Neural stem cells (NSCs) in the adult brain transit from the quiescent state to proliferation to produce new neurons. The mechanisms regulating this transition in freely behaving animals are, however, poorly understood. We customized in vivo imaging protocols to follow NSCs for several days up to months, observing their activation kinetics in freely behaving mice. Strikingly, NSC division is more frequent during daylight and is inhibited by darkness-induced melatonin signaling. The inhibition of melatonin receptors affected intracellular Ca²⁺ dynamics and promoted NSC activation. We further discovered a Ca²⁺ signature of quiescent versus activated NSCs and showed that several microenvironmental signals converge on intracellular Ca²⁺ pathways to regulate NSC quiescence and activation. In vivo NSC-specific optogenetic modulation of Ca²⁺ fluxes to mimic quiescent-state-like Ca²⁺ dynamics in freely behaving mice blocked NSC activation and maintained their quiescence, pointing to the regulatory mechanisms mediating NSC activation in freely behaving animals.

成人大脑中的神经干细胞 (NSC) 从静止状态转变为增殖状态以产生新的神经元。然而，在自由行为的动物中调节这种转变的机制却知之甚少。我们定制了体内成像协议，以跟踪 NSC 数天至数月，观察它们在自由行为小鼠中的激活动力学。引人注目的是，NSC 分裂在白天更频繁，并且被黑暗诱导的褪黑激素信号抑制。褪黑激素受体的抑制影响细胞内 Ca ²⁺动力学并促进 NSC 活化。我们进一步发现了静止与激活的 NSCs的 Ca ²⁺特征，并表明几种微环境信号会聚在细胞内 Ca ^{2+ 上}调节 NSC 静止和激活的途径。体内NSC 特异性光遗传学调节 Ca ²⁺通量以模拟自由行为小鼠中类似静止状态的 Ca ²⁺动力学，阻止 NSC 激活并维持其静止状态，这表明在自由行为动物中介导 NSC 激活的调节机制。