Adult neurogenesis

Abstract

Adult neurogenesis is the generation of new neurons in the adult brain. Adult neurogenesis is an exception, as the brain of mammals is non-neurogenic. Rodents and primates have two neurogenic zones, the hippocampus and the olfactory bulb. Lower vertebrates often have many more sites of adult neurogenesis. In the peripheral nervous system, there is high neurogenesis in the olfactory epithelium. Neurogenesis in the olfactory bulb originates from precursor cells in the wall of the lateral ventricle, the subventricular zone. New interneurons in the bulb are produced. In the dentate gyrus of the hippocampus, new excitatory granule cells are generated that add to the mossy fiber tract into hippocampal area CA3. Numerous factors are known to regulate neurogenesis: it seems that adult neurogenesis responds very sensitively to external stimuli. The current hypothesis is that adult hippocampal neurogenesis critically contributes to hippocampal function, allowing life-long adaptation processes. If adult neurogenesis fails, this might contribute to several important diseases, including dementias, major depression and schizophrenia, as well as temporal lobe epilepsy.