Figure 3.

Accuracy of inhibitory avoidance discrimination memory. Inhibitory avoidance retention latencies (mean ± SEM) in seconds. The different training procedures are shown as schematic for each of the experiments. (A) Rats were trained in Box B (Non-Shock box, blue) without footshock followed 1 min later by footshock training in Box A (Shock box, red). On the 48-h retention test rats were sequentially tested in all three inhibitory avoidance apparatuses in a random order and without delay. Retention latencies in the previously visited Box A and Box B did not differ from each other but were both significantly longer than those in Box C (Novel box, gray). ♦♦♦, P < 0.0001 vs. Box A and Box B. N = 30 rats. (B) The order of retention testing in the three boxes (ABC, ACB, BAC, BCA, CAB, CBA) did not significantly influence retention latencies. (C) On the training trial rats were first placed in Box C (Non-Shock box) followed 1 min later by footshock training in Box A (Shock box). Forty-eight-hour retention latencies in the two previously visited boxes (Box A and Box C) did not differ from each other but were both significantly longer than those in Box B (Novel box). ♦♦♦, P < 0.0001 vs. Box A and Box C. N = 13 rats. (D) Rats were trained in Box A (Shock box). Forty-eight-hour retention latencies in Box A were significantly longer than those in Box B and C. ♦♦♦, P < 0.0001 vs. Box A. N = 20 rats. (E) When the interval between training in Box B (Non-Shock box) and Box A (Shock box) was 2 min, 48-h retention latencies in Box A were significantly longer than those in Box B and Box C (Novel box). ★★★, P < 0.0001 vs. Box A. ♦♦♦, P < 0.0001 vs. Box A. N = 15 rats. (F) Yohimbine (0.3 mg/kg, sc) administered immediately posttraining enhanced 48-h retention latencies for the Shock box (Box A). Retention latencies in Box A (Shock box) were significantly longer than those in Box B (Non-Shock box) and Box C (Novel box). ★, P < 0.05 vs. the saline group. ★★, P < 0.01 vs. Box A. ♦♦♦, P < 0.0001 vs. Box A. N = 12 rats/group.