This study investigated gamma-band activity (GBA) and its phase synchrony in schizophrenia patients viewing human faces. Twenty-five schizophrenia patients were compared with 25 normal controls. Event-related potentials were recorded from all participants while they were viewing emotionally neutral faces. The spectral power and phase synchrony in the frequency band from 30 to 55 Hz were analyzed in midline electrodes (FCz, Cz, CPz, Pz, and POz). Three windows of interest, which showed discernable GBA differences between schizophrenia patients and normal controls, were selected by visual inspection: 0-100 ms (30-33 Hz), 250-300 ms (34-38 Hz), and 700-800 ms (40-45 Hz). And the phase synchrony of gamma band was analyzed. Repeated-measures ANOVA revealed that the GBA was lower in schizophrenia patients than in normal controls. Also there were significant location and time differences in GBA. GBA was significantly lower in the schizophrenia patients than in the normal controls at around 700-800 ms at the FCz electrode. The frontal (FCz) and central (Cz) GBA were significantly correlated with the number of hospitalization, and the negative symptoms of schizophrenia, respectively. The phase synchronization was significantly lower at 200-300 ms in the schizophrenia patients than in the normal controls. These findings suggest that the schizophrenia patients have impaired GBA and gamma-band synchronization during face perception. Furthermore, our results also suggest that the decreased GBA observed at the midline cortex of schizophrenia patients is closely related to their negative symptoms and disease progress.
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