MadSci Network: Neuroscience |
Neurogenesis is a term that refers to the process of making neurons. During embryogenesis, certain areas of the developing embryo, called the neuroectoderm will eventually become the nervous system. I don't have the space to describe all that is known to be involved in process and suggest that you refer to a basic neuroscience textbook. Probably the major question in developmental biology deals with the process of differentiation. In an adult, the cells that make up the various organs and structures have distinct characteristics - you can tell a liver cell from a muscle cell from a neuron. But there is a time during embryogenesis when this is not the case and an embryonic cell can become one of several types of cells (we often call these type of cells pleurypotent cells, precursor cells, or stem cells). These stem cells differentiate into specific types of cells (like liver cells or neurons) due to several different factors including what genes are turned on in them, proximity to other cells, and their extracellular environment. The precursor cells to neurons are called neuroblasts. The differentiation of neuroblasts into neurons is neurogenesis. Neurogenesis is also used to describe the formation of the various structures of the nervous system, for example the neocortex or the cerebellum. The nervous system is highly complex, very structured, and made up of many different types of neurons and non-neuronal cells. Each cell must end up in the proper place and perform the correct function if the nervous system is to work properly. Until recently, it was thought that there was no neurogenesis in the adult brain. It was thought that you were born with the entire complement of neurons you would ever have because neurons are 'terminally differentiated', that is, they do not divide once they become neurons. However, recent experimental evidence suggests that this is not necessarily the case and that neuronal precursor cells can still be found in the adult brain. I hope this helped to answer your question.
Try the links in the MadSci Library for more information on Neuroscience.