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 for the cup 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. It had been thought that cerebral cortex used sensory information for planning voluntary motor actions, but that sensory feedback for generating motor corrections was largely processed at only the spinal level. However, recent studies now suggest that cerebral cortex may play a more prominent role in processing sensory feedback from the limb during voluntary movements. This project will directly test this idea by transiently reducing neural activity (by cooling the cortical surface) in one of two key cortical regions in non-human primates 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. A 2nd project will explore whether these cortical areas also influence feedback corrections with the ipsilateral arm. 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.