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  • Cerebellum  (66)
  • Springer  (66)
  • 1970-1974  (66)
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  • Springer  (66)
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  • 1
    ISSN: 1432-1106
    Keywords: Cerebellum ; Fastigial nucleus ; Lateral reticular nucleus ; Inferior olive ; Neuronal computation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A detailed study of the latencies of the excitatory responses of fastigial cells disclosed an unexpected anomaly. Except for infrequent small responses the latency was many milliseconds longer than would be expected for excitation by axon collaterals of the fast spino-cerebellar pathways. There were many examples in which inhibition had an earlier onset than excitation; nevertheless the inhibitory latency was not so brief as to preclude its production by Purkyně cell discharge in response to the fast spino-cerebellar pathways. Histograms have been constructed for the latencies of the excitation and inhibition evoked in fastigial cells by four kinds of inputs: nerve volleys from forelimb and hindlimb; pad taps from forelimb and hindlimb. Electrical stimulation of the lateral reticular nucleus on the same side very effectively excited fastigial cells, usually with the latency expected for monosynaptic excitation. It was therefore postulated that with forelimb and hindlimb stimulation the dominant mode of excitation of fastigial cells was by excitatory collaterals from the spino-reticulo-cerebellar pathway. Stimulation of the contralateral inferior olive also was effective in evoking a short latency excitation of fastigial cells. It was therefore assumed that collaterals from the spino-olivo-cerebellar pathway provide an additional excitatory input to fastigial cells. A diagram was constructed in space-time coordinates graphically expressing the timing of the various excitatory and inhibitory pathways by which a hindlimb nerve stimulus acts on fastigial cells. An interesting design feature is thereby disclosed, namely that the dominant excitatory input to the fastigial cells via the slower spino-cerebellar paths is virtually synchronous with the inhibitory input from Purkyně cells discharging in response to the fast spino-cerebellar input. It is pointed out that the temporal pattern gives optimal conditions for the computer-like operation of the fastigial nucleus.
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  • 2
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    Electronic Resource
    Springer
    Experimental brain research 20 (1974), S. 385-401 
    ISSN: 1432-1106
    Keywords: Neck afferents ; Cerebellum ; Climbing fiber ; Mossy fiber ; Purkinje cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Afferent information from the neck plays an important role in the regulation of posture and the control of head and eye movements. The present series of experiments was designed in order to characterize the cerebellar projections of neck afferents in the cat. Both anesthetized and decerebrate animals were used, and recordings were obtained following electrical stimulation of the second cervical dorsal root (C2). 2. Following electrical stimulation of C2 dorsal root, field potentials were recorded in lobules V and VI. Amplitude was maximum in the lateral third of the ipsilateral lobule V. These field potentials were produced by combined mossy and climbing fiber (MF and CF) volleys arriving at the cerebellar cortex with different latencies: 8 msec for MF and 24 msec for CF (mean values). The threshold for electrical stimulation was lower for MF than for CF activation; CF responses were evoked by high threshold afferents from muscle and joint receptors. 3. A comparison was made between the latencies of cerebellar responses evoked by electrical stimulation of nuchal and other afferents (vestibular nerve, fore-and hindpaw). The latencies of MF responses vary widely, while those of the CF responses show a much smaller variation. 4. Projection of the afferents from the neck was also demonstrated in the pars intermedia at the limit of the caudal folium of lobule V and of lobule VI (lobule simplex). A study of the convergence to this portion of pars intermedia demonstrated that stimulation of extraocular muscle nerves, trigeminal nerve, and fore-and hindpaws, as well as the neck afferents, generates a strong localized CF response with actual convergence onto single Purkinje cells. The recordings suggest that this area of wide convergence on CFs is not restricted to the superficial cortex, but extends through the depth of the fissura prima. Implications of these findings, in relation to the functional organization of lobule VI and the fissura prima, are discussed.
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  • 3
    ISSN: 1432-1106
    Keywords: Cerebellum ; Maturation ; Hypothyroidism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The functional maturation of the cerebellum has been studied in normal rats from 3 days after birth until adulthood and over the same period in animals rendered hypothyroidic through propylthiouracile injections. Evoked field potentials and unitary activities were recorded from the cerebellar nuclei and from the molecular layer and Purkinje cell (P.C.) layer of the cerebellar cortex. The following observations are reported: 1. a few P.C. axons are functional and presumably connected to subcortical neurons as early as 3 days after birth. However the maturation of the bulk of P.C. axons only occurs after the 6th day; 2. climbing fiber responses of the P.C. (C.F.Rs) are also present on day 3, although the dendritic components of the response only appear several days later. C.F.R. maturation is achieved at the end of the first postnatal month and is only slightly disturbed by hypothyroidism; 3. some connections between mossy fibers (M.F.), granule cells and P.C. also seem to exist on days 3 to 4, but the functional maturation of the parallel fibers occurs principally during the 10th to 30th day period. This maturation is delayed to a considerable extent by hypothyroidism: 4. the efficiency of parallel fibers to excite P.C. increases strongly from the 10th to the 20th day; this evolution is also markedly slowed down in hypothyroid rats; 5. some inhibitory action can already be characterized in the cerebellar cortex on day 10, but most inhibitory interneurones and their synapses on P.C. become mature from the 10th to the 15th day. Furthermore, inhibition exerted by these cells on P.C. is more prolonged in the immature rat than in the adult. Hypothyroidism markedly delays the maturation of these inhibitory processes.
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  • 4
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Bilateral ventral flexor reflex tract (bVFRT) ; Spino-reticulo-cerebellar path ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Neurones in the lateral reticular nucleus (LRN) activated by the bilateral ventral flexor reflex tract (bVFRT-LRN neurones) were identified by their responses to stimulation of fibres descending in the contralateral ventral quadrant of the spinal cord which activate the bVFRT neurones monosynaptically. 2. Eighty-eight of the 134 bVFRT-LRN neurones encountered could be antidromically activated at a low stimulus strength from small areas of the cerebellar surface assumed to represent cortical termination points. 3. The bVFRT-LRN neurones occurred throughout the parvi- and magnocellular parts of the LRN and terminated bilaterally in the anterior lobe and sparsely in the ipsilateral paramedian lobule and in the pyramis. 4. The responses evoked in the bVFRT-LRN neurones on stimulation of the contralateral ventral quadrant at C5 and L1 made it possible to estimate the approximate spinal level from which the bVFRT fibres originated. On this basis the bVFRT-LRN neurones were divided into cervical, thoracic, and lumbar groups receiving bVFRT afferents from mainly one spinal level and a convergence group receiving bVFRT afferents from several levels. 5. The different bVFRT-LRN groups received excitation from different combinations of nerves in the four limbs. 6. The cervical, thoracic and lumbar groups of the bVFRT-LRN neurones occurred in successively more ventrolateral portions of the LRN. 7. The cervical, thoracic and lumbar groups of the bVFRT-LRN neurones terminated in successively more rostral areas of the anterior lobe. 8. The organization of the bVFRT-LRN path is compared with that of the ventral and rostral spinocerebellar tracts. The possible function of the bVFRT-LRN path is discussed.
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  • 5
    ISSN: 1432-1106
    Keywords: Cerebellum ; Hemicerebellectomy ; Saccadic eye movements ; Pursuit eye movements ; Vestibulo-ocular reflex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Unilateral cerebellar lobectomy was carried out in young and mature macaques. There is no significant abnormality in saccadic eye movement or in the vestibulo-ocular reflex. There is a constant drift of the eyes in the contralateral direction, and the abilities to maintain eccentric gaze and to make smooth pursuit movements are jointly affected. The syndrome is transient in young monkeys, and even bilateral cerebellar lobectomy carried out serially leaves some ability to hold eccentric gaze and pursue smoothly. The findings permit the conclusion that the primate oculomotor organization depends on the active maintainence of straight ahead gaze. Saccades move the eyes in a coordinated way, and are also associated with correlated innervation to hold the gaze in the new position. Since cerebellar interventions which cause centripetal drift also always produce defects in pursuit movements, the abilities to maintain eccentric gaze and to pursue smoothly must have a common origin.
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  • 6
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Reticulocerebellar projection ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The areas of the cerebellar cortex receiving fibres from the mLRN (major portion of the lateral reticular nucleus comprising its parvi- and magnocellular parts) were determined by identifying the low-threshold spots on the cerebellar surface from which 286 mLRN neurones could be antidromically activated. 2. The mLRN fibres terminate bilaterally in the anterior lobe and pyramis, and ipsilaterally in the paramedian lobule. Some fibres terminate also in the rostral part of lobule VI but hardly any in other parts of the cortex. It follows that the mLRN projects almost exclusively to the classical spinal receiving areas. 3. Neurones in the parvi- and magnocellular parts project to similar cortical areas. 4. Two regions in the mLRN were distinguished on the basis of their different projection areas. Region A, a dorsolateral portion of the magnocellular part, projects to the ipsilateral parts intermedia of the anterior lobe and the ipsilateral paramedian lobule. Region B, a ventral portion of the parvi- and magnocellular parts, projects bilaterally to the pars intermedia and vermis of the anterior lobe and sparsely to the pyramis. 5. Neurones throughout the parvi- and magnocellular parts receive monosynaptic excitation from fibres ascending in the ventral part of the ipsilateral lateral funiculus.
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  • 7
    ISSN: 1432-1106
    Keywords: Lateral reticular nucleus ; Spinoreticular tract ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The activation of neurones in the mLRN (major portion of lateral reticular nucleus comprising its parvi- and magnocellular parts) by two spinal tracts ascending through the ventral part of the lateral funiculus has been studied by recording from 277 neurones of which 187 could be antidromically activated by stimulation of the cerebellar surface. Forty-eight % of the neurones were activated by the bVFRT and described in a previous paper (Clendenin et al., 1975b) and 12% were activated by a previously unknown tract denoted the ipsilateral forelimb (iF) tract and described in the present paper. 2. The iF-tract is activated by stimulation of nerves in the ipsilateral forelimb only. The response consists of a train of impulses with a high initial frequency and an almost constant latency. Cutaneous afferents and high threshold muscle afferents contribute to the excitation which is mediated by interneurones. 3. The responses to stimulation of peripheral receptors were weak and difficult to classify. 4. The iF-tract activates neurones in the dorsolateral portion of the magnocellular part of the mLRN which projects to the ipsilateral pars intermedia of the anterior lobe and the ipsilateral paramedian lobule. 5. The possible information carried by the iF-tract is discussed.
