Adaptive filters for monitoring localized brain activity from surface potential time series

The problem of processing electroencephalographic (EEG) data to monitor the time series of the components of a current dipole source vector at a given location in the head is addressed. This is the spatial filtering problem for vector sources in a lossy, three-dimensional, zero delay medium. Dipolar and distributed sources at other than the desired location are cancelled or attenuated with an adaptive linearly constrained minimum variance (LCMV) beamformer. Actual EEG data acquired from a human subject serve as the interference in a case where the desired source is simulated and superimposed on the actual data. It is shown that the LCMV beamformer extracts the desired dipole time series while effectively canceling the subject´s interference