Investigating the sophistication of rapid corrective responses in the upper limb during reaching and postural control

dc.contributor.authorNashed, Joseph Y.en
dc.contributor.departmentNeuroscience Studiesen
dc.contributor.supervisorScott, Stephen H.en
dc.date2014-04-29 15:36:16.104
dc.date2014-04-29 16:54:12.489's University at Kingstonen
dc.descriptionThesis (Ph.D, Neuroscience Studies) -- Queen's University, 2014-04-29 16:54:12.489en
dc.description.abstractEveryday movements, such as reaching for a drink of water or typing on a keyboard highlight the relative ease with which we move and interact with our surroundings. However, the success of these skilled movements depends on the motor system’s ability to consider a variety of factors, such as the goal of the behavioral task, the surrounding environment and the physical properties of the musculoskeletal system. Recent theories of voluntary motor control, namely optimal feedback control, suggest that such skilled motor behavior is achieved through sophisticated feedback control. This thesis investigates one physiological implication of this theory. Specifically, we hypothesize that rapid feedback responses following mechanical perturbations possess many of the functional attributes thought to be reserved for voluntary control because these two systems have contributions from similar neural substrates (eg. motor areas in cortex). Our studies were specifically designed to investigate rapid feedback responses during the long-latency epoch, which occurs between 50-100ms following a mechanical perturbation. Consistent with our hypothesis, we found that the sophistication of the long-latency response rivals that of voluntary control. In our first study (Chapter 2) we examined if rapid feedback responses were sensitive to features of the end target. We found that muscle activity during the long-latency epoch was modulated by the size/shape of the end. In our second study (Chapter 3) we observed flexible responses in muscle activity during the long-latency epoch that reflected rapid ‘decisions’ during online control regarding how to navigate around obstacles in the environment as well as how to select amongst multiple potential goals. In our final study (Chapter 4) we examined if rapid feedback responses in the shortened muscle parallel the sophisticated responses observed in the lengthened muscle. We found that unloading a pre-excited muscle elicited sophisticated inhibitory responses, including knowledge of limb mechanics and rapid target selection, during the long-latency epoch that are comparable to the excitatory responses observed during loading. Taken together, the studies presented in this thesis demonstrate that the responses in the long-latency epoch reflect several functional attributes typically reserved for voluntary control.en
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectSensory Feedbacken
dc.subjectMotor Controlen
dc.titleInvestigating the sophistication of rapid corrective responses in the upper limb during reaching and postural controlen
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