This project is designed to determine how glucocorticoids, a class of stress hormones released from the adrenal cortex during emotional arousal, affect brain mechanisms regulating the formation of lasting memory. Previous evidence has indicated that glucocorticoids given peripherally or administered directly into certain brain regions enhance long-term memory of inhibitory avoidance training, a task in which rats receive a single footshock after stepping from a lighted compartment into a darkened compartment in a straight alley. However, such experiments could not determine whether the glucocorticoid administration enhances memory of the place where it received the footshock or of the shock experience itself. This research program will use a two-phase inhibitory avoidance paradigm in which rats will be exposed to the inhibitory avoidance apparatus (i.e., context) on one day and given a single brief shock in the apparatus on a second day. This modified paradigm makes it possible to investigate modulatory influences of glucocorticoids on memory for context separately from modulatory influences on memory for the brief shock experience in the same context. The findings of these studies will thus provide insight into the different aspects of experience modulated by glucocorticoids. Furthermore, by administering glucocorticoids into different brain regions, it will determine the contribution of specific brain regions in modulating memory for these different aspects of experience. As the footshock experience is much more emotionally arousing than exposure to the apparatus per se, additional experiments will determine whether differences in arousal-induced noradrenergic activation may underlie possible differential effects of glucocorticoid administration on memory for context or shock. The findings of these experiments will provide new understanding of the brain mechanisms that regulate why remembrance of emotionally arousing experiences is more vivid and persists longer than remembrance of emotionally neutral experiences. Several undergraduate students (many representing minority groups) will be actively involved in performing the experiments.
