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  • 1
    Electronic Resource
    Electronic Resource
    The inhibitory interneurones within the cerebellar cortex (1966)
    Springer
    Experimental brain research 1 (1966), S. 1-16 
    Details
    ISSN: 1432-1106
    Keywords: Inhibitory interneurones ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Extracellular microelectrode recording has been employed to study the responses of three types of interneurones in the cat cerebellar cortex: basket cells, superficial stellate cells and Golgi cells. The large unitary spike potentials of single cells were sharply localized and presumably were generated by impulse discharges from the cell somata. The characteristics of their responses described below sharply distinguished them from Purkinje cells. 2. The parallel fibre volleys generated by surface stimulation of a folium evoked brief repetitive discharges that were graded in respect of frequency and number. Maximum responses had as many as 10 impulses at an initial frequency of 500/sec. 3. At brief test intervals there was facilitation of the response to a second parallel fibre volley; at about 50 msec it passed over to depression for over 500 msec. 4. Stimulation deep in the cerebellum in the region of the fastigial nucleus (juxta-fastigial, J.F.) evoked by synaptic action a single or double discharge, presumably by the mossy fibre-granule cell-parallel fibre path, but climbing fibre stimulation from the inferior olive also usually had a weak excitatory action evoking never more than one impulse. 5. J.F. stimulation also had an inhibitory action on the repetitive discharge evoked by a parallel fibre volley. Possibly this is due to the inhibitory action of impulses in Purkinje cell axon collaterals. 6. There was a slow (7–30/sec) and rather irregular background discharge from all interneurones. The inhibitory actions of parallel fibre and J.F. stimulation silenced this discharge for some hundreds of milliseconds, probably by Golgi cell inhibition of a background mossy fibre input into granule cells. 7. All these various features were displayed by cells at depths from 180 to 500 μ; hence it was concluded that superficial stellate, basket and Golgi cells have similar properties, discrimination being possible only by depth, the respective depth ranges being superficial to 250μ, 250μ to 400μ, and deeper than 400μ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235206
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  • 2
    Electronic Resource
    Electronic Resource
    Parallel fibre stimulation and the responses induced thereby in the Purkinje cells of the cerebellum (1966)
    Springer
    Experimental brain research 1 (1966), S. 17-39 
    Details
    ISSN: 1432-1106
    Keywords: Parallel fibres ; Purkinje cells ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. When electrical stimuli were applied to the surface of a cerebellar folium by a local electrode (LOC), there was a propagated potential wave along the folium with a triphasic (positive-negative-positive) configuration. 2. Investigations by microelectrode recording established that this wave is produced by impulses propagating for at least 3 mm and at about 0.3 m/sec along a narrow superficial band or “beam” of parallel fibres. As expected from this interpretation, there was an absolutely refractory period of less than 1 msec and impulse annihilation by collision. 3. Complications occurred from the potential wave forms resulting from the excitation of mossy fibres by spreading of the applied LOC stimulus. These complications have been eliminated by chronically deafferenting the cerebellum. 4. When recording within the beam of excited parallel fibres there was a slow negative wave of about 20 msec duration, and deep and lateral thereto, there was a slow positive wave of approximately the same time course. 5. These potential fields were expressed in serial profile plots and in potential contour diagrams and shown to be explicable by the excitatory and inhibitory synaptic action on Purkinje cells: excitatory depolarizing synapses of parallel fibre impulses on the dendrites; and hyperpolarizing inhibitory synapses of stellate and basket cells respectively on the dendrites and somata. The active excitatory synapses would be strictly on the parallel fibre beam and the inhibitory concentrated deep and lateral thereto, which is in conformity with the axonal distributions of those basket and stellate cells that would be excited by the parallel fibre beam. 6. Complex problems were involved in interpretation of slow potentials produced by a second LOC stimulus at brief stimulus intervals and up to 50 msec: there was a potentiation of the slow negative wave, and often depression of the positive wave deep and lateral to the excited beam of parallel fibres. 7. Often the LOC stimulus evoked impulse discharge from the Purkinje cells, these discharges being inhibited by a preceding LOC stimulus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235207
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  • 3
    Electronic Resource
    Electronic Resource
    The mossy fibre-granule cell relay of the cerebellum and its inhibitory control by Golgi cells (1966)
    Springer
