Structural basis of sensory-motor control in the neocortex

Aman Maharjan1, Jason Guest1, Mythreya Seetharama1, Peter Strick2, Marcel Oberlaender1

2 University of Pittsburgh

The primary motor cortex(M1) is often mistakenly thought to be the exclusive source of voluntary motor control. Recent evidence in both non-human primates and rodents indicate that additional cortical areas can construct motor programs and execute movement independent of M1. Here, we address this question by investigating the structural basis of cortical motor control for the whisker systems in rats. We inject replication-competent rabies virus into single facial muscles that evoke whisker movements. Retrograde transport of the virus first labels motoneurons that control the injected muscle and then in a time-dependent manner spreads to the presynaptic neuronal population. We find that several cortical areas in both sensory and motor regions of the neocortex have an equal synaptic distance to the same muscle. We show that the motor-related areas are labeled in both hemispheres of the neocortex and sensory-related areas are labeled in the contralateral side of the injected muscle. We reveal a brain-wide population of pre- and postsynaptic neurons that are interconnected to the sensory-motor cortices. Our data, thereby, provide insight into organizational principles underlying whisker motor control and set the stage for a comparison of motor control across different muscle and species.