Behaviorally selective engagement of short-latency effector pathways by motor cortex

February 9, 2017 -
11:30am to 12:30pm
Andrew Miri, hosted by Rich Mooney

Blocking motor cortical output with lesions or pharmacological inactivation has identified movements that require motor cortex. Yet when and how motor cortex influences muscle activity during movement execution remains unresolved. We addressed this ambiguity using measurement and perturbation of motor cortical activity together with electromyography in mice during two forelimb movements that differ in their requirement for cortical involvement. Rapid optogenetic silencing and electrical stimulation indicated that short-latency pathways linking motor cortex with spinal motor neurons are selectively activated during one behavior. Analysis of motor cortical activity revealed a dramatic change between behaviors in the coordination of firing patterns across neurons that could account for this differential influence. Thus, our results suggest that changes in motor cortical output patterns enable a behaviorally-selective engagement of short-latency effector pathways. The model of motor cortical influence implied by our findings helps to reconcile many previous observations on the function of motor cortex.