    Experimental brain research 1 (1966), S. 82-101 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Mossy fibre input ; olgi cell inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The glomerulus in the cerebellar granular layer is composed of the three elements; the mossy fibre terminal, the granule cell dendrites and the Golgi cell axons. The afferent input to the cerebellar cortex through the glomerulus, the mossy fibre-granule cell relay (M.G.R.), and its inhibitory control by the Golgi cells were studied by recording, a) extracellular field potentials in the granular and molecular layers, b) unitary spikes of granule cells, and c) intracellular postsynaptic potentials in Purkinje cells. 2. Mossy fibres were activated by juxta-fastigial, transfolial, lateral cuneate nucleus and radial nerve stimulation. Stimulation of an adjacent folium (transfolial stimulation) could excite branches of mossy fibres under the stimulating electrode which supply other branches also to the folium under the recording electrode. This technique was utilized to distinguish the response due to mossy fibre activation from those due to the climbing fibre and Purkinje cell axons. 3. These stimulations resulted in, through the M.G.R., a powerful activation of granule cells whose axons (parallel fibres) excited in turn the Purkinje cells and the inhibitory interneurones, including the Golgi cells, in the molecular layer. 4. Field potentials and unitary spikes due to granule cell activity elicited by the stimulation of mossy fibres were markedly depressed for hundreds of milliseconds after the direct stimulation of parallel fibres (LOC stimulation). The postsynaptic potential in Purkinje cells evoked by mossy fibre activation was also depressed by the conditioning LOC stimulation in the same manner. The “spontaneous” background activities recorded from granule cells as unitary spikes and from Purkinje cells as inhibitory synaptic noise were silenced for hundreds of milliseconds after the LOC stimulation. 5. These depressions indicate that the parallel fibre activation evokes an inhibitory action upon M.G.R. On anatomical grounds this inhibition can be mediated only by the Golgi cell, and it is postulated that the inhibitory action is postsynaptic upon the dendrites of granule cells. 6. It is concluded that the Golgi cell inhibition regulates the mossy fibre input to the cerebellar cortex at the M.G.R. by a form of negative feed-back.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235211
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  • 4
    Electronic Resource
    Electronic Resource
    Intracellularly recorded responses of the cerebellar Purkinje cells (1966)
    Springer
    Experimental brain research 1 (1966), S. 161-183 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Purkinje cells ; Intracellular recording ; Postsynaptic potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Intracellular recording from Purkinje cells has been employed in investigating the excitatory and inhibitory synaptic action that is exerted on these cells by the mossy fibre input into the cerebellum. 2. These synaptic actions are evoked not directly by the mossy fibres, but probably always through granule cells and their axons, the parallel fibres. The intracellular records conform with the anatomical evidence that the parallel fibres directly exert a powerful synaptic excitatory action on Purkinje cells, and that the inhibitory pathway occurs via an inhibitory interneurone — a basket cell or a stellate cell. Direct stimulation of parallel fibres gives intracellular potentials closely resembling those produced by deep stimulation of mossy fibres. 3. As would be expected, direct stimulation of parallel fibres produces an EPSP with a latency 1 to 2 msec briefer than the IPSP. The IPSP has a duration usually in excess of 100 msec. The EPSP appears to be briefer, though its superposition on the IPSP greatly reduces its apparent duration. Neutralization of the IPSP by appropriate membrane polarization or by intracellular chloride injection reveals an EPSP duration of up to 50 msec. 4. The IPSP is typically affected by polarizing currents; reduced and even inverted by hyperpolarizing currents, and increased by depolarizing currents. The IPSP is converted to a depolarizing response by excess of intracellular chloride. It must therefore be generated by an increased ionic permeability of the inhibitory subsynaptic membrane, chloride ions being importantly concerned. 5. Often small irregular IPSPs can be observed occurring spontaneously, and they react to polarizing currents and to chloride injections in a manner identical to the evoked IPSPs. It is concluded that they are generated by the spontaneous discharges of basket cells. 6. A brief account is given of various spontaneous rhythmic responses of impaled Purkinje cells, and of the effect of synaptic inhibitory action upon them. 7. There is a general discussion of these findings in relation to the various neural pathways and neural mechanisms that have been postulated in the light of the preceding investigations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236869
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  • 5
    Electronic Resource
    Electronic Resource
    Functional linkage between the electrical activity in the vermal cerebellar cortex and saccadic eye movements (1977)
    Springer
    Experimental brain research 29 (1977), S. 1-14 
    Details
    ISSN: 1432-1106
    Keywords: Purkinje cells ; Eye movements ; Vermis ; Monkey ; Cerebellum ; Motor control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The temporal relation between the onset of electrical activity of Purkinje cells and the occurrence of rapid eye movements was studied. Experiments were performed in unanesthetized animals, the recordings being made under direct vision through the use of a chronically implanted teflon sleeve. The following results were obtained. 1. Correlation between the activity of Purkinje cells and eye movements indicates that Purkinje cell firing in vermal lobules VI and VII precedes eye movement by 11–24 msec, peak activity corresponding to the time of onset of eye movement. 2. This eye movement related activity of Purkinje cells occurred regardless of the direction of the eye movements but some cells showed directional biases. Best correlation between eye movement and Purkinje cell activity was found with fast eye movements toward the right regardless of recording side. 3. Electrical activity of Purkinje cells was mainly related to saccades. Slow eye movement modulation, although probably present, was not studied in detail. 4. In those cells where an extensive set of measurements could be made, Purkinje cell firing was found to be inversely proportional to the amplitude of the eye movement, small movements being preceded by highest Purkinje cell activity. The present results suggest that cerebellar vermis responds prior to the generation of eye movement and may probably serve to control eye movements in a ballistic manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236872
