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  • 1995-1999  (12)
  • 1985-1989
  • 1965-1969  (10)
  • 1840-1849
  • 1995  (12)
  • 1966  (10)
  • Cerebellum
  • 1
    ISSN: 1432-0568
    Keywords: Cerebellum ; Medial nucleus ; Paraventricular nucleus of the hypothalamus ; Horseradish peroxidase ; Fluoro-Gold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Retrograde transport of lectin-conjugated horseradish peroxidase and Fluoro-Gold was used in an attempt to obtain data to confirm the existence, predicted from physiological studies, of a direct, monosynaptic projection from the medial nucleus of the cerebellum (MN) to the paraventricular nucleus of the hypothalamus (PVH) in the rat. Injections of these two tracers that included the PVH and surrounding diencephalic structures, or that in the case of Fluoro-Gold were localized to the PVH, resulted in retrograde neuronal labeling in widely separated nuclei known to project to the areas included in the injection sites. Thus, effective uptake and transport of both tracers occurred under the experimental conditions employed in this study. However, injections confined to the PVH and regions of the hypothalamus adjacent to it, or to the PVH alone, produced no retrograde neuronal labeling in the medial nucleus, indicating that the MN does not project directly to the PVH. Alternative explanations for the findings from physiological experiments were sought. The possibility that electrical stimulation of fibers of passage through the region of the MN might produce a monosynaptic response in the contralateral PVH was discarded, because retrogradely labeled neurons in nuclei such as the locus ceruleus and lateral parabrachial nucleus were distributed mainly ipsilateral to hypothalamic injection sites. However, tracer injections into the MN produced retrograde labeling of neurons in the same region of the lateral paragigantocellular nucleus (LPGi) in which labeled cells were found following tracer injections into the PVH. Axon collaterals of individual neurons in the LPGi might, therefore, project both to the MN and to the PVH. The possibility that such a circuit could, in the absence of a direct MN to PVH projection, provide the basis to explain the physiological findings is discussed.
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  • 2
    ISSN: 1432-0533
    Keywords: Superoxide dismutase ; Menkes' kinky hair disease ; Cerebellum ; Purkinje cells ; Reactive astrocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This comparative immunohistochemical study deals with the expression of the cytosolic Cu/Zn-binding and mitochondrial Mn-dependent superoxide dismutases (SODs) in the cerebella of five patients with Menkes' kinky hair disease (MKHD) and five age-matched controls. Several cell types, including Purkinje cells and reactive astrocytes, of all MKHD patients examined were intensely stained by an antibody to Mn SOD, but not by an anti-Cu/Zn SOD antibody. By contrast, the cells of the five controls reacted very weakly or not at all with the anti-Mn SOD antibody, but were strongly reactive with the antibody to Cu/Zn SOD. These results suggest that the increased Mn SOD immunoreactivity in MKHD reflects enzyme induction as a protective mechanism against the highly toxic superoxide anion generated under the disease conditions.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 90 (1995), S. 400-402 
    ISSN: 1432-0533
    Keywords: Key words Leukomalacia ; Neonate ; Prematurity ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cystic necrosis in the cerebellar white matter was found in three premature infants. The necrosis was characteristically localized in the center of the white matter of the superficial cerebellar folia, sparing the overlying cortex. The patients were aged between 28 and 34 gestational weeks, and had a clinical history of severe systemic hypotension. Thus, cystic leukomalacia represents a characteristic brain lesion in premature infants which may be caused by cerebellar hypoperfusion.
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  • 4
    ISSN: 1432-0533
    Keywords: Key words Superoxide dismutase ; Menkes' kinky hair ; disease ; Cerebellum ; Purkinje cells ; Reactive astrocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This comparative immunohistochemical study deals with the expression of the cytosolic Cu/Zn-binding and mitochondrial Mn-dependent superoxide dismutases (SODs) in the cerebella of five patients with Menkes' kinky hair disease (MKHD) and five age-matched controls. Several cell types, including Purkinje cells and reactive astrocytes, of all MKHD patients examined were intensely stained by an antibody to Mn SOD, but not by an anti-Cu/Zn SOD antibody. By contrast, the cells of the five controls reacted very weakly or not at all with the anti-Mn SOD antibody, but were strongly reactive with the antibody to Cu/Zn SOD. These results suggest that the increased Mn SOD immunoreactivity in MKHD reflects enzyme induction as a protective mechanism against the highly toxic superoxide anion generated under the disease conditions.
