DISSERTATION RESEARCH: Assessing the Effects of Stress Physiology on Long-lasting Memory in a Free-living Animal

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Glucocorticoids, commonly known as "stress hormones", can affect the formation of short-term memories (i.e., memories that last from seconds to days), but the effects of stress hormones on memories that persist for months to years are unknown. Additionally, many memory studies use laboratory animals, which often have different behaviors and physiologies than their free-living counterparts. This research will assess the effects of stress hormones on the long-lasting memory of free-living Florida scrub-jays, a long lived bird that retains memories for years. A better understanding of how stress mediates memory may improve the post-release survival of captive-bred endangered species. Many conservation programs teach endangered animals the dangers of predators prior to release into natural habitats, and a strong memory of the identity of potential predators is essential for an animal's survival. This research may also have impacts on the study of human disorders that impair long-lasting memory, such as post-traumatic stress disorder and Alzheimer's disease. In addition, this research will provide research opportunities for University of Memphis undergraduates, over 40% of which are from groups underrepresented in science.Stress can mediate memory function via glucocorticoids (GCs), which are released at low baseline concentrations, but increase in response to a stressor. For example, exposure to increased levels of circulating GCs shortly after learning typically enhances long-term memory formation. Long-term memories last hours to weeks, whereas memories that persist for months to years are known as long-lasting memories. Despite the robust knowledge of the effects of GCs on short- and long-term memory, the understanding of the effects of GCs on long-lasting memory is essentially nonexistent. The goal of this study is to understand how circulating glucocorticoids affect the long-lasting memory of an emotionally arousing event. The researchers will manipulate circulating levels of GCs in free-living Florida scrub-jays (Aphelocoma coerulescens) during a fear conditioning protocol wherein subjects will be either conditioned to avoid an artificial, novel predator or exposed to a non-threatening control. The researchers will then measure subjects' avoidance of the novel predator 48 hours and 10 months post-conditioning to assess the role of GCs in consolidation and retention of the associative memory. All data and analysis from this research will be made publically and freely available on GitHub, a free, web-based Git repository hosting service, at https://github.com/Jonesbc.