Date of Award

Summer 2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biomedical Engineering - (Ph.D.)

Department

Biomedical Engineering

First Advisor

Tara L. Alvarez

Second Advisor

Bharat Biswal

Third Advisor

Mitchell Scheiman

Fourth Advisor

Kevin Pang

Fifth Advisor

Eugene Tunik

Abstract

While functional magnetic resonance imaging (fMRI) has identified which regions of interest (ROIs) are functionally active during a vergence movement (inward or outward eye rotation), task-modulated coactivation between ROIs is less understood. This study tests the following hypotheses: (1) significant task-modulated coactivation would be observed between the frontal eye fields (FEFs), the posterior parietal cortex (PPC), and the cerebellar vermis (CV); (2) significantly more functional activity and task-modulated coactivation would be observed in binocularly normal controls (BNCs) compared with convergence insufficiency (CI) subjects; and (3) after vergence training, the functional activity and task-modulated coactivation would increase in CIs compared with their baseline measurements. A block design of sustained fixation versus vergence eye movements stimulates activity in the FEFs, PPC, and CV. fMRI data from four CI subjects before and after vergence training are compared with seven BNCs. Functional activity is assessed using the blood oxygenation level dependent (BOLD) percent signal change. Task-modulated coactivation is assessed using an ROI-based task modulated coactivation analysis that reveals significant correlation between ROIs.

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