Topographical localization in the olivo‐cerebellar projection: An electrophysiological study in the cat

Abstract

Micro‐electrodes have been used to record the antidromic responses generated in olivary neurones by electrical stimulation of their axon terminations in the cerebellar cortex. This electrophysiological technique, in combination with precise histological methods for locating postions of the micro‐electrode tip, has been used to reinvestigate the topography of much of the olivo‐cerebellar projection. The results are partly in accord and partly in conflict with those of earlier investigations in which purely anatomical techniques were employed. In general, the terminations of a circumscribed group of olivary neurones have been found to be located within a longitudinal strip of the cerebellar cortex. Such strips frequently ignore the anatomical landmarks which divide the cerebellar cortex into lobules. The axons of a number of individual olivary neurones have been found to branch to provide a termination in both the anterior and the posterior lobe of the cerebellum. It was also found that olivary neurones projecting to a particular area of cerebellar cortex were in some cases situated in neighbouring regions of more than one of the main anatomical subdivisions of the olive (principal olive and medial and dorsal accessory olives). The discrepancies between the present findings and those made earlier are discussed.