Attenuated theta-band activity and cross-frequency coupling in schizophrenia during affective response inhibition

Background: Individuals with Schizophrenia (SZ) display impaired cognitive control, including trouble inhibiting context-inappropriate responses; however, the underlying neural mechanisms remain understudied and unclear. The current study examined the role of theta-band (4-7 Hz) neural oscillatory activity and cross-frequency coupling with gamma (30-50 Hz) activity in an affective cognitive control paradigm in SZ in comparison with healthy controls (HC) and those with bipolar disorder (BD). Methods: Thirty-seven participants with SZ, 67 with BD, and 48 HC completed an affective Go/No-Go Task with emotional face stimuli during electroencephalography (EEG) recording. Time-frequency decomposition was used to extract theta-band power and intertrial phase consistency (ITPC) over midline fronto-central areas. The Kullback-Leibler Modulation Index was used to index theta-gamma phase-amplitude coupling (PAC) within the midline frontal area as well as between midline frontal theta and bilateral parietal gamma regions. Results: Participants with SZ displayed decreased midline frontal theta power, ITPC, and theta-gamma PAC compared to HC, with BD falling in between SZ and HC groups across all these measures. Theta power, ITPC, and theta-gamma PAC were correlated with behavioral performance in various ways, particularly in the SZ group. Conclusions: Collectively, these findings show abnormalities across the amplitude, phase consistency, and cross-frequency coordination aspects of theta-related activity when individuals with SZ engage in affective cognitive control. Implications for their contribution to functional impairment and directions for treatment are discussed.