(A) 42 days after implicit learning, the habituation/cross habituation task indicated that there was still no discrimination between +lim and –lim in the non-enriched control group (Non-Enr) and that the enriched (Enr) group could not longer discriminate them. Indeed, investigation time remained similar between OTest and OHab4 in the non-enriched (Wilcoxon p=0.8, n = 5) and the enriched group (Wilcoxon p=0.34). Both groups habituated correctly (Friedman test, Non-Enr (n = 5, p=0.02; Enr (n = 5, p=0.01). (B) 42 days after implicit learning, no difference in spine density in the apical domain was observed between Non-Enriched (Non-Enr) and Enriched (Enr) animals (Mann-Whitney p=0.23; Enr: 48 dendritic segments n = 4 mice and Non-Enr: 38 dendritic segments n = 4 mice). (C) 37 days after implicit learning, the density of BrdU-positive cells has returned to control non-enriched level (Enr +37 d: n = 5; Anova group effect: F(2,12)=6 p=0.015; 7 days versus 37 days post enrichment, Bonferroni test p=0.04). The data are expressed as mean values ± SEM.