Date of Award
Master of Science (MS)
Kinesthesia refers to sensations of limb position and movement, and deficits of upper limb kinesthetic feedback are common after stroke, impairing stroke survivors’ ability to perform the fundamental reaching and stabilization behaviors needed for daily functions like self-feeding. I attempt to mitigate the negative impact of post-stroke kinesthesia deficits by evaluating the utility of vibrotactile sensory substitution to restore closed-loop kinesthetic feedback of the upper limb. As a first step, this study evaluated performance in healthy individuals during fundamental reaching, stabilization, and tracking behaviors while using supplemental vibrotactile feedback encoding either limb state information or goal-aware error information. First, I determined that performance in reaching and stabilization tasks varies systematically with the amount of limb position and velocity information encoded in limb state feedback and that there is an optimal combination. Next, I compared the utility of optimal limb state to goal-aware error feedback. Both types of feedback reduced error in the reaching and stabilization tasks. Random task-irrelevant sham feedback did not reduce error, demonstrating participants could perceive and understand the information contained within the vibrotactile feedback. Error feedback improved performance more than state feedback; however the relative difficulty of using error feedback outside of a laboratory setting means state feedback should not be discounted. The performance while tracking could not be quantified due to issues with the task design. As a second step, I performed a series of case studies in five chronic stroke survivors. The stroke survivors all tolerated the vibrotactile feedback well and were able to perceive and understand at least one of the limb state or error feedback encodings. Stroke survivors practiced each information encoding type for one session. During this short period our stroke survivors struggled to integrate visual and vibrotactile inputs and motor control in order to use the vibrotactile information to control the arm. However, two additional practice sessions with error feedback for one participant led to a two thirds reduction in reaching error. These results suggest stroke survivors can learn to use supplemental vibrotactile feedback to enhance control of the contralesional arm.