International Institute for Integrative Sleep Medicine, University of Tsukuba, Ibaraki 305-8575, Japan.
Department of Statistical Modeling, The Institute of Statistical Mathematics, Tokyo 190-8562, Japan.
Cereb Cortex. 2020 Jun 1;30(7):3977-3990. doi: 10.1093/cercor/bhaa012.
Sleep exerts modulatory effects on the cerebral cortex. Whether sleep modulates local connectivity in the cortex or only individual neural activity, however, is poorly understood. Here we investigated functional connectivity, that is, covarying activity between neurons, during spontaneous sleep-wake states and during and after sleep deprivation using calcium imaging of identified excitatory/inhibitory neurons in the motor cortex. Functional connectivity was estimated with a statistical learning approach glasso and quantified by "the probability of establishing connectivity (sparse/dense)" and "the strength of the established connectivity (weak/strong)." Local cortical connectivity was sparse in non-rapid eye movement (NREM) sleep and dense in REM sleep, which was similar in both excitatory and inhibitory neurons. The overall mean strength of the connectivity did not differ largely across spontaneous sleep-wake states. Sleep deprivation induced strong excitatory/inhibitory and dense inhibitory, but not excitatory, connectivity. Subsequent NREM sleep after sleep deprivation exhibited weak excitatory/inhibitory, sparse excitatory, and dense inhibitory connectivity. These findings indicate that sleep-wake states modulate local cortical connectivity, and the modulation is large and compensatory for stability of local circuits during the homeostatic control of sleep, which contributes to plastic changes in neural information flow.
睡眠对大脑皮层具有调节作用。然而，睡眠是否调节皮层中的局部连接，或者仅仅调节单个神经元的活动，目前还知之甚少。在这里，我们使用运动皮层中鉴定出的兴奋性/抑制性神经元的钙成像技术，在自发的睡眠-觉醒状态期间以及在睡眠剥夺期间和之后，研究了功能连接性，即神经元之间的协变活动。使用统计学习方法 glasso 估计功能连接性，并通过“建立连接的概率（稀疏/密集）”和“建立连接的强度（弱/强）”来量化。非快速眼动（NREM）睡眠时局部皮质连接稀疏，快速眼动（REM）睡眠时连接密集，这种情况在兴奋性和抑制性神经元中都相似。连接的整体平均强度在自发的睡眠-觉醒状态之间没有太大差异。睡眠剥夺诱导了强烈的兴奋性/抑制性和密集的抑制性连接，但没有兴奋性连接。睡眠剥夺后的随后的 NREM 睡眠表现出弱的兴奋性/抑制性、稀疏的兴奋性和密集的抑制性连接。这些发现表明，睡眠-觉醒状态调节局部皮质连接，这种调节在睡眠的稳态控制期间对局部回路的稳定性具有较大的补偿作用，有助于神经信息流的可塑性变化。
