Siclari Francesca, Bernardi Giulio, Riedner Brady A, LaRocque Joshua J, Benca Ruth M, Tononi Giulio
Department of Psychiatry, University of Wisconsin, Madison, Wisconsin.
Department of Psychiatry, University of Wisconsin, Madison, Wisconsin and Laboratory of Clinical Biochemistry and Molecular Biology, University of Pisa, Italy and Clinical Psychology Branch, University of Pisa, AOUP Santa Chiara, Pisa, Italy.
Sleep. 2014 Oct 1;37(10):1621-37. doi: 10.5665/sleep.4070.
To assess how the characteristics of slow waves and spindles change in the falling-asleep process.
Participants undergoing overnight high-density electroencephalographic recordings were awakened at 15- to 30-min intervals. One hundred forty-one falling-asleep periods were analyzed at the scalp and source level.
Sleep laboratory.
Six healthy participants.
Serial awakenings.
The number and amplitude of slow waves followed two dissociated, intersecting courses during the transition to sleep: slow wave number increased slowly at the beginning and rapidly at the end of the falling-asleep period, whereas amplitude at first increased rapidly and then decreased linearly. Most slow waves occurring early in the transition to sleep had a large amplitude, a steep slope, involved broad regions of the cortex, predominated over frontomedial regions, and preferentially originated from the sensorimotor and the posteromedial parietal cortex. Most slow waves occurring later had a smaller amplitude and slope, involved more circumscribed parts of the cortex, and had more evenly distributed origins. Spindles were initially sparse, fast, and involved few cortical regions, then became more numerous and slower, and involved more areas.
Our results provide evidence for two types of slow waves, which follow dissociated temporal courses in the transition to sleep and have distinct cortical origins and distributions. We hypothesize that these two types of slow waves result from two distinct synchronization processes: (1) a "bottom-up," subcorticocortical, arousal system-dependent process that predominates in the early phase and leads to type I slow waves, and (2) a "horizontal," corticocortical synchronization process that predominates in the late phase and leads to type II slow waves. The dissociation between these two synchronization processes in time and space suggests that they may be differentially affected by experimental manipulations and sleep disorders.
评估慢波和纺锤波的特征在入睡过程中如何变化。
对接受夜间高密度脑电图记录的参与者每隔15至30分钟唤醒一次。在头皮和源水平分析了141个入睡期。
睡眠实验室。
6名健康参与者。
连续唤醒。
在向睡眠过渡期间，慢波的数量和振幅遵循两条分离且相交的轨迹：慢波数量在入睡期开始时缓慢增加，在结束时迅速增加，而振幅起初迅速增加，然后呈线性下降。在向睡眠过渡早期出现的大多数慢波振幅大、斜率陡，涉及皮质的广泛区域，在前额内侧区域占主导，且优先起源于感觉运动和顶叶后内侧皮质。后期出现的大多数慢波振幅和斜率较小，涉及皮质的更局限部分，且起源分布更均匀。纺锤波最初稀疏、快速，涉及的皮质区域较少，然后变得更多、更慢，且涉及更多区域。
我们的结果为两种类型的慢波提供了证据，它们在向睡眠过渡过程中遵循分离的时间轨迹，具有不同的皮质起源和分布。我们假设这两种类型的慢波源于两种不同的同步过程：（1）一种“自下而上”的、皮质下皮质的、依赖唤醒系统的过程，在早期占主导并导致I型慢波，以及（2）一种“水平”的、皮质皮质同步过程，在后期占主导并导致II型慢波。这两种同步过程在时间和空间上的分离表明它们可能受到实验操作和睡眠障碍的不同影响。
