Brain & Behaviour Research Institute and School of Psychology, University of Wollongong, Wollongong 2522, Australia.
Clin Neurophysiol. 2011 Oct;122(10):2010-5. doi: 10.1016/j.clinph.2011.02.036. Epub 2011 Apr 12.
Studies indicate that the change from closed to open eyes in a resting condition results in an increase in skin conductance level (SCL) and a global decrease in EEG alpha activity, both indicative of increased arousal. Other studies show that ingestion of caffeine also produces SCL increase and alpha reduction. This study investigated the additivity of the effects of these two independent arousing variables.
EEG activity and SCL were recorded from 22 university students during both eyes-closed and eyes-open resting conditions, under the action of both caffeine and placebo, in a counterbalanced randomised double-blind study.
SCL increased significantly from eyes-closed to eyes-open conditions, and from placebo to caffeine, with no interaction. Global reductions in EEG alpha amplitude were apparent with opening of the eyes and caffeine ingestion; again, there was no interaction. Caffeine had a larger effect than opening the eyes on SCL, but their relative effect sizes were reversed in alpha. The two dependent measures showed the predicted negative correlation in both eyes-closed placebo and eyes-open caffeine conditions, with the latter substantially reduced relative to the former.
Caffeine and opening the eyes have additive effects on two measures of arousal, increasing SCL and reducing global EEG alpha. However, the independent variable effects are not equivalent, suggesting that one or both measures reflect additional non-arousal processes.
As caffeine is widely used by both children and adults, knowledge of the additivity of arousal effects of caffeine and opening the eyes is important in controlling participant state in EEG studies. The current results confirm the use of mean global alpha amplitude as a measure of resting-state arousal, but also point to non-arousal effects of visual input.
研究表明，在静止状态下，从闭眼到睁眼的转变会导致皮肤电导率（SCL）增加和 EEGα 活动整体减少，这两者都表明唤醒度增加。其他研究表明，咖啡因摄入也会导致 SCL 增加和α 减少。本研究探讨了这两种独立的唤醒变量的效果的相加性。
在一项随机双盲对照研究中，对 22 名大学生的 EEG 活动和 SCL 在闭眼和睁眼静息状态下，在咖啡因和安慰剂的作用下进行了记录。
SCL 在睁眼状态下从闭眼状态显著增加，在咖啡因摄入时从安慰剂状态显著增加，没有交互作用。EEGα 振幅的全局减少在睁眼和咖啡因摄入时明显；同样，没有交互作用。咖啡因对 SCL 的影响大于睁眼，但它们的相对效应大小在α中相反。在两种依赖于测量的情况下，在闭眼安慰剂和睁眼咖啡因条件下都出现了预期的负相关，后者相对于前者显著降低。
咖啡因和睁眼对两种唤醒测量有相加作用，增加 SCL 和减少全局 EEGα。然而，独立变量的影响并不相等，这表明一种或两种测量都反映了额外的非唤醒过程。
由于咖啡因被儿童和成人广泛使用，了解咖啡因和睁眼对唤醒作用的相加性对于控制 EEG 研究中的参与者状态非常重要。当前的结果证实了使用平均全局α 振幅作为静息状态唤醒的测量，同时也指向了视觉输入的非唤醒作用。
