Sekine A, Niiyama Y, Kutsuzawa O, Shimizu T
Department of Neuropsychiatry, Akita University School of Medicine, Akita, Japan.
Psychiatry Clin Neurosci. 2001 Oct;55(5):473-8. doi: 10.1046/j.1440-1819.2001.00892.x.
The present study examined the nature of the negative shift of event-related potential (ERP) recorded during the fully awake state, wakefulness with minor awareness deficit (light drowsiness) and stage 1 of NREM sleep. The cortical responses evoked by two types of auditory stimuli were recorded in nine subjects at the different levels of consciousness described above. A negative component with peak latency of 250-350 msec, N300, was identified in ERP during light drowsiness but not in the fully awake state. In stage 1a (stage 1 without vertex sharp waves), the amplitude of N300 was higher than that in light drowsiness, and it was higher in stage 1b than in stage 1a. The scalp distribution of N300 was predominantly on the vertex. It also confirmed that the vertex sharp wave evoked during stage 1 is maximal on the vertex and its peak latency is approximately 300 msec. Considering the similarity in scalp distribution and peak latency between N300 and vertex sharp wave, it is possible that these electroencephalogram phenomena are generated by an identical synchronizing mechanism in the brain. We assumed that N300 observed during light drowsiness may be an incomplete product of vertex sharp wave.
本研究考察了在完全清醒状态、存在轻微意识缺陷的清醒状态（轻度嗜睡）和非快速眼动睡眠第1阶段记录的事件相关电位（ERP）负向偏移的性质。在上述不同意识水平下，对9名受试者记录了两种类型听觉刺激诱发的皮层反应。在轻度嗜睡期间的ERP中识别出一个峰潜伏期为250 - 350毫秒的负向成分，即N300，但在完全清醒状态下未识别出。在1a期（无顶尖波的第1阶段），N300的波幅高于轻度嗜睡时，且在1b期高于1a期。N300的头皮分布主要在头顶。研究还证实，第1阶段诱发的顶尖波在头顶处最大，其峰潜伏期约为300毫秒。考虑到N300和顶尖波在头皮分布和峰潜伏期上的相似性，这些脑电图现象有可能是由大脑中相同的同步机制产生的。我们推测，在轻度嗜睡期间观察到的N300可能是顶尖波的不完全产物。