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  • 5
    ISSN: 1432-0533
    Keywords: Cerebellum ; Neuronal volume ; Methyl mercury ; Neuronal number ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methyl mercury intoxication causes ataxia. Structural changes of cerebellar and peripheral nerve tissues have been described. However, it is still unclear whether the ataxia is of cerebellar or peripheral origin. To clarify this question further, the effects of methyl mercury intoxication on the numbers of granule and Purkinje cells and the volume of Purkinje cell perikarya have been evaluated with stereological methods. Rats were intoxicated with methyl mercury, at a dose of 2 mg/kg per day for 19 successive days, and the analysis was carried out 2.5 or 4.5 weeks later. The total numbers of cerebellar granule cells and Purkinje cells were estimated using an optical fractionator and the mean volume of the Purkinje cells was estimated by the vertical rotator technique. The volumes of the granular cell layer, the molecular layer and the white matter were estimated using the Cavalieri principle. The intoxicated animals developed hindlimb incoordination when held by the tail. Although pronounced axonal degeneration occurred in the peripheral nervous system, no changes were found in cerebellar cell numbers or cell sizes in either of the test groups. The absence of detectable light microscopic changes in the cerebellum indicates that the peripheral nervous system is affected prior to the cerebellum in rats intoxicated with organic mercury.
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  • 6
    ISSN: 1432-0533
    Keywords: Calcium ; Ischemia ; Cerebellum ; Purkinje cell ; Microfluorometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes in levels of intracellular calcium ion ([Ca2+]i) induced by in vitro ischemic conditions in gerbil cerebellar and hippocampal slices were investigated using a calcium imaging system and electron microscopy. When the cerebellar slice was perfused with a glucose-free physiological medium equilibrated with a 95% N2/5% CO2 gas mixture (in vitro ischemic medium), a large [Ca2+]i elevation was region-specifically induced in the molecular laver of the cerebellar cortex (a dendritic field of Purkinje cells). When the hippocampal slice was perfused with in vitro ischemic medium, a large [Ca2+]i elevation was region-specifically induced in CA1 field of the hippocampal slices. Electron microscopic examinations showed that the large [Ca2+]i elevations occurred in Purkinje cells and CA1 pyramidal neurons. To isolate Ca2+ release from intracellular Ca2+ store sites, the slices were perfused with Ca2+-free in vitro ischemic medium. the increases in [Ca2+]i in both cerebellar and hippocampal slices were significantly lower than those observed in the slices perfused with the Ca2+-containing in vitro ischemic medium. However, the suppression of the [Ca2+]i-elevation in the molecular layer of the cerebellar slices was smaller than that in the CA1 field of the hippocampal slices. These results reinforce the hypothesis that calcium plays a pivotal role in the development of ischemia-induced neuronal death, and suggest that Ca2+ release from intracellular Ca2+ store sites may play an important role in the ischemia-induced [Ca2+]i elevation in Purkinje cells.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 89 (1995), S. 385-390 
    ISSN: 1432-0533
    Keywords: Key words Dysembryoplastic neuroepithelial tumour ; Cerebellum ; Cerebellar astrocytoma ; Granule neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of dysembryoplastic neuroepithelial tumour of the cerebellum occurring in a 28-year-old woman is presented. The lesion extended from the cortex of the inferior vermis upwards into the white matter. Histologically, it exhibited areas of microcystic cerebellar astrocytoma and glial regions with hamartomatous blood vessels as well as areas with oligodendrocyte-like cells (OLC) with a delicate, fibrillary stroma lying in a mucinous, often microcystic matr ix. The OLC showed prominent rosette formation and immunohistochemical features suggesting neuronal, i.e. granule cell, differentiation.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 90 (1995), S. 400-402 
    ISSN: 1432-0533
    Keywords: Leukomalacia ; Neonate ; Prematurity ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cystic necrosis in the cerebellar white matter was found in three premature infants. The necrosis was characteristically localized in the center of the white matter of the superficial cerebellar folia, sparing the overlying cortex. The patients were aged between 28 and 34 gestational weeks, and had a clinical history of severe systemic hypotension. Thus, cystic leukomalacia represents a characteristic brain lesion in premature infants which may be caused by cerebellar hypoperfusion.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 89 (1995), S. 385-390 
    ISSN: 1432-0533
    Keywords: Dysembryoplastic neuroepithelial tumour ; Cerebellum ; Cerebellar astrocytoma ; Granule neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of dysembryoplastic neuroepithelial tumour of the cerebellum occurring in a 28-year-old woman is presented. The lesion extended from the cortex of the inferior vermis upwards into the white matter. Histologically, it exhibited areas of microcystic cerebellar astrocytoma and glial regions with hamartomatous blood vessels as well as areas with oligodendrocyte-like cells (OLC) with a delicate, fibrillary stroma lying in a mucinous, often microcystic matrix. The OLC showed prominent rosette formation and immunohistochemical features suggesting neuronal, i.e. granule cell, differentiation.
