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Adaptations to chronic unpredictable threat stress: Effects on defensive behaviors and working memory

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dc.contributor.advisor Anderson, Brenda J. en_US
dc.contributor.author Kim, Diane J. en_US
dc.contributor.other Department of Biopsychology. en_US
dc.date.accessioned 2017-09-20T16:51:39Z
dc.date.available 2017-09-20T16:51:39Z
dc.date.issued 2015-08-01 en_US
dc.identifier.uri http://hdl.handle.net/11401/77012 en_US
dc.description 157 pg. en_US
dc.description.abstract In humans, stressors are often psychological and anticipatory in nature rather than directly harmful. In order to understand the consequences of chronic psychological stress and behavioral adaptations to repeated unpredictable threats, an ethologically relevant rodent model was developed that included the anticipation of a predator attack but without direct harm. In the unpredictable threat stress condition, rats faced risk while seeking resources through a tunnel over a three week period. When rats cross the tunnel, they were presented with random (p=0.25), simultaneous presentations of predator odor, flashing LEDs, and an abrupt auditory stimulus. The control group was housed in identical tunnels but never experienced threat stimuli. The aims of the study were the following: (1) to quantitatively test the effectiveness of the stimuli and the duration with which they remain effective over repeated presentations, (2) to further test whether the stimuli were perceived as threats of harm by measuring the frequency of behaviors known to be elicited in the face of predators, (3) to test for adaptations in direct defensive responses as well as behaviors with predictive validity for symptoms of anxiety and depression, (4) to test for changes in cognitive behavior with a standard rodent test of spatial working memory, and (5) to identify candidate sites of plasticity by metabolic factors that indirectly reflect rates of neural activity. While in the manipulation, foraging was reduced but there were no differences in food/water consumption and weight gain indicating no significant challenges to homeostasis. The stress group produced significantly more risk assessment behaviors than the control group confirming the aversive nature of the stimuli. After removal from the stress manipulation, the stress group exhibited greater defensive responding consistent with threat-related vigilance and hyper-reactivity, both of which would be expected to increase an organism's survival in high threat environments. There were no changes in passive avoidance or behavioral symptoms of depression. Metabolic changes were observed in brain regions associated with threat, which included the dorsal premammillary nucleus of the hypothalamus, a critical region in response to predator. Repeated exposure to threat over three weeks enhanced defense behaviors tested in high arousal conditions, but at the expense of spatial working memory tested in neutral test conditions. These shifts in behavior may be adaptive in unpredictable, high threat environments but may be maladaptive in safe environments. en_US
dc.description.sponsorship This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. en_US
dc.format Monograph en_US
dc.format.medium Electronic Resource en_US
dc.language.iso en_US en_US
dc.publisher The Graduate School, Stony Brook University: Stony Brook, NY. en_US
dc.subject.lcsh Psychobiology en_US
dc.subject.other adaptation, aggression, defense, psychological stress, unpredictable threat, working memory en_US
dc.title Adaptations to chronic unpredictable threat stress: Effects on defensive behaviors and working memory en_US
dc.type Dissertation en_US
dc.mimetype Application/PDF en_US
dc.contributor.committeemember Leung, Hoi-Chung en_US
dc.contributor.committeemember Lobel, Marci en_US
dc.contributor.committeemember Kotov, Roman. en_US


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