Sleep functions in synapse remodeling during development and learning

Sleep is maximal during early development and its duration also increases after learning later in life. However, the role of sleep in development and learning remains unclear. Using in vivo two-photon microscopy to monitor changes of synaptic connection and neuronal activity in the cortex of living animals, our recent studies indicate that sleep has multifaceted functions in brain development, learning and memory consolidation: non-rapid eye movement sleep promotes new synapse formation after motor learning by reactivating task-related neurons, while rapid eye movement sleep selectively eliminates and maintains newly formed synapses via dendritic calcium spike-dependent mechanisms.