Multiple-unit activity from rabbit cerebellar cortex and interpositus nucleus during classical discrimination/reversal eyelid conditioning.

Multiple-unit activity was monitored in the hemispheric lobule VI (HVI) and the interpositus nucleus of the cerebellum during classical discrimination and reversal eyelid conditioning in rabbits. During both phases of conditioning similar patterns of activity were observed in lobule HVI: conditioned response (CR)-related activity was present on conditioned stimulus (CS)+trials but not on CS-trials. Activity in the interpositus nucleus differed during the two phases of conditioning. After discrimination training, CR-related activity was present on CS+but not CS-trials. After reversal training, however, only a weak activation of the interpositus nucleus was seen on CS+trials with no activation present on CS-trials. These data suggest that lobule HVI and the interpositus nucleus may play different roles in classical eyelid conditioning.