied intestinal loops and in the tissue of the small intestine the glycosides were hardly metabolised.
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 128 (1969), S. 28-39 
    ISSN: 1432-0568
    Schlagwort(e): Arterial supply ; Corpus callosum ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung An 27 Katzen beiderlei Geschlechts wurde die Blutversorgung des Corpus callosum untersucht. Dabei wurden folgende Befunde erhoben: Der Balken der Katze wird im Bereich des Rostrum und Genu sowie im vorderen und mittleren Truncuabschnitt aus der Arteria cerebri anterior versorgt und zwar über Äste, die den Arteriae pericallosae und den Arteriae genu corporis callosi entstammen. Diese Äste wurden als Arteriae callosi superiores und inferiores bezeichnet. Lediglich im hinteren Truncusabschnitt und im Splenium erfolgt die Versorgung neben Ästen der A. pericall. auch über solche der Arteriae cerebri mediae und posteriores. Die Blutgefäße treten dolchartig in den Balken ein, teilen sich dann baumartig weiter auf und gehen in ein Capillarnetz über, das in Richtung des Nervenfaserverlaufes ausgezogen ist. Auf in der Literatur bereits bekannte, aber oft vernachlässigte Besonderheiten der Arteria carotis interna und des Circulus arteriosus wird hingewiesen.
    Notizen: Summary In investigations on 27 cats of both sexes, the arterial supply of the corpus callosum was studied. The findings are as follows: In the region comprising rostrum and genu as well as in the fore and middle trunk sections, blood supplied by branches of the arteriae pericallosae and the arteriae genu corporis callosi which originate from the arteria cerebri anterior. These branches were designated arteriae callosi superiores and inferiores. However, in the posterior section of the trunk and in the splenium the blood is supplied by branches of the aa. pericall. and, in addition, by branches of the arteriae cerebri media and posteriores. The blood vessels penetrate the corpus callosum in bayonet fashion, then arborise and finally become a capillary network which is elongated in the direction of the course of the nerve fibres. Attention is drawn to peculiarities of the arteria carotis interna and the circle of Willis which, although known in the literature, are rarely referred to.
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 128 (1969), S. 222-234 
    ISSN: 1432-0568
    Schlagwort(e): Postnatal development ; Fixation ; Neuroglia ; Corpus callosum ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Gehirne von Tieren aus 4 verschieden alten Würfen junger Katzen wurden teils lebensfrisch durch Perfusion, teils nach 24 Std durch Immersion fixiert und für Vergleichsuntersuchungen in Paraffin eingebettet. Bei Betrachtung der Gliazellen des Corpus callosum ergab sich: 1. Nach Perfusionsfixierung sind die Kerne der Gliazellen groß und elliptisch. Sie sind wasserklar und haben eine scharf gezeichnete Chromatinstruktur. Nach Immersionsfixierung 24 Std p.m. sind die Kerne dagegen klein und rund, homogen dunkel gefärbt und haben ein kaum zu erkennendes Chromatingerüst. 2. Nach Perfusionsfixierung sieht man im Balken der ganz jungen Tiere zahlreiche Mitosen. Sie fehlen bei den durch Immersion fixierten Geschwistertieren desselben Wurfes. 3. Die nach verschiedener Fixierung beobachteten Unterschiede in der Form der Gliazellkerne werden durch Messungen der Quer- und Längsachsen erfaßt.
    Notizen: Summary In four litters of young cats, some of the brains were fixed by perfusion and the others by immersion. The material was embedded in paraffin and the neuroglia was investigated in sections through the corpus callosum. It was found that: 1. After fixation by perfusion the nuclei of the glia cells are large and elliptic. The caryoplasm is clear and there is a distinct structure of the chromatin. After fixation by immersion the nuclei of the same cells are small and round. The caryoplasm is dense and the structure of the chromatin is not clearly visible. 2. After fixation by perfusion mitotic figures are present. They are absent in the brains fixed by immersion. 3. Following different fixation, there are differences in the shape of the nuclei of the glial cells. These differences have been investigated in detail by measuring the diameters of the nuclei.
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  • 44
    ISSN: 1432-1106
    Schlagwort(e): Lateral cervical nucleus ; Midbrain lesions ; Nauta method ; Ultrastructural investigation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The lateral cervical nucleus (LCN) has been studied with the light and electron microscope after midbrain lesions in kittens of different ages, and in adult cats. It has been shown that nerve cells remain within the contralateral LCN after hemisection of the midbrain. performed on 1 day old kittens. The estimated number of these remaining cells was 3–19% in the different cases. No fibers descending to the LCN from levels rostral to the midbrain could be demonstrated in adult cats with the Nauta technique. A combined Nauta and electron microscopical investigation was performed on kittens operated on at different ages and allowed to survive varying times postoperatively. At the operations the LCN-axons were transected at midbrain level. The Nauta investigation demonstrated silver impregnation of degenerating LCN-neurons on the affected side of the same type as has been described recently in other neuronal systems following axonal transection. The ultrastructural study revealed electron dense degenerating dendrites and probably also nerve cells within the LCN. The dense degenerative changes were very similar to the dense degeneration in terminal boutons following transection of parent axons. The potential value of the findings for electron microscopical research in neuroanatomy is discussed. The results in terms of connections of the LCN are discussed in the light of known anatomical and physiological data of the LCN.
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 7 (1969), S. 143-157 
    ISSN: 1432-1106
    Schlagwort(e): Reticular formation ; Convergence ; Inhibition ; Cat ; Chloralose
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Ein konditionierender corticaler Reiz inhibiert den somatischen Startlereflex bei Katzen unter Chloralosenarkose für eine Dauer von mehr als 200 ms. Die Interaktionen zwischen beiden Reizen laufen in der bulbären und pontinen Formatio reticularis ab. 2. Dem Startlereflex liegt eine polysynaptische Erregungsschleife zugrunde, die die bulbäre und pontine Formatio reticularis durchzieht. Die Resistenz der reticulären Neurone gegenüber repetitiver Stimulation wurde als Kriterium ihrer funktionellen Lokalisation auf dem polysynaptischen Reflexbogen gewertet. 3. Die corticale Inhibition wird im Verlaufe der polysynaptischen Erregungsschleife zunehmend stärker. Neurone, die von den Startlereflexafferenzen direkt erregt werden, werden durch den corticalen Reiz nicht inhibiert. Dies schliebt eine präsynaptische Inhibition der reticulopetalen Fasersysteme aus.
