Institute of Psychology, ELTE Eötvös Loránd University, 1064, Budapest, Hungary; Semmelweis University, Institute of Behavioural Sciences, 1089, Budapest, Hungary.
University of Calgary, Department of Psychology, 2500, Calgary, Alberta, Canada; Budapest University of Technology and Economics, Cognitive Science Department, 1111, Budapest, Hungary.
Neuroimage. 2019 Nov 15;202:116066. doi: 10.1016/j.neuroimage.2019.116066. Epub 2019 Aug 1.
Rapid Eye Movement (REM) sleep is a peculiar neural state showing a combination of muscle atonia and intense cortical activity. REM sleep is usually considered as a unitary state in neuroscientific research; however, it is composed of two different microstates: phasic and tonic REM. These differ in awakening thresholds, sensory processing, and cortical oscillations. Nevertheless, studies examining cortical oscillations during REM microstates are scarce, and used low spatial sampling. Here, we analyzed the data of 18 healthy individuals assessed by high-density sleep EEG recordings. We systematically contrasted phasic and tonic REM periods in terms of topographical distribution, source localization, as well as local, global and long-range synchronization of frequency-specific cortical activity. Tonic periods showed relatively increased high alpha and beta power over frontocentral derivations. In addition, higher frequency components of beta power exhibited increased global synchronization during tonic compared to phasic states. In contrast, in phasic periods we found increased power and synchronization of low frequency oscillations coexisting with increased and synchronized gamma activity. Source localization revealed several multimodal, higher-order associative, as well as sensorimotor areas as potential sources of increased high alpha/beta power during tonic compared to phasic REM. Increased gamma power in phasic REM was attributed to medial prefrontal and right lateralized temporal areas associated with emotional processing. Our findings emphasize the heterogeneous nature of REM sleep, expressed in two microstates with remarkably different neural activity. Considering the microarchitecture of REM sleep may provide new insights into the mechanisms of REM sleep in health and disease.
快速眼动 (REM) 睡眠是一种特殊的神经状态，表现为肌肉弛缓和皮质活动强烈的结合。在神经科学研究中，REM 睡眠通常被视为一个单一的状态；然而，它由两种不同的微状态组成：相位和紧张 REM。这些在唤醒阈值、感觉处理和皮质振荡方面存在差异。然而，研究 REM 微状态期间皮质振荡的研究很少，并且使用的空间采样率较低。在这里，我们分析了 18 名健康个体通过高密度睡眠 EEG 记录评估的数据。我们系统地对比了相位和紧张 REM 期在拓扑分布、源定位以及特定频率皮质活动的局部、全局和长程同步方面的差异。紧张期在前额中央导联显示出相对较高的高 alpha 和 beta 功率。此外，与相位状态相比，紧张状态下 beta 功率的较高频率成分表现出更高的全局同步性。相比之下，在相位期，我们发现低频振荡的功率和同步性增加，同时存在伽马活动的增加和同步性。源定位显示了几个多模态、高阶联合以及感觉运动区域，作为紧张期相对于相位 REM 时高 alpha/beta 功率增加的潜在来源。相位 REM 中伽马功率的增加归因于与情绪处理相关的内侧前额叶和右侧颞叶区域。我们的发现强调了 REM 睡眠的异质性，表现在两种具有显著不同神经活动的微状态中。考虑 REM 睡眠的微观结构可能为 REM 睡眠在健康和疾病中的机制提供新的见解。
