Motor Learning and Force Output Dynamics

Open Access
King, Adam C
Graduate Program:
Doctor of Philosophy
Document Type:
Date of Defense:
June 19, 2013
Committee Members:
  • Karl Maxim Newell, Dissertation Advisor
  • John Henry Challis, Committee Member
  • David A. Rosenbaum, Committee Member
  • Robert L Sainburg, Committee Member
  • motor learning
  • practice structure
  • retention
  • generalization
Motor learning is characterized by the relative persistent change of behavior over time and is a product of the dynamic changes that operate at multiple levels of analysis of the motor system. This dissertation addressed the questions of how practice influenced the ability to adaptively modulate the multiple time scale processes that support the learning of task outcomes and whether the practice environment facilitates the learning of shorter time scale mechanisms. In each of the experiments an isometric force tracking task was used that afforded the manipulation of force frequency structures. In Experiment 1, we found task-dependent modulation of slow and fast time scale processes as a function of practice and that constant and variable practice conditions produced differential effects on the organization of force output structure. Experiment 2 showed that the time course of a rest interval modified the dynamic organization of force output structure to emphasize low frequency components that are related to sensorimotor feedback mechanisms. The results of Experiment 3 revealed that individuals differentially used shorter time scales of visual information to facilitate a reduction in tracking error that was achieved through the broadening of the spectral profile of force output trajectories as a function of practice. Overall, the findings led to the conclusions that: (a) the practice environment differentially influences task outcome and force output structure as evident by the different time scales of change at each level of analysis; (b) the persistent and transient influence of practice is mediated across a broad bandwidth of frequency structures that generate force output dynamics; and (c) that the effects of variability of practice are differentially influenced by the variability of the pathway to be tracked.