Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
Beijing City Key Lab for Medical Physics and Engineering, Institution of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.
Hum Brain Mapp. 2022 Oct 1;43(14):4383-4396. doi: 10.1002/hbm.25961. Epub 2022 May 26.
Blood oxygenation level-dependent (BOLD) signals in the white matter (WM) have been demonstrated to encode neural activities by showing structure-specific temporal correlations during resting-state and task-specific imaging of fiber pathways with various degrees of correlations in strength and time delay. Previous neuroimaging studies have shown state-dependent functional connectivity and regional amplitude of signal fluctuations in brain gray matter across wakefulness and nonrapid eye movement (NREM) sleep cycles. However, the functional characteristics of WM during sleep remain unknown. Using simultaneous electroencephalography and functional magnetic resonance imaging data during wakefulness and NREM sleep collected from 66 healthy participants, we constructed 10 stable WM functional networks using clustering analysis. Functional connectivity between these WM functional networks and regional amplitude of WM signal fluctuations across multiple low-frequency bands were evaluated. In general, decreased WM functional connectivity between superficial and middle layer WM functional networks was observed from wakefulness to sleep. In addition, functional connectivity between the deep and cerebellar networks was higher during light sleep and lower during both wakefulness and deep sleep. The regional fluctuation amplitude was always higher during light sleep and lower during deep sleep. Importantly, slow-wave activity during deep sleep negatively correlated with functional connectivity between WM functional networks but positively correlated with fluctuation strength in the WM. These observations provide direct physiological evidence that neural activities in the WM are modulated by the sleep-wake cycle. This study provided the initial mapping of functional changes in WM during sleep.
血氧水平依赖（BOLD）信号在白质（WM）中已被证明通过在静息状态和任务特异性纤维通路成像中显示出结构特异性的时间相关性来编码神经活动，这些相关性在强度和时滞上具有不同程度的相关性。以前的神经影像学研究表明，在清醒和非快速眼动（NREM）睡眠周期中，大脑灰质的状态依赖性功能连接和信号波动的区域幅度存在差异。然而，睡眠期间 WM 的功能特征仍然未知。我们使用来自 66 名健康参与者的清醒和 NREM 睡眠期间同时进行的脑电图和功能磁共振成像数据，通过聚类分析构建了 10 个稳定的 WM 功能网络。评估了这些 WM 功能网络之间的功能连接以及多个低频带中 WM 信号波动的区域幅度。一般来说，从清醒到睡眠，浅层和中层 WM 功能网络之间的 WM 功能连接减少。此外，在浅睡眠期间，深部和小脑网络之间的功能连接较高，而在清醒和深度睡眠期间较低。区域波动幅度在浅睡眠期间总是较高，在深度睡眠期间较低。重要的是，深度睡眠期间的慢波活动与 WM 功能网络之间的功能连接呈负相关，而与 WM 中的波动强度呈正相关。这些观察结果提供了直接的生理证据，表明 WM 中的神经活动受睡眠-觉醒周期的调节。本研究提供了睡眠期间 WM 功能变化的初步映射。
