In anticipation of the massive burden of neurodegenerative disease within super-aged societies, great ef-forts have been made to utilize neural stem and progenitor cells for regenerative medicine. The capacity of intrinsic neural stem and progenitor cells to regenerate damaged brain tissue remains unclear, due in part to the lack of knowledge about how these newly b neurons integrate into functional circuitry. As sizable integration of adult-b neurons naturally occurs in the dentate gyrus region of the hippocampus, clarify-ing the mechanisms of this process could provide insights for applying neural stem and progenitor cells in clinical settings. There is convincing evidence of functional correlations between adult-b neurons and memory consolidation and sleep; therefore, we describe some new advances that were left untouched in our recent review.