    Notizen: Summary 1. The startle reflex evoked by cutaneous stimulation in cats under chloralose anesthesia is inhibited for more than 200 ms by a conditioning cortical volley. The interaction between the cutaneous and the cortical volley takes place in the bulbar and pontine reticular formation. 2. The startle reflex involves a series of reticular neurones. Resistance to repetitive stimulation has been determined to evaluate the functional localization of each neurone within this polysynaptic path. 3. Inhibition following the cortical volley becomes increasingly more effective along the course of the polysynaptic path and is completed within 5–6 ms. Reticular neurones excited directly by the spino-reticular afferents are not inhibited, thus excluding a presynaptic inhibition of the spinoreticular fibres.
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 9 (1969), S. 284-306 
    ISSN: 1432-1106
    Schlagwort(e): Cutaneous receptive fields ; Spinal cord ; Cat ; Pain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Examination of cutaneous receptive fields (RFs) of lamina 5 cells in the lumbar spinal cord of decerebrate cats shows them to have three distinct zones with respect to mechanical and electrical stimulation. The mean response rate to both mechanical and electrical stimulation in zone 1 increases steadily up to the highest strengths used; in zone 2, surrounding zone 1 mainly proximally, mild stimuli reduce the mean rate, stronger stimuli increase it; in zone 3, mainly proximal to zone 2, all stimuli reduce the rate. Temporally, zone 1, electric shocks near threshold produce bursts of firing followed by inhibition. With increased stimulus strength, the bursts lengthen to a second or more. In zones 2 and 3, inhibition at all strengths is preceded at higher strengths by bursts of firing. Cold-blocking the spinal cord at lower thoracic levels reversibly increases the ongoing activity of these cells, increases the area of zones 1 and 2, and almost completely suppresses all inhibition. Stimulation of dorsal columns and threshold stimulation of distant dorsal roots inhibits ongoing and induced activity. Barbiturate decreases ongoing activity and the duration of firing produced by cutaneous electrical stimulation but does not decrease inhibition. These results are consistent with a model in which low-threshold fibres are excitatory only over a small central area of the RF of a lamina 5 cell (zone 1), high threshold fibres are excitatory over a larger area (zones 1 and 2), and low threshold fibres are inhibitory over the entire receptive field (zones 1, 2 and 3) with a slower time-course. This inhibition is tonically enhanced by descending influences in the decerebrate cat. It is suggested that the high and low threshold fibres correspond approximately to the small and large diametre fibres whose balance is the basis for the coding of pain in the theory of melzack and wall.
    Materialart: Digitale Medien
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 7 (1969), S. 195-213 
    ISSN: 1432-1106
    Schlagwort(e): Corpus callosum ; EEG synchronization ; Homolateral sensory evoked potentials ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Spontaneous EEG-patterns and evoked potentials (EP's) of symmetrical cortical areas were recorded in chronic and acute cats before and after section of the corpus callosum, the commissura anterior and posterior and the massa intermedia. The spontaneous EEG was recorded without and with anesthesia, EP's after electrical stimulation of the fore-paws only during nembutal anesthesia. — No changes in the bilateral coordination of spontaneous and evoked EEG-patterns could be seen after commissurotomy (CT). The bilateral coherence of EEG-waves as revealed by cross-correlation is low already in the normal cats and does not change significantly after CT. The values of cross-correlation coefficients at T = ± 15 msec vary during one EEG-record between -0.25 and +0.25 in the somatosensory, suprasylvian and temporal areas (mean values slightly above 0). In the visual area occasionally positive values between 0.5 and 0.8 were seen, but also here a large variation was found in all animals and the mean values were below 0.1. No consistent phase shift between both sides was observed. EEG-patterns like spindles or arousal, still occurred together in both hemispheres after CT, the variability of their exact beginning or end was the same as in controls. Spontaneous spindles often lasted longer after section of the massa intermedia. Homolateral EP's in the somato-sensory area were still present after CT. Rhythmical afterdischarges could be restricted to the contralateral somato-sensory cortex even before CT.
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 9 (1969), S. 30-52 
    ISSN: 1432-1106
    Schlagwort(e): Climbing fibers ; Mossy fibers ; Vestibulo-cerebellar input ; Cat ; Frog ; Golgi cell inhibition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Field and unitary potentials evoked in the vestibulo-cerebellum of frog and cat following vestibular nerve stimulation were recorded with microelectrodes and correlated with their site of origin in the various layers of the cerebellar cortex. 2. In the frog, primary vestibular fibers project both as mossy and as climbing fibers onto the cerebellar auricular lobe. Secondary vestibulo-cerebellar fibers seem to end exclusively as mossy fibers in the auriculum. As a consequence of this dual projection, extra- and intracellular recordings from Purkinje cells in the auricular lobe show two kinds of responses to vestibular nerve stimulation: a) graded, repetitive firing mediated through mossy fiber-granule cell-parallel fiber pathways, and b) all-or-none burst responses caused by monosynaptic impingement of vestibular climbing fibers on Purkinje cells. 3. The field and unitary potentials evoked in the cat nodulus, flocculus and uvula following vestibular nerve stimulation are shown to be generated by mossy fibers exclusively. Considerable convergence of the two labyrinthine mossy fiber inputs to a given cerebellar area was found. 4. Interaction of contralateral and ipsilateral mossy fiber input at the level of the flocculus suggests that Golgi cell inhibition might operate not only as a simple inhibitory feedback loop, but also as a complex gating operator at the granule layer. 5. No short latency climbing fiber activation of Purkinje cells was observed following VIIIth nerve stimulation. Stimulation of the contralateral inferior olive evoked short latency climbing fiber EPSPs in Purkinje cells of the vestibulo-cerebellum. Suggestions are made as to the possible role of mossy and climbing fiber inputs to this area of the cerebellum.
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 9 (1969), S. 96-115 
    ISSN: 1432-1106
    Schlagwort(e): Pyramidal tract ; Fusimotor Neurons ; Forelimb ; Extensor ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effects of cortical stimulation upon dynamic and static sensitivities of the sensory endings in muscle spindles have been analyzed. 63 single afferent fibers from the muscle spindles of the forelimb extensors: M. flexor carpi radialis, M. flexor digitorum communis and M. palmaris longus were isolated in dorsal root filaments in 20 adult cats under chloralose-urethane anesthesia. They were identified by their response to stimulation of the median nerve. 1. Surface anodal repetitive stimulation of the anterior sigmoid gyrus was found to produce an enhancement of static response of single Group II fibers. Effective area was localized in a restricted region which corresponded to the forelimb motor area. The effect was obtained without any concomitant muscle contraction. Similarly, the stimulation increased the resting discharges of the Group Ia fibers from the same muscles. 2. Stimulation of the same area in the cerebral cortex was also found to increase the dynamic sensitivities of primary sensory endings. The increase was revealed by an enhancement of initial burst discharge during relaxation period of a twitch contraction caused by median nerve stimulation. 3. These results indicate that stimulation of the forelimb motor area has a facilitatory effect on both the static and dynamic fusimotor neurons innervating the muscle spindles of the test muscles. 4. The effects were reproduced in pyramidal tract preparations in which the brainstem was cut either at the level of the midbrain except for the cerebral peduncle or at the level of caudal medulla oblongata sparing the pyramid. 5. The threshold for the fusimotor effects was less than 1.3–1.5 times threshold of the pyramidal tract discharge, when the best spot for eliciting the fusimotor response was chosen. These results indicate that the effects of cortical stimulation are mainly mediated by the fast conducting pyramidal tract fibers.
