Impacts of disrupted stress responses on brain and behavior
Kinlein, Scott Aaron
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Stress is a term used in everyday life to describe everything from feelings of anxiety and grief, to shock and fear. However, at their most basic level, these psychological expressions of stress are all driven by similar underlying biological processes acting on neural circuits in the brain. These biological processes are evolutionarily ancient and serve the primary function of improving the odds of survival in dangerous or threatening circumstances. However, in modern society, these biological stress-response systems are frequently and persistently engaged in situations that do not pose a significant real threat to life and limb. This incessant and insidious activation results in a gradual breakdown in normal regulation of physiology in the brain and body and leads to negative outcomes for physical and mental health. One of the primary systems which mediates the effects of stress on physiology is the hypothalamic-pituitary-adrenal (HPA) axis, which exerts its effects on the brain and body through the secretion of the “stress hormones” known as glucocorticoids. Dysregulation of this system is strongly linked to the development of stress-related metabolic and psychiatric diseases, however the biological substrates through which improper HPA axis function causes these problems is unclear. The chapters comprising this dissertation describe how dysfunction of the HPA axis alters the normal patterns of neural adaptation in the brain and show that these changes are related to the way in which an organism responds behaviorally when faced with stress. Together, the findings presented support the idea that appropriate function of the neuroendocrine stress response is crucial for responding and adapting to stress.