Cortico-Cortical Feedback in Mouse S1 Regulates Motor Coordination Via Inhibitory Interneurons

Abstract

The primary somatosensory cortex (S1) is important for the control of movement as it encodes sensory input from the body periphery and external environment during ongoing movements. Mouse S1 consists of several distinct sensorimotor subnetworks that receive topographically organized cortico-cortical inputs from distant sensorimotor areas, including the secondary somatosensory cortex (S2) and primary motor cortex (M1). The role of the vibrissal S1 area and associated cortical connections during active sensing is well documented, but whether (and if so, how) non-whisker S1 areas are involved in movement control remains relatively unexplored. Here, we demonstrate that unilateral silencing of the non-whisker S1 area disrupts the balance of hindlimb movements during locomotion. S2 and M1 provide major feedback input to this S1 area, and they both synapse onto parvalbumin-expressing inhibitory interneurons in M1. Ablating parvalbumin interneurons in S1 or specifically silencing S2 feedback projections impairs motor coordination. We conclude that the S2–S1 cortical interaction mediated by parvalbumin interneurons is critical for the control of movement.