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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of electrical potentials evoked in the cerebellar anterior lobe by stimulation of hindlimb and forelimb nerves (1968)
    Springer
    Experimental brain research 6 (1968), S. 171-194 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Evoked responses ; Mossy fibers ; Climbing fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses were evoked in the anterior lobe of the cerebellum by volleys in group I and II fibers of forelimb and hindlimb nerves — cutaneous, muscular, joint and fascial. These responses have been observed along microelectrode tracks that traverse the whole depth of the anterior lobe. These tracks have been identified in histological sections, and the recording sites along these tracks have been determined. It has been shown that there are many distinguishing features for the responses produced by the two types of afferent input to the cerebellum: climbing fibers and mossy fibers. The depth profiles are of particular importance in the differentiation of the CF and MF responses, and they correspond to those already determined for the exposed surface areas of the cerebellar cortex. As would be expected from the distribution of synapses by the CF fibers to the Purkinje cell dendrites, there is a maximum extracellular negativity deep in the molecular layer with sources superficial and deep thereto. In contrast, the mossy fiber input produces a powerful synaptic excitation in the granular layer, which is recorded there as a negative wave (N2). The mossy fiber input by sequential relay also produces a negative wave (N3) in the molecular layer. This wave is distinguished from the CF-evoked negative wave because it is not reversed in the fissura and the adjacent superficial molecular layer. An important distinguishing feature of the MF- and CF-evoked responses is that the latencies of the former are shorter by 6–12 msec for forelimb nerves and by 9–15 msec for hindlimb nerves. It is thus possible to measure the sizes of the MF and CF responses in the same traces. Another distinguishing feature is the failure of the CF responses with stimulus frequencies of 5–15/sec, whereas the MF-evoked potentials are well maintained above 15/sec. Also CF-evoked responses show much more size and latency variance than the MF-evoked responses, and often the facilitation of two or three volleys is required in order to evoke a stable CF response. By utilizing these various tests it is always possible to distinguish between the CF- and the MF-evoked responses recorded along the microelectrode tracks in the anterior lobe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235123
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  • 2
    Electronic Resource
    Electronic Resource
    The pathways responsible for excitation and inhibition of fastigial neurones (1974)
    Springer
    Experimental brain research 19 (1974), S. 78-99 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233396
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  • 3
    Electronic Resource
    Electronic Resource
    Topographical investigations on the climbing fiber inputs from forelimb and hindlimb afferents to the cerebellar anterior lobe (1968)
    Springer
    Experimental brain research 6 (1968), S. 195-215 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellum ; Climbing fiber input ; Somatotopy of climbing fiber input
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Volleys in group I and II fibers of muscle nerves and group II fibers of cutaneous, joint and fascial nerves have evoked CF responses in the anterior lobe of the cerebellum. In the pars intermedia there is a fairly sharp somatotopic localization of the forelimb CF responses to the Vth lobule (Larsell) and the hindlimb to the IVth and IIIrd lobules. In the vermis there is much more admixture, with the hindlimb-evoked responses tending to dominate in the lateral vermis of the Vth lobule, and the forelimb more medially. In the IVth and IIIrd lobules forelimb responses were rare and were never large. In the medial vermis up to 1–1.7 mm from the midline there were no CF-evoked responses from the limb nerves. These distributions of CF-evoked responses are remarkably different from those reported by Oscarsson, and consideration is given to the factors responsible for this discrepancy. A more detailed examination was made of the CF-evoked responses from a large variety of hindlimb and forelimb nerves. Observations were made along many tracks usually arranged in a transverse plane, and it was found that between different recording sites along the same track or along adjacent tracks, there was a great deal of variation in the relative magnitudes of the CF-evoked responses from the different nerves. These distributions have an ill-defined patchy character so that at any focus there is opportunity for the most diverse kinds of piecemeal integration. These findings on the CF-input are considered in relationship to the mossy fiber input. It is pointed out that the pathways conveying CF-input to the cerebellum have a level of discriminative input adequate for the operation of fine control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235124
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  • 4
    Electronic Resource
    Electronic Resource
    Somatoiopic studies on cerebellar fastigial cells (1974)
    Springer
