We explore suitable spatiotemporal filters for inverse estimation of an equivalent cortical dipole layer (DL) distribution from the scalp electroencephalogram (EEG) for imaging of brain electric sources. We have previously developed the parametric projection filter (PPF)-based cortical dipole layer imaging technique, which allows estimating cortical dipole layer inverse solutions in the presence of noise covariance. We have expanded the PPF to the time-varying filter in order to handle the spatiotemporally varying nature of brain electrical activity. The present simulation results indicate that the estimation error is reduced substantially by taking the spatiotemporal properties of the noise into consideration, such as eye-blink artefacts, and the proposed time-variant PPF method provides enhanced performance in rejecting time-varying noise. (C) 2004 Elsevier B.V. All rights reserved.