Effect of Reinforcement Delay on Behavior Acquisition Comparing Wistar, Wistar-Kyoto, and SHR Rats: A Systematic Replication

• Grant number: 24/18032-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Humanities - Psychology - Experimental Psychology
• Principal Investigator: Fábio Leyser Gonçalves
• Grantee: Melissa Oliani Rodrigues
• Host Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil

Abstract

This research project aims to investigate the effect of delayed reinforcement on behavior acquisition in SHR rats, an animal model of Attention Deficit Hyperactivity Disorder (ADHD). The study is based on the hypothesis that spontaneously hypertensive rats (SHR) exhibit more pronounced reinforcement delay gradients, which may negatively impact the acquisition of new behaviors. The responses of SHR rats will be compared with those of Wistar (WIS) and Wistar-Kyoto (WKY) rats, the latter often used as a control in studies involving SHR. The experiment will be conducted over 30 sessions, during which the rats will be subjected to a tandem reinforcement schedule FR1 DRO 15s, where each response is reinforced after a 15-second delay, provided no other response is made during this interval. The central hypothesis is that SHR rats will take longer to learn to press the lever compared to WKY and WIS strains. The data generated is expected to provide a better understanding of the impacts of delayed reinforcement on the learning of new behaviors in the different strains used. In the end, the results will be analyzed and compared to evaluate the effectiveness of delayed reinforcement in shaping behaviors in SHR rats. The study may contribute to the development of new experimental paradigms that prioritize behavior acquisition, as well as offer a basis for future research on animal models of ADHD. The results will be presented at academic conferences and submitted for publication in scientific journals, with the intention of integrating the findings with other ongoing studies in the laboratory. (AU)