The majority of neurons constituting the mammalian brain develop from NPCs (see Glossary) during embryonic periods (Box 1) [1–5]. After neuronal production, generation of glial cells from NPCs follows and continues in the postnatal brain. Neurons are also continuously produced from NPCs in two restricted regions of the adult brain, the subventricular zone of the lateral ventricles and the subgranular zone of the hippocampal dentate gyrus; these neurons play important roles in learning and memory by remodeling the preexistent neural circuit [6–8].
