Topical projection of the olivocerebellar system in the cat: an electrophysiological study.

Abstract

AbstractUsing electrophysiological recording, topical aspects of the olivocerebellar projection were studied in the locally anesthetized cat immobilized with Flaxedil. Transcortical evoked potentials were recorded simultaneously from eight electrodes distributed over the cerebellar surface, and averaged with a LINC computer. Precautions were taken to eliminate virtual potentials from this volume conductor situation. The evoked potentials consisted of a 4–6 msec positive spike, latency 4.5–7 msec, followed by a 15–30 msec slow negative deflection. Each was recorded from one or two folia contralateral in distribution. Medial and dorsal accessory nuclei project largely to cerebellar vermis. A rostrocaudal relationship was found between posterior vermis and medial accessory nucleus, and vermal anterior lobe received its projection from the caudal and midportions of medial and dorsal accessory components. A dense representation of accessory nucleus responses was present over the declive as compared with other cerebellar areas. Paravermal responses of anterior lobe derived from rostral dorsal accessory olive, and principal olive connected to the hemispheral region. The ventral lamella of principal olive projected to Crus II, dorsal lamella to Crus I. These lobules are represented rostrally in the principal nucleus, whereas the source for paramedial lobules was situated more caudally. The results correlate well with the retrograde degeneration studies of Brodal ('40, '54) but differ in the detail of some projections.