[Truncated abstract] There is overwhelming evidence that PD leads to impairments in executing voluntary movements. However, it is less clear whether it also leads to impairment in the preparation of movement. The current investigation first aims to further our understanding of motor preparation in people with PD. Two techniques are commonly used to assess motor preparation. These are the manipulation of response complexity and cueing response-related information in advance of the imperative signal. They were both incorporated into a motor task in which participants performed two-movement sequences on a response board. In Experiment 1, people with PD (comprising two groups one on their anti-Parkinsonian medication, and the other following a delay in its normal administration) showed patterns in their motor performance that was similar to healthy age-matched adults. They showed lengthening in their reaction time (RT) with increased response complexity, indicating that the sequences were prepared before their initiation. In addition, both of the PD groups, as well as the healthy adult group, showed shorter RTs with valid cueing and longer RTs with invalid cueing relative to the neutral cue condition. In response to a part-invalid cue (with both valid and invalid information) all three groups had very similar RTs to that in the neutral cue condition. ... in the third experiment, participants were first presented with a sequence to perform, and then, while initiating and executing that sequence, they were presented with a second sequence, providing either valid or invalid visual information about the twomovement sequence. It was expected that if invalid visual information evokes a stronger obligatory response in people with PD, then these participants would experience greater difficulties ignoring such information. This was not found to be the case. Rather the PD group showed a similar pattern of performance to the healthy adults. This indicates that they were able to ignore visual information when it was invalid and unhelpful, and so suggests that people with PD use external information strategically. The results presented in this thesis suggest that motor preparation is largely intact in people with PD. Motor preparation may, however, be incomplete under reduced visual information. Furthermore, while visual information may be particularly important to people with PD, it does not seem to evoke a stronger obligatory response than in healthy adults. Rather, people with PD seem to use external information strategically.

The purpose of this thesis was to investigate the potential mechanisms and sites of neural adaptations that mediate cross-limb transfer of strength and motor learning that can occur subsequent to unilateral training. Better understanding of the mechanisms should allow therapeutic benefits of this effect to be assessed. There are two main classes of mechanisms that could contribute to cross-limb transfer. The first is described by the ??bilateral access?? hypothesis, which suggests that neural adaptations induced by training reside in bilaterally projecting motor areas that are accessible to the untrained (ipsilateral) hemisphere during task execution to facilitate performance. According to the alternative ??cross-activation?? hypothesis, activation of the untrained hemisphere during unilateral training leads to adaptations in the untrained hemisphere that cause improved performance with the opposite untrained limb. A series of studies were conducted in this research. We directly tested the cross-activation hypothesis via a reliable twitch interpolation technique involving transcranial magnetic stimulation (TMS). Four-weeks of strength training for the right wrist increased neural drive (from the untrained motor cortex) to the untrained left wrist. The data demonstrate that strength training of one limb can influence the efficacy of corticospinal pathways that project to the opposite untrained limb, consistent with the cross-activation hypothesis. To investigate the contribution of each hemisphere in cross-limb transfer, we applied repetitive TMS (rTMS) to the trained or the untrained motor cortex to disrupt brain processing after unilateral ballistic training. Learning to produce ballistic movements requires optimization of motor drive to the relevant muscles in a way that resembles high-force contractions performed during strength training. Ballistic skill transferred rapidly to the untrained hand and the improved performance was accompanied by bilateral increases in corticospinal excitability. Performance improvement in each hand was specifically suppressed by rTMS of the opposite hemisphere. Thus the motor cortex ipsilateral to the trained hand is critically altered during unilateral training; and neural adaptations within this untrained hemisphere are crucial in cross-limb transfer of ballistic skill. Overall, the data are in agreement with the cross-activation hypothesis for high-force and ballistic tasks, although they do not exclude the potential involvement of bilateral access mechanisms.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 68-71). Also available on the World Wide Web.

Thesis (Ed. D.)--Illinois State University, 1971. / Title from title page screen, viewed Sept. 21, 2004. Dissertation Committee: Max R. Rennels (chair), Frederick V. Mills, Hugh Stumbo, Tom Malone. Includes bibliographical references (leaves 80-83) and abstract. Also available in print.

Thesis (Ed. D.)--Illinois State University, 1972. / Title from title page screen, viewed Sept. 27, 2004. Dissertation Committee: Max R. Rennels (chair), Richard A. Salome, Ronald Halinski, Macon L. Williams, Fred V. Mills. Includes bibliographical references (leaves 75-79). Also available in print.

Thesis (Ed. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vii, 75 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 49-54).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--The University of North Carolina at Greensboro, 2008. / Title from PDF t.p. (viewed Aug. 21, 2009). Directed by Tom Martinek; submitted to the Dept. of Exercise and Sport Science. Includes bibliographical references (p. 49-51).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves [208]-221).

Thesis (D.P.E.)--Indiana University, 2004. / Includes bibliographical references (leaves 88-92). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.