Altered topography of EEG spectral content in schizophrenia.
EEG data were recorded in resting and in specific test conditions designed to activate different regions of the brain in a group (n = 10) of chronic schizophrenics and matched controls. EEG spectral energy was computed using the Fast Fourier Transform and numerical matrices representing the topographic distribution of spectral energy in a specified band were constructed and displayed as color images. Significance Probability Mapping was employed to identify regions of maximal group difference; it was found that the schizophrenic group showed increased low frequency energy (0-7 c/sec) in the frontal regions and increased fast activity (12-32 c/sec) in post-central areas and the left anterior temporal area. The different psychological test conditions were associated with different patterns of energy distribution. The consistency of our findings with other investigations suggests that topographic mapping of brain EEG spectral activity may play a useful role in the functional understanding of schizophrenia.