(A) Whole cell recordings were made from immature GCs in control and BaxKOim slices at six weeks post-tamoxifen injection, using picrotoxin to isolate glutamatergic EPSCs. Simultaneous fEPSPs were recorded in the molecular layer as in Figure 1. (B) Immature GCs in control and BaxKOim tdT mice had a similar input resistance that was higher than mature GCs (n = 12, 12, 16, respectively; one-way ANOVA p=0.0004, *p<0.05,***p<0.0001 Bonferroni post hoc test). (C) Left, examples of fEPSPs (top) and EPSCs (bottom) recorded in immature GCs. Middle, an increase in synaptic transmission to immature BaxKO GCs was revealed by the EPSC plotted against fiber volley (two-way ANOVA, Fgenotype (1,143)=18.55 p<0.0001, n = 12 control tdT, 12 BaxKOim tdT; *p<0.05 with Bonferroni post-tests). Right, the EPSC/FV ratio for all stimulus intensities (control 1.24 ± 0.07, n = 80; BaxKOim1.59 ± 0.09, n = 75; unpaired t-test p=0.0029). (D) Schematic showing simultaneous recordings from adjacent tdT- (BaxWT) and tdT+. (BaxKO) GCs in slices from BaxKOim tdT mice at 16 weeks after tamoxifen. (E) Adult-generated BaxKO GCs had larger EPSCs than simultaneously recorded unlabeled mature GCs. EPSCs were normalized to the maximum amplitude of the unlabeled (BaxWT) GC in each slice (two-way ANOVA, Fgenotype (1,94)=11.59 p=0.001, n = 6 pairs), scale bars: 10 ms, 100 pA. Comparing raw EPSCs between pairs of unlabeled and tdT+ GCs across all stimulus intensities confirmed EPSCs were larger in tdT+ GCs (not shown, paired t-test, p<0.0013).