Learning-specific differences in Purkinje-cell dendrites of lobule HVI (Lobulus simplex): intracellular recording in a rabbit cerebellar slice.

The cerebellum has been directly implicated in the associative learning exemplified by classical conditioning of the rabbit nictitating membrane response. Lesions of cerebellar lobule HVI (Lobulus simplex) can disrupt or even abolish classical conditioning. Electrical stimulation of inputs that converge at cerebellar lobule HVI and the deep cerebellar nuclei has been shown to support classical conditioning of the responses elicited by such stimulation. Here we report that intracellular recording in a slice of rabbit cerebellar lobule HVI revealed a conditioning-specific increase in the excitability of Purkinje-cell dendrites without significant changes in dendritic membrane potential or input resistance. The finding of a conditioning-specific change in lobule HVI lends support to the theory that associative learning involves local dendritic modification and provides further evidence for the involvement of the cerebellar cortex in classical conditioning of the rabbit's nictitating membrane response.