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 9 (1969), S. 307-324 
    ISSN: 1432-1106
    Schlagwort(e): Muscle spindle ; Gamma motor control ; Mesencephalic reticular formation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Effects of repetitive stimulation of the mesencephalic reticular formation (MRF) on the static discharge and dynamic sensitivity of muscle spindle primary endings (soleus muscle) were studied in cats anaesthetized with Halothane (Fluothane). By progressive increasing the depth of anaesthesia three different fusimotor effects could be observed: 1. A static effect; the static discharge of the primary endings was strongly increased; the response to phasic stretch was decreased or remained unaltered. 2. A dynamic effect; the dynamic sensitivity of the primary endings was powerfully increased while the rate of discharge under static conditions was only slightly augmented. 3. A depressant effect; the static discharge and the dynamic sensitivity of primary endings were decreased. Repeated stimulation elicited successive static and dynamic effects. No specific regions within the MRF could be related to a particular effect.
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  • 51
    ISSN: 1432-1106
    Schlagwort(e): Muscle spindle ; Gamma motor control ; Reticular formations ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. During a progressive increase of Fluothane (Halothane) anaesthesia, repetitive stimulation of the mesencephalic retioular formation (MRF) produces several fusimotor effects — static, dynamic or depressant — on primary endings of soleus muscle spindles (Vedel et Mouillac-Baudevin 1969). 2. Transection of the brain immediately rostral to the site of stimulation may increase the dynamic effect but does not alter the static or the depressant effects. 3. A section of the rubrospinal tract does not modify the fusimotor effects elicited by stimulation of the MRF. 4. Transections of the spinal cord have shown that the pathways responsible for the transmission of these effects are mainly situated in the ipsilateral ventral and ventrolateral funiculi which contain the efferent fibers from the pontine reticular formation (PRF), from the bulbar reticular formation (BRF) and from the vestibular nucleus. 5. Contra and ipsilateral PRF stimulation produces the static fusimotor effect; contralateral stimulation from a small anterior region produces the dynamic effect. 6. Stimulation of the lateral part of the ipsilateral BRF elicits the dynamic effect while stimulation of the medial part elicits the static effect.
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 9 (1969), S. 164-182 
    ISSN: 1432-1106
    Schlagwort(e): Emotional behaviour ; Hypothalamus ; Electricalstimulation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. In order to compare the selective value of repetitive cathodal pulses of 8 c.p.s. and of continuous sine-wave alternating currents of 5000 c.p.s. (middle frequency current) when applied to brain tissue, explorations were made in the region of the hypothalamus that had yielded defence and/or flight reactions in earlier experiments. The region was explored by stimulating each point in turn with both current forms. At the same time measurement was made of the impedance of the brain tissue, and the effects produced by altering the time of rise of the middle frequency current on threshold of responses were also studied. The experiments were carried out on unanaesthetized, freely moving cats. 2. Both stimulation types produced affective (“emotional”) responses. The patterns elicited by low frequency cathodal pulse stimulation were often associated with stimulus-bound phasic muscle activity, i.e., flapping of ears, and twitching of whiskers, or, rotation of the head. Such extraneous motor effects were rarely obtained when continuous middle frequency currents were applied, and were tonic in character when present. 3. Mapping of reactive points revealed that the area producing defence or flight following middle frequency stimulation is smaller in size than the field delimited by means of repetitive cathodal pulse stimulation. These results strongly suggest that spread of current can be reduced by using middle frequency current stimulation. This apparently local (and hence highly selective) action is paralleled by a lower impedance of the brain tissue to the rapidly changing polarity of this current. 4. The hissing (and/or growling) associated with the defence pattern showed adaptation to suddenly rising middle frequency currents of 30 secs duration. An increase in threshold of hissing occurred when the time of rise of the current was prolonged. Flight, in contrast, was obtained at the same critical intensity regardless of the time of rise of current. 5. The nature of the stimulatory action of middle frequency current (examined in the peripheral nerve by Wyss) and the advantages presented by this new method of brain stimulation are briefly discussed.
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 7 (1969), S. 32-50 
    ISSN: 1432-1106
    Schlagwort(e): Lateral cervical nucleus ; Spinal lesions ; Ultrastructural investigation ; Degenerating boutons ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ultrastructure of terminal degeneration within the lateral cervical nucleus (LCN) after transection of its spinal afferent fibers 2 days–2 years earlier is described. The degeneration after 2 days was of both the neurofilamentous and dense type. The highest number of degenerating terminals, about 15%, was found after 4–5 days. Then most of the degenerating boutons were of the dense type. The degenerating terminals had synaptic contact with cell bodies and dendrites of LCN-neurons. Removal of the degenerating boutons seemed to be effected by a phagocytic cell present in increased number compared to the normal LCN. In cases with long survival times an increase in the number of astroglial filaments was observed. In an animal where the spinal afferents to the LCN had been cut 2 years earlier a decrease in medium size of the neurons was observed. The amount of dendritic spines was also considerably smaller than normally.
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 7 (1969), S. 68-83 
    ISSN: 1432-1106
    Schlagwort(e): Medial geniculate body ; Inhibition ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Inhibitory activity in the cat medial geniculate body (MG) was examined by stimulating electrically and acoustically the input and output of the MG. 2. A longer and more profound depression of excitability occurs following a click-evoked potential in the MG than in the inferior colliculus (IC) in both anesthetized and unanesthetized states. Recovery is cyclic in the barbiturate MG preparation. 3. Electrical stimulation of the brachium of the inferior colliculus (BIG) evokes a field potential in the MG consisting of clearly distinguishable presynaptic and postsynaptic components. The presynaptic component recovers rapidly, while the postsynaptic component requires 100–200 msec for full recovery. This depression of excitability is localized within the MG since cortical ablation does not alter its occurrence. 4. Stimulation of the BIC mimics the effects of click stimulation on single units. Excitatory, inhibitory and reverberatory responses are evoked by the BIC shock. Suppression of single unit activity correlates with the depression of excitability following a BIC-evoked field response. 5. Cortical stimulation can evoke antidromic and trans-synaptic unit responses in the MG, as well as causing a variety of inhibitory effects and reverberation. In view of the fact that cortical ablation does not impair the recording of these responses to afferent stimuli, it is suggested that the cortical-evoked responses are at least partly mediated by antidromic conduction to MG. 6. Evidence is presented that inhibitory effects of both afferent and cortical stimulation are due to active inhibition of MG unit activity. Speculations are made as to the mechanisms producing inhibition and reverberation in the MG.
