Neurovascular coupling (NVC), the transient regional hyperemia following the evoked neuronal responses, is the basis of blood oxygenation level-dependent techniques and is generally adopted across physiological conditions, including the intrinsic resting state. However, the possibility of neurovascular dissociations across physiological alterations is indicated in the literature. To examine the NVC stability across sleep–wake states, we used electroencephalography (EEG) as the index of neural activity and functional magnetic resonance imaging (fMRI) as the measure of cerebrovascular response. Eight healthy adults were recruited for simultaneous EEG-fMRI recordings in nocturnal sleep. We compared the cross-modality (EEG vs. fMRI) consistency of functional indices (spectral amplitude and functional connectivity) among five states of wakefulness and sleep (state effect). We also segregated the brain into three main partitions (anterior, middle and posterior) for spatial assessments (regional effect). Significant state effects were found on δ, α and fMRI indices and regional effects on the α and fMRI indices. However, the cross-state EEG changes in spectral amplitude and functional connectivity did not consistently match the changes in the fMRI indices across sleep–wake states. In spectral amplitude, the δ band peaked at the N3 stage for all brain regions, while the fMRI fluctuation amplitude peaked at the N2 stage in the central and posterior regions. In regional connectivity, the inter-hemispheric connectivity of the δ band peaked at the N3 stage for all regions, but the bilateral fMRI connectivity showed the state changes in the anterior and central regions. The cross-modality inconsistencies across sleep–wake states provided preliminary evidence that the neurovascular relationship may not change in a linear consistency during NREM sleep. Thus, caution shall be exercised when applying the NVC presumption to investigating sleep/wake transitions, even among healthy young adults.

中文翻译：

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睡眠-觉醒状态下脑电图和 fMRI 指数之间的不一致表明动态神经血管耦合

神经血管耦合 (NVC) 是诱发神经元反应后的短暂局部充血，是血液氧合水平依赖技术的基础，通常在生理条件下采用，包括内在静息状态。然而，文献中指出了跨生理改变的神经血管分离的可能性。为了检查睡眠 - 觉醒状态下的 NVC 稳定性，我们使用脑电图 (EEG) 作为神经活动的指标，使用功能磁共振成像 (fMRI) 作为脑血管反应的测量。招募了八名健康成年人在夜间睡眠中同时进行 EEG-fMRI 记录。我们比较了跨模态（EEG vs. fMRI) 五种清醒和睡眠状态（状态效应）之间功能指标（频谱幅度和功能连接）的一致性。我们还将大脑分为三个主要分区（前、中和后）用于空间评估（区域效应）。在 δ、α 和 fMRI 指数上发现了显着的状态效应，对 α 和 fMRI 指数发现了区域效应。然而，频谱幅度和功能连接的跨状态脑电图变化与睡眠-觉醒状态下 fMRI 指数的变化并不一致。在频谱幅度上，δ波段在所有脑区的N3期达到峰值，而fMRI波动幅度在中区和后区的N2期达到峰值。在区域连通性方面，各区域δ波段的半球间连通性在N3阶段达到顶峰，但双边 fMRI 连接显示前部和中央区域的状态变化。跨睡眠-觉醒状态的跨模态不一致提供了初步证据，表明神经血管关系在 NREM 睡眠期间可能不会以线性一致性发生变化。因此，即使在健康的年轻人中，在将 NVC 假设应用于调查睡眠/觉醒过渡时也应谨慎行事。