Neurogenesis in the Adult Mammalian Brain

Over the past decades, it has become well established that neurogenesis occurs in the adult mammalian brain. The new neurons arise from stem or progenitor cells that exist throughout the central nervous system. In culture, stem cells can give rise to neurons, glia and oligodendrocytes. In vivo local factors restrict the genesis of new neurons to the olfactory bulb and hippocampus. The production of new cells in these areas is regulated by a variety of environmental, pharmacological, hormonal, and genetic factors. Although factors that increase neurogenesis have been correlated with improved cognition and mood, the functional significance of the birth of new cells in the adult brain remains unknown at this time.