Doctor of Philosophy (PhD)
This is a three-study dissertation in which we aimed to broaden our knowledge of the mechanisms contributing to a 45° clockwise visuomotor adaptation by including variations in workspace. We provide behavioral and in one study physiological outcomes as evidence to support our conclusions. In the first experiment, we observed the adaptation of movement parameters such as pathlength, movement time, resultant velocity, and normalized jerk across groups trained with rotated visual feedback with both the left and right hands. Workspace location and hand differentially affected movement trajectory length. The group that practiced the task with their nondominant, left hand showed larger after-effects, thus deviations in pathlength and initial direction error than those who practiced with their right hand. We also observed the transfer of pathlength from the left to the right hand but no ensuing after-effects. These findings failed to support the dynamic dominance model of bilateral transfer asymmetry, which posits the right hand is uniquely adapted for movement trajectory information. In the second experiment, participants adapted to the visuomotor rotation and generalized the adaptation to other workspaces. Subjects adapted to the visuomotor rotation in all three workspace locations. Corresponding neural measures indicated workspace related changes, with the biggest differences between contralateral and ipsilateral workspaces consistent with the observed behavioral results. The observed neurophysiological patterns were mainly in the right central and parietal– cortical areas involved in spatial processing. We argue these brain areas may be involved in workspace-related inhibition to allow the left hemisphere work efficiently. In the final experiment we investigated how manipulation of visual feedback and workspace location affected visuomotor adaptation for groups using real and remembered targets during performance. We showed participants visuomotor rotation transferred from the central to the ipsilateral workspace location. Also removing the target during rotational adaptation decreased, thus improved reaction time for unrotated real target trials regardless of workspace. Since gaze strategies differed between groups, we reasoned that gaze does not significantly contribute to visuomotor adaptation. The current studies add to existing evidence for understanding mechanisms responsible for adapting to a visuomotor rotation under different contexts.
Addison, Reuben N., "Visuomotor Rotation Adaptation and Workspace Manipulation: A Behavioral and Cognitive Emphasis" (2022). LSU Doctoral Dissertations. 5778.
Van Gemmert, Arend