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  • 10
    Electronic Resource
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    Springer
    Anatomy and embryology 191 (1995), S. 145-153 
    ISSN: 1432-0568
    Keywords: Turtle ; Cerebellum ; Microvascularization Corrosion casts ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cerebellar blood supply and microvascular patterns were studied in 12 freshwater turtles Pseudemys scripta elegans by scanning electron microscopy (SEM) of microvascular corrosion casts and histology. Vascular densities were estimated by point counting methods from casts and thin sections (7 μm). Short A2-arterioles and recurrent branches from A3-arterioles supply the capillary bed of the molecular layer, while V2 and V3 venules drain it. The Purkinje cell layer is supplied by horizontal branches (“parallel arteries”) of A4 and A3 arterioles, which capillarize toward the granular and molecular layers. V2, V3 and V4 venules drain the areas supplied by A3 arterioles. The deep granular and subependymal layers are supplied by A4 arterioles, those adjacent to the Purkinje cell layer also by A3 arterioles. The areas supplied by A4 arterioles drain via V4 venules. The granular and Purkinje cell layers taken together have an estimated vascular density of 4.1%, while in the molecular layer this value is 3.3%. Our findings largely confirm published data from Testudo geometrica and Pseudemys scripta elegans with respect to gross supply and drainage. The microvascular patterns are similar to those of the human cerebellar cortex, particularly the basic patterns of intracortical arterioles and venules. The molecular layer, like that in the human brain, has a circulatory bed largely independent of that of the Purkinje cell and granular layers. In contrast to the human brain, a cerebellar pial capillary network is present in the brain of the turtle.
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  • 11
    ISSN: 1432-1106
    Keywords: Cerebellum ; Motor learning ; Reaching ; Cerebellar nuclei ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was designed to examine the changes in the modulation of small populations of cerebellar neurons during the acquisition of a complex, operantly conditioned forelimb task in cats. The experiments are based on the general postulate that, during the learning of a complex motor behavior, the cerebellum is important for generating a coordinated movement that meets the task's objectives, and that, as the cerebellum participates in this process, it acts to reinforce the effective motor pattern once it has been established. This specific study examines whether the changes in the modulation of cerebellar nuclear neurons during the learning of this task are consistent with this view. Cats were required to learn to move the manipulandum through a novel pattern of 2–3 consecutive straight grooves connected end to end in different spatial configurations, e.g., the letter L, an inverted L, and the letter C. Throughout the acquisition process, 6–12 single units were recorded simultaneously in the cerebellar nuclei, and the kinematics of the movement were evaluated using an Optotrak system. Cells were recorded from the two interposed nuclei and the dentate nucleus in these initial studies. Trials were sorted off-line based on the level of skill at which the required movement was performed. This was assessed using several objective criteria such as movement times, kinematic characteristics, and smoothness (number of peaks in the velocity profile). Event-related histograms then were constructed from each group of sorted trials. Changes in modulation related to a specific event were measured in successive histograms for each neuron. One of the most consistent findings across the cells in all nuclei was that the magnitude of the task-related modulation reached a peak at the time the task was first performed reasonably well and then progressively decreased (but did not disappear) as the task became well practiced. Both the initial increase and the subsequent decrease in response amplitude were significant statistically. The implications of these observations are discussed in the context of the role the cerebellum may play in the acquisition of complex motor tasks.
