Date of Award

Fall 2007

Document Type

Thesis

Degree Name

Master of Science in Biomedical Engineering - (M.S.)

Department

Biomedical Engineering

First Advisor

Tara L. Alvarez

Second Advisor

Bharat Biswal

Third Advisor

Mesut Sahin

Abstract

Motor learning is critical to the survival of a species and changes throughout life via neuroplasticity. The brain receives most of its information about the external world via the visual system. Eye movements are used to direct the visual information of interest to the fovea, the area of the retina which has the highest density of photoreceptors, and the largest amount of cortical area. This research will study how two of the five eye movement systems utilize oculomotor learning. Saccadic eye movements are used to quickly shift the fovea to objects using conjugate movements typically used during reading. The vergence system encompasses disconjugate movements of the eyes and provides perception of the depth of the objects. When a visual task is learned by a person, the latency and the peak velocity, inversely modulate according to each other under predictable and non-predictable conditions. This research will compare neural activity results during predictable and non-predictable visual conditions using Functional Magnetic Resonance Imaging (fMRI) in humans. FMRI indirectly measures neural activity by directly measuring the hemodynamics of neural responses. There were three primary results from this research; 1) activation was observed in occipital, frontal, temporal and cerebellar regions, 2) short-term neuroplasticity via recruitment and synchronization was observed in the cerebellar vermis 4/5, and 3) the frontal eye fields within the frontal lobe had distinct areas of activity allocated for saccadic versus vergence eye movements. Activity was observed in the integration of oculo-motor functions and cognitive functions such as memory corresponding to the occipital lobe, the prefrontal cortex, the frontal lobe, and the parietal lobe of the brain was observed in subjects. Furthermore, software was written to quantify the amount of cortical area involved in different areas of activation. The saccadic and vergence systems show similarities in the use of predictive learning as well as distinct cortical locations allocated to each system. Neuroplasticity was observed which was person dependent.

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