Date of Completion

9-6-2019

Embargo Period

9-6-2019

Keywords

spatial memory, hippocampus, estradiol, anxiety, stress

Major Advisor

Robert Astur

Associate Advisor

John Salamone

Associate Advisor

Etan Markus

Associate Advisor

R. Holly Fitch

Associate Advisor

Karyn Frick

Field of Study

Psychology

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Spatial memory is a critical cognitive function that involves for navigating, interpreting, and representing environments, planning a route, remembering the location of an object or event, and understanding spatial configurations. The three studies presented are original investigations on how estradiol, anxiety, and stress influence hippocampal-dependent spatial memory. The first study assessed the impact of estradiol level on spatial memory in young adult women. Salivary assays were obtained to determine the exact estradiol level. Women at the high and low estradiol phases of their natural menstrual cycle were compared to each other and to women on oral contraceptives (OCs). Behavioral performance on a virtual version of the Morris water task, a virtual version of the radial arm maze, and a mental rotation task was examined. Results indicated that higher levels of circulating estradiol were shown to be beneficial in comparison to lower levels for memory retention in spatial navigation across a 24-hour period. The second study examined how general anxiety levels impacts learning and memory. Performance on spatial and verbal memory tasks in men, women in the ovulatory phase their cycle, women in the non-ovulatory phase of their cycle, and women on OCs was measured. Behavioral performance on the virtual Morris water task, a declarative verbal memory task, and a verbal fluency task was assessed. Results indicated that general anxiety had no impact on spatial or verbal memory. Finally, the third study explored how an acute induced stressor affected spatial memory in men, women in the ovulatory phase their cycle, women in the non-ovulatory phase of their cycle, and women on OCs. Stress was induced via a virtual version of the Trier social stress task. Behavior was measured on the Morris water task, an object location task, a spatial working memory task, and a mental rotation task. Both men and women that underwent induction of stress had protected memory retention in spatial navigation compared to control participants. Induced stress also impaired performance on an object location task in men but had no impact in women. Stress had no impact on spatial working memory and mental rotation ability. Overall, the findings from all three studies suggest that estradiol level impacts spatial memory retention, anxiety does not affect spatial memory, and induced stress does influence some spatial tasks, dependent on sex.

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