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  • 12
    ISSN: 1432-1920
    Keywords: Key words Venous angioma ; Cerebellum ; Developmental venous anomaly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A rare (arteriolo-)capillo-medullary venous anomaly of the cerebellum was examined with CT, MRI, and angiography. Unlike the usual venous angioma, this case had such extraordinary features as: infratentorial location, involvement of the whole left cerebellum, an arteriolocapillary component and a history of progressive vomiting and chronic constipation in a 7-year-old boy. CT and MRI were consistent with an extensive vascular malformation, but the actual diagnosis was reached by angiography.
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  • 13
    Electronic Resource
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    Springer
    Experimental brain research 2 (1966), S. 18-34 
    ISSN: 1432-1106
    Keywords: Cerebellum ; Parallel fibres ; Basket cells ; Purkinje cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Stimulation through concentric electrodes on the surface of a wide cerebellar folium was employed to set up a parallel fibre volley or beam. Serial recording of the field potential was made over a range of depths along microelectrode tracks arranged in a transverse plane across the folium in order to discover the action on Purkinje cells, both those that were on-beam for the parallel fibre volley and those at various distances off-beam. A juxta-fastigial electrode was carefully placed so that an applied stimulus could excite the axons of Purkinje cells distributed across the folium under investigation, the antidromic propagation of impulses thus obtained being utilized to test the effect of parallel fibre volleys upon Purkinje cells. 2. The observations were in accord with the two actions that a parallel fibre volley would be expected to exert on Purkinje cells: a direct excitatory action by the synapses made by parallel fibres with the spines of the Purkinje cell dendrites; an inhibitory action mediated by the stellate and basket cells that themselves are directly excited by the parallel fibre volley. 3. The excitatory synaptic action would result in the two types of responses that were restricted to the narrow zone and superficial location of the parallel fibre volley: active sinks formed by this excitatory synaptic action on the superficial dendrites of Purkinje cells would account for the observed depth profile of extra-cellular slow potentials, a superficial negative wave reversing to a deeper positive wave formed by passive sources on deeper dendrites; superficial synaptic excitation would also account for the facilitation of the propagation of antidromic impulses into the superficial dendrites. 4. The inhibitory synaptic action would result in the two types of responses that were widely dispersed transversely and in depth, far beyond the traject of the parallel fibre volley: a slow positive potential wave with a maximum at a depth usually of 300–400 μ; an inhibitory action on the antidromic invasion of Purkinje cells. The transverse profiles of these two presumed indices of inhibitory action on Purkinje cells apparently revealed that a basket cell may give inhibitory synapses up to 1000 μ laterally from the location of its soma and dendrites. 5. A description is given of the variants in the transverse profiles of the deeper positive waves and of inhibitory actions of a parallel fibre volley that presumably are mediated by basket cells and also by the superficial stellate cells. These physiological findings are correlated with the histologically determined distribution of synapses from a basket cell onto Purkinje cells.
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  • 14
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    Experimental brain research 1 (1966), S. 1-16 
    ISSN: 1432-1106
    Keywords: Inhibitory interneurones ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Extracellular microelectrode recording has been employed to study the responses of three types of interneurones in the cat cerebellar cortex: basket cells, superficial stellate cells and Golgi cells. The large unitary spike potentials of single cells were sharply localized and presumably were generated by impulse discharges from the cell somata. The characteristics of their responses described below sharply distinguished them from Purkinje cells. 2. The parallel fibre volleys generated by surface stimulation of a folium evoked brief repetitive discharges that were graded in respect of frequency and number. Maximum responses had as many as 10 impulses at an initial frequency of 500/sec. 3. At brief test intervals there was facilitation of the response to a second parallel fibre volley; at about 50 msec it passed over to depression for over 500 msec. 4. Stimulation deep in the cerebellum in the region of the fastigial nucleus (juxta-fastigial, J.F.) evoked by synaptic action a single or double discharge, presumably by the mossy fibre-granule cell-parallel fibre path, but climbing fibre stimulation from the inferior olive also usually had a weak excitatory action evoking never more than one impulse. 5. J.F. stimulation also had an inhibitory action on the repetitive discharge evoked by a parallel fibre volley. Possibly this is due to the inhibitory action of impulses in Purkinje cell axon collaterals. 6. There was a slow (7–30/sec) and rather irregular background discharge from all interneurones. The inhibitory actions of parallel fibre and J.F. stimulation silenced this discharge for some hundreds of milliseconds, probably by Golgi cell inhibition of a background mossy fibre input into granule cells. 7. All these various features were displayed by cells at depths from 180 to 500 μ; hence it was concluded that superficial stellate, basket and Golgi cells have similar properties, discrimination being possible only by depth, the respective depth ranges being superficial to 250μ, 250μ to 400μ, and deeper than 400μ.
