Figure 2: Preferential spiking of mature GCs in response to EC stimulation.

(a) Diagram of dual stimulation in the medial and lateral EC (MEC/LEC) in horizontal slices. (b) The fraction of spiking mature GCs was increased by gabazine (3 μM, magenta, n=32). Repeated-measures two-way ANOVA: factor Gbz, F_(1,62)=12.35, P=0.008; factor stimulus, F_(4,248)=17.04, P=0.0001; Interaction, F_(4,248)=2.84, P=0.025, Tukey’s post-test *P<0.05; **P<0.01). Inset, example EPSPs in control (black) and gabazine (magenta). Scale, 40 mV, 40 ms. All symbols are mean±s.e.m. (c) Reconstructions of a typical immature (teal) and mature (black) GC, showing the smaller dendritic arbor of immature GCs²². Scale, 50 μm. (d) Sequential recordings from mature GCs (black) and immature GCs (teal) show smaller EPSCs in immature GCs (n=18 pairs of mature and immature GCs). Scale, 20 pA, 50 ms. Repeated-measures two-way ANOVA: factor cell age, F_(1,34)=9.6, P=0.004; factor stimulus, F_(4,136)=12.8, P<0.0001; interaction, F_(4,136)=3.6, P=0.008; and Tukey’s post-test *P<0.05;**P<0.01. (e) EPSPs were also smaller in the same mature and immature GC recordings (n=18). Scale, 5 mV, 50 ms. Repeated-measures two-way ANOVA: factor cell age, F_(1,34)=10.18, P=0.003; factor stimulus, F_(4,136)=30.6, P<0.0001; interaction, F_(4,136)=3.3, P=0.012; Tukey’s post-test *P<0.05;**P<0.01. (f) The spiking probability of immature GCs remained 0 at all MEC/LEC stimulus intensities, even when inhibition was blocked (magenta). Insets, EPSPs were enhanced by gabazine and all immature GCs could spike with current injections. Scale bar: 5 mV, 20 ms (top); and 20 mV, 200 ms (bottom). ANOVA, analysis of variance.