SPECTRAL-ANALYSIS OF P300 GENERATION IN DEPRESSION AND SCHIZOPHRENIA

In the past it was reported in several studies that both depressive an d schizophrenic patients exhibit reduced P300 amplitudes compared to h ealthy controls. In order to elucidate the underlying mechanisms of sp ectral P300 generation, we analysed P300 responses in depression and s chizophrenia by a frequency based approach. Herefore, the amplificatio n (poststimulus/prestimulus) of spectral power in different frequency bands was evaluated for nontarget and target epochs. Generally, we fou nd that P300 responses are accompanied by a pronounced frequency ampli fication in the delta and theta range. For the depressive patients we detected only under target condition a statistically significant reduc tion of alpha and gamma amplification compared to controls. In contras t to this, we observed a highly significant reduction of delta amplifi cation in schizophrenic patients, under both target and non-target con ditions.