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  • 8
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cerebral cortex ; Mossy fibers ; Climbing fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The patterns of convergence of nerve and cortical inputs representing the forelimb and hindlimb were studied in Purkyně cells of the cat. The most important inputs to Purkyně cells of the pars intermedia come from peripheral nerves and the areas of the sensorimotor cortex concerned with the same limb. In lobule V, the forelimb nerve and cortical inputs are dominant, while in lobules III and IV the hindlimb inputs are dominant. Lobules IVa–Va represent a zone of hindlimb-forelimb overlap, with the nerve and cortical inputs making parallel transitions from the hindlimb dominance of IVa to the forelimb dominance of Va. Furthermore, within the nerve and cortical projections to the pars intermedia, mossy fiber and climbing fiber systems have similar projection patterns. In addition to the hindlimb-forelimb overlap in lobules IVa–Va, nearly half (44%) of the Purkyně cells throughout lobules III, IV, and V of the pars intermedia respond with weak or moderate responses to cortical or nerve inputs from the non-dominant limb, some of which are clearly important physiologically. By pairing stimuli to nerve and cortex, it was shown that these two inputs converge onto single inferior olive neurons for the climbing fiber system, whereas the nerve and cortical inputs have separate mossy fiber-granule cell pathways, finally converging onto the Purkyně cell. For both the mossy fiber and climbing fiber systems, the nerve and cortical inputs appear to be transmitted most efficiently through the cerebellar cortex when the two inputs arrive simultaneously at the cerebellar cortex and inferior olive, respectively.
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  • 9
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cerebral cortex ; Mossy fibers ; Climbing fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The responses of single Purkyně cells in the pars intermedia of the anterior lobe were studied following stimulation of the sensorimotor cortex in the cat. The cortical inputs display the same kind of mossy fiber and climbing fiber duality as previously described for nerve inputs (Eccles et al., 1971 b). Stimulation of the cerebral cortex elicits short latency excitation (4–8 msec) and inhibition (8–12 msec) via the mossy fiber system and a longer latency climbing fiber excitation (12–19 msec). The response of a Purkyně cell may consist of any combination of these possible components and depends upon the cortical area stimulated. The mossy fiber system is activated by a single shock, is increased by a second volley, and follows relatively high repetition rates. On the other hand, the climbing fiber system has a higher threshold, and only follows repetition rates up to 5–20 Hz. Two or more volleys are needed for efficient transmission.
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  • 10
    ISSN: 1432-1106
    Keywords: Cerebellum ; Fastigial nucleus ; Cutaneous mechanoreceptors ; Excitation ; Inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper gives an account of the responses of cerebellar fastigial cells to various afferent inputs from ipsilateral forelimb or hindlimb. Most of the preparations (17 out of 25) have been decerebrate and unanesthetized. The remainder were under anesthesia — chloralose, pentothal or surital. The afferent inputs have been provided by stimulation of predominantly cutaneous limb nerves or by three types of mechanical stimulation: taps to foot pads; pressure on foot pads; air jets to hairy skin. Recording from single fastigial cells was extracellular by glass microelectrodes, and computer averaging techniques of spike responses were employed as described in previous papers. Identification of fastigial cells was simply from location in the large fastigial nucleus, this location being later confirmed by identification of microelectrode tracks in histological sections. Fastigial cells display a fairly steady background discharge, the mean being 37 Hz for the decerebrate and considerably lower for the anesthetized. Pad taps usually evoked a diphasic (excitatory-inhibitory) response, but in some cases the inhibitory was dominant, in others the excitatory. The threshold was below 0.2 mm, and several fastigial cells were excited or inhibited by taps of only 0.01 mm. Air jet stimulation of hairy skin of the foot evoked similar responses. Durations of excitation were usually about 10 msec but inhibition was longer, usually about 50 msec. Nerve stimulation evoked responses of comparable type, but the latency was at least 4 msec shorter, corresponding to the more direct and shorter pathways from the site of stimulation. With some fastigial cells steady pressure to central foot pads of 2 sec duration evoked only brief phasic responses (excitatory or inhibitory) at ‘on’ and ‘off’. With other cells there were tonic responses — excitation or inhibition or admixtures thereof — for the whole duration of the pressure. Usually 500 g was almost maximally effective, and the threshold was always below 100 g. In an indeterminate type of response (the semitonic) the excitation or inhibition at ‘on’ persisted for up to 500 msec, an effect matching the response of the rapidly adapting receptors of the pads. With repetitive stimulation both the excitatory and inhibitory responses to pad taps were reduced with frequencies above 1 Hz and greatly depressed at 5 to 7 Hz. However a small inhibition was observed to persist during tap frequencies as high as 65 Hz. In a preliminary study both the background and the evoked responses of fastigial cells were found to be very sensitive to barbiturate anesthesia.
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  • 11
    ISSN: 1432-0533
    Keywords: Hormones ; Organ Culture ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fragments of cerebellar cortex from adult rats were maintained as organ cultures for 10 days. Insulin (1.0–1000 μg/ml), triiodothyronine (1.0–1000 ng/ml) and corticosterone (0.1–100 μg/ml) were added to the media of 85 cultures, while 25 with no added hormones served as controls. Survival of neurons and of connective tissue was somewhat improved in the presence of insulin, the optimal level being 100 μg/ml. Triiodothyronine was toxic to all components of the cultures to an extent proportional to the concentration. Corticosterone caused some neuronal damage and suppressed the growth of connective tissue, though these effects were not clearly related to the concentrations in the media. The actions of the hormones on cultured CNS tissue are discussed in relation to their effects on the injured CNSin vivo.
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  • 12
    ISSN: 1432-0568
    Keywords: Cerebellum ; Mormyrid fishes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The corpus cerebelli of mormyrid fishes is strongly developed and differentiated into four lobes: C1−C4. Although all of these lobes contain the characteristic cerebellar layers: granular, ganglionic and molecular, they show distinct architectonic differences. A previous study revealed that the ganglionic layer of C1, in addition to Purkinje elements contains conspicuous giant cells. In the present paper the results of a further analysis of C1 are reported. This analysis is based on serially sectioned brains of Gnathonemus petersii, stained according to Nissl, Bodian and Häggquist. Semi-thin sections were stained with p-phenylenediamine. Routine EM techniques were used to visualize synaptic relations. Mossy fibres and granule, Golgi, Purkinje and stellate cells are located characteristically throughout C1. It appeared that the giant cells of a previous study represent the largest elements of a population which has been termed now the eurydendroid cells. The average size of the latter is somewhat larger than that of the Purkinje cells, but both groups of cells show a considerable overlap in the size of their somata. Purkinje cells and eurydendroid cells are present throughout the ganglionic layer and both have a flattened, sagittally oriented, dendritic tree that extends into the molecular layer. Yet, the eurydendroid cells (EC) display the following characteristics which distinguish them from Purkinje cells (PC): (1) In EC the Nissl substance is dispersed diffusely throughout the soma, whereas in PC it tends to be concentrated around the nucleus, (2) The soma/nucleus ratio for EC is distinctly larger than for PC, (3) The dendritic trees of EC extend over a larger stretch of the molecular layer than those of PC, hence the term EC, (4) The dendrites of EC are more widely spaced and oriented less strictly parallel to each other than those of PC, (5) The dendrites of EC are somewhat irregular in outline and not covered with spines, in contrast to those of PC, (6) The axons of EC are oriented radially and join bundles of coarse fibres which leave the cerebellum whereas the axons of PC extend and ramify within the ganglionic layer, (7) The somata of EC, contrary to those of PC, are enveloped by a dense axonal plexus which forms numerous synaptic terminals on them. The numerical ratio of EC: PC was 1:5.5. The circuitry in C1 and the possible functional roles of its constituent neurons are discussed. It is pointed out that in this lobe the axons of PC impinge on EC and that the latter constitute its output system.
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  • 13
    ISSN: 1432-0568
    Keywords: Cerebellum ; Thalamus ; Electron microscopy ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An experimental electron microscopical study has been made on the mode of termination of the cerebellothalamic projections in the cat. Supporting experimental light microscopical studies of silver impregnated sections following a large lesion of the cerebellar nuclei and light microscopical autoradiographic studies of the thalamus following injections of tritiated leucine in parts of the cerebellar nuclei, have been made as well. Following large lesions of the cerebellar nuclei, only the largest occuring type of bouton in the cat's VL and VA (type LR bouton) degenerates. Following such lesions, type LR boutons undergo a filamentous hypertrophy before becoming electrondense. One degenerating LR bouton establishes complex synapses with the dendrites of both thalamocortical relay cells and interneurons. Not all type LR boutons in VL and VA degenerate following lesions of the cerebellar nuclei. Light microscopical autoradiographic studies as well as experimental electron microscopical investigations indicate that cerebellothalamic fibers end in clusters within VL and VA, and that the areas of termination lie more rostrally within these thalamic nuclei than has been inferred from experimental studies of silver impregnated sections following lesions of the cerebellar nuclei. The findings are discussed with respect to relevant morphological and physiological data.
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  • 14
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    Acta neuropathologica 27 (1974), S. 163-169 
    ISSN: 1432-0533
    Keywords: Cerebellum ; Development ; X-Irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The heads of seven day old rats were irradiated with 600 rads. The permanent long-term effects on the cerebellum were examined histologically seven months after irradiation. The effects of radiation were not homogenous, with selective loss or abnormal distribution of granular cells and disorientation of Purkinje cells. The possible reasons for these modifications in cerebellar structure are discussed.
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  • 15
    ISSN: 1432-0533
    Keywords: Cell Nests ; External Granular Layer ; Capillaries ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Serial sagittal sections of the postnatally developing cerebellum of Wistar rats were studied to determine the incidence, origin, and relation to other cerebellar structures of nests of heterotopic cells. These nests were found to consist of small, darkly staining cells of either irregular or elongate shape with large, dark nuclei and bore close resemblance to cells of the external granular layer. They were present in every animal from the day of birth to at least day 15 of life and were confined to the uvula, nodulus, and pyramis of the vermis. In addition, the cell nests were found to be perivascular and continuous with the external granular layer via a narrow tongue of cells surrounding capillaries which penetrated to the medullary layer of the cerebellum from the subarachnoid space. The significance of the nests in relation to other studies, and their involution after day 15 of life is briefly considered.
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  • 16
    ISSN: 1432-2013
    Keywords: Cerebellum ; Vestibular System ; Visual System ; Climbing Fibers ; Mossy Fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrical or flash stimulation of the visual pathway evoked in the vestibulocerebellum of barbiturate anesthetized cats, field and unitary potentials characteristic of climbing fiber (CF) activation of Purkinje cells. The latency of the CF field potentials was 11–15 msec in the flocculus and 14–19 msec in the nodulus/ventral uvula. Mossy fiber (MF) related field and unitary responses were not observed following visual stimulation. Conversely, electrical stimulation of the VIIIth nerve evoked in the vestibulocerebellum MF-related field and unitary potentials, exclusively. Despite this dichotomy, the field potentials evoked by visual and vestibular stimulation frequently overlapped within the cerebellar cortex. This overlap was shown at the level of individual Purkinje cells by means of extra- and intracellular recordings which demonstrated vestibulo-visual convergence. These observations indicate that a given sensory modality may reach specific cerebellar areas utilizing only one of the two cerebellar afferent systems. It is concluded that the MF and CF afferent systems, when considered as sensory inputs, can operate as independent information channels.
