Figure 1.

Innate and induced neurogenesis in the adult central nervous system. (A) Innate adult neurogenesis mainly occurs in the subgranular zone (SGZ) of the hippocampal dentate gyrus and the subventricular zone (SVZ) of the lateral ventricle. Neural stem cells in these regions generate neurons under physiological and certain pathological conditions. Neurons generated in the SGZ remain in the dentate gyrus, whereas neurons originated from SVZ migrate along the rostral migratory stream (RMS) into the olfactory bulb. (B) Induced adult neurogenesis occurs through cell fate reprogramming in multiple regions of the brain, spinal cord, and retina. Resident glial cells can be directly reprogrammed into mature neurons or progenitors. The induced progenitors can expand through proliferation and eventually give rise to mature neurons. These induced neurons may integrate into the neural networks and promote functional recovery following neural injury or degeneration.