Adult neurogenesis in the dentate gyrus

The dentate gyrus (DG) is a critical component of the hippocampal circuit involved in episodic and spatial memory. The DG contains granule cells (DGCs) that receive excitatory input from the entorhinal cortex (EC) via the perforant pathway and send excitatory mossy fiber projections to the CA3 region. Because of its unique electrophysiologic characteristics and connectivity, the DG may play a major role in the mechanisms of pattern separation that enable the processing of similar experiences as distinct memories. The subgranular zone (SGZ) of the DG is one of the 2 areas that undergo neurogenesis in the adult CNS. Experimental evidence indicates that newly formed DGCs generated during adult neurogenesis, due to their unique properties, have an important role in DG function, including pattern separation. Neurogenesis in the DG is an activity-dependent plastic process that is regulated by multiple chemical signals and environmental factors including stress and physical activity. Neurogenesis in the DG is affected by aging and in several neurologic and psychiatric disorders, including mesial temporal lobe epilepsy (TLE), Alzheimer disease (AD), depression, and schizophrenia, and may be the target for both nonpharmacologic and pharmacologic intervention. These subjects have been extensively reviewed.1–14