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  • 17
    ISSN: 1432-2013
    Keywords: Cerebellum ; Proline ; Transmitter ; Iontophoresis ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Iontophoretic experiments with the aid of multibarreled micropipettes demonstrate a reversible depressant effect ofl-proline on the spontaneous discharge of Purkinje cells in the cat cerebellar cortex. The failure of a specific interaction with strychnine and bicuculline leads to the conclusion that proline acts neither on receptors for “glycine-like” nor on receptors for “GABA-like” amino acids. Autoradiographic investigations reveal a differential distribution of radioactivity after injection of3H-leucine and3H-proline into the cerebellar cortex. After leucine injection, high grain density can be observed over Stellate, Basket, Golgi and especially Purkinje cells. In contrast after application of3H-proline, the silver grains are concentrated primarily in the tissue adjacent to the Purkinje cells, mainly in the supraganglionic region and between these faintly labelled cerebellar cells. These results suggest the possibility that proline is involved in inhibitory neurotransmission.
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  • 18
    ISSN: 1432-0878
    Keywords: Cerebellum ; Neurons ; Neuroglia ; Guinea pig ; Tissue culture ; Microcinematography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Guinea-pig cerebellum has been cultured in three in vitro systems: Maximow slides, Leighton tubes and Rose chambers. The best results were obtained from foetuses at the 34th day of gestation. Myelination appeared at the 21st day in vitro and progressed until after one month in culture. It was observed in 62% of the cultures on Maximow slides or in Leighton tubes. Myelination was quite variable in Rose chambers. The organization of the cultures was quite similar to that previously described in other species. Most types of neurons and glia were identified by phase contrast microscopy and microcinematographic analysis. Various histological stains and impregnations accompanied studies of living cells. Despite the lack of specificity of metal impregnations when applied to tissue cultures, successive study of similar or identical fields by phase contrast and such methods has facilitated cellular identification and demonstrated the limits of each of the techniques used. The difficulty of cell identification in the outgrowth zone is emphasized. Nevertheless, the following cell types have been identified: u neurons: external granule cells, internal granule cells, Purkinje cells, roof nucleus type I and II neurons, glial cells: immature cells, oligodendrocytes, astrocytes, histiocytic cells. The guinea-pig cerebellum is characterized in vitro as it is in vivo by a particularly slow development when compared to other mammals.
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  • 19
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    Cell & tissue research 149 (1974), S. 399-411 
    ISSN: 1432-0878
    Keywords: Cerebellum ; Man ; Lugaro cell ; Cytoarchitectur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Mit Hilfe einer neu entwickelten Methode zur Darstellung von Neurolipofuscinen wird das Pigmentbild der Kleinhirnrinde des Menschen beschrieben. Purkinjezellen—wie auch die Stern- und Korbzellen der Molekularschicht—sind frei von Pigmentablagerungen oder enthalten nur wenige Lipofuscinkörnchen. Jede Körnerzelle enthält einen kleinen Pigmentfleck. Unter den großen Neuronen der Körnerschicht lassen sich mit Hilfe des Pigmentbildes zwei Zelltypen eindeutig voneinander unterscheiden. Die Mehrzahl von ihnen liegt nahe der Purkinjezellschicht und bildet die Gruppe der Golgizellen, welche nur in geringem Umfang Lipofuscinkörnchen speichern. Von diesen schwach pigmentierten Elementen hebt sich eine geringe Zahl großer Neurone deutlich ab, deren Zelleiber mit stark färbbaren Lipofuscinkörnchen überladen sind. Sie bilden die Gruppe der Lugarozellen. Ihre bipolaren oder triangulären Perikaryen sind über die ganze Purkinjezell- und Körnerschicht verstreut und finden sich häufig auch noch im Marklager der Kleinhirnfolien. Die Lugarozellen sind nicht gleichmäßig über die verschiedenen Folien des Kleinhirns vereilt. In den Wurmabschnitten des Lobus anterior (Lobulus I–V) und den vorderen Folien der Declive (Lobulus VI d, e, f), die in die Fissura prima hineinragen, findet sich nur eine mittlere Anzahl von Lugarozellen, während dieser Zelltyp in den oberflächlichen Folien der Declive (Lobulus VI a, b, c) fehlt. In Tuber und Folium vermis (Lobulus VIII) erscheinen die Lugarozellen wieder und zeigen das gleiche Verteilungsmuster wie in den vorderen Folien der Declive (Lobulus VI, d, e, f). Ihre Anzahl nimmt im Bereich der Pyramis und Uvula (Lobulus VIII–IX) erheblich zu. Hier wird die dichteste Lagerung der Lugarozellen innerhalb des ganzen Kleinhirns erreicht. Nur wenige Lugarozellen finden sich im Bereich des Nodulus (Lobulus X). In den verschiedenen Hemisphaerenabschnitten des Kleinhirns ähnelt das Verteilungsmuster der Lugarozellen dem der entsprechenden Wurmabschnitte.
    Notes: Summary By means of a newly developed method (Braak, 1970a) for the demonstration of neurolipofuscines the distribution of these pigments in the cerebellar cortex of man is described. Purkinje cells as well as the stellate and basket cells of the molecular layer are free of pigment deposits or contain only a few lipofuscin grains. Within each of the granule cells a small pigment granule can be found. With the aid of pigment picture it is possible to distinguish unequivocally between two forms of larger neurons within the granular layer. The majority of these cells lies mainly in the vicinity of Purkinje neurons and represents the Golgi cells, which store only few lipofuscin granules. Some of the large elements within the granular layer differ from this type of pigment distribution in that they contain vast amounts of heavily staining lipofuscin granules, constituting the Lugaro cell group. Their bipolar or triangular cell bodies are scattered throughout the Purkinje cell and granular layer, frequently extending into the medullary rays of the cerebellar folia. Concerning the distribution of the Lugaro cells outstanding differences between the various folia of both the vermal and hemispheral parts of the cerebellum can be found. Within the vermal parts of the anterior lobe (lobulus I–V) and those of the anterior folia of the declive (lobulus VI d, e, f) facing the primary fissure occurs only a medium number of Lugaro cells, whereas these elements are lacking within the superficial declival folia (lobulus VI a, b, c). Within the folium and tuber vermis (lobulus VII) Lugaro cells reappear and show the same distribution pattern as within the anterior declival folia (lobulus VI d, e, f). Their number increases considerably within the pyramis and uvula (lobulus VIII–IX), reaching their densest distribution within the whole cerebellum, whereas only few Lugaro elements are scattered throughout the nodular lobe (lobulus X). Within the various hemispheral parts of the cerebellum the distribution pattern of Lugaro cells resembles that of the corresponding vermal folia.
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  • 20
    ISSN: 1432-1106
    Keywords: Cerebellum ; Barbiturates ; Unitary activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In precollicular decerebrate cats, limb nerves have been stimulated and field potentials and unitary activity recorded from the cerebellar cortex. Doses of pentothal up to 8 mg/kg affect neither the activity evoked in the fast mossy fibre pathways, nor the size of the postsynaptic potentials in granule cells, but the axon discharge in these latter cells is clearly affected. With 4–8 mg/kg the axon discharge of granule cells is abolished and as a consequence Purkinje cells do not respond to the peripheral stimulation via the mossy fibres. In contrast the activity evoked through the climbing fibres is enhanced. This effect takes place at precerebellar level. Both the effects on the mossy fibre and climbing fibre pathways show a recovery in 15–60 min depending on the dose.
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  • 21
    ISSN: 1432-1106
    Keywords: Spino-reticulo-cerebellar pathway ; Adequate stimulation ; Cutaneous mechanoreceptors ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Mechanoreceptors in the footpad and in the hairy skin of the cat's fore- and hindlimbs were stimulated adequately. Evoked activity was recorded extracellularly, using averaging techniques, from 149 cells of the lateral reticular nucleus, LRN, and from 40 axons of its major spinal afferent tract, the bVFRT of Lundberg and Oscarsson (1962). 2. For both LRN cells and bVFRT axons the responses usually consisted of rather complex patterns of excitation and inhibition. 3. The following features were common for LRN cells and bVFRT axons: a) Most units showed a convergence from different types of receptors in one limb. b) Most units displayed a wide receptive field, comprising often both fore- and hind hindlimbs. However, receptors in forelimb usually proved more effective than those in hind limb; hairy skin receptors were more effective in distal than in proximal parts of the limb. 4. Although the latency histograms for both excitatory and inhibitory responses to mechanical stimulation of forelimb pad receptors display wide distributions, early peaks occur in the latency range of 10–14 ms. Distinct excitatory and inhibitory responses were observed as early as 8 ms. 5. Responses from mechanoreceptors were found to be much weaker in normal cats under nitrous oxide anaesthesia than in decerebrabe cats with the pyramidal tracts spared. This suggests an important control via descending pathways of the peripheral afferent input to the spino-reticulo-cerebellar paths.
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  • 22
    ISSN: 1432-1106
    Keywords: Cerebellum ; Vestibular ; Spinocerebellar ; Purkinje ; Deiters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The organization of the cerebellar, vestibular and spinal inputs to the lateral and medial vestibulospinal tract (LVST and MVST) cells was studied in anaesthetized rabbits. Synaptic actions of these inputs were determined by recording postsynaptic potentials intracellularly and also unit spike discharges extracellularly from a number of LVST and MVST cells. As reported previously in cats, inhibition was evoked very frequently from the vermal cortex of the cerebellar anterior lobe and less frequently from that of the posterior lobe. However, no such inhibition was derived from the flocculus. The cerebellar inhibition was exerted upon both LVST and MVST cells, whether they received monosynaptic activation from the primary vestibular afferents (second-order) or not and whether they conducted impulses fast or slowly. However, the inhibition was frequently absent in “slow” “second-order” MVST cells. The vast majority of LVST and MVST cells received an excitatory input from the spinocerebellar afferents ascending the funiculus posterolateralis. This input was particularly prominent from the upper cervical cord. The spinal excitation thus obtained occurred in close connection with the cerebellar inhibition. Hence, it appears that the cerebellar vermis receives the spinal signals that drive LVST and MVST cells and in turn sends out inhibitory signals to adjust the reflex activity in these cells.