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  • 55
    ISSN: 1432-1106
    Schlagwort(e): Electron microscopy ; Pontine nuclei ; Experimental neuroanatomy ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The electron microscopical changes occurring in the pontine nuclei following unilateral lesions of the primary sensorimotor cortex have been studied in 7 cats with a survival time from 2–23 days. A description is also given of the fine structure of the pontine regions in receipt of the fibres. These regions are shown in Fig. 1. The study shows that the boutons are practically only in synaptic contact with dendrites. The bouton density on these is only 16%. The boutons are of the en passage and terminal type, with the latter as the most common (Figs. 4a-e). The synaptic vesicles are rounded or elongated. The formaldehyde fixed material had 17.8% boutons with vesicles of the elongated type; the material fixed with a mixture of formaldehyde and glutaraldehyde had only 11.5% of such boutons. The degenerating boutons show the dark type of reaction and the majority of the corticopontine fibres are of the type shown in Figs. 4d and 4e. Astrocytes and microglial cells participate in the removal of degenerating boutons and terminal fibres. Degenerating boutons are present even at the 23 day stage and some have apparently only started to degenerate.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 8 (1969), S. 79-96 
    ISSN: 1432-1106
    Schlagwort(e): Evoked potential thresholds ; Factor analysis ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Zur Beschreibung von Korrelationen zwischen zahlreichen elektrophysiologischen Daten aus verschiedenen Hirngebieten wurde eine Faktorenanalyse nach der Hauptachsenmethode gerechnet. Ausgangsmaterial dieser Analyse waren Schwellen subcortical ausgelöster und abgeleiteter Antwortpotentiale auf Einzelreize. Das resultierende Faktorenmuster ermöglicht ein quantitatives Konzept der Schwellendetermination subcorticaler Reizantworten und zugleich ein Modell von Funktionsbeziehungen zwischen einigen Hirnstrukturen. Die Reizungen und Ableitungen erfolgten bei 35 encéphale isolé-Katzen mit Hilfe bipolarer Elektroden in folgenden Arealen: Amygdala, Hippocampus, Septum, N. dorsomedialis Thalami, Hypothalamus posterior und Formatio reticularis mesencephali. Es wurden 435 Korrelationskoeffizienten zwischen den Schwellen von 30 subcorticalen Verbindungen gebildet und zum Zwecke einer Datenreduktion durch eine Matrix von 5 Faktoren reproduziert. 1. Jeder Faktor repräsentierte hohe Schwellenkorrelationen zwischen den efferenten Projektionen jeweils eines Kerngebietes. Demnach nimmt im allgemeinen die Aktivität des Reizortes den größten Einfluß auf die Schwelle eines Antwortpotentials. Diese Hypothese ist durch pharmakologische Untersuchungen belegt worden [27] 2. Kovariationen von Reizantworten mit identischen Ableiteorten ergaben sich ausnahmslos, wenn die Latenzzeiten mehr als 11 msec betrugen. 3. Zusätzlich zeigte die Faktorenmatrix Schwellenkorrelationen zwischen: a) den hypothalamischen Efferenzen und mehreren hippokampalen Afferenzen langer Latenz (positive Korrelationen) b) retikulo-limbischen Verbindungen und „primären” Efferenzen von Amygdala und Hippocampus (positive Korrelationen) c) Antwortpotentialen, die durch Reizung der Formatio reticularis, und solchen, die durch Reizung des N. Amygdalae ausgelöst waren (negative Korrelationen) d) den Efferenzen des N. dorsomedialis Thalami und limbischen Projektionen langer Latenz zur mesencephalen Formatio reticularis (positive Korrelationen) Die Interpretation dieser Zusammenhänge bestätigt und erweitert einige bekannte Modelle von Beziehungen zwischen subcorticalen Kerngebieten. Abschließend wird mit Rücksicht auf die Linearität der mathematischen Methode die Anwendbarkeit der Faktorenanalyse auf Schwellen von Reizantworten diskutiert.
    Notizen: Summary In 35 cats (encéphale isolé) evoked responses were elicited and recorded with bipolar electrodes from the amygdala, hippocampus, septum, dorsomedial thalamic nucleus, posterior hypothalamus, and mesencephalic reticular formation. Correlations between the thresholds of responses in different areas following stimulation of other areas were described by a factor analysis according to the principal axis method. 435 coefficients of correlation were calculated and reproduced by a matrix of 5 factors for the purpose of data reduction. Each factor represented high threshold correlations between the efferent projections of one region, which suggests that the activity of the stimulated site exerts a major influence on the evoked potential threshold. This is supported by pharmacological studies [27, 49]. Covariations of responses recorded in the same nucleus were always found, if the latencies exceeded 11 msec. The factor matrix indicated threshold correlations between: the efferent projections of the hypothalamus and several long latency afferent projections to the hippocampus (positive correlations); reticulo-limbic connections and “primary” efferent connections of the amygdala and hippocampus (positive correlations); evoked potentials following reticular and amygdaloid stimulation (negative correlations); the efferent projections of the dorsomedial thalamic nucleus and long latency limbic projections to the mesencephalic reticular formation (positive correlations). The interpretation of these relationships confirms and extends some well known models of relations between subcortical regions. The applicability of factor analysis to evoked potential thresholds is discussed with regard to the linearity of the mathematical method.
    Materialart: Digitale Medien
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  • 57
    ISSN: 1432-1106
    Schlagwort(e): Emotional Behaviour ; Hypothalamus ; Electrical stimulation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. The results presented in the present paper are an extension of preceding work devoted to exploration of the hypothalamic defence and flight fields using coaxial electrodes with small cathode. In 33 cats simultaneous stimulation was applied to two points which upon single stimulation had yielded defence, flight, or defence and flight respectively. Results were compared with those produced at either point alone. In 2 cats combined stimulation of a defence and a flight point was carried out with a stuffed cat present. 2. The latencies and rates of the vocal effects associated with defence (growling and hissing), and the latencies of flight (jump from the table) were measured. 3. Simultaneous stimulation of two points which had yielded defence, or of two points which had yielded flight resulted in facilitation (spatial summation) of the effects evoked: a more complete defence response associated with decrease of the latencies and increase in the rates of the vocal effects; decrease of flight latencies and increase of flight impetuosity. 4. Simultaneous stimulation of a defence point which had yielded growling at lower threshold than hissing, and of a point which had yielded flight resulted in facilitation of hissing. Growling and flight were often suppressed; when they occurred, latencies were lengthened and growling rates were increased somewhat. 5. Stimulation of a defence point with a dummy present produces striking (fending off). Simultaneous stimulation of a flight point resulted in facilitation of both hissing and striking. 6. It is concluded that the complex patterns obtained when defence is combined with flight are the result of facilitatory and inhibitory interaction between the elements of the individual patterns.
