Functional imaging of the brain in psychiatry--mapping of EEG and evoked potentials.

Topographic brain mapping of EEG and evoked potentials permits the display of spontaneous and event-related activity of the brain. This new method is superior to conventional polygraphy because of the topographic approach which delineates structural and functional brain lesions. Data from 16 to 20 scalp electrodes were evaluated. Not only spontaneous EEG but also EEG during various testing conditions which activated particular brain regions was measured. For EEG fast Fourier transformation (FFT) was used for mapping. For late evoked potentials (VEP, AEP, SEP and P300) a single value representing the amplitude of EP at each 2-ms poststimulus latency point was used. Statistical techniques (Students'-test, correlation coefficient) were used to render the regions where a clinical population differs from normal subjects. The results show abnormalities of EGG and EP in patients with psychiatric and neurological diseases.