No description available.

No description available.

Two studies of voluntary movement in Parkinson's disease were carried out. In the first study, both parkinsonians and age-matched controls performed unconstrained prehensile movements in which subjects produced reaching and grasping (hand opening/closing) movements under varying conditions of movement amplitude, speed and object size. The act of prehension requires the intersegmental coordination of limb transport and grasp trajectories. Although parkinsonians were slower overall than controls, patients and controls similarly adjusted the spatial and temporal characteristics of their limb movement and grasp in response to changes in task demands. All groups showed increases in the speed of limb transport, the speed of hand opening and began hand opening proportionately earlier at faster movement speeds. All groups similarly increased hand opening velocity and initiated grasp earlier for smaller amplitude movements. Likewise, grasp was initiated earlier when reaching for wider objects. However, in contrast to controls, the onset time of hand opening during limb transport was delayed in these patients and was found to be more closely coupled with the timing of limb transport than in the controls. Moreover, patients showed greater curvature in their motion paths at the wrist during limb transport suggesting that the timing of joint motion (shoulder and elbow) may be different in these patients as well. Underlying differences between the groups in the temporal sequencing of movement are discussed. / In a second study, parkinson and control subjects performed continuous tracking movements in pursuit of sinusoidal and constant-speed target trajectories varying in frequency and amplitude. This task provided explicit temporal and spatial accuracy constraints by requiring subjects to reproduce the precise trajectory (i.e., velocity profile) of target movement. The results show that patients, similar to controls, were capable of modifying peak movement velocity while varying their times to reversal (i.e., movement durations) in response to changes in the movement time requirements of target motion. Indeed, both patients and controls were shown to alter the timing of movement deceleration in order to maintain their movement durations within the temporal limits of target movement. In contrast to controls, patients show progressive reduction in endpoint accuracy (undershooting the target) and, hence, reduced movement amplitudes, over the course of the trial. However, when endpoint accuracy requirements were reduced, by providing mechanical constraints on movement amplitude, patients were able to increase movement amplitudes while satisfying the temporal requirements of the task. These results are interpreted in terms of tradeoffs in performance between competing spatial and temporal demands of pursuit tracking. The significance of movement accuracy constraints on motor function in parkinsonian performance is discussed.

Thesis (Ph. D.)--University of Sydney, 2006. / Title from title screen (viewed May 1, 2007). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Occupation and Leisure Sciences. Includes bibliographical references. Also issued in print.

Thesis (M.S.)--Bowling Green State University, 2009. / Document formatted into pages; contains viii, 55 p. Includes bibliographical references.

No description available.

Thesis (M.S.)--Florida State University, 2003. / Advisor: Dr. Tonya Toole, Florida State University, College of Human Sciences, Dept. of Nutrition, Food, and Exercise Sciences. Title and description from dissertation home page (viewed Sept. 23, 2003). Includes bibliographical references.

Thesis (PhD)--University of South Australia, 1995

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 189-202).

Thesis (Ph. D.)--Illinois State University, 2001. / Title from title page screen, viewed April 13, 2006. Dissertation Committee: Paul A. Garris (chair), John E. Baur, Hou T. Cheung, Maarten E.A. Reith, David L. Williams. Includes bibliographical references (leaves 170-186) and abstract. Also available in print.