Exploring the dynamics of P300 amplitude in patients with schizophrenia.

This study investigated the time-frequency dynamics of P300 generation in patients with first-onset schizophrenia. A group of 40 patients with first-onset schizophrenia and 40 controls performed an auditory oddball task. Wavelet analysis of the single-trial data was used to compute the Event-Related Spectral Perturbation (ERSP) and the Inter-Trial Phase Coherence (ITC) for the delta, theta, alpha, beta and gamma bands on the 50ms window around peak P300 amplitude. The contribution of power and synchrony for P300 amplitudes was studied through correlation and regression analysis. Further, two sub-samples in which patients had lower or higher P300 amplitudes than their control match were contrasted. P300 amplitude did not differ between patients and controls. The frequency domain analysis revealed that controls display larger reductions on gamma power than patients. However, this gamma activity might be the result of micro-saccadic muscular artifacts. Regression analysis shows that P300 amplitude is highly dependent on delta power and synchronization. The analysis of the subsamples confirmed that while gamma power differences are dependent on the diagnosis, delta and theta synchronization are related to P300 amplitude, irrespective of diagnosis.