    Experimental brain research 19 (1974), S. 100-118 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellar nuclei ; Fastigial neurones ; Somatotopy ; Cerebellar function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The somatotopic inputs into fastigial cells have been studied in relation to cutaneous mechanoreceptors of forelimb and hindlimb. Some fastigial cells were very discriminative, not only in respect of the limb, but also to restricted areas of hairy skin and related toe pads. Others were much less so, forelimb and hindlimb cutaneous receptors evoking similar excitatory-inhibitory responses. In addition, from the contralateral hindlimb, responses were evoked which were comparable with those from the ipsilateral limb. Somatotopic diagrams have been constructed which show in four experiments the sites of fastigial cells in the parasagittal plane of the microelectrode tracks. For each experiment four separate plottings give a comparison of the sizes of responses evoked for forelimb and hindlimb: excitation from nerve volleys; inhibition from nerve volleys; excitation from pad taps; inhibition from pad taps. In this way it is shown that fastigial cells with similar somatotopic relations often occur in clusters, particularly when assessed by their inhibitory responses. Since fastigial inhibition is largely due to Purkyně cells, there is an attempt to correlate the somatotopic relations of Purkyně cells with the somatotopy of fastigial cell inhibition. The excitation of fastigial cells exhibits less somatotopic discrimination, which conforms with the poor somatotopic discrimination of cells of the lateral reticular nucleus. In a final discussion there is consideration of two principal projections from the vermis of the anterior lobe: Purkyně cells inhibiting Deiters neur; Purkyně cells inhibiting fastigial cells which in turn monosynaptically excite Deiters neurones, the inhibition of Deiters neurones being then by disfacilitation. The degree of forelimb-hindlimb convergence in these pathways is reconsidered and is diagrammatically illustrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233397
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  • 5
    Electronic Resource
    Electronic Resource
    Presynaptic inhibition of the monosynaptic reflex following the stimulation of nerves to extensor muscles of the ankle (1967)
    Springer
    Experimental brain research 4 (1967), S. 34-42 
    Details
    ISSN: 1432-1106
    Keywords: Monosynaptic reflex ; Presynaptic inhibition ; Extensor nerve ; Spinal cord ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Electrical stimulation of extensor nerves of the ankle has been used to investigate the presynaptic inhibition in a synergic monosynaptic reflex arc. 2. Depression of monosynaptic reflex response as well as increase in excitability of Ia afferent terminals in the MG (medial gastrocnemius) reflex arc is found following the conditioning stimulation of LGS (lateral gastrocnemius-soleus) nerve at Group I strength. 3. Excitability increase of the Ia terminals of the LGS nerve is also found following the conditioning stimulation of either a group of fibres of the same nerve or the MG nerve. 4. Conditioning by Group I afferent volleys from either the LGS or the PBST (posterior biceps-semitendinosus) muscles produces comparable changes in excitability of the Ia terminals from MG muscle. 5. The hypothesis is advanced that the depression of the monosynaptic reflex discharge during repetitive stimulation is mainly caused by the depolarization of the Ia afferent terminals, i.e. by presynaptic inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235215
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  • 6
    Electronic Resource
    Electronic Resource
    Cutaneous mechanoreceptors influencing impulse discharges in cerebellar cortex. I. In mossy fibers (1972)
    Springer
    Experimental brain research 15 (1972), S. 245-260 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235910
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  • 7
    Electronic Resource
    Electronic Resource
    Cutaneous mechanoreceptors influencing impulse discharges in cerebellar cortex. II. In Purkyně cells by mossy fiber input (1972)
    Springer
    Experimental brain research 15 (1972), S. 261-277 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235911
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  • 8
    Electronic Resource
    Electronic Resource
    Cutaneous mechanoreceptors influencing impulse discharges in cerebellar cortex. III. In Purkyně cells by climbing fiber input (1972)
    Springer
    Experimental brain research 15 (1972), S. 484-497 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236404
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  • 9
    Electronic Resource
    Electronic Resource
    Integration by Purkyně cells of mossy and climbing fiber inputs from cutaneous mechanoreceptors (1972)
    Springer
    Experimental brain research 15 (1972), S. 498-520 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236405
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  • 10
    Electronic Resource
    Electronic Resource
    Excitatory and inhibitory responses of neurones of the cerebellar fastigial nucleus (1974)
    Springer
    Experimental brain research 19 (1974), S. 61-77 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233395
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