Absolute Level of Gamma Synchrony is Increased in FirstEpisode Schizophrenia during Face Processing

Abstract

Most studies of gamma band synchrony in schizophrenia conclude that it is reduced, relative to what is observed in healthy people, during stimulus processing. However, these findings may, in part, be an artifact of greater absolute levels of synchrony in schizophrenia even at baseline. We examined absolute level of gamma band synchrony before and during emotionally neutral face processing in 28 patients with schizophrenia after their first episode of psychosis (FES) (20 male) and 71 controls (53 male) across a range of frequency bins, brain regions and time-bands. We also examined how absolute synchrony prior to stimulus onset related to synchrony change during stimulus processing, and how it related to symptoms. The FES group showed greater absolute gamma synchrony across all time-points in frontal and temporal regions. Baseline absolute synchrony predicted post-stimulus change in these regions in a pattern consistent with previous reports. However, synchrony change was not related to symptoms. These results support the recommendation that studies in this field should examine baseline absolute synchrony when attempting to characterize task-related gamma synchrony in schizophrenia.