Adrenal hormones (glucocorticoids) regulate the body's responses to stress, but also influence cognition. Glucocorticoids can either improve or impair memory formation and retrieval, depending on the severity and length of stress. Despite extensive research on the effects of these hormones on cognition in laboratory rodents, little is known about how glucocorticoids influence biologically relevant learning by animals in natural contexts. This information has clinical applications because high levels of glucocorticoids are associated with depression, Alzheimer's disease and addiction behaviors, and because synthetic glucocorticoids are often prescribed for people with arthritis or adrenal dysfunctioning. Knowledge how long-term changes in glucocorticoids influence learning and memory would aid in the development of pharmacological treatments for such patients. The proposed studies extend this body of research to investigations of learning and memory in a free-living animal model, Belding's ground squirrels (Sperinophilus beldingi). In particular, these studies will focus on the role of glucocorticoids in enhancing or impairing the development of antipredator behavior, and whether variation in glucocorticoids early in development has long-term effects on adult behaviors. Many of the studies will use non-invasive fecal hormone assays to monitor adrenal functioning. This research will enhance our understanding of both the mechanisms underlying cognition as well as the ecological and developmental factors that influence it. In addition, the development of species-typical behaviors, especially those critical to survival, has been a relatively unexplored area of learning and memory, and this research will provide a rare example of how adrenal functioning affects cognition in freely behaving, outbred animals.

R01MH063921

2002-04-01

2009-01-31