(A) AAV-DIO-YFP or AAV-Flex-taCaspase3 injection scheme into the MS of adult VGAT-Cre mice. (B) Experimental scheme of chronic ablation of MS GABAergic neurons in VGAT-Cre mice. (C) Confocal images showing selective ablation of GABAergic neurons in the MS 6 weeks after AAV injection. Scale bar: 50 µm. (D) Number of GABAergic neurons in the MS. (n=3 for control and caspase). (E) Number of cholinergic neurons in the MS (n=3 for control and caspase). (F) Confocal images of the nestin+ and EdU+ cells in the DG from control and caspase conditions at 6 wpi. Scale bar: 50 µm. (G–I) rNSC activation and rNSC pool at 1, 2, and 6 wpi. Data are normalized to control. (G) Normalized fold change in percent of rNSC activation, (H) nestin+ rNSC pool and (I) activated NSCs (nestin+EdU+). (1 and 2 wpi: n=4 for control and caspase. 6 wpi: n=5 for control, and n=4 for caspase). (J) Confocal images of Tbr2 and EdU+ cells in the DG for the control and caspase conditions at 6 wpi. Scale bar: 50 µm. (K) Density of proliferating cells (EdU+), proliferating progenitors (Tbr2+EdU+) and mitotic neuroblasts (DCX+EdU+) at 6 wpi. (n=4 for control and caspase). (L) Density of differentiating astrocytes (GFAP+EdU+). (n=4 for control and caspase). *p<0.05, **p<0.01, ***p<0.001 by Student’s t-test. Values represent mean ± S.E.M. See also Figure S6.