Fig. 5.

Effects of the adenosine A₁ receptor agonist CHA (0.0625 mg/kg) on IRT distributions for rats performing on a DRL 72-s schedule in both the absence and the presence of the adenosine A₁ receptor antagonist DPCPX (0.31 mg/kg). Cumulative IRT distributions for the entire group of 13 rats are plotted for each of the respective dose conditions, including a replication of the CHA-alone effect. Only the two different CHA-alone treatments were significantly different from the vehicle condition. ***, p < 0.001, K-S test.