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  • 6
    Electronic Resource
    Electronic Resource
    Cerebellar modulatory action on the vestibulo-trochlear pathway in the cat (1972)
    Springer
    Experimental brain research 15 (1972), S. 364-385 
    Details
    ISSN: 1432-1106
    Keywords: Vestibulo-trochlear reflex ; Reverberation ; Floccular inhibition ; Commissural inhibition ; Cerebellar influence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Field and intracellular potentials were recorded at the level of the trochlear nucleus (TN) following stimulation of the ipsi- or contralateral vestibular nerve (Vi, Vc) or the cerebellar flocculus (Floc). Vi and Vc stimulation produced clear presynaptic field potentials in the TN as the vestibulo-trochlear volleys ascending from the vestibular nucleus reached the trochlear motoneurons (TMns). Paired Vi-Vi or Vc-Vc stimulation at different intervals demonstrated a clear depression of the second of the two presynaptic potentials in the TN. A similar finding was obtained intracellularly from TMns. These results indicate a marked reduction in the excitability of the vestibular neurons following the conditioning stimulus. This period of subnormality may last for as long as 40 msec. Electrical stimulation of Vi and Vc generated an IPSP and EPSP respectively in TMns. In most instances these synaptic potentials occurred in a repetitive fashion after a single stimulation to either nerve. This reverberatory-like tendency of the vestibulo-trochlear pathways was absent in decerebellate animals, implying a cerebellar modulatory mechanism on vestibulo-trochlear transmission. Floccular stimulation produced a strong monosynaptic depression of the field and intracellular potentials evoked in the TN by Vi activation. In chronic experiments where the vestibular nerve had been transected, Floc stimulation generated a disinhibition of TMns through its suppression of the ipsilateral inhibitory vestibular neurons which project to the TN. Contralateral Floc stimulation produced a clear disfacilitation of TMns by the inhibition of contralateral excitatory vestibular neurons. Direct evidence was obtained for commissural inhibition acting on both the inhibitory and excitatory vestibular neurons projecting to the TN. The functional implications of the interaction between ipsi- and contralateral vestibular nuclei and the cerebellum and vestibular nuclei are considered in the Discussion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234124
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  • 7
    Electronic Resource
    Electronic Resource
    The olivo-cerebellar system: Functional properties as revealed by harmaline-induced tremor (1973)
    Springer
    Experimental brain research 18 (1973), S. 69-87 
    Details
    ISSN: 1432-1106
    Keywords: Climbing fiber ; Inferior olive ; Tremor ; Harmaline ; Cerebellar nuclei
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intracellular recording from Purkinje cells in cat cerebellar cortex demonstrated an 8–10/sec burst activity following intravenous administration of harmaline (10 mg/kg), a drug known to produce tremor at the same frequency. The burst activation of Purkinje cells was generated by large all-or-none depolarizations similar to climbing fiber (CF) excitatory postsynaptic potentials (EPSPs). Polarization of the cell membrane through the recording electrode (via a Wheatstone bridge) revealed that the all-or-none depolarization had an equilibrium potential and time course identical to the electrically evoked CF-EPSP, demonstrating directly that tremor is associated with specific activation of the CF afferent system. Interspike frequency histograms of the burst responses of Purkinje cells show that the rhythmic CF activity may continue for several hours with approximately 10% frequency scatter, the actual frequency depending on the level of anesthesia. Simultaneous extracellular recordings from Purkinje cells near the midline vermis indicated that CFs projecting to this area fire in a synchronous manner, while simultaneous recording from three Purkinje cells at different lateralities from the midline showed that the rhythmic activity is reduced in the lateral vermis and may be absent in the cerebellar hemispheres. Intra- and extracellular recordings from cerebellar nuclear cells (fastigial) disclosed a bursting type of activation following harmaline; a similar type of activity could be recorded in the reticular formation neurons and at inferior olive level. At spinal cord level, harmaline induced a repetitive and rhythmic activation of motoneurons which was not modified by dorsal root section. Cooling of the cerebellar cortex produced a definite desynchronization of the rhythmic motoneuronal firing. However, the basic 10/sec firing of the spinal cord motoneurons could still be observed. Following lesion of the inferior peduncles which interrupted the olivo-cerebellar pathway, the rhythmic activation of Purkinje cells, nuclear cells, vestibular and reticular cells and motoneurons disappeared. However, the rhythmic activity was maintained at inferior olivary level. It is suggested that harmaline acts directly on the inferior olive since in animals with low decerebration, cerebellectomy and spinal transection, rhythmic activity of the inferior olive could still be observed. The results of these experiments strongly suggest that the inferior olive is able to generate the activation of motoneurons and that such influence can only take place through the activation of the cerebellar nuclei. Possible functions of the inferior olive as a generator of fast muscular transients are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236557
