| Abstract: Spontaneously Hypertensive Rats (SHR)has been considered as a valid animal model of attention deficit hyperactivity disorder (ADHD). Several theories propose that ADHD would be less responsive to positive reinforcement, especially delayed and conditioned reinforcement. The aim of this paper is to compare conditioned reinforcement on SHR, Wistar Kyoto (WKY) and Wistar rats. For that 16 SHR, 15 WKY and 12 Wistar were submitted to a Multiple FI2min-Ext5min schedule where a feedback light was manipulated (Experiment 1) or to a conditioned reinforcement procedure where a 3s lights-off stimulus (LO) was associated to food with or without delay, and then tested as reinforcer under extinction for the primary reinforcer (Experiment 2). On Experiment 1, ANOVA Type Nonparametric Statistics indicated differences between strains [F (1,644, 16) = 12.097; p<0.001], but not feedback light as conditioned reinforcement [F (1, 14.61985) = 2.688; NS]. Experiment 2 Indicated a main effect of strain [F(1.9, 4.3) = 3.199; p<0.05], lever [F(1, 8)=64.862; p<0.001], and phase [F(4.3, 3.6) = 4.977; p<0.001] and all interactions (between p<0.001 and p<0.05). Relative treatment effects indicated that SHR responded more under extinction than WKY and WIS. Together, experiments suggests that SHR would have a greater deficit on extinction than on reinforcement process. |