Post-training cerebellar cortical activity plays an important role for consolidation of memory of cerebellum-dependent motor learning

► We examined how the cerebellar cortex acts to consolidate motor memory in mice. ► Adaptation of reflex eye movement was induced by 1 h of training daily for 4 days. ► Daily post-training inactivation of cerebellar cortex abolished adaptation. ► The post-training cortical activity is important for consolidation of motor memory. Adaptation of mouse horizontal optokinetic response (HOKR) eye movement provides an experimental model for cerebellum-dependent motor learning. Our previous study revealed that the memory trace of HOKR adaptation is initially encoded in the cerebellar flocculus after hours of optokinetic training, and transferred to the vestibular nuclei to be consolidated to long-term motor memory after days of training [28]. To reveal how the cerebellar cortex operates in the transfer of the memory trace of adaptation, we examined the effects of shutdown of the cerebellar cortex after daily training. Three groups of mice received 1 h of optokinetic training daily for 4 days, and showed similar amounts of adaptation after the end of 1 h of training throughout 4 days. However, in the mice which daily received bilateral floccular muscimol infusion under gas anesthesia in the post-training period, consolidation of memory of the adaptation was markedly impaired, compared with the control mice which daily received bilateral floccular Ringer's solution infusions under gas anesthesia or those which daily received only gas anesthesia. These results are consistent with the studies of the effects of inactivation of cerebellar cortex on the consolidation of motor memory of rabbit eyeblink conditioning [2,4,18], and suggest that the post-training cerebellar cortex activity play an important for the consolidation of motor memory of HOKR adaptation.