Influence of the training protocol on the premature responses in the DRRD procedure

• Grant number: 15/22171-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2016
• End date: January 31, 2017
• Field of knowledge: Humanities - Psychology - Experimental Psychology
• Principal Investigator: Marcelo Bussotti Reyes
• Grantee: Luana Prado Rolim de Oliveira
• Host Institution: Centro de Matemática, Computação e Cognição (CMCC). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil

Abstract

A task widely used in the study of the perception of time in rats is the differential reinforcement according of response duration (DRRD). In this task, the experimental subject must sustain a response (pressing a lever, for example) for a minimum time criterion. Answers lasting above the criteria are reinforced while shorter do not generate consequences. After several trials, the subjects modify their behavior and begin to generate responses that are longer than the criterion (on average) and with a distribution similar to a Gaussian. However, a significant number of short answers is also observed where the animals are clearly disengaged task. Such responses are called premature and are observed even after many training sessions. These responses do not generate reinforcement and the fact that they are not extinct is still object of study. A possible hypothesis for the permanence of premature responses are in the training protocol. Typically the animals are trained to press levers for one or two sessions before DRRD protocol itself. At this stage, the subjects are reinforced by any response, regardless of its duration, and therefore are reinforced several times for very short times. Thus the permanence of premature responses in trained animals can be a behavioral reflection of this initial training phase. To investigate this issue, we propose a modification of the training protocol, eliminating the initial phase, going directly to the DRRD protocol and causing the rats are never reinforced for short answers. Our hypothesis is that I) there will be a decrease of premature responses in later stages of training and II) up with the speed of learning the animals will be higher than in the conventional protocol. We believe that these results can contribute to the understanding of functional mechanisms related to learning time and can generate a faster training protocol.