Sleep promotes branch-specific formation of dendritic spines after learning

TLDR

The role of sleep in learning and memory remains unclear. Sleep following motor learning selectively induces new dendritic spines on specific branches of layer V pyramidal neurons, protects these spines from elimination, and requires neuronal reactivation during NREM, thereby supporting learning‑dependent synapse formation and memory storage.

Abstract

How sleep helps learning and memory remains unknown. We report in mouse motor cortex that sleep after motor learning promotes the formation of postsynaptic dendritic spines on a subset of branches of individual layer V pyramidal neurons. New spines are formed on different sets of dendritic branches in response to different learning tasks and are protected from being eliminated when multiple tasks are learned. Neurons activated during learning of a motor task are reactivated during subsequent non-rapid eye movement sleep, and disrupting this neuronal reactivation prevents branch-specific spine formation. These findings indicate that sleep has a key role in promoting learning-dependent synapse formation and maintenance on selected dendritic branches, which contribute to memory storage.