Differential kinematic coding in sensorimotor striatum across behavioral domains reflects different contributions to movement.

The sensorimotor arm of the basal ganglia is a major part of the mammalian motor control network, yet whether it supports all movements or is specialized for task-oriented behaviors remains unclear. To examine this, we probed the contributions of the rat sensorimotor striatum (dorsolateral striatum (DLS)) in two behavioral domains: free exploration, in which naturalistic behaviors are expressed, and during a motor task. In contrast to prior work, which showed the DLS being essential for generating task-specific learned movements, DLS lesions had no effect on naturalistic behaviors like rearing, grooming or walking. To explore the neural basis of this functional dissociation, we compared DLS activity across the two domains. Although neural activity reflected movement kinematics in both, the kinematic codes differed starkly. These findings suggest that sensorimotor basal ganglia are not essential parts of mammalian motor control but, rather, shift their output into a motor-potent space to shape task-specific behaviors.