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 25 (1973), S. 36-45 
    ISSN: 1432-0533
    Keywords: Metronidazole ; Rats ; Encephalopathy ; Spongy Dystrophy ; Brain Stem ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Trichomonacidum Metronidazole in daily doses of 600 and 800 mg/kg was applicated per throat-sound to six week old SPF-Wistar-rats each day for six weeks. Increase of body-weight, food-demand and the usual clinical watch-over showed no difference to controll-group. Already three days after begin of application behaviour-research showed motion-changes, especially balance-disturbance of femal rats. Measure of running-speed proved no changes. Histological sections of the perfused CNS after treatment with 800 mg/kg Metronidazole showed relatively sharp bounded, usually symetric lesions in the nuclei vestibularis and cochlearis, in the nuclei of the cerebellar roof, paramedial in the colliculus anterior and in the superior olive. These alterations are qualitatively and topographically comparable to CNS-lesions in rats caused by B1-avitaminosis and lesions seen in Wernicke's-encephalopathy in adults and children. The initial and progressed stages of such an experimental CNS insult in rats open numerous possibilities to clear up the pathogenesis of this and other spongiform dystrophies.
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  • 24
    ISSN: 1432-0568
    Keywords: Rat ; Columns ; Swirls ; Interneurons ; Projection neurons ; Subdivisions ; Morphology ; Golgi ; Nissl ; Axons ; Dendrites ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The lateral nucleus in the rat is investigated with several variants of the rapid Golgi method and in Nissl preparations. The neurons are divided into two classes according to their size and the disposition of their axons. The smaller neurons or interneurons have cross sectional areas less than 180 μm2, and short axons that ramify in the vicinity of the cell bodies. Small neurons have also been seen on rare occasions with longer axons that may leave the nucleus. The larger cells (areas greater than 180 μm2) have long axons that leave the nucleus and emit short, beaded, recurrent collaterals. In the rostral and caudal poles of the lateral nucleus, the large projection neurons as well as the small neurons are multipolar with swirled dendritic arborizations. Neurons in the dorsal rim and ventral third of the nucleus have similar dispositions of their dendrites. In the central columnar zone, the projection neurons have dendrites that are arranged in columns directed diagonally across the body of the nucleus in the 4 to 10 o'clock direction in the right lateral nucleus and the 8 to 2 o'clock direction in the left nucleus. A collection of small neurons is generally found in the medial hilus zone. In each part of the lateral nucleus, the neurons are arranged in characteristic ways.
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  • 25
    ISSN: 1432-0568
    Keywords: Cerebellum ; Synapses ; Rat ; Interneuron ; Axons ; Perikarya ; Neuroglia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Profiles of large neurons in the lateral nucleus range from 16 μm to 35 μm in diameter with dimpled nuclei, large Nissl bodies, and well developed Golgi apparatus. Two types of perikarya are distinguished, those that are smooth and those with irregular somatic and dendritic protuberances. About 86% of all large neuronal somata are covered with axosomatic synapses, predominantly with terminals of Purkinje axons and a few belonging to axons of the small neurons. The remaining 14% have no axosomatic synapses. The thick, fleshy dendrites of these cells are covered with terminals, the majority of which synapse directly upon the dendritic shaft. A few are present on spines. The initial segment of the large neuron is thick and robust and receives synapses upon its shaft or upon a spinous projection. The small neurons measure less than 12 μm in diameter and have very lobulated nuclei in a sparse cytoplasm characterized by small Nissl bodies and a poorly elaborated Golgi apparatus. About 52% of all small neuronal somata bear no synapses whereas the remaining 48% are covered with axosomatic synapses, mainly from the axons of Purkinje cells and a few axons of other small cells. The slender long dendrites of both large and small cells bear synapses with six classes of axons in the neuropil. Synaptic protuberances of two varieties occur on the surfaces of both perikarya and dendrites, (a) dome-shaped ones capped with a pronounced asymmetrical synaptic junction and (b) ones with thin long necks and bulbous heads having synapses on both parts. Frond-like dendritic excrescences are borne on the processes of some small and large neurons and they are postsynaptic to many axon terminals clustered around them.
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  • 26
    ISSN: 1432-0533
    Keywords: Cerebellum ; Granule Cell ; Necrosis ; Enzyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Selective necrosis of the granular layer of the cerebellum was induced in 14 of 25 rats by subcutaneous injections of thiophen. Pyknosis of the granule cell nuclei can be seen before any alteration in the cytoplasmatic oxidative enzymes or acid phosphatases. After the termination of the thiophen injections there is a temporary fall in the NADH-tetrazolium reductase in the Purkinje cells. This may be due to a transneuronal influence of the altered granule cells.
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  • 27
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    Electronic Resource
    Springer
    Cell & tissue research 143 (1973), S. 301-312 
    ISSN: 1432-0878
    Keywords: Synaptic junctions ; PTA ; Cerebral cortex ; Cerebellum ; Hippocampus ; Thalamus ; Spinal cord
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An analysis has been made of the staining properties of phosphotungstic acid (PTA) on non-osmicated, glutaraldehyde fixed brain tissue, with regard to differences arising from the commercial source of the PTA, its water content, methanol as opposed to ethanol dehydration, and perfusion as contrasted with immersion fixation. The quality of the micrographs varied depending on the source of the PTA, the principal component of the synaptic junctions to be affected being the cleft material. Variation in the water content of the PTA solution was also reflected in the appearance of the cleft material, tissues stained with high hydration PTA resulting in cleft material with considerably less electronopacity than the corresponding dense projections and postsynaptic thickening. Low hydration PTA produced the typical picture of cleft densities. Methanol dehydration was unsuccessful in this series of experiments, while immersion and perfusion fixation yielded comparable results. Synaptic junctions from cerebral cortex, cerebellar cortex, thalamus, hippocampus and spinal cord of the rat were examined. In addition to the typical paramembranous densities, subjunctional bodies are present in cerebellar and hippocampal junctions, and subsynaptic profiles in some spinal cord ones. The spinal cord junctions are characterized by a prominent synaptic plate and by a postsynaptic thickening which in places appears to be separated from the underlying postsynaptic membrane.
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  • 28
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cutaneous mechanoreceptors ; Mossy fibers ; Climbing fibers ; Integration ; Purkyně cell groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The preceding two papers gave accounts of mossy fiber (MF) or of climbing fiber (CF) inputs to Purkyně cells under conditions where the other input was depressed by the experimental procedure. By utilizing either chloralose anesthesia or decerebration with sparing of the pyramidal tracts it has been possible to study the convergence of MF and CF inputs onto single Purkyně cells. The stimulation of cutaneous mechanoreceptors, the recording procedures for unitary Purkyně cell discharges and the computer averaging techniques were as previously described. Testing by taps to the footpads evoked a combined MF and CF response more commonly than either response alone, and often both inputs were very effective. There was a tendency for such phasic CF responses to be more frequently observed than the tonic responses to pad pressure, but such responses did occur. Purkyně cells were located by the usual procedure along the microelectrode tracks later identified in serial sections. Those cells activated by the fast MF inputs from the pad receptors were found to be closely associated in groups or colonies. The delayed MF inputs probably via spino-reticular pathways were more widely dispersed. The topographical relationships of these colonies are displayed on maps of the unfolded cerebellar cortex for lobules II to VI of both vermis and pars intermedia. In general these distributions of Purkyně cells activated from forefoot and hindfoot appear as islands in the larger fields that degeneration procedures exhibit for the cuneocerebellar and dorsal spinocerebellar tracts respectively. The CF inputs from the footpads also project to these same colonies, so that there are conjoint MF and CF colonies. The several modalities of the cutaneous mechanoreceptors of the forefoot or hindfoot often participate in the receptive fields of individual Purkyně cells. Such a field may be restricted to one or other side of the foot, all tested cutaneous mechanoreceptors then sharing approximately in the same restriction. Finally it is shown how these experimental findings relate to the theories of cerebellar function, particularly to the dynamic loop hypothesis.
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  • 29
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cutaneous mechanoreceptors ; Climbing fibers ; Purkyně cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An account is given of single Purkyně cell responses that are evoked by cutaneous mechanoreceptors acting via climbing fibers (CF). There was no complication by mossy fiber input, which was selectively depressed by light pentothal anesthesia. Brief mechanical pulses (taps) to the footpads and air jets on hairy skin were very effective in evoking CF responses, the usual range of latencies being 25–35 msec for the hindfoot and 19–30 msec for the forefoot. There was often a considerable difference in the effectiveness of the different pads of the same foot. For any particular Purkyně cell there was a close correspondence between the receptive fields for footpads and hairy skin. The threshold was often below 0.02 mm taps for the most sensitive pads, and was even lower for more prolonged mechanical displacements. Mechanical pulses of 80 to several hundred msec in duration were effective in evoking CF responses of Purkyně cells at “off” as well as at “on.” This finding and the very low threshold strongly suggest Pacinian corpuscles as the principal receptors concerned in activating the CF system. Repetitive taps to footpads were effective at slow frequencies, 5 or 10 Hz, but there was a response only to the first tap with a frequency of 65 Hz.
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  • 30
    ISSN: 1432-1106
    Keywords: Cerebellum ; Purkyně cell ; Muscle afferent fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Investigations were made in the decerebrate cat of the effect of muscle vibration on the activity of 342 Purkyně cells in the ipsilateral anterior lobe of the cerebellum. The effects were studied for three different muscle groups: in the hindlimb, the anterior tibial group (extensor digitorum longus, peroneus longus, brevis and tertius, and tibialis anterior) and gastrocnemius-soleus; and in the forelimb, the extensor digitorum lateralis and communis muscles. The responses of Purkyně cells were mediated by both the mossy fibre and climbing fibre inputs. The mossy fibre induced responses were generally inhibitory and had latencies only a few msec longer than responses evoked by stimulation of the nerve supplying the muscle. In contrast, the latencies of responses mediated by the climbing fibres were long and variable. Nine cells out of 342 Purkyně cells showed weak response to vibration of less than 60 μ amplitude, as compared to approximately 40% of those which responded to vibration of above 60 μ up to 200 μ amplitude, indicating the preponderant action of Group II afferents on the Purkyně cells in contrast to far less influence from Group Ia afferents. There was no obvious difference in threshold of vibration amplitude regarding the response mediated by the climbing or mossy fibres. Purkyně cell responses mediated by both mossy and climbing fibre inputs displayed temporal summation in response to muscle vibration, although no tonic effects were observed in response to maintained periods (1–5 sec) of vibration. Purkyně cell responses evoked by the mossy fibre input were unable to follow the individual cycles of vibration at frequencies above approximately 50 cps. Those evoked by the climbing fibres could follow at frequencies of less than 10 cps.
