Neurogenesis and Brain Repair

Neurogenesis is a critical process in the formation and development of the neurons that comprise the brain. More recently, the identification of neurogenic regions in the adult brain has suggested that the general process of neurogenesis assumes a role in maintaining the normal brain as well as contributing to the repair of the brain following injury. As identified, adult neurogenesis is the production of new neurons in the adult brain. This is a complex process that is initiated with the division of a precursor cell and, in some cases, neural stem cells that progresses to the generation of functional new neurons. The environments within these neurogenic regions provide intrinsic factors to stimulate and maintain this as a normal process. These include a number of the various growth factors. In addition, there are a number of extrinsic factors that can stimulate this process including life style and environment, as welll as, factors that can inhibit the normal process, such as depression. The potential of these cells to assist in the repair of the brain following injury has fostered the generation of a significant body of research to determine the signals and factors that stimulate the generation and survival of newly generated cells. In addition, efforts to understand the various stimuli that can drive the progenitor or stem cell to a mature neuron or to an oligodendrocyte for the production of myelin have contributed a wealth of information on the nature and plasticity of these cells and this process. The current chapter will address the basic dynamics of neural development with regards to the generation, migration, and maturation of neurons as they provide information to understand the dynamics required for the adult neurogenesis. The identification and details of the neurogenic regions in the adult brain, the growth factors that contribute to maintaining these regions, and the response to injury will be discussed. It is the intent of this chapter to serve as an introduction to adult neurogenesis that can be used as a base for further study and evaluation of the increasing amount of data that is currently being generated.