Date of Award

2018

Document Type

Open Access Thesis

Department

Exercise Science

Sub-Department

The Norman J. Arnold School of Public Health

First Advisor

Troy M. Herter

Abstract

BACKGROUND. Stroke is a cerebrovascular event that causes permanent damage to brain regions and decreases in connectivity (disconnection) between brain regions. Most stroke survivors have permanent difficulties performing functional motor tasks, thus research into how damage and disconnection produce difficulties performing motor tasks can help guide post-stroke rehabilitation. Previous studies have examined the extent to which cortical damage produces motor impairments, but the extent to which disconnection produces motor impairments remains unclear. Furthermore, studies have focused on how motor impairments contribute to difficulties performing motor tasks, whereas the role of visuospatial impairments has received little attention. Neuroimaging techniques for quantifying stroke-induced damage and disconnection of brain networks are powerful tools for examining the neural mechanisms that underlie difficulties performing visuomotor tasks.

OBJECTIVE. The purpose of the proposed research study is to examine the extent to which cortical damage and disconnection independently contribute to deficits in visuomotor task performance.

HYPOTHESES. Three hypotheses will be tested. Hypothesis 1: Cortical damage and disconnection will be largely independent of each other. Hypothesis 2: Damage and disconnection involving two different (but partially overlapping) cortical networks will be associated with motor and visuospatial impairments. Hypothesis 3: Damage and disconnection of cortical motor and visuospatial networks will independently contribute to deficits in task performance.

METHODS. The proposed study will examine 47 subjects with a single, unilateral stroke of the left middle cerebral artery at least six months before testing. Subjects will perform a bimanual, visuomotor task (Object Hit), which will be used to quantify Task Performance (Object Hits), Motor Impairment (Hand Speed Bias), and Visuospatial Impairment (Spatial Miss Bias). Magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) will be used to quantify Damage (Lesion Volume) and Disconnection (Connectivity Bias) of cortical visuomotor regions. These measures will be used to test the hypotheses of the proposed study.

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