Reference Estimation in EEG: Analysis of Equivalent Approaches

This letter demonstrates the theoretical equivalence between the different ICA/beamforming based solutions proposed in the literature for the reference-estimation problem in electroencephalographic (EEG) recordings . By reference, we understand an unknown, non-null, time-varying potential, measured at the reference electrode situated sufficiently distant from the measuring electrodes. Despite the theoretical equivalence of the various approaches, they do not yield identical results in practice. This discrepancy is primarily due to the practical implementation of the underlying approach. We show in this context that the most reliable solution avoids blind source separation and montage transformation in addition to making full use of available a priori knowledge.