Date of Award
12-2025
Degree Name
Master of Arts
Department
Psychology
First Advisor
Al Poling, Ph.D.
Second Advisor
Lisa Baker, Ph.D.
Third Advisor
Cynthia Pietras, Ph.D.
Access Setting
Masters Thesis-Open Access
Abstract
Impulsivity is a key behavioral trait with broad implications for clinical disorders such as Attention Deficit Hyperactivity Disorder ADHD, and substance use disorders SUD, where impaired inhibitory control contributes to maladaptive outcomes. In preclinical research, animal models provide valuable tools for examining behavioral processes associated with impulsivity. The Differential Reinforcement of Low Rates (DRL) schedule, offers a precise measure of response inhibition and timing by requiring subjects to withhold responses for reinforcement. This study employed DRL72s schedule to investigate impulsive action in male and female Sprague-Dawley rats, with an emphasis on sex-based differences and the potential influence of environmental factors.
Sixteen rats (eight male, eight female) were trained under progressively increasing intervals. On the 5th session of DRL 36s half of the animals were exposed to collateral objects in the operant chambers, and performance was evaluated across measures of response rates, reinforcers earned, efficiency ratios, and direct object interactions. Results indicated emerging sex differences, with females generally exhibiting higher reinforcement efficiency and greater responsiveness to environmental conditions. Object presence further shaped behavior, particularly in females, who engaged more frequently in exploratory and object-directed activity.
These findings highlight the importance of considering sex as a biological variable in behavioral neuroscience, in alignment with recent research guidelines. They also suggest that environmental context interacts with biological factors to influence impulse control, offering potential insights into sex-specific vulnerability and resilience in addiction models. By demonstrating the utility of DRL schedules in capturing subtle aspects of impulsivity, this study contributes to a more inclusive and nuanced understanding of inhibitory control, with implications for future research on addiction, pharmacological intervention, and sex-based behavioral regulation.
Recommended Citation
Graham, Cassidy M., "An Investigation of Collateral Activity Effects on Behavior Maintained by a DRL 72‑Second Schedule" (2025). Masters Theses. 5492.
https://scholarworks.wmich.edu/masters_theses/5492