Figure 1  Two overlapping phases of NSCs – expansion of the stem cell pool and the subsequent switch to the neurogenic period–during embryonic development. Changes in stem and progenitor cells (gray cells) and neural precursors (orange cells) during these phases may contribute to later cortical phenotypes found in neuropsychiatric disorders. These changes are driven by both extrinsic and intrinsic factors to stem and progenitor cells, which influence each other in complex manner.