Sensorimotor Integration in the Spinal Cord, from Behaviors to Circuits: New Tools to Close the Loop?

Sensorimotor behaviors are by definition “closed-loop” processes in which sensory feedback modulates behavioral output. Sensory feedback can be provided by visual, auditory, and vestibular inputs or direct proprioceptive inputs from muscle contraction. Although sensory feedback is not necessary for oscillation underlying locomotion to occur, there is evidence in the cat that sensory feedback can initiate locomotion [128] or reset the rhythm [183]. The contribution of sensory feedback to active locomotion is however difficult to estimate for technical reasons. Indeed, most physiological studies of genetically identified cells in spinal circuits involved in sensorimotor integration rely on preparations where mechano-muscles are paralyzed or dissected out, and are therefore deprived of sensory feedback.