Both the H-RI and L-RI rats displayed increases in responding on the active lever (i.e. heroin lever) in parallel with decreases in responding on the inactive lever. For the active lever (Fig. S2A), two-way repeated ANOVA revealed a significant main effect of Session [F(6,181) = 6.38, p<0.001]. Newman-Keuls post hoc tests showed that both the H-RI and L-RI rats displayed significantly higher responding on the active lever in Session 7 than that in Session 1 (p<0.001) and Session 2 (p<0.001). The NR rats did not show differences in the active lever responding between Session 7 and Session 1. In Session 7, both the H-RI and L-RI rats responded significantly more on the active lever than the NR rats (p<0.05), with no difference between the H-RI and L-RI rats. On the inactive lever (Fig. S2B), ANOVA revealed a significant main effect of Session [F(6,181) = 5.70, p<0.001]. Newman-Keuls post hoc tests showed that the H-RI rats displayed significantly lower responding on the inactive lever in Session 7 than that in Session 1 (p<0.001). The L-RI or NR rats did not show differences in the inactive lever responding between any Sessions. In Session 7, there were no differences between groups.
