Dex was administered at P1 or P7 and behavioral tasks were performed at P56. (A) The freezing response in contextual fear-conditioning task was significantly greater in the Dex-P7 group than in the other groups (two-way ANOVA with Bonferroni multiple comparisons test, n = 8 for each group *p < 0.05), and Dex-P7 group was significantly greater than NS-P7 group (F[1,28] = 4.59, *p < 0.05). (B) The freezing response in the cued fear-conditioning task was not significantly altered among the four groups (n = 8 for each group). (C) The proportion of time spent searching in target quadrant was significantly higher in the Dex group (64.50 ± 1.50) than in the NS group (48.75 ± 1.56) (Mann-Whitney test, n = 5 for each group, *p < 0.05). (D) The number of crossings in the platform location was higher in the Dex group (12.20 ± 0.22) than in the NS group (6.75 ± 0.55) (Mann-Whitney test, n = 5 for each group, *p < 0.05). The data are expressed as mean ± SEM of three independent experiments.