Changes in synaptic connections are believed to underlie long-term memory storage. Previous studies have suggested that sleep is important for synapse formation after learning, but how sleep is involved in the process of synapse formation remains unclear. To address this question, we used transcranial two-photon microscopy to investigate the effect of postlearning sleep on the location of newly formed dendritic filopodia and spines of layer 5 pyramidal neurons in the primary motor cortex of adolescent mice. We found that newly formed filopodia and spines were partially clustered with existing spines along individual dendritic segments 24 h after motor training. Notably, posttraining sleep was critical for promoting the formation of dendritic filopodia and spines clustered with existing spines within 8 h. A fraction of these filopodia was converted into new spines and contributed to clustered spine formation 24 h after motor training. This sleep-dependent spine formation via filopodia was different from retraining-induced new spine formation, which emerged from dendritic shafts without prior presence of filopodia. Furthermore, sleep-dependent new filopodia and spines tended to be formed away from existing spines that were active at the time of motor training. Taken together, these findings reveal a role of postlearning sleep in regulating the number and location of new synapses via promoting filopodial formation.

突触连接的变化被认为是长期记忆存储的基础。先前的研究表明，睡眠对于学习后的突触形成很重要，但睡眠如何参与突触形成的过程仍不清楚。为了解决这个问题，我们使用经颅双光子显微镜来研究学习后睡眠对青春期小鼠初级运动皮层中新形成的树突状丝状伪足和第 5 层锥体神经元的刺的位置的影响。我们发现，在运动训练后 24 小时，新形成的丝状伪足和刺与沿着单个树突节的现有刺部分聚集在一起。值得注意的是，训练后的睡眠对于促进在 8 小时内形成树突丝状伪足和与现有棘刺成簇的棘刺至关重要。这些丝状伪足的一部分在运动训练后 24 小时被转化为新的刺，并有助于形成簇状刺。这种通过丝状伪足形成的依赖睡眠的脊柱形成不同于再训练诱导的新脊柱形成，后者是从没有先前存在丝状伪足的树突轴中出现的。此外，依赖睡眠的新丝状伪足和棘刺往往是在运动训练时活跃的现有棘刺之外形成的。总之，这些发现揭示了学习后睡眠通过促进丝状足形成来调节新突触的数量和位置的作用。它从树突状轴中出现而没有事先存在丝状伪足。此外，依赖睡眠的新丝状伪足和棘刺往往是在运动训练时活跃的现有棘刺之外形成的。总之，这些发现揭示了学习后睡眠通过促进丝状足形成来调节新突触的数量和位置的作用。它从树突状轴中出现而没有事先存在丝状伪足。此外，依赖睡眠的新丝状伪足和棘刺往往是在运动训练时活跃的现有棘刺之外形成的。总之，这些发现揭示了学习后睡眠通过促进丝状足形成来调节新突触的数量和位置的作用。