Campbell Kenneth B, Colrain Ian M
School of Psychology, University of Ottawa, Ottawa, Canada K1N 6N5.
Int J Psychophysiol. 2002 Dec;46(3):197-214. doi: 10.1016/s0167-8760(02)00112-5.
The loss of consciousness during the sleep onset period is associated with dramatic changes in information processing. Human event-related potentials (ERPs) reflect these changes. Short- and mid-latency ERPs are only minimally affected by sleep onset. On the other hand, long-latency ERPs are very much affected. A negative wave, N1, peaking at approximately 100 ms gradually decreases in amplitude until it reaches baseline level during definitive stage 2 sleep. The changes in N1 are especially apparent when the subject no longer signals awareness of the external stimulus or when stage 1 is dominated by theta activity in the EEG. The positive peaks, P1 and P2, peaking at approximately 50 and 180 ms, respectively, may appear to increase in amplitude (i.e. also be less negative). A long-lasting processing negativity (PN) may overlap and summate with these peaks during the waking state. During sleep onset, the PN dissipates, thus explaining the apparent positive baseline shift in the ERP waveform. In an oddball task, when an alert and awake subject detects a rare, relevant stimulus, a large positive wave, P300, maximum over parietal areas of the scalp, is observed. This P300 is, however, widely dispersed and can be observed over frontal areas of the scalp. When the subject no longer signals detection of this target stimulus, P300 can no longer be recorded. During stage 1, the parietal P300 remains large, providing the subject overtly detects the target. The amplitude of the frontal aspect of P300 is much reduced as response times slow. This may reflect deactivation of the frontal lobes during the sleep onset period. The infrequent change of an otherwise rapidly presented homogenous train of stimuli is associated with another long-lasting negativity, the mismatch negativity (MMN). The MMN also decreases in amplitude during the sleep onset period, reaching baseline level during definitive sleep. The vertex sharp wave (VSW) becomes apparent during the sleep onset period. Associated with the VSW is a late negative ERP, sometimes called the sleep N2 or the N350, peaking between 300 and 350 ms. It is unique to the sleep onset and sleep periods, becoming very large during stage 1-theta or when the subject no longer shows signs of awareness of the external stimulus.
睡眠开始阶段的意识丧失与信息处理的显著变化有关。人类事件相关电位（ERP）反映了这些变化。短潜伏期和中潜伏期ERP受睡眠开始的影响最小。另一方面，长潜伏期ERP受影响很大。一个负波，N1，在大约100毫秒达到峰值，其幅度逐渐减小，直到在确定的2期睡眠期间达到基线水平。当受试者不再表明对外部刺激有意识，或者当1期以脑电图中的θ活动为主时，N1的变化尤为明显。正峰，P1和P2，分别在大约50毫秒和180毫秒达到峰值，其幅度可能会增大（即负性也减小）。在清醒状态下，一个持续时间较长的加工负波（PN）可能会与这些峰值重叠并叠加。在睡眠开始时，PN消散，从而解释了ERP波形中明显的正性基线偏移。在一个oddball任务中，当一个警觉且清醒的受试者检测到一个罕见的、相关的刺激时，会观察到一个大的正波，P300，在头皮顶叶区域达到最大值。然而，这个P300分布广泛，也可以在头皮额叶区域观察到。当受试者不再表明检测到这个目标刺激时，就无法再记录到P300。在1期，顶叶P300仍然很大，前提是受试者能明显检测到目标。随着反应时间变慢，P300额叶部分的幅度会大幅降低。这可能反映了睡眠开始阶段额叶的失活。在一系列快速呈现的同质刺激中偶尔出现的变化与另一个持续时间较长的负波，失匹配负波（MMN）有关。MMN在睡眠开始阶段幅度也会减小，在确定的睡眠期间达到基线水平。顶点尖波（VSW）在睡眠开始阶段变得明显。与VSW相关的是一个晚期负性ERP，有时称为睡眠N2或N350，在300到350毫秒之间达到峰值。它是睡眠开始和睡眠阶段所特有的，在1期-θ阶段或当受试者不再表现出对外部刺激有意识的迹象时变得非常大。