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  • 31
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cutaneous mechanoreceptors ; Mossy fibers ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper gives an account of single mossy fiber responses when three types of mechanical stimulation are applied to the forefoot and hindfoot of the cat which is either decerebrate and unanesthetized or lightly anesthetized by pentothal or chloralose. The mechanical stimuli were applied either to footpads (brief pulses, taps, or longer square pulses or ramps) or to the hairy skin by air jets. Recording of single mossy fibers was extracellular by glass microelectrodes that were inserted into the granular layer of the cerebellar cortex or the subjacent white matter. As described in previous papers computer averaging techniques usually of 64 responses have been employed to enhance reliability. Taps evoked pure excitatory responses from many mossy fibers, which were usually brief high frequency bursts resembling those evoked by nerve volleys. Usually the threshold displacement was less than 0.2 mm and thresholds as low as 0.01 mm were observed. There were often considerable differences in the intensities of responses from different pads of the same foot. Successive pulses of mechanical stimulation evoked mossy fiber responses of diminished intensity. Longer mechanical stimuli with square or ramp onsets evoked various admixtures of phasic and tonic responses. Hair stimulation was often a very effective excitant, the receptive field for a single mossy fiber usually covering a considerable area of foot and leg. Taps and pressure to the pads were also effective in inhibiting the background discharge of some mossy fibers, and admixtures of excitatory and inhibitory actions were observed. The results are discussed in relationship to the discharges evoked in primary afferent fibers by cutaneous mechanoreceptor stimulation. They provide an intermediate stage of information between mechanoreceptor stimulation and the response of Purkyně cells as described in the next paper.
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  • 32
    ISSN: 1432-1106
    Keywords: Cerebellum ; Cutaneous mechanoreceptors ; Mossy fibers ; Purkyně cells ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper gives an account of single Purkyně cell responses when three types of mechanical stimulation, as in the previous paper, are applied to the forefoot and hindfoot of the decerebrate unanesthetized cat. Attention was concentrated on the effects of brief mechanical pulses to the footpad. Recording was extracellular by glass microelectrodes and special precautions were taken in identifying the spike responses as being due to a single Purkyně cell and in securing its effective isolation for our computer averaging techniques, as described in the previous papers. All Purkyně cells were in the ipsilateral anterior lobe in the lateral vermis or pars intermedia of lobules III, IV, V, except for a few recordings in the extreme rostral zone of lobule VI. Mechanical pulses or taps evoked responses from many Purkyně cells which were pure excitatory, pure inhibitory or admixtures thereof. The latencies of onset were usually in the range of 12–20 msec from the onset of the tap, which tends to be a little longer than the observed latencies for mossy fiber responses described in the preceding paper. There was often a considerable difference in the sizes of the responses evoked from different pads of the same foot, and the usual threshold for response was below 0.2 mm amplitude. Durations of responses were usually 10–20 msec for excitation and 50–100 msec for inhibition. Pressure pulses to the central foot pads of 2 sec duration evoked a wide variety of responses: brief phasic at “on” and “off” that could be admixtures of excitation and inhibition; almost pure tonic excitations or inhibitions that were well maintained during the 2 sec; phasic-tonic responses in various relative degrees. Usually 500 g was maximally effective and the threshold was below 100 g. Hair receptors were stimulated preferentially by brief air jets, there being brief excitatory or inhibitory responses much as with taps, but with rather longer latency. The effective area was usually fairly extensive over the hairy skin of the foot. In general the effects on Purkyně cells by cutaneous mechanoreceptors acting via mossy fibers were in accord with the mossy fiber responses reported in the preceding paper and with the well-known excitatory and inhibitory effects that are exerted by mossy fiber inputs on Purkyně cells.
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  • 33
    ISSN: 1432-1106
    Keywords: Cerebellum ; Vision ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cats without general anaesthesia electric stimulation of the optic chiasma evoked usually in the depth of the cerebellar cortex of lobuli VI and VII a sequence of waves at a latency of 7–10 msec which have been shown to be due to the mossy fibre input. A later wave at a latency of 18–20 msec was also sometimes found in isolation or in association with the early wave. This later field has been identified as due to the climbing fibre input. Unitary recordings have given support to this interpretation. Some correlation has been made with recordings obtained by electric stimulation of the superior colliculus and by flash stimulation of the retinae. It is concluded that the optic pathways project to the visual area of the cerebellar cortex through both mossy and climbing fibre inputs, although from this study based mainly on the laminar analysis of evoked fields, the former input seems to be more widespread and more consistently obtained than the latter.
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  • 34
    ISSN: 1432-1106
    Keywords: Cerebellum ; Thalamus ; Cerebral Cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Cerebello-cerebral projections were electrophysiologically investigated in cats under light Nembutal anaesthesia. Marked responses were produced by stimulation of the interpositus and the lateral nucleus of the cerebellum not only in the pericruciate but also in the suprasylvian cortical areas, both areas being contralateral to the cerebellar nuclei stimulated. Medial nucleus stimulation set up little or no response in the cerebral cortex. 2. The previous electrophysiological study on thalamo-cortical (T-C) projections showed two different kinds of responses in the cortex due presumably to two different T-C projection systems, i. e., deep and superficial T-C responses (see Sasaki et al., 1970). According to laminar field potential analysis, the response in the pericruciate area is characterized by a deep T-C response which is often followed by a superficial T-C response, whereas the response in the parietal cortex consists of a pure superficial T-C response. Intracellular potential changes in cortical neurones elicited by cerebellar nucleus stimulation were consistent with the results of laminar field potential analysis. 3. Comparison between laminar field potentials in the same cortex produced by thalamic and cerebellar nucleus stimulation suggests that the response in the pericruciate cortex is mediated by the ventral lateral nucleus and that the response in the parietal cortex is relayed by the ventral anterior nucleus of the thalamus.
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  • 35
    ISSN: 1432-1106
    Keywords: Cerebellum ; Thalamus ; Parietal Cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The cerebello-thalamo-cerebral projection system mediating the cerebellar-induced “superficial thalamo-cortical (T-C) response” (the basic type of the so-called recruiting response) to the anterior part of the middle suprasylvian gyrus was investigated electrophysiologically. Responses of thalamic neurones to stimulation of the cerebral cortex and the cerebellar nucleus (medial, interpositus and lateral) were recorded by microelectrodes. 2. In the anterior portions of the ventral thalamic nuclear complex, presumably in and/or around the ventral anterior (VA) nucleus, there were found neurones responding antidromically to stimulation of the suprasylvian cortex and orthodromically to that of the interpositus and the lateral nucleus of the cerebellum. They were called P neurones. The neurones responding antidromically to stimulation of the anterior sigmoid cortex and orthodromically to that of the cerebellar nuclei located mostly caudo ventrolateral to the place of P neurones, presumably in and/or around the ventral lateral (VL) nucleus. These were called F neurones. 3. The cerebellar excitation of P neurones was estimated on its latency to be monosynaptic and was usually followed by an inhibition lasting for more than 100 msec. Large unitary EPSPs were sometimes noted in P neurones on cerebellar stimulation as well as spontaneously. It was concluded that P neurones constitute the direct T-C projection system mediating the superficial T-C response (e. g., recruiting response) to the parietal cortex.
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  • 36
    ISSN: 1432-1106
    Keywords: Cerebellum ; Purkyně cell ; Climbing fibers ; Muscle afferent fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of isometric contraction of the gastrocnemius-soleus muscle group was investigated on the responses of 79 cerebellar Purkyně cells (P-cells) in the decerebrate cat. Forty three percent of the P-cells tested were responsive to contraction via a pathway that acted by way of climbing fibres. The latency of these responses was long (mean 60 msec following ventral root stimulation) and variable. It was concluded that the responses were attributable to Group Ib afferent input. An excitatory action of the contraction on spindle afferent fibres was excluded because the responses were: a) evoked by submaximal contractions produced by weak single shock stimulation of the ventral root; b) negligible following isotonic contractions; and, c) augmented when a stretch was superimposed on the rising phase of the twitch. The effects of both muscle contraction and muscle vibration were studied for many of the P-cells in order to investigate the convergence from afferents of both spindle and tendon organ origin. Few P-cells had evidence of a convergent input from Group Ia, II, and Ib fibres. In contrast convergence from Group II and Group Ib input was quite common. With some cells, there appeared to be an input from only Group Ib or Group II fibres.
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  • 37
    ISSN: 1432-0568
    Keywords: Cerebellum ; Neurogenesis ; Autoradiography ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Time of origin of various neuronal elements in the cerebellum of rat was established with the aid of tritiated-thymidine-autoradiography. The earliest nerve cells to form were the Purkinje cells, and they came into existence on days 15 and 16 of gestation. Interstitial nerve cells had their genesis on days 15, 16, 17 and 18, and the marginal cells on day 16 of the embryonic development. The Golgi cells were found to come into existence on days 17, 18 and 19 of gestation. On day 21 of gestation a number of small-medium-sized nerve cells, which were smaller than the Golgi cells but larger than the granule cells, were seen to come into existence. Finally, the earliest stock of granule, basket and stellate cells, primarily in the nodulus, flocculus and para-flocculus, were observed to have been formed on the day 21 of embryogenesis.
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  • 38
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    Anatomy and embryology 138 (1972), S. 227-240 
    ISSN: 1432-0568
    Keywords: Pial cells ; Proliferative cells ; Epithelioid cells ; Ependymal cells ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the developing cerebellum of 8-day old rats surgical lesions were made. During regeneration of the cerebellum the pia mater was found to penetrate inside the neural tissue. Partially differentiated Purkinje cells and granule cells, that were in close contact with the pial cells, were found atrophied. When the profilerative cells of external granular layer came into contact with the pial cells, they were reduced to a primitive type of epitheloid cells. In this instance epithelio-mesenchymal interaction was found deleterious to the precursors of neurons. However, when the epithelioid cells were freed from the contact with the pial cells by intervening basement membrane, they differentiated into ependymal cells. Such ependymal cells gave rise to small as well as large new ventriculer structures, and structures resembling chorioid plexus.
