The engram found? Role of the cerebellum in classical conditioning of nictitating membrane and eyelid responses

Abstract

Electrophysiological recording of neural unit activity during paired training trials from the ipsilateral cerebellum in rabbits well trained in short-delay classical conditioning of the nictitating membrane (NM) and eyelid responses showed CS- and UCS-evoked responses and a pattern of increased neural activity that correlates with the learned behavioral response. Large ablations of the ipsilateral cerebellum completely and permanently abolished the conditioned response in well trained animals, as did more localized stereotaxic lesions. These lesions had no effect at all on the unconditioned reflex response. In marked contrast, conditioned responses were easily trained in the eye contralateral to the cerebellar lesion. We suggest that at least a part of the “engram,” the essential neuronal plasticity that codes the learned response, may be localized to the cerebellum. © 1981, The psychonomic Society, Inc.. All rights reserved.