Differential effects of skilled reaching training on the temporal and spatial organization of somatosensory input to cortical and striatal motor circuits

Abstract

It has been hypothesized that to perform sensorimotor transformations efficiently, somatosensory information being fed back to a particular motor circuit is organized in accordance with the mechanical loading patterns of the skin that result from the motor activity generated by that circuit. Rearrangements of sensory information to different motor circuits could in this respect constitute a key component of sensorimotor learning. We here explored whether the organization of tactile input from the plantar forepaw of the rat to cortical and striatal circuits is affected by a period of extensive sensorimotor training in a skilled reaching and grasping task. Our data show that the representation of tactile stimuli in terms of both temporal and spatial response patterns changes as a consequence of the training and that spatial changes particularly involve the primary motor cortex. Based on the observed reorganization, we propose that reshaping of the spatiotemporal representation of the tactile afference to motor circuits is an integral component of the learning process that underlies skill acquisition in reaching and grasping.NEW & NOTEWORTHY Sensorimotor transformations are fundamental to the function of the nervous system and determine how patterns of sensory input are converted into appropriate movements. We here investigated the extent to which experience-dependent processes can reshape the organization of somatosensory input feeding into cortico-basal ganglia motor structures. Our data point to a particularly important role for the primary motor cortex in the functional adaptions associated with skilled motor learning.