6533b857fe1ef96bd12b428f

RESEARCH PRODUCT

Drawback of ICA Procedure on EEG: Polarity Indeterminacy at Local Optimization

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Independent component analysis (ICA) has been extensively applied to reject artifacts in electroencephalography (EEG) signal processing. The first step is to extract the independent component activations from the electrode records, and then project the desired components back to the electrodes. After the composition of the projected component is analyzed in details under ICA procedure, this study shows that since ICA may extract some source components at the local optimization in high-dimensional EEG signal space, the artificial polarity indeterminacy may happen on the projected component at some electrodes. By numerical simulations, this issue also exhibits that this polarity ambiguity occurs. Hence, we conclude that the abnormal polarity reversal should be corrected, and that without prior knowledge on the desired target activation or the artifacts, the polarity of the projected component may be not reliable under ICA procedure.