Lexe West

she/her

Education: Bachelor of Science in psychology (May 2023)

McNair Project: Abbreviated Fixed-Interval Intervention Effects on Accuracy and Precision in Interval Timing (2022)

Mentor: Kimberley Kirkpatrick, Ph.D.

Exposure to fixed, time-based interventions are effective for improving self-control in male and female rats. Such interventions may increase timing accuracy and precision when delivered for extended training periods. The current studies assessed the efficacy of abbreviated interventions and whether timing improvements could occur during a post-intervention impulsive choice task. Experiment 1 manipulated the intervention timeline by exposing rats to fixed interval (FI) intervention lengths ranging 6 (FI 200) to 45 (FI 1500) sessions. During the choice procedure, rats chose between smaller-sooner (SS) delays or a larger-later (LL) delay. Timing precision and accuracy data were collected from peak interval trials randomly intermixed with the post-intervention choice task. Results revealed that rats exposed to the shortest intervention were the most accurate at the 30 second SS delay, but all rats improved in their precision and accuracy across the experiment. Experiment two sought to replicate the abbreviated 6 session FI intervention results compared to a control condition. Additionally, the effects of a pre-intervention choice test with and without breaks in the experimental timeline were assessed. Across smaller-sooner delays, groups that received a pre-intervention choice task before the time-based intervention were significantly more accurate and precise compared to the groups that did not receive a pre-test. Altogether, results suggest that the experiments improve accuracy and precision, but experience with the impulsive choice task may facilitate these improvements instead of the intervention itself. Future research will investigate the role of the dorsal striatum, prelimbic cortex, and medial agranular cortex in interval timing