Аннотация:We propose an approach to the differentiation of signal and noise based on separation of cortical and deep components of the electrical brain activity recorded from the surface of the scalp with the factor analysis of the dynamics of electric potentials. Statistical reduction of all available factors at given interval of electroencephalogram or evoked potential allows to identify common and specific factors. Common factors, loaded by leads which correlate well between each other, describe the dipole potential propagating through the volume conductor. Each typical factor describes the dynamics of activity only in one lead, and in the aggregate they reflect the activity of superficial structures of the brain. The proposed method does not depend on the rotation and the interpretation of factors. The method was effectively used to localize brain activity during an object categorization task.