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  • 15
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    Experimental brain research 1 (1966), S. 17-39 
    ISSN: 1432-1106
    Keywords: Parallel fibres ; Purkinje cells ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. When electrical stimuli were applied to the surface of a cerebellar folium by a local electrode (LOC), there was a propagated potential wave along the folium with a triphasic (positive-negative-positive) configuration. 2. Investigations by microelectrode recording established that this wave is produced by impulses propagating for at least 3 mm and at about 0.3 m/sec along a narrow superficial band or “beam” of parallel fibres. As expected from this interpretation, there was an absolutely refractory period of less than 1 msec and impulse annihilation by collision. 3. Complications occurred from the potential wave forms resulting from the excitation of mossy fibres by spreading of the applied LOC stimulus. These complications have been eliminated by chronically deafferenting the cerebellum. 4. When recording within the beam of excited parallel fibres there was a slow negative wave of about 20 msec duration, and deep and lateral thereto, there was a slow positive wave of approximately the same time course. 5. These potential fields were expressed in serial profile plots and in potential contour diagrams and shown to be explicable by the excitatory and inhibitory synaptic action on Purkinje cells: excitatory depolarizing synapses of parallel fibre impulses on the dendrites; and hyperpolarizing inhibitory synapses of stellate and basket cells respectively on the dendrites and somata. The active excitatory synapses would be strictly on the parallel fibre beam and the inhibitory concentrated deep and lateral thereto, which is in conformity with the axonal distributions of those basket and stellate cells that would be excited by the parallel fibre beam. 6. Complex problems were involved in interpretation of slow potentials produced by a second LOC stimulus at brief stimulus intervals and up to 50 msec: there was a potentiation of the slow negative wave, and often depression of the positive wave deep and lateral to the excited beam of parallel fibres. 7. Often the LOC stimulus evoked impulse discharge from the Purkinje cells, these discharges being inhibited by a preceding LOC stimulus.
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  • 16
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    Experimental brain research 1 (1966), S. 65-81 
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cerebellar synaptology ; Climbing fibers ; synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An attempt is made to identify, under the electron microscope, the climbing fibers of the cerebellum (in the cat) and their synaptic contacts with Purkinje cells and other cortical neurons. — Two kinds of axonal profiles, having synaptic contacts with primary and secondary dendrites of Purkinje neurons, can be recognized: One being terminal fibers densely packed with neurofilaments, having mainly contacts “de passage” with the dendrite surface, with small accumulations of synaptic vesicles at the presynaptic side of the contact. The others are rather knob-shaped contacts filled with synaptic vesicles and poor in neurofilaments. In chronically isolated folia, in which only local neurons and their processes have survived, all filamentous profiles have disappeared while vesicular ones are not appreciably reduced in number. It is inferred from this, that the neurofilamentous profiles correspond to climbing fibers, whereas the vesicular ones could be the endings of outer stellate axons, recurrent Purkinje axon collaterals, or ascending basket axon collaterals. — Similar two kinds of axon-terminal profiles are found in synaptic contact with Golgi and basket cell bodies. As in chronically isolated folia only the vesicular profiles survive, it is inferred that the climbing fiber has axo-somatic terminals on Golgi cells and basket cells as well. Previous information of this kind, gained with the light microscope and with degeneration studies, is thus substantiated with the aid of the electron microscope. The vesicular presynaptic profiles on Golgi and basket neurons are in the first case certainly and in the second with high probability endings of recurrent Purkinje axon collaterals. — The few axosomatic synapses found on outer stellate neurons may also be terminals of climbing fibers, but degeneration evidence for this is not conclusive. — The observations are summarized and evaluated from the functional point of view in a diagram, with consideration to recent physiological information on the function of climbing fibers.
