the dynamic dominance hypothesis as a general theory of human motor control

Open Access
Author:
Tomlinson, Tucker
Graduate Program:
Kinesiology
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
January 24, 2012
Committee Members:
  • Robert L Sainburg, Dissertation Advisor
  • Stephen Jacob Piazza, Committee Member
  • Vladimir M Zatsiorsky, Committee Member
  • Henry Joseph Sommer Iii, Committee Member
Keywords:
  • motor control
  • lateralization
  • handedness
Abstract:
The role of lateralization in the control of human motion is difficult to assess. Lateralization of skilled control, or handedness is a readily observable yet incompletely understood facet of human control of the upper extremity. Despite the ease with which hand preference is identified, the specific mechanisms producing these differences in control are difficult to integrate into existing models of control. The Dynamic Dominance hypothesis of human motor control, builds a general theory of human motor control from descriptions of the lateralization of hand and arm control. The Dynamic Dominance hypothesis stipulates that the advantage displayed by the dominant limb is in the anticipation and utilization of the dynamics of movement across multiple segments. Additionally the Dynamic Dominance hypothesis proposes that the non-dominant arm has an advantage for specifying limb postures, which often results in advantages in final position accuracy. Further these advantages are due to the lateralization of neural circuits specialized to regulate different aspects of movement. Importantly, the Dynamic Dominance hypothesis proposes that movement of each arm relies on both contralateral and ipsilateral cortex to supply different aspects of control. The studies presented in this dissertation explore the generalizability of Dynamic Dominance as a model of control. These studies address three specific limitations of past work. First, since Dynamic Dominance was developed based upon data collected from constrained, planar reaches, we wished to test how well the hypothesis generalized to conditions in which gravity must be accounted for. Second, we tested the feasibility of a simple control model that simulated the discrete contribution of the two proposed hemisphere mechanisms to control to of a single movement. We were particularly interested in the ability of such a model to describe the differences in control observed in dominant and non-dominant arm movements. Finally, we examined predictions of how each hemisphere is activated during unilateral reaching. Based upon the control requirements of the task, we predicted the activity over specific areas of cortex, based upon dynamic Dominance. These studies extend our understanding of lateralization of the human motor control system.