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.

This thesis describes three boys diagnosed with dyspraxia and their whanau (families and extended families) as they enter and become part of a community gymnastics group in a city in New Zealand. The study builds on literature that has defined dyspraxia in terms of dysfunction, but generally failed to resolve the disorder. Through the social perspective of health and well-being, participation of children and adults with disabilities has been explored in terms of the person and the environments in which they participate; however, the influence activity itself has on participation has not been thoroughly described. There has been a growing interest in the participation of children with disabilities in recreation and leisure activities and this study provides an in depth cultural perspective of such participation in New Zealand context. This study aims to answer the question "What do children with dyspraxia and their whanau do in a gymnastics group, and what does it mean to them to participate?". The overarching question is "What is the culture of a community gymnastics group in which children with dyspraxia participate?". Ethnographic methodology is employed to ensure that the participants' perspectives, including the beliefs, values and meaning that their participation holds is portrayed, while the associated activities and behaviours are also captured. As the boys with dyspraxia and their whanau entered the gym, they built on their previous experiences to make sense of what they needed to do and what meaning the environment held. I had not planned on the boys being integrated with an established group, but on the first night they spontaneously joined in with a noncompetitive, mixed age, boys group. The parents perceived the Club as professional, while the boys were initially intimidated. Fortunately, the equipment, which made the gym look like a playground, enticed the boys to participate. To shift the boys from their initial perception of the gym being a playground, the coaches used two styles of An Ethnography of Children with Dyspraxia Participating in Gymnastics coaching to support and encourage their participation, while suppressing behaviour that did not fit with the norms of the Club. The boys needed to develop gymnastics skills and fit into the group to become gymnasts. The boys succeeded in fitting into the group by both developing skills and adapting their behaviour, while the type of boys without dyspraxia, the style of coaching afforded, the range of equipment and the activity of gymnastics itself meant that some of their initial difficulties were accommodated and they were seen as group members. The participants developed values and beliefs about what the boys participation in the group meant. Having fun and developing confidence and fitness were highlighted, while the social aspects (making friends and the whanau experiences) were also seen as important. The parents and coaches felt that the boys' experiences in gymnastics had an impact on them that would transfer to the world beyond the gym. This study contributes a qualitative perspective on the participation of children with disabilities in a sports occupation, with a focus on the cultural context of their participation.

[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).