Abstract
It is thought that action execution, perception, and imagination share a common motor pathway. One area of the brain thought to be involved in each of these processes is the posterior parietal cortex (PPC). The present study investigated the effects of transcranial direct current stimulation (tDCS) on the PPC and the subsequent influence on execution, perception, and imagination of a cyclical aiming task. tDCS is a non-invasive neuromodulation technique, that can increase or decrease activity in a targeted cortical region. Participants received anodal, cathodal, and sham stimulation on separate days. During each session, participants executed, imagined and perceived cyclical aiming movements of the hand before and after tDCS. The amplitude of the movement and the widths of the targets were varied to create 3 different movement environments for the 3 index of difficulties of 2, 3, and 4. It was found that movement time for each of the tasks was altered following tDCS. Specifically, results indicated that the correlations between movement time and movement difficulty in movement execution were significantly lower following cathodal stimulation. Performance in the execution task was not affected by anodal or sham stimulation. In addition, no stimulation protocol affected movement imagination and perception. These results will be discussed with respect to the role that the PPC plays in motor behavior. Future work will explore the roles of tDCS on the PPC and other areas of the brain, as well as potential use of these tasks and techniques for better assessing and understanding movement disorders.
