a, The 5-day positive memory stimulation group showed a significant increase of adult new-born cells in the DG as measured by doublecortin (DCX)-positive cells (one-way ANOVA followed by Bonferroni post-hoc test, F5, 72 = 7.634, P < 0.01) relative to control groups.. b–g, Representative images of DCX-positive cells in the DG for the 5-day (b), 1-day (c), Neutral (d), No Stimulation (e), Natural (f), and No Stress (g). h–m, Representative PSA-NCAM images corresponding to data appearing in Figure 4d. n = 5 slices per animal, 13 animals per group for data appearing in (a and b). *P<0.05, n.s. not significant. Data are means +/− SEM.