Lemos M S, Fisch B J
Columbia College of Physicians and Surgeons, New York, NY 10032.
Electroencephalogr Clin Neurophysiol. 1991 Nov;79(5):361-70. doi: 10.1016/0013-4694(91)90201-e.
In this article we describe the implementation of a linearly weighted average reference montage. This montage differs from the commonly used source derivation montage in that the reference includes all the scalp electrodes of the 10-20 system; and it differs from all other montages implemented thus far in that the weighting of the reference electrodes is based on directly measured interelectrode distances. Using EEG and computer generated signals we have been able to demonstrate that the weighted average reference montage combines topographic selectivity and accuracy in the display of both focal and regional background changes. In comparison to the source derivation montage, ectopic peaks and troughs of localized potential fields are less prominent and interhemispheric symmetry is better preserved. In comparison to the common average reference montage the frequent prominent ectopic displacement of high amplitude (e.g., vertex waves) or widespread potentials (e.g., alpha background activity) is suppressed. We believe that the spatial filtering characteristics of the weighted average reference montage, which are intermediate between those of the common average reference montage and the source derivation and Laplacian montages, will make it a useful alternative for topographic analysis. Our results also indicate that actual scalp measurements should be used to calculate reference electrode weighting factors because such measurements yield values that are substantially different from those derived from other methods of estimation presented thus far. A weighted average montage derived from pooled scalp measurements can be easily implemented using the weighting factors provided herein.
在本文中，我们描述了一种线性加权平均参考导联的实现方法。这种导联与常用的源推导导联不同，因为其参考导联包括了10-20系统的所有头皮电极；并且它与迄今为止实现的所有其他导联也不同，因为参考电极的加权是基于直接测量的电极间距离。利用脑电图（EEG）和计算机生成的信号，我们已经能够证明加权平均参考导联在显示局灶性和区域性背景变化时兼具地形选择性和准确性。与源推导导联相比，局部电位场的异位峰和谷不太明显，半球间对称性得到了更好的保留。与普通平均参考导联相比，高振幅（如顶点波）或广泛电位（如α背景活动）频繁出现的明显异位位移受到了抑制。我们认为，加权平均参考导联的空间滤波特性介于普通平均参考导联与源推导导联和拉普拉斯导联之间，这将使其成为地形分析的一种有用替代方法。我们的结果还表明，应使用实际头皮测量值来计算参考电极加权因子，因为这些测量值与迄今为止提出的其他估计方法得出的值有很大不同。使用本文提供的加权因子，可以轻松实现从汇总头皮测量值得出的加权平均导联。
