Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel.
Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
Cereb Cortex. 2018 Apr 1;28(4):1297-1311. doi: 10.1093/cercor/bhx043.
During sleep, external sensory events rarely elicit a behavioral response or affect perception. However, how sensory processing differs between wakefulness and sleep remains unclear. A major difficulty in this field stems from using brief auditory stimuli that often trigger nonspecific high-amplitude "K-complex" responses and complicate interpretation. To overcome this challenge, here we delivered periodic visual flicker stimulation across sleep and wakefulness while recording high-density electroencephalography (EEG) in humans. We found that onset responses can be separated from frequency-specific steady-state visual evoked potentials (SSVEPs) selectively observed over visual cortex. Sustained SSVEPs in response to fast (8/10 Hz) stimulation are substantially stronger in wakefulness than in both nonrapid eye movement (NREM) and REM sleep, whereas SSVEP responses to slow (3/5 Hz) stimulation are stronger in both NREM and REM sleep than in wakefulness. Despite wake-like spontaneous activity, responses in REM sleep were similar to those in NREM sleep and different than wakefulness, in accordance with perceptual disconnection during REM sleep. Finally, analysis of amplitude and phase in single trials revealed that stronger fast SSVEPs in wakefulness are driven by more consistent phase locking and increased induced power. These results suggest that the sleeping brain is unable to effectively synchronize large neuronal populations in response to rapid sensory stimulation.
在睡眠期间，外部感觉事件很少引起行为反应或影响感知。然而，感觉处理在清醒和睡眠之间有何不同仍不清楚。该领域的一个主要困难源于使用短暂的听觉刺激，这些刺激通常会引发非特异性的高振幅“K-复合”反应，从而使解释变得复杂。为了克服这一挑战，我们在这里在人类睡眠和觉醒期间进行周期性的视觉闪烁刺激，同时记录高密度脑电图 (EEG)。我们发现，起始反应可以与仅在视觉皮层上选择性观察到的特定频率的稳态视觉诱发电位 (SSVEP) 分开。对快速 (8/10 Hz) 刺激的持续 SSVEP 在觉醒时比在非快速眼动 (NREM) 和 REM 睡眠时都要强得多，而对慢速 (3/5 Hz) 刺激的 SSVEP 反应在 NREM 和 REM 睡眠时都比在觉醒时要强。尽管有类似于觉醒的自发活动，但 REM 睡眠中的反应与 NREM 睡眠中的反应相似，与 REM 睡眠期间的感知分离不同。最后，对单试次的幅度和相位分析表明，在觉醒时更强的快速 SSVEP 是由更一致的相位锁定和增加的诱发电功率驱动的。这些结果表明，睡眠中的大脑无法有效地响应快速感觉刺激来同步大量神经元群体。
