Very few of the previously published GBR studies of patients with schizophrenia (Krishnan et al., 2009) examined the combination of synchronous and asynchronous neural activity by reporting total power. Accordingly, our study, which includes the total power GBR in schizophrenia patients and patients at risk for developing psychosis, represents a significant extension of prior studies. The fact that total gamma power was not reduced in CHR patients, and only showed a trend toward reduction in our young schizophrenia patients, suggests that the magnitude of early auditory gamma band activity is relatively spared early in the course of schizophrenia. Moreover, this lack of total power deficits suggests that the significant evoked gamma power reduction in the patients mainly resulted from poor gamma phase synchrony across trials rather than from reduced magnitude of the gamma oscillations.