    Materialart: Digitale Medien
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 8 (1969), S. 37-52 
    ISSN: 1432-1106
    Schlagwort(e): Retinal Ganglion Cells ; Spatial Summation ; Center Inhibition ; Dynamic Organisation of Receptive Fields ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. An retinalen Ganglienzellen der Katze wurde die räumliche Summation im receptiven Feldzentrum (KFZ) bei Dunkeladaptation und Helladaptation durch mittelpunktzentrierte Lichtreize verschiedener Flächengrößen untersucht. Als Kriterium dienten die Entladungsraten der ersten 200 und 500 msec nach Licht-an oder Licht-aus. Das Summationsverhalten wurde sowohl für Einzelneurone als auch gruppenstatistisch für die beiden Neuronen-Systeme B (on-Zentrum) und D (off-Zentrum) untersucht. 2. Die räumliche Summation ist auf den inneren Bereich des RFZ beschränkt: bei on-Zentrum-Neuronen steigt die Entladungsrate nur bis zu Reizflächen, die etwa 1/5 der Fläche des RFZ belichten, bei off-Zentrum-Neuronen bis zu Reizflachen von ca. 1/10 des RFZ. Bei Variation der Reizfläche zwischen 20 und 100% der Fläche des RFZ bleibt das Entladungsniveau konstant (asymptotischer Verlauf der Summationskurve). 3. Die Begrenzung der räumlichen Summation auf einen kleinen Bereich des RFZ beweist eine bereits im Feldzentrum wirksame Hemmung. Diese Zentrum-Inhibition begrenzt die Erregungssummation im RFZ bei zunehmender Flächengröße des Lichtreizes. 4. On- und off-Zentrum-Neurone unterscheiden sich in beiden Adaptationszuständen in der Höhe des Entladungsniveaus. Die Entladungsraten der on-Zentrum-Neurone nach Licht-an übertreffen um ein Mehrfaches die Entladungsraten der off-Zentrum-Neurone nach Licht-aus. Die Unterschiede sind gruppenstatistisch hoch signifikant. Die interneuronale Variabilität der Entladungsraten ist bei den onZentrum Neuronen erheblich geringer als bei den off-Zentrum-Neuronen. 5. Dunkel -und Helladaptation führt zu signifikantem Unterschied der Entladungsraten: bei Helladaptation liegt die Impulsrate beider Neuronentypen höher als bei Dunkeladaptation und der Summationsbereich ist um 5–10% größer. 6. Für die mathematische Beschreibung der Summationsverläufe ist die Hyperbel besser geeignet als die logarithmische und Potenzfunktion. Logarithmus- und Potenzfunktionen beschreiben den konstanten asymptotischen Teil der Summationskurven ungenügend und eigenen sich nur für den Kurventeil im innersten Summationsbereich. Die Bedeutung der Befunde für eine dynamische Interpretation der visuellen Feldorganisation und mögliche Beziehungen zur lateralen Umfeldhemmung werden diskutiert.
    Notizen: Summary 1. Spatial summation of suprathreshold light stimuli within receptive field centers (RFZ) of retinal ganglion cells was investigated during dark and light adaptation in cats. The mean discharge rates for 200 and 500 msec following light on or off were the computed response criteria. The summation effects were analyzed for single neurones and statistically for grouped neuron populations of the two neuronal subsystems B (on-center-neurones) and D (off-center-neurones). 2. Spatial summation is restricted to a small part of the RFZ. On-centerneurones increase their on-discharge rates with increasing spot sizes, only if the stimulus illuminates less than 1/5 of the RFZ. The summating area of the off-centerneurones is smaller (about 1/10 of the RFZ). 3. The limitation of spatial summation to a small part of the RFZ indicates the existance of inhibition within the RFZ. This center-inhibition sets a constant limit for excitation summation in the RFZ. 4. The mean neuronal response rates for the 2 subsystems show significant differences: The on-discharges of the on-center-neurones exceed the off-discharges of the off-center-neurones by a factor of 3–5. These highly significant differences occur at both adaptation levels and are not due to different spontaneous activity. Interneuronal response variability of the off-center-neurones was twice as large as that of the on-center-neurones. 5. Change from dark to light adaptation had only a small but significant influence on summation properties. The poststimulus discharge rates were higher during light adaptation and the summating area was slightly larger (about 5–10%). 6. A comparative curve fitting procedure for three suitable mathematical functions revealed that the hyperbola describes the neuronal summation curves better than a logarithmic or power function. The latter do not fit the constant asymptotic part of the curve. The significance of the results for a dynamic interpretation of the organisation of visual receptive fields is discussed.
    Materialart: Digitale Medien
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 8 (1969), S. 53-65 
    ISSN: 1432-1106
    Schlagwort(e): Lateral geniculate body ; Spatial summation ; Off-center-characteristics ; Geniculate transfer ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Die räumliche Summation im receptiven Feldzentrum von Neuronen des Corpus geniculatum laterale (CG-L) wird beschrieben und mit entsprechenden Untersuchungen an retinalen Ganglienzellen verglichen. Neben größerer interneuronaler Variabilität ergeben sich ausgeprägtere Unterschiede der Summationseigenschaften der on-und off-Zentrum-Neurone. Der effektive Summationsbereich von etwa 1/5 der Fläche des RFZ ist in Retina und CGL etwa gleich. 2. Die on-Zentrum-Neurone des CGL zeigen in beiden Adaptationszuständen einen ähnlichen Summationsverlauf wie in der Retina. Das Entladungsnieau ist im CGL jedoch erheblich geringer und nicht durch Unterschiede in der Spontanaktivität zu erklären. 3. Die Mehrzahl der off-Zentrum-Neurone des CGL zeigt bei DA inverse Summationsverläufe wie in der Retina: durchgehende Verminderung der Entladungsrate der off-Antworten bei Vergrößerung der Reizfläche im RFZ. Eine kleine Gruppe zeigt einen parabelförmigen Summationsverlauf mit Entladungszunahme bis zu Reizflächen von 10–30% der Fläche des RFZ und darauffolgender Entladungsminderung. Bei Helladaptation zeigen fast alle off-Zentrum-Neurone diesen Parabelverlauf. Das durchschnittliche Entladungsniveau ist von dem retinaler offZentrum-Neurone nicht signifikant verschieden. 4. Die interneuronale Variabilität der Summationsvorgänge im RFZ von CGLNeuronen ist gegenüber den retinalen Ganglienzellen deutlich größer. Dies gilt insbesondere für die off-Zentrum-Neurone. Das Summationsverhalten von CGLNeuronen läßt sich daher nicht wie in der Retina durch einen Funktionstyp beschreiben. 5. Die Befunde sprechen für eine Transformation des retinalen Eingangs der off-Zentrum-Neurone im CGL, während die on-Zentrum-Neurone außer der bekannten Frequenzuntersetzung keine wesentliche Umformung erkennen lassen.
