Temporal dynamics between the whisker sensorimotor cortex and the olivocerebellar module in awake mice.

Introduction: The precise timing of the long-range bidirectional connections between the cerebral cortex and the cerebellum remains a critical factor in elucidating their respective and integrated functions. The key role of the cerebellum in both motor and non-motor domains is exerted through numerous cerebro-cerebellar closed loops that sustain different forms of motor coordination, in which the response timing of the various types of cerebellar neurons may constitute a significant component of neural computation. Methods: In this study, we investigated the cerebral sensorimotor cortex and the corresponding cerebellar region (Crus I) of the murine whisker system during electrical stimulation of the whisker pad. In addition, the firing of Golgi cells, Purkinje cells (PC), deep cerebellar nuclei (DCN) neurons, and inferior olive (IO) neurons was analyzed during electrical stimulation of the whisker pad (Wh), the somatosensory (wS1) and motor (wM1) cortices. Results: We demonstrated that, although peripheral Wh stimulation evoked cortical, cerebellar and IO responses at the same early latency (~3 ms), the transmission within the olivocerebellar circuit was slower when the signal was elicited by wS1 stimulation than by peripheral input, and even slower when wM1 was stimulated. Discussion: We discussed the different possibilities regarding the transmission of the efference copy and the forward dynamic model within these circuits, and we speculated that the relative slowing of wM1 input into the olivo-cerebellar circuit reflects the increased computational demand associated with the elaboration of the final motor command.