Effects of Predator Odor Stress on Habit Learning in Long-Evans Rats (2024)

Undergraduate: Alejandro Mosera

Faculty Advisor: Brooke Bender
Department: Alcohol Studies, Neuroscience, Psychology

---

Since 1980, PTSD has been a widely-known disorder that has developed in millions of people around the world. In the past, studies have been conducted and have shown that single prolonged stress exposure has led to enhanced habit formation in rodents. A PTSD stress model was created for 48 adult Long-Evans rats, both male and female. The rats were randomly divided into control and predator odor (TMT) exposed groups. Over several weeks, these rats underwent sweetened solution self-administration training with a devaluation test to distinguish between each rat's exhibited habitual and goal-directed behaviors. This experiment measured the effects of the predator odor on the devaluation phase, hypothesizing that TMT exposure would lead to an increase in habitual lever pressing. Results indicated that predator odor exposure did not significantly affect the self-administration reward learning. However, coping strategies during stress exposure, such as an increase in time digging, shows a slight positive correlation with reduced habit learning. This finding suggests that the manner in which rats respond to stress might influence the development of habits. Future research needs to be conducted to the understanding of the relationship between stress responses and habit formation, which could have significant implications for the treatment of substance use disorders and other stress-related conditions. In addition, more studies are need to identify potential areas for future investigation, including the specific brain regions involved in habit learning and stress response.