Fagan J E, Downard F G, Yolton R L
Am J Optom Physiol Opt. 1985 Jun;62(6):418-22. doi: 10.1097/00006324-198506000-00011.
Among the possible causes of steady-state visual evoked response (VER) amplitude variability are: concurrent electroencephalographic (EEG) activity occurring at frequencies other than that of the VER (alpha rhythms, etc.), and EEG activity occurring at the same frequency as the VER (Noise). To evaluate these two factors, 10 steady-state VER's (7.8 Hz pattern reversal rate) and 10 samples of resting EEG activity were obtained from each of 20 normal subjects. The correlations between VER and concurrent EEG activity at other frequencies were calculated from simultaneous determinations of Fourier-derived VER and EEG amplitudes. No significant correlations were found. Because EEG Noise occurring at the same frequency and time as the VER cannot easily be separated from the VER by Fourier transformation, two indirect techniques for assessing the amplitude of this Noise were evaluated: measurement of simultaneously recorded activity at frequencies directly adjacent to the 15.6 Hz VER frequency and measurement of EEG activity at 15.6 Hz obtained just before the VER measurements. Neither of these procedures could predict trial-by-trial variations in the amplitude of the Noise at 15.6 Hz. However, across subjects both procedures provided good estimates of the mean EEG Noise underlying the VER.
稳态视觉诱发电位（VER）振幅变异性的可能原因包括：与VER频率不同的并发脑电图（EEG）活动（α节律等），以及与VER频率相同的EEG活动（噪声）。为了评估这两个因素，从20名正常受试者中每人获取了10次稳态VER（7.8 Hz图形反转率）和10份静息EEG活动样本。通过同时测定傅里叶导出的VER和EEG振幅，计算VER与其他频率并发EEG活动之间的相关性。未发现显著相关性。由于与VER在相同频率和时间出现的EEG噪声不易通过傅里叶变换与VER分离，因此评估了两种间接评估该噪声振幅的技术：测量与15.6 Hz VER频率直接相邻频率处同时记录的活动，以及在VER测量前获取的15.6 Hz EEG活动测量。这两种方法均无法预测15.6 Hz噪声振幅的逐次试验变化。然而，在所有受试者中，这两种方法都能很好地估计VER背后的平均EEG噪声。
