Fig. (2).

Hippocampal circuitry remodeling in the epileptic brain and signaling pathways regulating adult hippocampal neurogenesis. Upper panel: Schematic of the hippocampus in normal physiological conditions, sparse DGC-DGC connections are shown. Newborn neurons in the SGZ pass through several consecutive developmental stages. Different signaling pathways exert stage- and cell-specific effects. Lower panel: Schematic of the epileptic brain demonstrating increased recurrent DGC-DGC connections and preferential inputs from hilar ectopic DGCs to adult-born DGCs; back projections from CA3 pyramidal cells preferentially onto adult-born DGCs. Inhibitory inputs (blue dashed line) onto adult-born DGCs from interneurons are maintained, while those onto early-born DGCs are diminished. Increased excitatory inputs (red dashed line) and outputs (black dashed line) indicate their contributions to epileptogenesis. (A higher resolution / colour version of this figure is available in the electronic copy of the article).