Developmental dynamics of neurogenesis and gliogenesis in the postnatal mammalian brain in health and disease: Historical and future perspectives

Abstract

The mature mammalian brain has long been thought to be a structurally rigid, static organ since the era of Ramón y Cajal in the early 20th century. Evidence accumulated over the past three decades, however, has completely overturned this long‐held view. We now know that new neurons and glia are continuously added to the brain at postnatal stages, even in mature adults of various mammalian species, including humans. Moreover, these newly added cells contribute to structural plasticity and play important roles in higher order brain function, as well as repair after damage. A major source of these new neurons and glia is neural stem cells (NSCs) that persist in specialized niches in the brain throughout life. With this new view, our understanding of normal brain physiology and interventional approaches to various brain disorders has changed markedly in recent years. This article provides a brief overview on the historical changes in our understanding of the developmental dynamics of neurogenesis and gliogenesis in the postnatal and adult mammalian brain and discusses the roles of NSCs and other progenitor populations in such cellular dynamics in health and disease of the postnatal mammalian brain.