Grant: Project Grant

We take for granted our ability to perform simple daily activities such as reaching for a cup of coffee. Impressively, if we are accidentally bumped while reaching we automatically make swift and agile corrections to reach and grasp the cup. These motor corrections require the brain to quickly process sensory information about the body and the world around us, and convert this information into patterns of muscle activity to attain the goal. While cerebral cortex has been known to be involved in planning voluntary motor actions, recent studies suggest cerebral cortex may play a more prominent role in processing sensory feedback from the limb during voluntary movements. In Project 1, we will directly test this idea by transiently reducing neural activity (by cooling the cortical surface) in one of two key cortical regions in monkeys and quantifying how motor corrections to unexpected disturbances of the contralateral arm are altered during voluntary motor actions. Our preliminary data demonstrate that inhibiting neural activity in one of two brain regions, dorsal premotor cortex (PMd) or parietal area 5 (A5), alters the ability of the animal to generate motor corrections, demonstrating their causal role in feedback control of the arm. We develop mathematical models that highlight the patterns of errors associated with each cortical region are similar to that expected if PMd is involved in generating motor commands, and A5 is involved in sensory processing for online control. In Project 2, we will explore whether these cortical areas also influence feedback corrections with the ipsilateral arm by observing how cooling of PMd and A5 bilaterally or unilaterally impact motor corrections to unexpected limb disturbances. This work provides important new knowledge on the role of cerebral cortex in voluntary control that will guide our ongoing clinical studies quantifying motor impairments associated with various brain injuries and diseases.