The polar average reference effect:: a bias in estimating the head surface integral in EEG recording
The polar average reference effect:: a bias in estimating the head surface integral in EEG recording
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DOI：
10.1016/s1388-2457(99)00044-9
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发表时间：
1999-06-01
影响因子：
4.7
通讯作者：
Braun, C
中科院分区：
文献类型：
--
作者：
Junghöfer, M;Elbert, T;Braun, C
一种与参考信号无关的电位测量方法有助于多通道脑电的研究。无论脑电源的活动和分布如何，在身体表面上积分的电位都是恒定的，即随时间而不活动。因此，平均参考值，即每个时间点所有记录通道的平均值，可用于近似非活动参考值。然而，这种近似仅在头皮场的精确空间采样下有效。准确的采样需要足够的电极密度和头部表面的完全覆盖。如果电极集中在表面的一个区域，例如仅在头皮上，则平均值偏向该区域。与平均值的差异将在区域的中心（例如，顶点）处比在外围处更小。在本文中，我们说明了这种极平均参考效应（帕雷）可能会创建的密度不足和EEG电极的分布不均。体积导体的表面的覆盖范围越大，平均参考越接近理想的无源参考。(C)1999爱思唯尔科学爱尔兰有限公司保留所有权利。
A reference-independent measure of potential is helpful for studying the multichannel EEG. The potentials integrated over the surface of the body is a constant, i.e, inactive across time, regardless of the activity and distribution of brain electric sources. Therefore, the average reference, the mean of all recording channels at each time point, may be used to approximate an inactive reference. However, this approximation is valid only with accurate spatial sampling of the scalp fields. Accurate sampling requires a sufficient electrode density and full coverage of the head's surface. If electrodes are concentrated in one region of the surface, such as just on the scalp, then the average is biased toward that region. Differences from the average will then be smaller in the center of the region, e.g. the vertex, than at the periphery. In this paper, we illustrate how this polar average reference effect (PARE) may be created by both the inadequate density and the uneven distribution of EEG electrodes. The greater the coverage of the surface of the volume conductor, the more the average reference approaches the ideal inactive reference. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.