Figure 1.

Effects of drugs on memory acquisition, consolidation, and retrieval. Data are expressed as mean latency (sec) ± SEM to enter the dark compartment. (A–C) Show latencies during the adaptation trial (A), learning trial (B), and retention test (C) for rats that received a drug or vehicle injection only before the learning trial. None of the groups differed from vehicle controls during the adaptation or learning trials. During the retention test, performed 24 h after the learning trial, rats that had received scopolamine or THC before the learning trial had significantly shorter latencies than control rats, indicating that these drugs impaired memory acquisition. In contrast, latencies were significantly higher than controls in rats that had received URB597 or WY14643 before the learning trial, indicating that these drugs enhanced memory acquisition. (D) Panel shows that neither URB597 nor WY14643 had a significant effect on latencies during the test in groups that received these drugs immediately after the learning trial or (E) 20 or 40 min, respectively, before the test, indicating that these drugs did not alter memory consolidation or retention. Latencies during the habituation and learning trials for the rats in D are not shown, but were similar to those seen in A and B. From left to right, Ns for the bars in A, B, and C were: 7, 8, 10, 10, 11, 7, 10, 8, 8, and 7; in D: 10, 10, 10, 10, 10, and 9; and in E: 10, 9, 10, 8, 10, and 10. (*) P < 0.05 compared with vehicle control (VEH), paired comparisons performed with Tukey procedure.