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  • 17
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    Experimental brain research 1 (1966), S. 82-101 
    ISSN: 1432-1106
    Keywords: Cerebellum ; Mossy fibre input ; olgi cell inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The glomerulus in the cerebellar granular layer is composed of the three elements; the mossy fibre terminal, the granule cell dendrites and the Golgi cell axons. The afferent input to the cerebellar cortex through the glomerulus, the mossy fibre-granule cell relay (M.G.R.), and its inhibitory control by the Golgi cells were studied by recording, a) extracellular field potentials in the granular and molecular layers, b) unitary spikes of granule cells, and c) intracellular postsynaptic potentials in Purkinje cells. 2. Mossy fibres were activated by juxta-fastigial, transfolial, lateral cuneate nucleus and radial nerve stimulation. Stimulation of an adjacent folium (transfolial stimulation) could excite branches of mossy fibres under the stimulating electrode which supply other branches also to the folium under the recording electrode. This technique was utilized to distinguish the response due to mossy fibre activation from those due to the climbing fibre and Purkinje cell axons. 3. These stimulations resulted in, through the M.G.R., a powerful activation of granule cells whose axons (parallel fibres) excited in turn the Purkinje cells and the inhibitory interneurones, including the Golgi cells, in the molecular layer. 4. Field potentials and unitary spikes due to granule cell activity elicited by the stimulation of mossy fibres were markedly depressed for hundreds of milliseconds after the direct stimulation of parallel fibres (LOC stimulation). The postsynaptic potential in Purkinje cells evoked by mossy fibre activation was also depressed by the conditioning LOC stimulation in the same manner. The “spontaneous” background activities recorded from granule cells as unitary spikes and from Purkinje cells as inhibitory synaptic noise were silenced for hundreds of milliseconds after the LOC stimulation. 5. These depressions indicate that the parallel fibre activation evokes an inhibitory action upon M.G.R. On anatomical grounds this inhibition can be mediated only by the Golgi cell, and it is postulated that the inhibitory action is postsynaptic upon the dendrites of granule cells. 6. It is concluded that the Golgi cell inhibition regulates the mossy fibre input to the cerebellar cortex at the M.G.R. by a form of negative feed-back.
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  • 18
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    Experimental brain research 1 (1966), S. 161-183 
    ISSN: 1432-1106
    Keywords: Cerebellum ; Purkinje cells ; Intracellular recording ; Postsynaptic potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Intracellular recording from Purkinje cells has been employed in investigating the excitatory and inhibitory synaptic action that is exerted on these cells by the mossy fibre input into the cerebellum. 2. These synaptic actions are evoked not directly by the mossy fibres, but probably always through granule cells and their axons, the parallel fibres. The intracellular records conform with the anatomical evidence that the parallel fibres directly exert a powerful synaptic excitatory action on Purkinje cells, and that the inhibitory pathway occurs via an inhibitory interneurone — a basket cell or a stellate cell. Direct stimulation of parallel fibres gives intracellular potentials closely resembling those produced by deep stimulation of mossy fibres. 3. As would be expected, direct stimulation of parallel fibres produces an EPSP with a latency 1 to 2 msec briefer than the IPSP. The IPSP has a duration usually in excess of 100 msec. The EPSP appears to be briefer, though its superposition on the IPSP greatly reduces its apparent duration. Neutralization of the IPSP by appropriate membrane polarization or by intracellular chloride injection reveals an EPSP duration of up to 50 msec. 4. The IPSP is typically affected by polarizing currents; reduced and even inverted by hyperpolarizing currents, and increased by depolarizing currents. The IPSP is converted to a depolarizing response by excess of intracellular chloride. It must therefore be generated by an increased ionic permeability of the inhibitory subsynaptic membrane, chloride ions being importantly concerned. 5. Often small irregular IPSPs can be observed occurring spontaneously, and they react to polarizing currents and to chloride injections in a manner identical to the evoked IPSPs. It is concluded that they are generated by the spontaneous discharges of basket cells. 6. A brief account is given of various spontaneous rhythmic responses of impaled Purkinje cells, and of the effect of synaptic inhibitory action upon them. 7. There is a general discussion of these findings in relation to the various neural pathways and neural mechanisms that have been postulated in the light of the preceding investigations.
