NREM sleep improves behavioral performance by desynchronizing cortical circuits

Sleep improves cognitive performance, yet little is known about the neural mechanisms of this improvement. We performed multielectrode recording in macaque visual and dorsolateral prefrontal cortex while animals performed a visual discrimination task before and after non-rapid eye movement (NREM) sleep. Although sleep induces synchronized fluctuations in population activity across cortical areas, the post-sleep population activity became more desynchronized relative to the pre-sleep state. The changes after sleep were correlated with an increase in information encoded in population activity in each area and improved behavioral performance. Electrically stimulating visual cortex at 4 hertz emulated the beneficial effects of sleep on network and perceptual performance. A large-scale neural network model indicated that asymmetric depression of local intracortical synapses is consistent with the observed changes in neural activity after sleep.