Meier T, Rosburg T, Arnold M, Kreitschmann-Andermahr I, Sauer H, Nowak H, Witte H
Department of Psychiatry, Friedrich-Schiller-University Jena, Germany.
Electroencephalogr Clin Neurophysiol. 1998 Nov;108(6):526-35. doi: 10.1016/s0168-5597(98)00031-8.
In a magnetoencephalographic investigation of the auditory evoked field (AEF) in 17 schizophrenics and 17 controls, 37% of the schizophrenics and 12% of the controls showed eye artifacts in every second trial or even more frequently. In the uncorrected average fields, the ratio between the power of artifacts and the power of the magnetoencephalogram (MEG) exceeded the value of 0.1 for 48% of the schizophrenics and for 29% of the controls. Ocular artifacts biased the locations of equivalent current dipoles of the M100 component towards deeper positions. A regression algorithm for the correction of ocular artifacts in raw data and an identification technique of ocular artifacts based on the topography of transmission coefficients is described.
A linear dependence of ocular artifacts in AEF on the electrooculogram (EOG) was confirmed. Possible errors introduced by the correction are discussed. Transmission coefficients should be calculated for several individual trials with the same type of artifact. Errors due to evoked potentials in the EOG were found to be comparable in amplitude to noise in the AEF. Examples of transmission coefficients from the EOG to the MEG are given.
在一项针对17名精神分裂症患者和17名对照者的听觉诱发电场（AEF）的脑磁图研究中，37%的精神分裂症患者和12%的对照者在每隔一次试验中甚至更频繁地出现眼伪迹。在未经校正的平均场中，48%的精神分裂症患者和29%的对照者的伪迹功率与脑磁图（MEG）功率之比超过了0.1。眼伪迹使M100成分的等效电流偶极子位置偏向更深的位置。描述了一种用于校正原始数据中眼伪迹的回归算法以及一种基于传输系数地形图的眼伪迹识别技术。
证实了AEF中眼伪迹与眼电图（EOG）呈线性相关。讨论了校正可能引入的误差。应针对具有相同类型伪迹的多个个体试验计算传输系数。发现EOG中诱发电位引起的误差在幅度上与AEF中的噪声相当。给出了从EOG到MEG的传输系数示例。