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  • 19
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    Experimental brain research 1 (1966), S. 306-319 
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Reticulocerebellar tract ; Spinoreticular tract ; Cerebellum ; Flexor reflex afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Mass discharges were recorded from the dissected left restiform body in unanaesthetized, decerebrate, and decerebellate cats. The spinal cord was severed in the thoracic or cervical region sparing only the left ventral quadrant. In this preparation the discharges were shown to relate largely or exclusively to activity in the reticulocerebellar tract originating from the lateral reticular nucleus. The ascending spinal tract was identified with the bilateral ventral flexor reflex tract (bVFRT) of Lundberg and Oscarsson (1962). The reticulocerebellar tract was activated from the flexor reflex afferents and nerve volleys from each of the four limbs were equally effective. It is concluded that the lateral reticular nucleus is not responsible for the somatotopically organized projection of cutaneous afferents, as assumed before. The bVFRT is strongly influenced from the cerebellar cortex and the organization of the closed loop formed between the cortex and the spinal cord is discussed.
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  • 20
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    Experimental brain research 1 (1966), S. 320-328 
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Reticulocerebellar tract ; Spinoreticular tract ; Cerebellum ; Flexor reflex afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The experiments were done on unanaesthetized, decerebrate, and decerebellate cats. Recording was made from axons originating in the lateral reticular nucleus on stimulation of various nerves, cutaneous receptors, and certain descending tracts. Excitatory and inhibitory effects were evoked from the flexor reflex afferents of receptive fields which included most of the body surface. It is concluded that the lateral reticular nucleus with respect to its afferent inflow is similar to the non-cerebellar nuclei of the reticular formation. The possibility that the reticulocerebellar tract is important in determining the background excitation of cortical neurones is discussed. The effects evoked by stimulation of descending tracts were consistent with the disclosure that the bilateral ventral flexor reflex tract is the afferent path to the lateral reticular nucleus.
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  • 21
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    Experimental brain research 1 (1966), S. 329-337 
    ISSN: 1432-1106
    Keywords: Inferior olive ; Olivocerebellar tract ; Spinoolivary tract ; Cerebellum ; Flexor reflex afferents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The discharges were recorded from the dissected right restiform body in unanaesthetized, decerebrate, and decerebellate cats. The spinal cord was severed in the thoracic and/or cervical region sparing only the left ventral quadrant. The discharges were shown to relate largely or exclusively to activity in the olivocerebellar tract. The olivocerebellar discharges were elicited by stimulation of the flexor reflex afferents. Large responses were evoked from the right hindlimb nerves and small responses from the left hindlimb nerves. The responses had a latency of about 20 msec. The spinoolivary tract is tentatively identified with the contralateral ventral flexor reflex tract of Lundberg and Oscarsson (1962).
    Type of Medium: Electronic Resource
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  • 22
    ISSN: 1432-1106
    Keywords: Cerebellum ; Nucleus interpositus anterior ; Red nucleus ; Somatotopy ; Degeneration study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Small lesions were done in various areas of the nucleus interpositus anterior (NIA) of the cerebellum, and the distribution of terminal degeneration was studied in the red nucleus with the methods of Nauta and Glees. The NIA projects to the contralateral red nucleus. Two principles of organization can be demonstrated in the projection: a caudorostral arrangement in the red nucleus corresponds to a mediolateral organization in the NIA and a mediolateral arrangement in the red nucleus corresponds to a caudorostral organization of the NIA. The latter distribution coincides with the somatotopical areas of the red nucleus defined by Pompeiano and Brodal (1957). Special attention has been paid to the questions of the subdivision of the cerebellar nuclei and of the course of the fibres issuing from the nuclei in the cerebellar hilus. The present findings on the projection of the NIA to the red nucleus have been correlated with recent anatomical and physiological data on the cerebellum and the red nucleus.
    Type of Medium: Electronic Resource
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