Neurogenesis

Neurogenesis is the process through which neurons form in the brain. It is an important and complex process in which neurons are generated from stem cells. Neurogenesis is the foundation for the formation of new brain circuitry and is fundamental for learning and memory. During fetal development, neurogenesis primarily takes place in the subventricular zone of the forebrain and the ventricular–subventricular zone of the midbrain. Neural stem cells in these regions give rise to post-mitotic neurons that migrate to their final destination in the developing brain. At birth, the newborn brain has almost the same number of neurons as the adult brain. After birth, neurogenesis continues to occur in the adult brain in two regions of the brain, the subgranular zone of the dentate gyrus of the hippocampus and the subventricular zone of the frontal lobe. In the subgranular zone, neural stem cells generate granule neurons of the dentate gyrus. In the subventricular zone, neural stem cells generate interneurons of the olfactory bulb. The stem cells that form neurons in the adult brain are not the same as those that form neurons in the developing brain and are referred to as adult neural stem cells (ANSCs). ANSCs are multi-potent, meaning they can form multiple types of neurons. They are also plastic, meaning they can respond to different biological and environmental cues and migrate to different areas of the brain. It is thought that one purpose of neurogenesis in the adult brain is to support memory formation in the hippocampus. While the mechanism of how neurogenesis contributes to memory formation is unclear, research suggests that newly formed neurons integrate into existing networks in the hippocampus through neuronal connections and that these connections contribute to the formation of new memories. Neurogenesis is an important and complex process of brain development. It is responsible for generating neurons from stem cells, enabling the formation of new circuitry throughout the brain and is likely to be involved in memory formation. In order to better understand the process, continued research on neurogenesis across species and its potential implications is needed.