Abstract
The problem of functional localization in the cerebellum is one which has received considerable attention. Recent comparative anatomical studies 1 and ablation experiments 2 have supported a division of the cerebellum based on afferent fiber connections. Recently Dow 3 has recorded action potentials in the cerebellum as a result of stimulating various afferent fiber tracts, and his results are in accord with Larsell's anatomical findings. The present work is an attempt to explore by the oscillographic method the projections of the cerebral cortex to the cerebellar cortex.
Methods and Results. Twelve cats, under barbiturate anesthesia, were used in this work. The method of stimulating and recording is described elsewhere. 4 Single electrical shocks were applied to the cerebral cortex by means of bipolar electrodes about 1 mm apart resting lightly on the pia. Monopolar recording was employed, the active electrode being a chlorided silver wire in light contact with the pia of the cerebellar cortex. Fig. 1 is a record of a cerebellar action potential obtained in this way. Following the shock artefact there is a surface positive wave having a latency of about 25 msec to the crest of the wave, and a second positive wave having a latency as long as 200 msec. The second wave by no means always accompanies the first, but the factors causing this wave have not been determined.
Stimulation of one cerebral cortical point may produce simultaneous potentials in as many as 14 distinct points on the cerebellar cortex. Considering the extensive foliation of this structure, it must be true that only a small fraction of the total surface was explored; the total number of points which yield potentials must be far greater than this. The most easily detected potentials are on the contralateral side, and in general for each of these potentials there is a smaller potential on the ipsilateral side at a point roughly symmetrical to it.
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