Adult Brain Neurogenesis, Neural Stem Cells and Neurogenic Niches

During the late 60's, the experiments with brain lesions in rats, suggested the possibility of neurogenesis in the adult brain. Three decades later, the conceptual link between adult neurogenesis and stem cells was proposed. We now know that the adult mammalian brain may have the ability to regenerate through adult neural stem cells (NSCs). Here are briefly reviewed classical and current theories in adult neurogenesis, NSCs and neurogenic niches. Experiments in developmental biology have shown different neurogenic regions according to the capacity of neurogenesis and its presence in different species. Advances in the methodology such as optogenetics and gene reprogramming, allowing the manipulation of different conditions, will guide the discovery of new signaling pathways and interactions, to better understand some aspects recently discussed such as the variation of cell cycle length and the influence of disease conditions, cell heterogeneity and DNA changes. New discoveries in adult neurogenesis, NSCs and neurogenic niches and the developing of new technological tools should guide the NSCs-based therapy, such as gene reprogramming and the insertion of transposable elements (TEs) controlling flanking genes, causing a functional impact for different conditions.