    Notizen: Summary 1. Spatial summation in the receptive field center of neurones of the lateral geniculate body (CGL) is limited by inhibition to a small part of field center. Variations of stimulus size are only effective if the stimulus is smaller than about 1/5 of the area of receptive field center. Thus, the active summating area of the field center in the CGL corresponds to that of the retina. Geniculate neurones, however, show less homogeneous responses and the summation properties of the two neuronal subsystems (on-center-and off-center-cells), show greater differences than in the retina. 2. The form of summation curves for the on-center-neurones of the CGL is similar to those of the retina at both adaptation levels. However, the average responses rates in the CGL are considerably lower. This is not due to differences of spontaneous activity. 3. The summation characteristics of off-responses of off-center-neurones of the CGL are quite different from those in the retina. In dark adaptation the majority of CGL neurones respond with decreasing discharge rates to increasing spot-sizes within the field center. A small number show an initial increase of discharge rates up to stimulus sizes of about 1/10 of the receptive field center before a decrease occurs. This parabolic summation type is typical for most off-center-neurones in light adaptation. The mean discharge levels are the same as those of the retinal offcenter-neurones. 4. The higher interneuronal variability of summation curves especially of the off-center-neurones of the CGL indicates a more complex determination of the discharge properties of CGL neurones. This functional differentiation of single neurones is congruent with the more complex structural and synaptic organisation in CGL. 5. With respect to spatial summation, the results indicate a transformation of the retinal input of the off-center-neurones at the geniculate level, whereas the oncenter-neurones are nearly unchanged.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 14 (1969), S. 164-166 
    ISSN: 1432-2072
    Schlagwort(e): Benperidolum ; Cat ; Extrapyramidal Side Effect ; EEG ; Toxicity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Daily doses of 1–10 mg Benperidol were given perorally to cats during 26 months. The general behaviour and the EEG were unchanged during the treatment, in particular no signs of dyskinesia were observed. After discontinuation of the administration, the behaviour and the EEG of the animals stayed normal. Thus no lasting and irreversible side effects could be observed.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 15 (1969), S. 382-391 
    ISSN: 1432-2072
    Schlagwort(e): LSD ; Retina ; LGN ; Single Unit Activity ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of LSD 25 (i. v. injection) on the spontaneous and evoked activity of the visual system was investigated in cats. 50 γ/kg did not change significantly the ERG and the visual cortical evoked potential. The spontaneous discharge rate of 14 out of 21 retinal ganglion cells showed an increase which reached its maximum within 20–30 min and which could still be present 1 hour following the injection. One third of the retinal units showed a slight depression of their spontaneous dischaRge rate with about the same time course. Single units of the LGN showed about the same behaviour. The response to light stimulation was slightly increased in some units and light induced inhibition was slightly shortened. The possible mechanism of the LSD-effect on retinal ganglion cell activity is discussed.
    Materialart: Digitale Medien
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 309 (1969), S. 285-309 
    ISSN: 1432-2013
    Schlagwort(e): Labyrinthine Stimulation ; Types of Abducens Neurones ; Frequency Analysis ; Cat ; Labyrinthreizung ; Abducensneurone ; Frequenzanalyse ; Katze
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Single cell activity was recorded extracellularly from neurones in cat's abducens nuclei in unanesthetized, decerebrate preparations. Two types of neurones were found. i) The motoneurones (type IIA) increased their firing linearly or exponentially to contralateral constant angular accelerations and decreased firing to ipsilateral rotation. The increased frequency was maintained at a constant level without any sign of adaptation. This constant level of maximum frequency was proportional to the logarithm of the acceleration applied. No significant differences of the frequency responses of tonic and silent motoneurones were found. The conduction velocities of the axons of spontaneously firing type IIA cells were slower than in silent neurones. Electrical stimulation of the contralateral VIIIth nerve led to activation of the type IIA cells; stimulation of the ipsilateral nerve resulted in inhibition of both spontaneous discharge and antidromic invasion of the motoneurones. ii) The type IA units increased their firing rate to ipsilateral rotation and ceased to discharge in response to contralateral rotation. They never were excited antidromically by stimulation of the VIth nerve. However, they were excited by stimulation of the ipsilateral VIIIth nerve. Their possible functional role in the vestibulo-ocular system was discussed.
    Materialart: Digitale Medien
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  • 63
    ISSN: 1432-2013
    Schlagwort(e): Cat ; Decerebration ; Afferents to Respiratory Centers ; Medulla Oblongata ; Reticular Formation ; Katze ; Decerebrierung ; Afferenzen zu Atemzentren ; Medulla oblongata ; Formatio reticularis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung An 11 intercolliculär decerebrierten Katzen wurde geziegt, daß Kälteblockade eines eng umschriebenen Feldes auf der ventralen Oberfläche der Medulla oblongata, wie früher für anaesthesierte Tiere beschrieben, zu Atemstillstand führt, wenn die kontralaterale Stelle auf der Medulla oblongata, die Sinusnerven und die Vagi ausgeschaltet sind. Zu Atemstillstand kam es auch, wenn statt der Kälteblockade 2% Novocain durch lokale Superfusion bei gleichzeitiger Gegenspülung der Umgebung mit künstlichem Liquor angewandt wurde, oder wenn ein mit 1% Novocain getränkter Tupfer lokal aufgelegt wurde. Außerdem führte Kälteblockade zu Atemstillstand, wenn durch kontinuierliche auch während der Kälteblockade anhaltende elektrische Reizung eines N. femoralis oder hinterer Lumbalwurzeln an decerebrierten Katzen oder des Hypothalamus an einer anaesthesierten Katze Steigerungen der Ventilation ausgelöst worden waren. Elektrische Reizung eines Sinusnerven führte zu Atemsteigerungen. Bei Sinusnervenreizung während eines durch Kälteblockade ausgelösten Atemstillstands kam es zu rhythmischer Atmung. Aus diesen Untersuchungen wird geschlossen, daß mit der Ausschaltung der beschriebenen Felder auf der ventralen Oberfläche der Medulla oblongata am sonst desafferentierten Tier die Gesamtheit der für die zentrale CO2-Empfindlichkeit verantwortlichen Strukturen erfaßt ist, daß nach Ausschaltung der zentralen und der peripheren Chemosensibilität eine unspezifische Aktivierung der Atmungszentren unwirksam ist und daß die Atmungszentren zur Ausbildung einer rhythmischen Atmung von spezifischen Antrieben abhängig sind.
