Neural oscillatory abnormalities duringgaze processing in schizophrenia: Evidence of reduced theta phase consistency and inter-areal theta-gamma coupling

Abstract Background Abnormal gaze discrimination in schizophrenia (SZ) is associated with impairment in social functioning, but the neural mechanisms remain unclear. Evidence suggests that local neural oscillations and inter-areal communication through neural synchronization are critical physiological mechanisms supporting basic and complex cognitive processes. The roles of these mechanisms in abnormal gaze processing in SZ have not been investigated. The present study examined local neural oscillations and connectivity between anterior and bilateral posterior brain areas during gaze processing. Methods Twenty-eight SZ and 34 healthy control (HC) participants completed a gaze discrimination task during electroencephalography (EEG) recording. Time-frequency decomposition of EEG data was used to examine neural oscillatory power and inter-trial phase consistency at bilateral posterior and midline anterior scalp sites. In addition, connectivity between these anterior and posterior sites, in terms of cross-frequency coupling between theta phase and gamma amplitude, was examined using the Kullback-Leibler Modulation Index (KLMI). Results SZ showed reduced total power of theta-band activity relative to HC at all sites examined. This group difference could be accounted for by SZ’s reduced inter-trial phase consistency of theta activity, which was related to reduced gaze discrimination accuracy in SZ. In addition, SZ exhibited reduced KLMI indexing both feedforward and feedback connectivity between the posterior and anterior sites. Conclusions These findings suggest abnormal theta phase consistency and dysconnection between posterior face-processing and anterior areas may underlie gaze processing deficits in SZ.