The effect of stroke-induced somatosensory and motor deficits on body representation
E. Weltings · Utrecht University Repository (Utrecht University) · 2019
A continually updated representation of our body is essential for efficient interaction with the external world. This study aims to investigate the effects of somatosensory and motor deficits on body representation. It consists of two parts, one focused on stroke patients and a second studying the role of hand orientation on the rubber hand illusion. For the first part, based on the literature, it is hypothesized that on a body mapping task, healthy controls show a distorted representation of their hand with shorter fingers and broader hands. Post-stroke patients, however, are expected to perceive the affected hand as larger than healthy controls due to the absence of somatosensory feedback signals. Second, it is hypothesized that post-stroke patients show a larger ownership over the rubber hand as measured by a larger proprioceptive drift towards the rubber hand compared to healthy controls. With respect to the study on the rubber hand illusion with healthy participants, it is hypothesized that for the 0° position condition, healthy controls show ownership over the rubber hand measured in a decrease in skin temperature in the experimental left hand. The present study consisted of a total sample size 61 participants (31 age-matched healthy controls, 10 patients, 20 students). Subjects participated in several tasks measuring body representation and body ownership. Results show that % of misestimation of actual finger length and actual hand width did not differ significantly between controls and patients. In the rubber hand illusion, proprioceptive drift was significantly larger in controls for the left and right hand compared to stroke patients. For the experiment with the rubber hand illusion in healthy participants, temperature appeared to be is unrelated to hand orientation and body ownership. Overall, the current study could not fully replicate previously done research on body representation and body ownership.