Date of Award

2022

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Cook, Peter

Area of Concentration

Marine Biology

Abstract

Populations of wild California sea lions (Zalophus californianus) are an opportunistic disease model for study of the effects of the algal toxin domoic acid. Common symptomology of chronic domoic acid toxicosis in these animals includes hippocampal atrophy and seizures. Distributed neural pathology is less well understood. The thalamus shares dense connections with the hippocampus, and there has been some evidence of thalamus lesioning in exposed sea lions and human cases, but these findings have been anecdotal. Relatedly, temporal lobe epilepsy in humans can lead to thalamus atrophy. In the present study, high resolution diffusion tensor imaging data obtained postmortem was compared between two animals: one with and one without clinical signs of domoic acid toxicosis. Anterior thalamus and hippocampus were segmented and white matter connections were traced to compare volumetry and diffusion measures respectively between specimens for each region. Anterior thalamus did not display clear mean trends in diffusion measures, but mean diffusivity maps provided anecdotal evidence of bilateral differences.

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