The occurrence of dreaming during rapid eye movement (REM) sleep prompts interest in the role of REM sleep in hippocampal-dependent episodic memory. Within the mammalian hippocampus, the dentate gyrus (DG) has the unique characteristic of exhibiting neurogenesis persisting into adulthood. Despite their small numbers and sparse activity, adult-born neurons (ABNs) in the DG play critical roles in memory; however, their memory function during sleep is unknown. Here, we investigate whether young ABN activity contributes to memory consolidation during sleep using Ca²⁺ imaging in freely moving mice. We found that contextual fear learning recruits a population of young ABNs that are reactivated during subsequent REM sleep against a backdrop of overall reduced ABN activity. Optogenetic silencing of this sparse ABN activity during REM sleep alters the structural remodeling of spines on ABN dendrites and impairs memory consolidation. These findings provide a causal link between ABN activity during REM sleep and memory consolidation.

快速眼动（REM）睡眠期间做梦的发生促使人们对REM睡眠在海马依赖性情节性记忆中的作用感兴趣。在哺乳动物海马中，齿状回（DG）具有表现出持续到成年的神经发生的独特特征。尽管数量少且活动稀疏，但DG中的成年神经元（ABNs）在记忆中起着关键作用。但是，他们在睡眠中的记忆功能尚不清楚。在这里，我们调查年轻的ABN活动是否有助于使用Ca ^2+的睡眠过程中的记忆巩固自由移动小鼠的成像。我们发现情境恐惧学习招募了一群年轻的ABN，这些ABN在随后的REM睡眠期间会在ABN总体活动减少的背景下重新激活。REM睡眠期间这种稀疏ABN活性的光遗传沉默可改变ABN树突上棘的结构重塑，并损害记忆巩固。这些发现提供了REM睡眠期间ABN活动与记忆巩固之间的因果关系。