    Notizen: Summary It was shown in 11 decerebrated cats, that cooling of a small and well defined area on the ventral surface of the medulla will cause respiratory arrest if the contralateral area of the medulla, the vagi and sinus nerves are eliminated. This confirms earlier observations obtained in anesthetized cats. Apnea was also produced by local superfusion of 2% procain with simultaneous flushing of the immediate surrounding area with mock spinal fluid. Local application of a small sponge soaked with 1% procain had the same effect. Electrical stimulation of femoral nerves or posterior roots which results in hyperventilation on the decerebrated cat failed to show any effect during periods of cold blockade. There was no respiratory response to direct stimulation of the hypothalamus in an anesthetized cat during cooling. Electrical stimulation of one sinus nerve caused an increase of ventilation. Sinus nerve stimulation during apnea induced by cold blockade resulted in rhythmical respiration. It is concluded from these experiments: Blocking of the area under discussion on the ventral surface of the medulla, inhibits all structures responsible for the central CO2-sensitivity in the deafferentiated animal. There was no response to non-specific stimuli of the respiratory center after elimination of central and peripheral chemosensitivity. The respiratory centers apparently depend on specific stimuli to support rhythmical respiration.
    Materialart: Digitale Medien
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 8 (1969), S. 113-129 
    ISSN: 1432-1106
    Schlagwort(e): Emotional behaviour ; Hypothalamus ; Electrical stimulation ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Affective behaviour patterns produced by electrical stimulation of the hypothalamus were studied in unanaesthetized, freely-moving cats. Bipolar stimulation with coaxial electrodes and small cathode was used to elicit defence, attack or flight. The development of these responses was studied by varying stimulation strength. In some experiments a stuffed animal was introduced in order to study the reactions of the cat to changes in the environment during stimulation. 2. The following responses were evoked at threshold intensity: (i) growling reaction; (ii) hissing reaction; (iii) two types of flight — type a preceded by hastily looking to and fro as if in search of an exit, type b preceded by inspection of surroundings, in most cases associated with sniffing. 3. Increasing stimulation 1.5 times threshold often yielded combined patterns. At points yielding the growling reaction a defence response in which growls alternated with hisses was obtained. The points yielding flight type a sometimes yielded hissing followed by flight. Increasing stimulation at hissing points yielded either a defence reaction or the combined effect hissing-flight. 4. The growling reactions were obtained from the tuber region. The hissing responses were obtained from points above the tuber. The flight reactions, type a, were produced from the intermediate zone extending from the level of the preoptic area to the mamillary bodies and type b from the caudo-lateral hypothalamus. 5. The reactions of the cats to a dummy during stimulation varied depending on the type of response which had been evoked in the absence of the dummy. The defence reaction was converted into threatening and striking of the dummy, the combined effects into threatening, striking or biting, culminating in sudden flight. The dummy was ignored during stimulation of points yielding flight type a, but examined by sniffing during stimulation of points yielding flight type b.
    Materialart: Digitale Medien
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 8 (1969), S. 219-231 
    ISSN: 1432-1106
    Schlagwort(e): Cerebral cortex in vitro ; Chloride transport ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The kinetics of the uptake of chloride by slices of cat cerebral cortex incubated in vitro have been studied for a wide range of concentrations of chloride and potassium in the incubation media. 1. In studies with 36Cl at a constant concentration of external K+, the rate of entry of chloride into slices of cat cerebral cortex (after equilibration with the fluid of the extracellular space) followed Michaelis-Menten kinetics with Vmax=7.7 μmoles/g/min and Km=245 mM. The kinetic data so described differ significantly from a curve describing simple diffusion (P 〈 0.02). 2. A clear dependence on concentration of K+ in the incubation medium was demonstrated. When external chloride was held constant at 6.8 mM and concentrations of potassium were varied over a range of 27–100 mM, the apparent rate of entry of chloride followed Michaelis-Menten kinetics with Vmax=0.191 μmoles/ g/min and Km=30.3 mM. 3. Under similar equilibrium conditions, the rate of influx of chloride was not statistically different from the rate of efflux, and the value for extracellular space (355 μl/g) derived by extrapolation from efflux data was of an identical order of magnitude to the value (352 μl/g) obtained from influx data. These values are essentially identical to those previously determined for chloride space of cat cerebral cortex in vivo (Bourke, Greenberg and Tower 1965). 4. The total, membrane-delimited content of chloride in cerebral cortex, as defined in these studies in vitro, was a function of the concentration of K+ in the incubation medium.
    Materialart: Digitale Medien
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 8 (1969), S. 232-248 
    ISSN: 1432-1106
    Schlagwort(e): Cerebral cortex in vitro ; Edema ; Fluid compartmentation ; Chloride transport ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The ionic parameters of incubation media which foster both the development and subsequent reduction of swelling of slices of cerebral cortex under isosmotic conditions of incubation in vitro are described. A linear relationship between increasing chloride concentrations in incubation media and progressive swelling of tissue slices (under conditions of constant temperature and K+ concentrations and isotonicity of incubation media) is demonstrated. Subsequent reduction of chloride concentration in incubation media together with reciprocal replacement by isethionate is associated with significant and characteristic reduction in the volume of tissue swelling when all other conditions of incubation, including isotonicity of the media, are kept constant. The ionic composition of the fluid of swelling under different conditions of incubation is derived together with the ionic composition and expected transmembrane potentials of the neuronal compartment of cerebral cortex in vitro. Mechanisms involved in the development and subsequent reduction of swelling of cerebral cortex in vitro are discussed, and proposals for possible clinical applications are suggested.
