Gasser T, Ziegler P, Gattaz W F
Central Institute of Mental Health, Mannheim, Federal Republic of Germany.
Eur Arch Psychiatry Clin Neurosci. 1992;241(6):352-6. doi: 10.1007/BF02191960.
The effect of ocular artefacts on spectral EEG parameters is assessed statistically. These artefacts are caused by movements of the eyeball and/or of the lid. Further, methods for correcting ocular artefacts are presented and evaluated. This methodological study is based on data from an investigation comparing the EEG of schizophrenic patients (n = 17) with healthy controls (n = 15). Ocular artefacts are monitored by the bipolar vertical and the bipolar horizontal electro-oculogram (EOG). It is shown that the influence of ocular artefacts on the measured electrical activity in the frontal region is larger than the cerebral potentials which the EEG is ideally intended to record. The more frequent occurrence of blinks and eye movements in schizophrenic patients may lead to an artificial enhancement of slow frequency EEG power for schizophrenics and eventually "false significances". In contrast to this, we found more significant group differences when correcting for EOG artefacts than without it. This can be attributed to a very much inflated sample variability of the uncorrected EEG, due to the individually varying EOG power. We conclude that it may not be sufficient to select visually epochs for analysis that are considered artefact-free. Rather, one should monitor EOG artefacts and apply an appropriate correction.
对眼部伪迹对脑电图频谱参数的影响进行了统计学评估。这些伪迹是由眼球和/或眼睑的运动引起的。此外，还介绍并评估了校正眼部伪迹的方法。这项方法学研究基于一项调查的数据，该调查比较了精神分裂症患者（n = 17）和健康对照组（n = 15）的脑电图。通过双极垂直和双极水平眼电图（EOG）监测眼部伪迹。结果表明，眼部伪迹对额叶区域测量的电活动的影响大于脑电图理想记录的脑电位。精神分裂症患者眨眼和眼球运动的更频繁发生可能导致精神分裂症患者低频脑电图功率的人为增强，并最终导致“假显著性”。与此相反，我们发现校正EOG伪迹时比不校正时的组间差异更显著。这可归因于未校正脑电图的样本变异性因个体EOG功率不同而大幅膨胀。我们得出结论，仅通过视觉选择被认为无伪迹的时段进行分析可能是不够的。相反，应该监测EOG伪迹并应用适当的校正方法。
