Grant: Travel Awards - Institute Community Support

Making precise reaching movements with the arm is commonly affected as we get older and after stroke. Our research is based on the idea that problems in making reaching movements are related to changes how we use visual and other sensory information. The goal of this study was to identify the role of vision and touch on the accuracy of pointing in older people and in people with stroke. For the purpose of this project, older participants and participants with stroke performed two sequences of 10 movements each with each arm. The movement was performed by alternatively touching the tip of the nose (ReachIn direction) and a target (ReachOut direction) placed at 90% arm-length, as fast as possible. The task was performed under four different conditions: a) eyes open touching the target, b) eyes closed, touching the target, c) eyes open, not touching the target, and d) eyes closed, not touching the target. We used a motion capture system (Optotrak system) to reconstruct and measure the movements of the arms and trunk. With both vision and touch, subjects with stroke made more curved and less precise reaching movements compared to controls. Movement precision was lower with eyes closed compared to eyes open and without touch compared to with touch in both groups. Subjects with stroke had larger errors (lower precision) than controls without vision and without touch. Movement accuracy was worse when movements were performed towards the target (ReachOut direction) compared to when they were performed towards the nose (ReachIn direction) in both groups in all 4 conditions. Absence of vision and tactile feedback diminished task performance more in stroke compared to control individuals. The results of this study will inform practitioners about the extent to which the disruption of the task is related to the integrity of vision and touch.