Anatomical and electrophysiological studies of the ascending inflows into the cerebellum of the cat and the monkey

Abstract

Neurological, anatomical and electrophysiological techniques have been combined in a sequence of studies designed to elucidate further the nature and characteristics of the influx ascending the neuraxis to the cerebellum. The form and course of the electrical activity initiated in the cerebellum by these various components are included in the study as is the distribution of their terminations within the cerebellum. This study includes the cerebellopetal flows from the ventral spino-cerebellar tract, the inferior olives, and the lateral reticular nuclei. Characterization of the ventral spino-cerebellar system has been completed. This pathway causes, primarily in the lobulus centralis, the very late component of the cerebellar electrical activity evoked by stimulation of the afferent nerves from the lower limbs. This response is ipsilateral and occurs at approximately 20 msec. after stimulation of the sciatic nerve. It is abolished by section of the anterolateral column of the contra1ater)al spinal cord, or of the ipsilateral superior cerebellar peduncle. Section of these pathways, while eliminating the late potential does not affect the earlier sequence known to arise from activity of the dorsal spino-cerebellar tract. Similar analyses of the influence of other ascending systems on the cerebellum are in process and will be presented in terms of the electrophysiological findings and the anatomical relations.