Date of Award

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Neuroscience

College

College of Graduate Studies

First Advisor

Colleen A. Hanlon

Second Advisor

Mark S. George

Third Advisor

Steven A. Kautz

Fourth Advisor

Jens H. Jensen

Fifth Advisor

Joseph P. Schacht

Sixth Advisor

Gonzalo J. Revuelta

Abstract

White matter consists of myelinated axons which integrate information across remote brain regions. Following stroke white matter integrity is often compromised leading to functional impairment and disability. Despite its prevalence among stroke patients the role of white matter in development of post-stroke rehabilitation has been largely ignored. Rehabilitation interventions like repetitive transcranial magnetic stimulation (rTMS) are promising but reports on its efficacy have been conflicting. By understanding the role of white matter integrity in post-stroke motor recovery, brain reorganization and TMS efficacy we may be able to improve the development of future interventions. In this dissertation we set out answer these questions by investigating the relationship between white matter integrity and 1) bimanual motor performance following stroke, 2) cortical laterality following stroke and 3) TMS signal propagation (in a group of cocaine users without stroke). We identified white matter integrity of the corpus callosum as a key structure influencing bimanual performance using kinematic measures of hand symmetry (Chapter 2). Second, we found that reduced white matter integrity of corpus callosum was correlated with loss of functional laterality of the primary motor cortex during movement of the affected hand (Chapter 3). Lastly, we found that reduced white matter tract integrity from the site of stimulation to a downstream subcortical target, was correlated to the ability to modulate that target (Chapter 4). Taken together these studies support white matter integrity as a valuable biomarker for future rTMS trials in stroke. To emphasize the implications of these findings, we provide an example of how to incorporate white matter integrity at multiple levels of rTMS study design.

Rights

All rights reserved. Copyright is held by the author.

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