Effects of fluoxetine on the effectiveness of conditioned reinforcers

Author(s)

Fábio Leyser Gonçalves

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Psicologia (IP/SBD)
• Defense date: 2000-12-18

Examining board members

Maria Teresa de Araujo Silva; Maria Helena Leite Hunziker; Erica Maria Machado Santarem

• Advisor: Maria Teresa de Araujo Silva
• Field of knowledge: Humanities - Psychology
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP; Index Psi Teses - IP/USP
• Location: Universidade de São Paulo. Biblioteca do Instituto de Psicologia; BF199.5; G635e

Abstract

Depression, as seen by the Experimental Analysis of Behavior, has been related to reinforcement rate, establishing operations and decreased sensitivity to positive reinforcers. The biobehavioral approach to reinforcement has implicated the dopaminergic system (DA), in the neural basis of reinforcement. Also DA agents have been demonstrated to change the effectiveness of conditioned reinforcers. Finally, it has been suggested that the DA system plays an important role on depression and on antidepressant drugs action. The present study was aimed at investigating the effects of the antidepressant drug fluoxetine (FLX), a selective serotonin reuptake inhibitor, on the effectiveness of conditioned reinforcers. Experiment 1 validated the Conditioned Reinforcement (CR) procedure. The final procedure was: 1) Pre-exposure - 5 sessions in which presses on two levers were registered, each lever led to presentation of one out of two neutral stimuli (LO and TONE); 2) Conditioning – 4 sessions in which LO was paired with food pellets; e 3) Test – 2 sessions in which the procedure was the same as Pre-exposure. Experiment 2 investigated the effects of chronic fluoxetine and prolonged food deprivation on the effectiveness of CR. Results indicate that FLX does not directly influence CR effectiveness. Nor does prolonged deprivation appear to interact with treatment. It is suggested, however, that chronic exposure to mild stressors might alter the effectiveness of CR, interacting with antidepressant treatment. (AU)