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  • 39
    ISSN: 1432-0568
    Keywords: Cerebellum ; Cytoarchitecture ; Man ; Rhesus monkey ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In der Kleinhirnrinde von Mensch, Rhesusaffe und Katze lassen sich Unterschiede in der Zellgröße und Zellzahl in verschiedenen Kleinhirnabschnitten nachweisen. Im ältesten Kleinhirnabschnitt, dem Lobus nodulofloccularis sind die Purkinjezellen und die Körnerzellen stets größer als in den Lappen des Corpus cerebelli. Außerdem besteht noch eine Größendifferenz zwischen Wurm und Hemisphären. In den vermalen Abschnitten aller Kleinhirnlappen sind die Purkinjezellen und die Körnerzellen größer als in den dazugehörigen Hemisphärenanteilen. Daneben bestehen Unterschiede in der Zellzahl. Im Lobus nodulofloccularis ist die Zellzahl signifikant geringer als in den übrigen Kleinhirnabschnitten. Ähnlich wie bei der Zellgröße bestehen aber auch bei der Zellzahl Unterschiede zwischen den Hemisphären- und Wurmanteilen eines Kleinhirnlappens. In den Wurmabschnitten ist die Zellzahl geringer als in den Hemisphären. Die regionalen Unterschiede in der Cytoarchitektonik und das zahlenmäßige Verhältnis der Purkinjezellen zu den Körnerzellen bei Mensch, Rhesusaffe und Katze werden im Hinblick auf den evolutiven Status der Gehirne diskutiert.
    Notes: Summary In different parts of the cerebellar cortex of man, rhesus monkey and cat there are variations in the size and number of cells. In the lobus nodulofloccularis, the Purkinje cells and the granule cells are larger in diameter than in the corpus cerebelli. Moreover, the Purkinje cells and the granule cells in the vermal parts of the nodulofloccular lobe, the posterior lobe and the anterior lobe are always larger in size than in the hemispheres of these lobes. In addition there are differences in the number of cells: In the nodulofloccular lobe the number of cells per unit volume is significantly lower than in the different parts of the corpus cerebelli; in the vermal parts the number of cells is smaller than in the respective parts of the hemispheres. Thus there are parallels between the differences in size and in number of Purkinje cells and granule cells in the phylogenetic older (vermis) and younger (hemispheres) parts of the cerebellum. The regional differences in cytoarchitectonics of the cerebellar cortex in man, rhesus monkey and cat are discussed with respect to evolution.
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  • 40
    ISSN: 1432-0533
    Keywords: Ectopic Neurones ; Experimental Malformations ; Developmental Mechanisms ; Cerebellum ; X-Irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An attempt was made systematically to produce ectopic cells in the cerebellar molecular layer by means of X-irradiation. The influence of the age of the animal at the time of irradiation and the dose of X-rays, was studied. Based on the results and on data from the literature, a hypothesis is put forward as to the mechanism involved. It is suggested that partial destruction of one of the cerebellar matrices is followed by regeneration, which results in a de-synchronization of the morphogenetic events. As a consequence, a numerical mismatching occurs between the ingrowing mossy fibres and the descending granule cells, leading to invasion of the molecular layer by some of the mossy fibres and the formation of ectopic synapses. Dose- and age-dependency of the results of X-irradiation are in agreement with deductions from this hypothesis. Similar mechanisms may well be involved in the pathogenesis of other developmental abnormalities of the central nervous system.
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  • 41
    ISSN: 1432-0533
    Keywords: Mercury Intoxication ; Nerve Cells ; Dorsal Root Ganglion ; Cerebellum ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary When given to rats, both organic and inorganic mercury compounds were found to be neurotoxic. After CH3HgCl intoxication, focal cytoplasmic degradation was the most characteristic lesion observed in the neurons of the dorsal root ganglion. A large cytoplasmic vacuole was formed in many neurons as a result of such lesions. After HgCl2 poisoning, the dorsal root ganglion neurons developed peripheral vacuoles, which were formed by the retraction of the neuron from its surrounding satellite cells. Extensive fragmentation of these neurons occurred as such vacuolation progressed. Multiple small lesions varying from 0.1–1.2 μ were found in the neuronal cytoplasm after both organic and inorganic mercury intoxication. Mercury could be demonstrated histochemically to have a close association with these lesions. In the anterior horn motoneurons, neither mercury compound produced any permanent pathological lesions in the nerve cell bodies, although there was severe dilatation of the cisternae of the endoplasmic reticulum and the nuclear envelope at early stages of the intoxication. In the cerebellum, both organic and inorganic mercury compounds produced extensive coagulative or lucid changes in the granule cells. Degeneration of the Purkinje cells was also found at late stages of the poisoning.
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  • 42
    ISSN: 1432-0533
    Keywords: Spongy Degeneration ; Cerebellum ; Electron Microscopy ; Enzyme Histochemistry ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopic and enzyme histochemical studies were performed on the cerebellum from a 9 month old Jewish boy with spongy degeneration. Histologically, the main pathological changes were noted in the Purkinje cell layer, the deeper areas of the granular cell layers and the subcortical white matter. Ultrastructurally, multiple vacuoles were present within the swollen cytoplasm and processes of protoplasmic astrocytes in the cortex, while in the subcortical white matter vacuoles were observed within splitting myelin lamellae as well as within astrocytes. There were also abnormal mitochondria within swollen protoplasmic astrocytic cytoplasm and processes which in ATPase preparations showed little or no reaction product. However, the fibrillary astrocytes were not swollen and contained intact mitochondria which showed normal reaction product in ATPase preparations. Since the myelin changes are known to be nonspecific and secondary to abnormal fluid accumulation, the characteristic distribution of the multiple vacuoles in the central nervous system in this disorder seems primarily to be related to swelling of the protoplasmic astrocytes.
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  • 43
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    Electronic Resource
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    Pflügers Archiv 337 (1972), S. 119-134 
    ISSN: 1432-2013
    Keywords: Deiters Neurones ; Excitation ; Inhibition ; Cerebellum ; Ascending Pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were carried out on cats anesthetized with chloralose, small doses of Thiopental being added in about half of the animals. Recordings were made from neurones located in Deiters' nucleus. Single shocks applied to the spinal cord evoked membrane potential changes consisting of different types of PSPs. Current analysis revealed: EPSPs, IPSPs, and potential changes due to disinhibition; such components differing in their latencies. Upon stimulation at C2, there were EPSPs with brief (mean 1.7 ms) and longer (mean 5.8 ms) latencies, denoted “EE” and “CE”, respectively. Also, IPSPs showed up with brief (mean 3.6 ms, “MI”) and longer (mean 7.3 ms, “CI”) latencies. Moreover, there was a prolonged inhibition usually turning into a longlasting (up to several hundred milliseconds) disinhibitory depolarization. Of Deiters neurones exhibiting PSPs upon spinal cord stimulation, 66% showed the complete synaptic pattern, 34% short latency or long latency components in isolation. The patterns obtained intracellularly corresponded well to discharge patterns recorded extracellularly. The results were essentially similar in control experiments performed on precollicularly decerebrated cats.
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  • 44
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    Electronic Resource
    Springer
    Pflügers Archiv 337 (1972), S. 367-372 
    ISSN: 1432-2013
    Keywords: Climbing Fiber ; Purkinje Cell ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The inhibitory effects of the climbing fiber input on cerebellar Purkinje cells was studied in cats. 1. The excitatory and the inhibitory effect of the CF input was observed independent from each other. 2. At C-T intervals longer than 20 msec the EPSP of the Purkinje cell produced by CF activation was reduced by a preceding inferior olive stimulation. 3. At the period of greatest depression of a CF response the N3 wave of a mossy fiber input was not reduced by a conditioning CF input. It is suggested that basket cells are the interneurons mainly involved in the inhibition of Purkinje cells.
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  • 45
    ISSN: 1432-1912
    Keywords: Central Depressants ; Rabbit ; EEG ; Cerebellum ; Red Nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The action of central depressant drugs (CDD) was investigated on the electrical activity of the cerebellum (CB) and/or red nucleus (RN). They can be divided into different groups according to their effect on the cerebello-rubral system: 1. Classical hypnotics (barbiturates, paraldehyde, chloral hydrate, piperidinedione derivatives, methaqualone, ethinamate, bromvalurea), transquilizers (benzodiazepine derivatives, meprobamate) and one volatile anesthetic agent (methoxyflurane) regularize the “spontaneous” activity of the CB and RN. The frequency of the drug-induced rhythm depends on the depth of anesthesia. 2. Diethyl ether, urethane, ethyl alcohol and halothane do not regularize the electrical activities in the CB and RN; rather they desynchronize the “spontaneous” activity of these brain areas. 3. Trichlorethylene induces a high frequency and high amplitude rhythm in both the CB and RN during deep anesthesia. 4. With all CDD tested the drug-induced CB rhythm is identical with the RN rhythm.
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  • 46
    ISSN: 1432-1912
    Keywords: Anesthetics ; Rabbit ; Single Neuron Activity ; Red Nucleus ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The action of three typical anesthetic agents, pentobarbital, halothane and trichlorethylene on the activity of single neurons of the pars magnocellularis of the red nucleus was investigated in the rabbit and compared with the electrical activity of the cerebellum induced by these drugs: 1. Pentobarbital induces a regular slow wave activity with a frequency between 5 to 25 Hz and a burst firing pattern of single red nucleus neurons, which is correlated with the slow wave rhythm. 2. Halothane induces an irregular low voltage slow wave activity and also an irregular firing pattern of single red nucleus neurons. 3. Trichlorethylene induces a rhythm with a frequency between 40 and 90 Hz and, similar as in the case of pentobarbital, a firing pattern of single red nucleus neurons which is correlated with this rhythm. 4. Thus, the differential action of these three agents on the slow wave activity of red nucleus and the cerebellum is reflected in an analogous action on the activity of single red nucleus neurons.
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  • 47
    ISSN: 1432-1106
    Keywords: Thalamus ; Corpus striatum ; Pyramidal tract ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of stimulation of the Entopeduncular nucleus on the thalamic ventrolateral nucleus (VL) was studied by recording with macroelectrodes and microelectrodes in cats anesthetized with chloralose or under local analgesia. An asynaptic response (0.5 ms shortest latency) was evoked in the VL following the Entopeduncular stimulation. It is demonstrated that this response is attributable to the activation of the Entopeduncular-VL fibers described by anatomists. The postsynaptic events revealed, since only a small proportion of VL cells are affected by Entopeduncular stimulation, that the influence exerted by the Entopeduncular nucleus on the VL is much weaker than the cerebellar one.
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  • 48
    ISSN: 1432-1106
    Keywords: Cerebellum ; Inhibition ; Strychnine ; Picrotoxin ; Bicuculline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stimulation of the parallel fibres, or the mossy fibres, in the cerebellar cortex depresses the potential generated in the granular layer by anti-dromic invasion of the Purkinje cells (N1), and that generated by the axon discharge of granule cells (P2). The reduction of these potentials indicate inhibitions mediated respectively by basket and Golgi cells. The depressions of both N1 and P2 potentials are unaffected by strychnine at doses of up to 1 mg/kg. Picrotoxin and bicuculline reduce or suppress both inhibitions at doses of 2 to 5 mg/kg and 0.2 to 0.4 mg/kg respectively. The action of the picrotoxin is long lasting or even possibly irreversible, whereas that of bicuculline lasts only a few minutes. The ratio by weight between the dose of picrotoxin and that of bicuculline necessary to reduce the N1 and P2 depression exceeds 10. These results indicate that gamma-aminobutyric acid may be the chemical inhibitory transmitter at basket cell — Purkinje cell and Golgi cell — granule cell synapses.
