Figure 2.
Effects of local intra-accumbens injections of CGS 21680 on lever pressing on two variable interval schedules with different ratio requirements. a, Stimulation of A2A receptors in the accumbens had no effect on VI60/FR1 performance but induced a substantial decrease in responding in variable interval schedule with the higher ratio requirement attached (*p < 0.05, VI60/FR10, different from vehicle). b, c, Cannula placements from intracranial injections in animals trained in the VI60/FR10 and the VI60/FR1 schedules, respectively, were localized in the nucleus accumbens (Nac) core. d, Cannulas placements for the dorsal control site. c, d, Modified from Paxinos and Watson (1997), their Figures 11–13.