A schematic of the experimental procedure for the one-trial, step-down avoidance inhibitory task (IA) and drug administration schedule, which was the same for all of the animal groups except for the CS group. The rats evaluated by the IA task were subjected to one training session (a 2-s, 0.5-mA footshock (US) associated with a context (CS)). The animals were subjected to five retention test sessions (trials) of IA tasks, and the step-down latencies were measured. No footshock was administered in the test sessions. The interval between trials T1, T2 and T3 was 24 h. T4 and T5 comprised 240- and 480-h intervals, respectively.