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  • 49
    ISSN: 1432-1106
    Keywords: Cuneocerebellar tract ; External cuneate nucleus ; Main cuneate nucleus ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The origin and termination was determined for cells belonging to the cuneocerebellar tract in the cat, which consists of one proprioceptive component (P-CCT) activated by group I muscle afferents and one exteroceptive component (E-CCT) activated by cutaneous afferents. The recording sites of the cells were histologically verified and the termination of the axons assessed by antidromic activation from the cerebellar surface. 2. The P-CCT originates from cells in the external cuneate nucleus, where forelimb muscles are somatotopically represented. The observations suggest that practically all cells in this nucleus project to the cerebellum and are activated by muscle afferents. 3. The E-CCT originates from cells in the rostral part of the main cuneate nucleus, where they occur intermingled with lemniscal neurones. 4. The CCT terminates in the pars intermedia of lobule V of the anterior lobe and in the four rostral folia of the paramedian lobule. The majority of the cells send one branch to each projection area. 5. The P-CCT and E-CCT terminate in the same projection areas. 6. CCT neurones activated from distal and proximal parts of the limb terminate diffusely in the entire projection area, although there is some tendency for neurones activated from distal parts to terminate caudally and for neurones activated from proximal parts to terminate rostrally.
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  • 50
    ISSN: 1432-1106
    Keywords: Cerebellum ; Purkyně cell discharges ; Mossy fibers ; Climbing fibers ; Afferent volleys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Impulses discharged by Purkyně cells provide the only output from the cerebellar cortex. Usually the Purkyně cells can be identified with certainty because they alone respond by the brief bursting discharge generated by climbing fiber (CF) impulses, as well as by the ubiquitous simple spikes. The discharges from single Purkyně cells in the anterior lobe have been studied in lightly anesthetized and in decerebrate unanesthetized cats. All of our 275 identified cells had an average background discharge frequency in the range of 5/sec to 100/sec. The discharge was increased and/or depressed by afferent volleys from a number of limb nerves. In addition there was usually a slow rate of CF-evoked spike bursts at 0.5–2/sec, and many afferent inputs also evoked CF responses. The firing patterns of Purkyně cells are often very irregular, but by the technique of computer averaging of many sweeps, usually 128, the responses of the cell under observation have been accurately and reliably displayed as post-stimulus time histograms and their cumulative frequency distributions. In this manner the distinctive features of the responses evoked by the mossy fiber and climbing fiber inputs have been determined under a wide variety of conditions. The most direct mossy fiber responses — excitatory or inhibitory — had a shorter latency than the climbing fiber responses, usually by more than 10 msec. However, there were also later responses to both types of input. Repetitive afferent volleys were used to study facilitation of the mossy fiber responses at short intervals, and the effectiveness of repetition on both kinds of inputs at slower frequencies. Repetitive mossy fiber inputs apparently can give a maintained enhancement or depression of the Purkyně cell discharge.
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  • 51
    ISSN: 1432-1106
    Keywords: Cerebellum ; Mossy fibers ; Granule cells ; Afferent volleys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This paper is the first of a series in which the processing of information in the cerebellum has been studied by investigating the effects that known inputs from limb nerves produce on the unitary spike potentials in the cerebellar cortex. These spikes have been recorded extracellularly at all depths along microelectrode tracks in the 5th, 4th and 3rd lobules of the anterior lobe in the lateral vermis or in the pars intermedia. These units have a background frequency of discharge, often very irregular, and computer averaging techniques have been employed in order to derive reliable information on the time course and intensity of the excitatory and/or inhibitory actions produced by the input against this background. Most of the spike responses recorded from the granular layer fall into two classes, one characteristic of impulses in mossy fibers, and the other of impulse discharges from granule cells. Both in the spontaneous background and in the response to afferent volleys in limb nerves the mossy fibers exhibit a performance in close accord with that described for the discharges up the spino-cerebellar tracts. The short latency of 6–9 msec for hindlimb stimuli and the high frequency burst response of 2–4 impulses are characteristic. The mossy fibers displayed a wide variety of responses to the wide range of testing inputs, there being various combinations of excitatory and inhibitory responses and also delayed excitatory actions, all of which must be assumed to be reflections of synaptic influences on the cells of origin of the mossy fibers in the spinal cord. Granule cells have a longer latency by several milliseconds, 9–20 msec for the hindlimb, and a slower frequency in their burst response which tended to be longer and more irregular. The small unitary spike potentials are more difficult to isolate. Also with repetitive stimulation granule cells are more readily depressed than are mossy fibers. Usually a granule cell exhibits a wider range of response to the various cutaneous and muscular afferents of a limb. Both mossy fibers and granule cells may display reciprocal responses to volleys from muscle nerves to antagonistic muscles. This attempt to define properties of the mossy fiber and granule cell spike potentials should help in their identification in future investigations.
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  • 52
    ISSN: 1432-1106
    Keywords: Cerebellum ; Purkyně cells ; Integration ; Topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The 275 Purkyně cells identified by the criteria of the previous paper have been investigated with respect to their role as units integrating the input to the anterior lobe from various limb nerves. The discharges from single Purkyně cells have been studied in lightly anesthetized (pentothal) or in decerebrate unanesthetized cats, there being averaging usually of 128 responses in the form of post-stimulus time histograms and cumulative frequency distributions. Single Purkyně cells exhibited a wide variation in their responses to the diverse inputs from the various afferent nerves. Attention was focussed on excitatory and inhibitory responses evoked by mossy fibers with a short latency, usually 10–15 msec for hindlimb afferents. With most Purkyně cells these responses were predominantly evoked from cutaneous nerves, low threshold fibers being particularly effective. A few Purkyně cells were preponderantly excited by afferent volleys from muscle nerves, but there was a large group with a mixed input from cutaneous and muscle nerves. Graded strengths of stimulation of muscle nerves showed that sometimes group I volleys were prepotent, but other Purkyně cells were selectively excited by group II volleys. Though sometimes the afferent volleys from antagonistic muscles had a reciprocal action on a Purkyně cell, as on a motoneurone, it was more common to find similar actions. Also convergence of inputs from forelimb and hindlirnb nerves, both cutaneous and muscular, was not uncommon, particularly in marginal areas between hindlimb and forelimb zones. A special design feature is the convergence onto a Purkyně cell of mossy fiber and climbing fiber inputs evoked by the same afferent volley. This convergence was of particular interest along the parasagittal strip of hindlimb climbing fiber distribution in lobule V. It was not possible to translate the observations into some map of the cerebellar cortex on which are marked the territorial distributions from the various limb afferent nerves. Rather, there was an ill-defined patchy character, closely adjacent Purkyně cells often receiving very different subsets of the total input from the various limb nerves. The unitary integrations accomplished by the individual Purkyně cells are further integrated when their axons converge onto and inhibit the neurones of the cerebellar nuclei, and this integration by convergence would occur in each successive relay on the output pathways from the cerebellum. It is pointed out that the experimental findings on the integrative action of the individual Purkyně cells provide basic information for attempts to construct models simulating cerebellar performance and control.
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  • 53
    ISSN: 1432-1106
    Keywords: Electron microscopy ; Cerebellum ; Purkinje cells ; Diphenyl-hydantoin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopic examination of Purkinje Cells was performed in sections from the cerebellum of three albino rats aged 4 1/2 month, intoxicated with diphenylhydantoin for 51 days. Three untreated albino rats served as controls. There were no difference between the substructure of the Purkinje cells from the two groups of animals. It was concluded that diphenylhydantoin in toxic but sublethal doses does not change the substructure of the Purkinje cells.
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  • 54
    ISSN: 1432-1106
    Keywords: Deiters' Cells ; Cerebellum ; Somatic Inputs ; Vestibular
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of the cerebellum on the activity of Deiters' cells has been studied by comparing the extracellularly recorded activity of single cells in decerebellate cats and in those with an intact cerebellum. The tonic inhibitory influence of the cerebellum is reflected in three ways: a smaller proportion of those cells projecting to the spinal cord is spontaneously active; fewer cells are found which do not project to the spinal cord, indicating that activity in this population of cells is depressed; among those cells that are spontaneously active, the rates of discharge are lower. In the decerebellate cat, stimulation of either ipsior contralateral limb nerves facilitates many cells, whereas in the presence of the cerebellum, peripheral stimulation evokes facilitation followed by inhibition. The inhibition is ascribed to activation by peripheral stimulation of Purkinje cells projecting to Deiters' nucleus from the cerebellum. The thresholds for facilitation and inhibition are similar but longer stimulus trains are required to evoke inhibition. Inputs from many different nerves converge upon the same cell. Among the nerves to muscles, quadriceps was the only nerve effective at stimulus strengths below the group III range. Three populations of cells are found in Deiters' nucleus: cells receiving somatic inputs but not labyrinthine inputs; cells receiving inputs from both the labyrinth and ascending somatic systems; cells activated from the labyrinth but free of somatic influences.
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  • 55
    ISSN: 1432-1106
    Keywords: Cuneocerebellar tract ; Proprioceptive path ; Exteroceptive path ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The afferent connections to 180 cuneocerebellar tract (CCT) neurones were studied in the cat. The neurones were classified into two groups, proprioceptive and exteroceptive. 2. The proprioceptive neurones (P-CCT) occurred in the external cuneate nucleus and were monosynaptically activated by group I muscle afferents. About 60% of these neurones received additional excitation from group II muscle afferents. 3. The P-CCT neurones received excitation from one nerve only. 4. The P-CCT neurones received postsynaptic inhibition from muscle nerves not supplying excitation. 5. The exteroceptive neurones (E-CCT) occurred in the main cuneate nucleus and received di- and polysynaptic excitation from cutaneous afferents. Most neurones received additional excitation from high threshold muscle afferents. The latter originated from receptors that were sometimes activated by pressure against deep structures but seldom, if ever, from slowly adapting stretch receptors in muscle. 6. The E-CCT neurones were usually activated from several skin and muscle nerves. 7. Stimulation of the sensorimotor area of the cerebral cortex evoked inhibition in some P-CCT neurones and excitation and/or inhibition in some E-CCT neurones. 8. The afferent organization of the CCT is compared with that of the dorsal spinocerebellar tract. The information carried by the two tracts is discussed.
