REM sleep selectively prunes and maintains new synapses in development and learning

We show that rapid eye movement sleep prunes newly-formed postsynaptic dendritic spines of layer 5 pyramidal neurons in the mouse motor cortex during development and motor learning

Wei Li; Lei Ma; Guang Yang; Wen-Biao Gan

2017

Scholarcy highlights

  • Because of its close association with dreaming, the function of rapid eye movement sleep has been a topic of substantial interest and speculation
  • To examine whether REM sleep has a role in synapse pruning, we first used transcranial two-photon microscopy to identify newly-formed and existing postsynaptic dendritic spines of layer V pyramidal neurons in the motor cortex of mice at postnatal day 21
  • By investigating how REM sleep affects postsynaptic dendritic spines of L5 pyramidal neurons, we have revealed multifaceted functions of REM sleep in development and learning via dendritic calcium spike-dependent mechanisms
  • REM sleep contributes to memory consolidation by selectively strengthening and maintaining a fraction of learning-induced new spines that are important for the improvement of motor skills
  • Our studies suggest a role of REM sleep in “unlearning” as REM sleep prunes recently-formed new spines to facilitate subsequent formation of new spines and performance improvement after new learning
  • ND: 30.9 ± 4.3%, NREM sleep disturbance: 35.7 ± 4.5% versus REM sleep deprivation: 13.9 ± 3.8% for new spines formed over 16–24 h and located with 2 μm to transient new spines formed 0–8 h
  • Because dendritic calcium spikes generated during REM sleep differ from those occurring during awake and non-REM sleep states, our findings strongly suggest that endogenous neuronal activity during REM sleep is fundamentally and perhaps uniquely important for the selective maintenance of new synapses during development and in adult life
  • Future studies are required to examine the involvement of Ca2+ spike-timing dependent plasticity and signaling pathways in selectively strengthening and pruning new spines in order to better understand the functions of rapid eye movement sleep in development and learning

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