In the adult neurogenic niches, neural stem cells (NSCs) generate neurons throughout life. During aging, the number of newborn neurons is clearly reduced, although it is still very debated what specifically happens to the NSCs: do they die, increase their quiescence or change their fate? It is emerging that NSCs are heterogeneous, with different subtypes, in particular quiescent and active NSCs, responding differently to neurogenic stimuli, including aging. However, due to difficulties in distinguishing NSCs subtypes in vivo, their behavior in the physiological environment, their molecular hallmarks, and especially how those are changed during aging are still elusive. These are key questions in neuroscience and stem cell biology. Thanks to the combination of the host laboratory expertise with mine, the current action proposes to develop a strategy to discriminate different NSCs in vivo and shed new light on their behavior, molecular properties and the changes occurring during life. The expected results are going to provide critical information on the regenerative potential of NSCs subtypes and on whether and how the aging phenotype can be reverted, with a consequent strong scientific and social impact.