Dissertation Defense - Sofia Aremi Lopez
Investigating the Role of Glucocorticoids in Mediating Dopamine-dependent Cue-reward Learning
Dr. Shelly Flagel, Chair
Daily we are surrounded by an overwhelming amount of cues in the environment. Through associative learning processes, these cues often guide our behavior in advantageous ways. For some, however, discrete environmental cues can trigger complex emotional responses, and consequently, aberrant patterns of behavior. The ability of seemingly neutral cues to promote aberrant behavior is a hallmark of several psychiatric disorders including, addiction, post-traumatic stress disorder, eating disorders, and obsessive-compulsive disorder. Thus, it is important to uncover the neural mechanisms by which such cues can attain inordinate control and promote psychopathological behavior. Studies outlined in this dissertation aim to address the role of glucocorticoids, primarily recognized for regulating the stress response, in the attribution of incentive value to cues, a psychological process that transforms such cues into powerful motivators of aberrant behavior. Additionally, we focus on the relationship between glucocorticoids and dopamine, the latter of which is critical to the process of incentive salience attribution. These questions are addressed using a preclinical animal model, the goal-tracker/ sign-tracker model, which allows us to capture individual differences the propensity to attribute incentive value to cues. Our results serve as evidence for a role of glucocorticoids, beyond negative valence systems, particularly in cue-reward learning. It appears that while glucocorticoids influence the propensity to attribute incentive value to reward cues, the state under which they are acting may impact their interaction with dopamine and subsequent influence on behavior. This work will serve as a foundation for future studies probing the role of glucocorticoids in cue-motivated behaviors relevant to psychopathology.