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  • 8
    Electronic Resource
    Electronic Resource
    Physiological responses of frog vestibular fibers to horizontal angular rotation (1971)
    Springer
    Experimental brain research 13 (1971), S. 378-407 
    Details
    ISSN: 1432-1106
    Keywords: Vestibular afferents ; Vestibular efferents ; Response to rotation ; Frog vestibular modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Single neuronal discharges in frog's vestibular nerve were recorded in unanesthetized preparations with glass microelectrodes. The nerve fibers supplying the horizontal semicircular canal are divided into two types according to the characteristics of their frequency responses to natural stimulation of the horizontal canal. The afferent fibers increase their firing rate only on ipsilateral rotation and cease to fire on contralateral acceleration. The efferent fibers usually increase their frequencies on rotation in either direction or show an increase in firing on contralateral rotation only. The thresholds of efferent fibers are generally higher as compared to afferent fibers. In addition, most of them show multisensory convergence. 2. Of the afferent fibers 65% showed frequency adaptation in response to prolonged acceleration steps whereas 35% did not show any sign of frequency decrease on prolonged stimulation. 3. Thirty out of 49 afferent units showed a non-linear relation between frequency increase and angular acceleration; in 19 units an approximately linear relationship was noted. In both types of responses the thresholds for frequency increase were in the range between 0.3–2.5°/sec2. 4. The time constants of the majority of fibers measured in the linear range were about 3 sec with a range between 1 and 10 sec. It is suggested that fibers having short time constants to acceleration and velocity step input represent acceleration-sensitive units whereas those having long time constants monitor angular velocity. Apparent ‘time constants’ were adopted for the non-linear range of non-linear units. These values decreased as the acceleration rate increased. 5. An approach to vestibular modeling, based on the present experimental results, is described in the Appendix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234338
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  • 9
    Electronic Resource
    Electronic Resource
    Cerebellar Purkinje cell responses to physiological stimulation of the vestibular system in the frog (1971)
    Springer
    Experimental brain research 13 (1971), S. 408-431 
    Details
    ISSN: 1432-1106
    Keywords: Vestibulo-cerebellar input ; Purkinje cells ; Mossy fibers ; Climbing fiber ; Responses to rotation ; Frog cerebellum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The electrical activity of single Purkinje cells was studied in the auricular lobe and in the vestibular cerebellum of Rana catesbeiana during horizontal angular acceleration. This form of physiological stimulation allowed the Purkinje cells to be categorized into four main classes, depending on the general properties of their responses. 1. Type I Purkinje cells responded to ipsilateral horizontal acceleration. Their discharge was blocked during contralateral rotation. Within this group, individual Purkinje cell responses to a protracted acceleration varied from purely phasic to purely tonic discharge. 2. Type II Purkinje cells were characterized by their activation following contralateral horizontal acceleration and by lack of response to the ipsilateral rotation. Both type I and II Purkinje cells were encountered mainly in the auricular lobe. 3. Type III, the most common form of Purkinje cell response, was activated by rotation in either ipsi- or contralateral direction. Their response, as that of type I, could vary from a purely phasic to a purely tonic discharge. The study of field potentials and unitary responses evoked by electrical stimulation of the vestibular nerve demonstrated that type III Purkinje cell response was evoked via a polysynaptic pathway different from that which activated Purkinje cells in the auricular lobe. 4. Type IV Purkinje cells were characterized by the reduction of spontaneous firing during acceleration in either ipsi- or contralateral directions. 5. A comparison of the responses evoked by type III Purkinje cells in the cerebellar cortex demonstrated that neighboring Purkinje cells may respond in different fashions to the same vestibular input. Furthermore, the tonic or phasic character of a given Purkinje cell was very similar for ipsi- and contralateral rotation, suggesting that the subtle differences between responses in neighboring Purkinje cells may be related to differences in their dynamic properties rather than differences in the types of afferents received. 6. Climbing fiber activation of Purkinje cells during horizontal rotation was clearly demonstrated in five cells. These responses are considerred to be mediated through the saccular or utricular systems rather than through the semi-circular canals. The conclusion is derived that the semi-circular canal input to the cerebellum is subserved mainly by mossy fiber input. 7. The possible functional meaning of the different types of Purkinje cell response is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234339
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  • 10
    Electronic Resource
    Electronic Resource
    Afferent neck projection to the cat cerebellar cortex (1974)
    Springer
    Experimental brain research 20 (1974), S. 385-401 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237383
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