Abstract

We recorded multiple-unit activities (MU As) in the cerebellar interpositus nucleus(INT) and the dorsal accessory inferior olive(DAO) simultaneously to investigate dynamic functional cooperation of cerebellum and brain stem structures. MU As were monitored during delay conditioning(ISI=300msec) following trace conditioning(ISI=700msec). Behavioral and neuronal data were divided into four categories based on the stimuli presented and the response performed in each trials :CS(Conditioned Stimulus)-only trials, US(unconditioned stimulus)-only trials, CR(conditioned response)-paired trials, and noCR-paired trials. We made the smoothing curve by Savitzky-Golay method and the fitting curve by multiple Gaussian functions from 4 msec time bin histogram of neuronal activities to compare and analyze time correlation. In both sites, conditioning-related activities were developed in CR-trials but not in noCR-trials. These activities are preceding behavioral CR with different time lead. Rather than an increase, CS period-activities of INT in noCR trials are reduced after CR acquisition. INT may participate directly in motor command for CR. DAO showed large US-evoked activity, which remained unchanged during training. The presence of CR-related DAO activity suggests that DAO may receive CR-related feedback information from cerebellum and provide CR-related information to cerebellum. Conditioning-related neuronal activities established m DAO were lasting continuously. These activities suggest that lower level of brain structures involve actively in producing CR.