    Materialart: Digitale Medien
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  • 67
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 262 (1969), S. 73-86 
    ISSN: 1432-1912
    Schlagwort(e): Strophanthidine Derivatives ; Toxicity ; Absorption ; Guinea-Pig ; Cat ; Strophanthidinderivate ; Toxicität ; Resorption ; Meerschweinchen ; Katze
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es wurde die Wirksamkeit verschiedener Ester und Äther von Helveticosid und Helveticosol bei i.v. und intraduodenaler Zufuhr an Katzen und Meerschweinchen geprüft. 1. Bei i.v. Dauerinfusion waren Helveticosol und seine Derivate bei Meerschweinchen etwa doppelt so wirksam wie die analogen Helveticosidverbindungen. Bei der Katze bestand kein Unterschied. Die Monomethyläther Cymarin und Cymarol waren gleich oder sogar stärker wirksam, alle übrigen Derivate deutlich schwächer als die Ausgangssubstanzen. 2. Die tödlichen Dosen bei intraduodenaler Injektion lagen beim Meerschweinchen für einige Substanzen in gleicher Größenordnung oder niedriger als die Titer bei i.v. Infusion. Diese hohe enterale Wirksamkeit kann bei Helveticosid und seinen Derivaten durch eine Reduktion zu dem wirksameren Helveticosol, bei Estern außerdem durch eine Hydrolyse zu wirksameren Glykosiden vorgetäuscht werden. 3. Bei intraduodenaler Infusion an Katzen waren alle geprüften Ester und Äther wirksamer als Helveticosid und Helveticosol. Die aus dem Verhältnis der toxischen Dosen bei i.v. und intraduodenaler Infusion berechnete enterale Wirksamkeit lag zwischen 20 und 50%. 4. Unterschiede in der Dauer der intraduodenalen Infusion bei Katzen lassen sich berücksichtigen, wenn man von der theoretischen Annahme einer exponentiellen und vollständigen Resorption ausgeht und die Halbwertszeit für die Resorption berechnet. Die minimale Resorptionsgeschwindigkeit lag bei einigen Derivaten in gleicher Größenordnung wie bei Digoxin und Digitoxin. Es wird auf den Unterschied zwischen der auf Grund der pharmakologischen Wirkung bestimmten relativen enteralen Wirksamkeit und der Resorptionsquote hingewiesen. Letztere ist für die Verläßlichkeit der therapeutischen Wirkung eines Glykosids bei oraler Gabe maßgebend.
    Notizen: Summary The efficacy of several esters and ethers of Helveticosid and Helveticosol was assayed by intravenous and intraduodenal administration to cats and guinea-pigs. 1. In guinea-pigs, Helveticosol and its derivatives were approximately twice as active on intravenous infusion as the analogous derivatives of Helveticosid; in cats there was no significant difference. The monomethylethers Cymarin and Cymarol were equally or slightly more potent, all other derivatives were weaker than the original compound. 2. In guinea-pigs the lethal doses of some compounds on intraduodenal injection were equal to or even lower than those on intravenous infusion. This may partly be accounted for by a reduction of Helveticosid and its derivatives to the more potent Helveticosol analogues, partly by a hydrolysis of the esters, yielding compounds of higher activity. 3. On intraduodenal infusion in cats, all the investigated esters and ethers were more active than Helveticosid and Helveticosol. The relative enteral activity calculated from the ratio of the toxic doses on intravenous and intraduodenal infusion varied between 20 and 50%. 4. Due to a delayed absorption from the gastrointestinal tract, the toxic dose falls with a reduced speed of intraduodenal infusion. Assuming an exponential and complete absorption, the half time of absorption was calculated. For some of the compounds investigated, the speed of absorption was comparable to that of Digoxin and Digitoxin. The difference between the relative enteral activities determined by comparing equiactive doses on enteral and parenteral administration and the percentages of the glycosides which are absorbed from the gastrointestinal tract is pointed out. The latter is of prime importance for obtaining reproducible effects after enteral administration.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 101 (1969), S. 607-620 
    ISSN: 1432-0878
    Schlagwort(e): Glandula bulbourethralis ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Parenchym der Glandula bulbourethralis der Katze besteht aus weitlumigen, gebuchteten intraglandulären Gängen, in welche kurze, englumige, zumeist unverzweigte Tubuli einmünden. Der Drüse fehlt eine äußere Organkapsel, so daß ihre peripheren Tubuli stellenweise direkt zwischen den Fasern des quergestreiften M. bulboglandularis liegen. Die Drüsentubuli und die Buchten der intraglandulären Gänge sind mit einem einschichtigen Zylinderepithel ausgekleidet, auf den Gangfalten ist das Epithel abschnittsweise mehrreihig, Die sezernierende Epitheloberfläche ist durch die Ausbildung von interzellulären Sekretkapillaren vergrößert. Breite Zwischenzellspalten (Durchmesser etwa 1,5μ), in welche schlanke interdigitierende Cytoplasmafortsätze hineinragen, erstrecken sich von der Basalmembran bis kurz unter das Tubulusbzw. Ganglumen. Die lumenseitigen Zellgrenzen tragen einige stummelförmige Mikrovilli und besitzen zerklüftete Außenkonturen, die durch glykogenreiche Cytoplasmaprojektionen bedingt sind. Alle Epithelzellen sind reich an Mitochondrien. Die supranuklearen Abschnitte der meisten Gang- und Tubuluszellen enthalten Sekretgranula, welche im Elektronenmikroskop unterschiedliche optische Dichten aufweisen können. Die Granula enthalten ein PAS-positives, neuraminsäurehaltiges epitheliales Muzin, das in einzelnen Sekretkörnchen auch eine histochemische Reaktion auf Sulfatgruppen gibt. Alle Epithelzellen reagieren sehr stark auf unspezifische Esterase und stark auf β-D-Glucuronidase, β-D-Glactosidase sowie die Enzyme des Citronensäurezyklus, der Glykolyse und der Atmungskette (NAD-ICDH, SDH, ALD, LDH, ADH, GDH, NADH-T-Red, Cyt-Ox).
    Notizen: Summary The bulbourethral glands of sexually mature male cats are studied with the light and electron microscope. The parenchyma consists of spacious, sinus-like intraglandular ducts and short, narrow, mostly unbranched tubular endpieces. The gland has no complete connective tissue capsule, consequently some of the peripheral tubules are situated directly in between the fibers of the surrounding bulboglandularis muscle. The endpieces and the sinus of the intraglandular ducts are lined by a simple columnar epithelium, whereas the folds of the ducts are generally covered by a low pseudostratified epithelium. The secretory surface of the cells is increased by intercellular canaliculi which communicate with the gland lumen. These canaliculi are identified on the light microscopic level by their strong 5′-nucleotidase activity. Furthermore widened intercellular spaces (approximately 1,5 μ in diameter) filled with slender, interdigitating cytoplasmic processes extend from the basal lamina to the apical junctional complexes. The luminal cell pole exhibits some short microvilli and forms irregularly shaped, glycogen containing protrusions. Within the cytoplasm of the gland cells numerous spherical mitochondria, some dense bodies, a typical Golgi apparatus, free ribosomes and a poorly developed endoplasmic reticulum are to be observed. Secretory granules which can be grouped into three types on the basis of their electron density occur in the supranuclear regions of most of the cells. According to histochemical tests all granules contain a periodate reactive sialomucin and some of them also sulfate groups. The glandular parenchyma is site of an exceptionally strong unspecific esterase activity and is rich in β-D-glucuronidase, β-D-glactosidase, aldolase, α-glycerophosphate dehydrogenase, lactate dehydrogenase, alcohol dehydrogenase, NAD-dependent isocitrate dehydrogenase, succinate dehydrogenase and cytochrome oxydase.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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