Neither adult born DGCs nor early born DGCs contribute to recurrent excitation in the dentate gyrus in CCI-injured mice. A–C, Representative examples of current traces indicate no eEPSCs in ChR2-negative mature DGCs. Single light pulses (blue lines, 30 ms duration, every 30 s) were used to produce eEPSCs. Five consecutive current traces are shown for CCI ipsilateral, CCI contralateral, and sham controls of DGCs born just before CCI. D–F, DGCs born just before CCI. G–I, DGCs born just after CCI. J–L, Early born DGCs. Summary of proportion of DGCs showing eEPSCs (D,G,J), EPSC number (E,H,K), and EPSC amplitude (F,I,L). M–O, Summary of proportion of DGCs showing eEPSCs observed in Mg²⁺-free ACSF containing bicuculline (30 μm). The numbers above the bars indicate number of mature DGCs showing eEPSCs/number of tested mature DGCs. The numbers next to solid circles indicate number of mature DGCs included in EPSC frequency and amplitude measurements. Data are mean ± SEM.