Fig. 2.

Effects of the adenosine A₁ receptor agonist CHA (0.0313–0.125 mg/kg) on inter-response time (IRT) distributions for rats performing on a DRL 72-s schedule. Cumulative IRT for this group of rats obtaining the relative frequency of all responses for each rat separately for each dose condition. The cumulative IRT distribution for the entire group for each CHA dose was compared with the group cumulative IRT distribution for the vehicle condition by using the nonparametric Kolmogorov-Smirnov test. ***, p < 0.001.