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  • 56
    ISSN: 1432-1106
    Keywords: Nucleus reticularis tegmenti pontis ; Cerebral cortex ; Cerebellum ; Experimental neuroanatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The distribution of degenerating fibres in the nucleus reticularis tegmenti pontis (N.r.t.) has been examined in Nauta (1957) impregnated sections from cats with discrete lesions of various cortical regions. The following cortical regions send fibres to the N.r.t.: Ms I, Sm I, Sm II, the orbital gyrus, the proreate gyrus, the parietal cortex and parts of the medial surface of the frontal lobe. The projection is bilateral, but mainly ipsilateral. The main terminal area of fibres from all cortical regions mentioned is the ventral part of the N.r.t. at middle rostrocaudal levels. Within this territory most cortical regions have their particular terminal sites in the N.r.t., but there is considerable overlapping. The anatomical organization and the role of the N.r.t. as a cerebrocerebellar relay station are discussed. The regions of the N.r.t. not receiving cortical fibres are supplied by fibres from other sources. These fibre groups have their preferential, although overlapping, areas of termination. In its organization the N.r.t. differs markedly from the pontine nuclei proper. Like the two other precerebellar reticular nuclei the N.r.t. appears to provide possibilities for an integration of impulses from the cerebral cortex with those from many other sources before they influence the cerebellum.
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  • 57
    ISSN: 1433-8491
    Keywords: Cerebrum ; Cerebellum ; Neuronal Clusters ; Reliability ; Großhirn ; Kleinhirn ; Neuronengruppierungen ; Projektionssicherung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Arbeit gibt eine Übersicht über die säulenartige Ordnung von Neuronen mit ähnlichen Funktionen in der Großhirnrinde und vergleicht diese mit entsprechend gruppierten Neuronpopulationen im Kleinhirn. Die Zellsäulen bilden senso-motorische Funktionseinheiten von Neuronengruppen. Im somatosensiblen Cortex meldet jede Zellsäule jeweils die gleiche Sinnesmodalität, in der Sehrinde die gleiche Raumorientierung von Konturen. Der motorische Cortex enthält ebenfalls senkrechte Zellsäulen von Pyramidenzellen, die spezifische Bewegungen auslösen. Die Säulenordnung der Hirnrinde wird als Parallelschaltung von Neuronen ähnlicher Funktion in einzelnen Gruppen gedeutet. So entstehen geordnete kollektive Neuronenleistungen trotz unregelmäßiger Hintergrundsentladung der einzelnen Nervenzellen. Mehrere Neurone eines Kollektivs konvergieren jeweils auf ein Integrationsneuron (target neurone), dessen Entladung die summierte Leistung der Zellsäulen in zeitlicher Abfolge wiedergibt. Neuere Untersuchungen am Kleinhirn zeigen eine ähnliche Kollektivordnung der Purkinje-Zellen mit Gruppen von ähnlichen receptiven Feldern. Diese PurkinjeAxone konvergieren auf Neurone der Kleinhirnkerne, z. B. den Dachkern, der ebenfalls funktionell geordnete Neuronenkollektive enthält. Allgemeine Folgerungen. Die kollektive Gruppenordnung der Neurone kann sowohl im Großhirn wie im Kleinhirn neben einer Verstärkung und Integration einlaufender Signale und einer Kontrastverschärfung durch Umfeldhemmung vor allem durch räumliche Summation vieler ähnlich arbeitender Neurone bedeutsame Signale aus dem Rauschpegel herausheben. Dann können die Axone dieses Zellkollektivs ihre gesamte Information auf die Integrationsneurone projizieren. Die Projektionen der neuronalen Funktionseinheiten verlaufen in mehrfachen Sequenzen und Stufen komplexer sensomotorischer Erregungskonstellationen, die durch eine afferente Eingangsmeldung ausgelöst werden.
    Notes: Summary An account is given of the columnar arrangement in the cerebral cortex that has been discovered for neurones having a similar receptivity. This has been observed in the somaesthetic cortex for neurones with similar modality sensitivities and in the visual cortex for neurones with similar directional sensitivities. The anatomical basis is discussed. In the motor cortex also there is an arrangement in clusters of pyramidal cells that are responsible for particular movements. The functional significance of this organization in clusters in the cerebral cortex is discussed in relationship to the problem of securing a reliable performance despite the irregular background discharge of the individual neurones. It is proposed that reliability is secured by the in-parallel arrangement of neurones with similar receptivities in the clusters. The neurones of a cluster tend to converge onto common target neurones, which, as it were, read out the summed performance of the cluster from moment to moment. Recent work on the cerebellum also discloses that there is an arrangement of Purkyně cells in clusters with somewhat similar receptive fields and that their axons tend to converge onto neurones of the cerebellar nuclei (fastigial nucleus), which likewise are arranged in functional clusters. The general concept emerges that the arrangement of neurones in clusters both in the cerebrum and in the cerebellum, achieves functional significance not only in giving opportunity for amplification and integration of incoming signals and for their sharpening by surround inhibition, but it is also important in the output performance. Signals are lifted out of noise by the spatial summation deriving from the many similarly performing neurones that project by their axons to the same cluster of target neurones; and this orderly projection can go on sequentially through all the complexities of on-going actions initiated by some input.
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  • 58
    ISSN: 1432-0568
    Keywords: Cerebellum ; Cytology ; Synapses ; Mossy fibers ; Glomeruli ; Golgi II neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Mossy fibers engage in synapses en marron with the somata of some Golgi II cells. These synapses resemble in all particulars the synapses en marron made by climbing fibers except for the distinctive characteristics of the presynaptic terminal. The mossy fiber, with its axial stream of neurofilaments and mitochondria and its loose aggregations of round synaptic vesicles, makes an extensive contact with the wrinkled surface of the Golgi II perikaryon. Synaptic complexes are confined to the depths and sides of the furrows in the Golgi cell. The free side of the mossy fiber terminal often articulates with large numbers of granule cell dendrites, an arrangement similar to that found in ordinary glomeruli. These synaptic connections may be interpreted in the light of the physiological evidence that Golgi II cells inhibit granule cells that are not strongly activated by mossy fibers. Since each granule cell receives four to six mossy fibers, strong activation may require either a selected frequency pattern or synchrony of several inputs. The collateral inhibition indirectly evoked by the same mossy fiber via Golgi II cells would suppress those granule cells not receiving concurrent excitation from other mossy fibers or the favored pattern of excitation. In contrast, granule cells simultaneously activated by other mossy fibers would not be inhibited but would send impulses to the molecular layer. Thus, the glomerulus would behave as a filter that increases the signal-to-noise ratio of the excitatory input to the Purkinje cells.
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  • 59
    ISSN: 1432-1106
    Keywords: Thalamus ; Motor cortex ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cats anesthetized with chloralose, a topographic study of the relations between the ventrolateral nucleus and the precruciate cortex has been performed. It has revealed a mediolateral topography inside the ventrolateral nucleus such that the medial neurones project to area 6 and the more lateral ones to area 4. Postsynaptic spikes were evoked in ventrolateral nucleus by stimulation of the precruciate cortex, with the same topography. The postsynaptic spikes are usually preceeded by an antidromic spike. The possible action of the cerebellum on axial musculature by way of the ventrolateral nucleus and the motor cortex is discussed.
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  • 60
    ISSN: 1432-1106
    Keywords: VL neurones ; Cerebellum ; Cerebrum ; EPSP ; IPSP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Cerebello-thalamo-cortical relay transmission was studied by intracellular recording from cells of the ventrolateral (VL) nucleus of cat's thalamus. The VL relay cells were identified by their antidromic invasion from the pericruciate cortex as well as by their monosynaptic activation from the cerebellar nuclei. 2. Impulses conducting along the cerebello-thalamic pathway at a mean velocity of 18 m/sec produced in VL relay cells excitatory postsynaptic potentials (EPSPs) monosynaptically. Cerebello-thalamic transmission was characterized by relatively large sizes of unitary EPSPs that amounted to 0.8–3.2 mV in peak amplitude. Spontaneously arising EPSP-noise had a similarly large unitary size. 3. The spot from which the EPSPs were produced with the lowest threshold was determined for each of 50 VL relay neurones. The EPSP origin thus determined lay within both lateral and interpositus nuclei. 4. The cerebellar-evoked EPSPs were often followed by inhibitory postsynaptic potentials (IPSPs) with an additional delay of 0.9–2.5 msec. The possibility is suggested that this inhibitory pathway contains at least one interneurone, presumably located within VL. For 10 VL relay cells, the low threshold points for inducing the polysynaptic IPSP were found to be distributed within the interpositus nucleus. 5. Stimulation to the pericruciate cortex produced EPSPs monosynaptically in VL relay cells, the pathway having a conduction velocity of 4–14 m/sec. The time course of the cortical-evoked EPSPs was characteristically slow, in contrast to that of the cerebellar induced EPSPs. This suggests that cortico-thalamic fibers make contact with the peripheral dendrites of the VL neurones, whereas the cerebello-thalamic ones impinge onto their somas or proximal dendrites.
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  • 61
    ISSN: 1432-0533
    Keywords: Cerebellum ; Development ; Irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Kleinhirn junger Ratten verschiedenen Alters wurde bestrahlt. Die Wirkung auf die Kleinhirnmorphogenese wurde untersucht; sie wurde mit zunehmendem Alter zum Zeitpunkt der Bestrahlung geringer. Die histologische Untersuchung des geschädigten Kleinhirns legt einen Zeitplan der Kleinhirnreifung nahe, der mit dem mittels anderer Methoden gewonnenen in guter Übereinstimmung steht. Die weitere physiologische und pharmakologische Untersuchung des geschädigten Kleinhirns scheint im hohen Maße erfolgversprechend.
    Notes: Summary Cerebella of young rats of various ages were irradiated. The effect on cerebellar morphogenesis was studied. This effect decreased with increasing age at the time of irradiation. Histological examination of the abnormal cerebella suggests a time-table of cerebellar maturation that is in good agreement with that obtained by other means. Further physiological and pharmacological investigation of these abnormal cerebella seems highly rewarding.
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  • 62
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    Springer
    Anatomy and embryology 131 (1970), S. 283-290 
    ISSN: 1432-0568
    Keywords: Interstitial neurons ; Isodendritic neurons ; Reticular formation ; Cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Large multipolar interstitial neurons, isodendritic in their morphology, present in the medullary regions of the cerebellum are described. Histochemically these nerve cells are characterized by an intense acetylcholinesterase activity. On the basis of their morphological criteria and histochemical properties, and in continuation with our earlier study on the interstitial neurons in the white-matter regions of the central nervous system, it is suggested that the interstitial nerve cells form a vast nerve net within the central nervous system, which is an extension of the diffuse reticular formation.
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  • 63