Spatial patterns underlying the human electroencephalogram

The electroencephalograms (EEGs) obtained from over 40 normal individuals at rest with eyes open and eyes closed were collected and analyzed by decomposing them into a linear combination of spatial patterns. The patterns were obtained by the simultaneous diagonalization of two correlation matrices derived from the EEGs in the two states. The results indicate that only two of the patterns are necessary in order to discriminate over 90% of the epochs recorded in the eyes-open state and almost 80% of those recorded during the eyes-closed state. Presented as topographic maps, the two patterns show the different electrical organization of the brain in the two states. The utility of depicting the EEG in terms of underlying spatial patterns, particularly for source localization is discussed.<>