Use of sensory feedback for voluntary control

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It is easy to be impressed when a hockey player speeds down the ice and scores a goal. Even if they are***jostled by the defensemen, great athletes quickly adjust or even change where they shoot the puck to his or her advantage. Engineering control theory provides important insight on how our motor system can convert sensory information into rapid motor corrections to perform these impressive feats of skill. Inspired by control theory, the focus of this research program is to examine how visual and proprioceptive (muscle sensory signals) support our ability to make these rapid motor corrections. Our previous work demonstrated how online control using proprioceptive feedback can be adjusted to consider factors such as target shape or the presence of obstacles in the environment. Our first project explores whether and how quickly visual feedback also considers these task-related factors. Our preliminary data on human subjects highlights it can but requires at least 130ms, 60ms longer than for proprioceptive feedback. Our second project explores the impact of this delay in processing visual as compared to proprioceptive feedback. As sensory signals can have noise and also have delays in transmitting information to the brain, a key problem is to understand how the motor system combines sensory signals for online control. Should you use the more accurate (vision) or the fastest (proprioceptive)? Here we examine this multi-sensory integration problem by manipulating visual and proprioceptive feedback during reaching. Our preliminary data highlight that proprioceptive feedback initially dominates over visual feedback during movement, matching mathematical models that consider variability and delays. Finally, our third project will explore how dynamic goals (targets moving in the environment) influence our rapid motor corrections. The present research program will provide important fundamental properties about our voluntary motor system and it supports our ability to move and interact in the world. The research projects will provide important training opportunities for several trainees, including the use of advanced technologies to study motor function. The proposal will also impact our future studies exploring how neurological injuries, such as stroke, impact one's ability to use proprioceptive and visual information to guide motor actions.