Upper-Extremity Torque Perceptual Impairments in Chronic Hemiparetic Stroke

There are 5.6 million current US stroke survivors who face great difficulty performing activities of daily living (ADLs), probably in part because they are unable to accurately judge the relative torques they generate with their two arms. The impact of this deficit on ADLs is unknown, but my preliminary results suggest that the impact is substantial, particularly during bimanual tasks. We know that after a hemiparetic stroke an individual’s paretic arm lacks the strength and control of their non-paretic arm. Therefore, these stroke survivors must relearn to use their arms to interact with the world. For unimanual tasks, they normally relearn how to use each arm independently. For bimanual tasks, individuals with stroke nearly always use their paretic arm to assist their non-paretic arm rather than the reverse. Therefore, my central hypothesis is that torque perception is: i) intact within each arm during unimanual tasks and ii) impaired only in the unusual condition when the non-paretic arm must assist the paretic arm to execute bimanual tasks. Consequently, I propose that the torque perceptual impairment, when the non-paretic arm assists the paretic arm, will hinder a stroke survivor’s ability to safely deal with unfamiliar and potentially dangerous bimanual tasks. For example, stroke survivors will be vulnerable when slicing a tomato or cutting an apple since they will be unable to react appropriately if the knife unexpectedly slips. In this K25 award, I propose to examine the validity of my central hypothesis that torque perceptual impairments only arise when the non-paretic arm assists the paretic arm to execute bimanual tasks. More specifically, I will investigate the cause of the torque perceptual impairment, as well as its magnitude, and will test a novel training paradigm that may mitigate its effect. This research and training plan benefits from its ability to bring together engineers, neuroscientists, and clinicians to quantify changes in torque pe