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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 81-94 
    ISSN: 1432-1106
    Keywords: Cerebellar inhibition ; Golgi cells ; Basket cells ; Purkinje cells ; Granule cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. There has been a comparative study of two kinds of inhibition in the cerebellar cortex: basket cell inhibition of Purkinje cells; and Golgi cell inhibition of granule cells. These inhibitory actions were assayed by the degree of inhibition of the potential waves that juxta-fastigial (J.F.) stimulation evoked in the granular or molecular layers: basket cell inhibition by the N1 wave generated by antidromic invasion of Purkinje cells; and Golgi cell inhibition of the N3 or P2 waves evoked by the mossy fibre volley in the molecular and granular layers respectively. 2. The Golgi cell inhibition produced by a parallel fibre volley (LOC stimulation) extended transversely for no more than 200 μ on either side of the narrow beam of the excited parallel fibres, whereas the spread of basket cell inhibition was much larger — to as far as 1 mm. 3. When activated by the on-beam LOC stimulation, the Golgi cell and the basket cell inhibition showed much the same threshold of the stimulation. The off-beam LOC stimulation produced only the basket cell inhibition which is in conformity with the different transverse distributions described in (2) above. 4. When evoked by J. F. or trans-folial (T. F.) stimulation, the Golgi cell inhibition had a much lower threshold than the basket cell inhibition. It is suggested that in part at least this is attributable to the direct synaptic connection from mossy fibres to Golgi cells. 5. The Golgi cell inhibition elicited by the LOC stimulation showed a relatively short time course, the maximum being attained by about 10 msec, after which there was an approximately exponential decrease so that the total duration was only about 100 msec. On the other hand, the basket cell inhibition had a much slower time course, maximum being attained at a latency of 20 to 40 msec, the total duration being even in excess of 200 msec. Suggestions are made with respect to the factors responsible for the slow time course of the basket cell inhibition.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 55 (1984), S. 60-68 
    ISSN: 1432-1106
    Keywords: Compensatory motor function ; Somatosensory cortex ; Motor cortex cooling ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The motor cortex was temporarily impaired by local cooling during repeated execution of visually initiated hand movements in monkeys. The effects of cooling were examined by recording premovement cortical field potentials in the forelimb motor and somatosensory cortices and by measuring reaction time and force exerted by the movement. The cortex was cooled by perfusing cold water (about 1° C) through a metal chamber placed on the cortical epidural surface. Cooling of the forelimb motor area lowered temperature of the cortex under the chamber to 20–29° C within 4–5 min. Recording electrodes for cortical field potentials were implanted chronically on the surface and at 2.5–3.0 mm depth of various cortical areas including that being cooled. Spread of cooling to surrounding cortical areas was prevented by placing chambers perfused with warm water (38–39° C) on the areas. Cooling of the forelimb motor area greatly reduced its premovement cortical field potentials, followed by prolonged reaction times of weakened contralateral wrist muscles. Simultaneous recording from the primary somatosensory cortex revealed an enhancement of its premovement field potentials. All changes were completely reversible by rewarming of the motor cortex. Concomitant cooling of the motor and somatosensory cortices entirely paralysed the contralateral wrist muscles. These results suggest that the motor function of the somatosensory cortex becomes predominant and compensates for dysfunction of the motor cortex when it is temporarily impaired.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1106
    Keywords: Compensatory motor function ; Somatosensory cortex ; Cerebellar hemispherectomy ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrical activities of the motor and somatosensory cortices preceding visually-initiated hand movements were recorded with electrodes chronically implanted on the surface and at 2.5–3.0 mm depth in the cortex of monkeys, and changes in field potentials in these cortices after cerebellar hemispherectomy were observed for many weeks. As previously reported, a unilateral cerebellar hemispherectomy including the lateral and interpositus nuclei eliminates the cerebellar-mediated superficial thalamo-cortical (T-C) responses recorded in the forelimb motor cortex contralateral to the hemispherectomy. These T-C responses normally precede the hand movement, and the operation results in the delay of movement initiation. The electrodes in the forelimb area of the contralateral primary somatosensory cortex showed an enhancement of superficial T-C responses of the somatosensory cortex for 30–40 days after the operation. The enhanced potentials preceded the delayed movement as do the cerebellar-mediated superficial T-C responses of the motor cortex in normal situations. Local cooling of the somatosensory cortex following the cerebellar hemispherectomy disturbed the reaction time movement for a few weeks after the operation. This effect was rarely encountered in normal monkeys. The present study suggests the compensatory motor function of the somatosensory cortex for the dysfunction of the motor cortex in early weeks after cerebellar hemispherectomy.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 3 (1967), S. 58-80 
    ISSN: 1432-1106
    Keywords: Mossy fibres ; Cerebellar cortex ; Golgi cells ; Granule cells ; Purkinje cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Potential fields and unitary spikes in the cat cerebellar cortex were generated specifically by mossy fibre volleys and recorded by means of microelectrodes. The mossy fibres were excited by trans-folial (T. F.) stimulation which was compared with juxtafastigial (J.F.) stimulation. Both were conditioned by local stimuli of parallel fibres. 2. In the granular layer, an incoming mossy fibre volley evoked a small diphasic potential (P1 N1) and about 0.4 msec later a second negative wave (N2) due to the excitatory synaptic current generated by synapses of mossy fibres with granule cells and Golgi cells. In the typical configuration the N2 wave usually had a superimposed double spike potential, which is due to impulses discharged first by Golgi cells and then, about 0.5 msec later, by granule cells. 3. The transmission of impulses along the perpendicular axons of the granule cells and thence along the parallel fibres gave the fairly sharp positive potential (P2) in the granular layer, and simultaneously the negative wave (N3) in the molecular layer. The parallel fibre impulses, in turn, synaptically excited and so evoked local responses and action potentials in the dendrites of Purkinje and other cells, which aided in the production of the latter part of the N3 wave. 4. The impulses in the Purkinje cell dendrites propagate into the granular layer via the Purkinje cell somata and axons so producing the negative wave (N4) in the Purkinje and the granular layer. 5. The late and prolonged positive wave (P3) may be attributable to the deep active sources produced by postsynaptic inhibition of Purkinje cells and of granule cells by basket and Golgi cells respectively. 6. There has been good correlation between the physiological findings and the anatomical structures of the various types of cells and the synaptic connections, even to the synapses of mossy fibres on Golgi cell dendrites that have been recently described by HÁmori and SzentÁgothai.
    Type of Medium: Electronic Resource
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