CEREBELLAR ACTION POTENTIALS IN RESPONSE TO STIMULATION OF THE CEREBRAL CORTEX IN MONKEYS AND CATS

Abstract

Single shock electrical stimulation of the sigmoid, coronal, anterior ectosylvian and anterior parts of the lateral, suprasylvian or middle ectosylvian gyri of the cat''s cerebral cortex resulted in cerebellar action potentials in the lobulus ansiformis, culmen, lobulus simplex, folium and tuber vermis, pyramis, lobulus paramedianus and para-flocculus. Potentials in corresponding cerebellar lobulus plus the uvula were also present in Macaca mulatto following stimulation of areas 4, 6 or the postcentral gyrus. In addition, stimulation of areas 7, 8, 9, 10, 21, 22, 18 or 19 caused action potentials in the lateral and posterior cerebellar lobules, particularly the lobulus ansiformis. All responses were most marked on the contralateral side but homolateral responses were also seen. No predominance of projection from any topographical or cytoarchitectonic subdivision of the cat''s cerebral cortex to any specific cerebellar lobule could be detected. In the monkey, in addition to differences in projection from cytoarchitectonic areas, as above, there was a slight tendency for the face areas to be richer in connections to the rostral cerebellar lobules and the leg areas richer to the caudal lobules. This tendency was shown by the relative differences in the threshold and an amplitude of the responses in the several lobules when the points in the face, arm and leg areas of the sorcalled "sensory" cortex were stimulated. No significant differences between the connections of Crus I and Crus II of the lobulus ansiformis could be detected by this method.