Torque Perceptual Ability while Lifting in Individuals with Chronic Hemiparetic Stroke

Stroke is a leading cause of long-term disability, resulting in 5.6 million individuals in the USA facing great difficulty when performing simple activities of daily living. The most common impairment in the upper limbs among stroke survivors is a flexion synergy, which is the abnormal joint coupling at the elbow, wrist, and fingers while lifting at the shoulder of their paretic arm. The negative impact caused by the flexion synergy on one's motor outcome is well-characterized in that it constrains movements and limits the active range of motion in individuals with stroke. However, the deficits caused by the flexion synergy in terms of force perception remains unclear. Almost every functional task of daily living, including drinking from a cup, requires not only the ability to coordinate movements, but also to accurately perceive forces generated. Our group's preliminary results indicate that 50% of stroke survivors may have a torque perceptual impairment in the absence of the flexion synergy. I propose that force perception needs to be assessed in the presence of the flexion synergy to determine whether potential perceptual deficits need to be rehabilitated in the stroke population. Here, I propose to evaluate torque perceptual ability in individuals with stroke in the absence and presence of the flexion synergy. I will use mechatronic tools to control and monitor the elbow flexion torque generated by each participant in the paretic arm or between arms, while lifting at the shoulder or at rest. By comparing perceptual ability with and without the flexion synergy, I will determine whether the flexion synergy contributes to a torque perceptual deficit in stroke survivors. This research project will be one of the first efforts to bridge the disconnect in knowledge between motor impairments and sensory perceptual deficits in the stroke population. By focusing on the identification of torque perceptual impairments, this study will lead to the development of novel therapeutic treatments that can improve the ability of stroke survivors to effectively control their movements by correcting their perceptual error.