Brain waveforms reconstructed at source level, like in beamforming, suffer polarity indeterminacy, which precludes direct group averaging of associated waveforms. We describe a polarity alignment method as an alternative of averaging rectified (i.e. absolute value) waveforms. Using MEG from an auditory localisation task, we compare the ability of the two approaches to enable signal detection in the primary auditory cortex over increasing sample size. The two methods are comparable in signal detection sensitivity, but the alignment method preserves group-average polarity alternation.

中文翻译：

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一种在MEG波束成形应用中在源级别对事件相关神经信号进行组平均的极性对齐方法

像在波束成形中一样，在源级别重建的脑波形会受到极性不确定性的影响，从而无法对相关波形进行直接的组平均。我们描述了一种极性对准方法，作为平均整流波形（即绝对值）的一种方法。使用来自听觉定位任务的MEG，我们比较了两种方法在样本量增加的情况下在主要听觉皮层中实现信号检测的能力。两种方法在信号检测灵敏度上可比，但是对齐方法保留了基团平均极性的交替。