Independent On-line Information Processing in Bimanual Coordinated Movements

Open Access
Waltz, Lauren Ann
Area of Honors:
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Robert L Sainburg, Thesis Supervisor
  • Andrzej Przybyla, Thesis Supervisor
  • Peter J Butler, Honors Advisor
  • Stephen Jacob Piazza, Faculty Reader
  • motor control
  • bimanual coordination
A coordinated movement is the act of multiple muscles (in this case, the muscles of the two arms) working together in order to perform a single purposeful movement. Some researchers hypothesize that there are complex interactions between the individual control mechanisms for both arms in such coordinated movements, replacing or overshadowing the neurons that control the arms individually. This may be explained, in part, by the development of motor synergies, which limit the number of controlled variables and stabilize the performance of task outcomes. Our research hypothesis is that the parameter specification for motor synergies is a continuous process, and that corrective control of the individual arms remains largely separate through movement execution. To show this, a series of experiments was conducted to determine the degree of flexibility in the independent control of both arms while contributing to a bimanual goal-directed movement. Using specialized hardware for recording arm movements in a virtual-reality like setting, subjects used both arms to guide a single, shared cursor toward a target. The contribution (gain) to the perpendicular component of cursor movement was varied for the left and right arms, altering the effect that each arm had on the resultant movement of the cursor. The results of this thesis suggest that bimanual goal-directed movements are continuously assessed by the central nervous system, and that developed motor synergies can be modified based on subtle changes in visual feedback, particularly when the movements of the individual arms are homologous. Differences in the movement errors observed for the individual contributing arms supports the hypothesis that independent correction mechanisms for both arms are present and effective at modulating a bimanual movement when guiding a cursor toward a visual target.