Neural Stem Cells Behave as a Functional Niche for the Maturation of Newborn Neurons through the Secretion of PTN

？ Ablation of NSCs impairs newborn neuron development in the adult brain ？ NSCs regulate newborn neuron development through the secretion of PTN ？ PTN activates AKT signaling through ALK receptor in newborn neurons ？ Reactivation of AKT signaling ameliorates age-induced defects in newborn neuron