Generalized Slowing of Resting-State Neural Oscillations in People With Schizophrenia

Background: Recent interest in how neural oscillations reflect the flow of information through the brain has led to partitioning electroencephalography (EEG) recordings into periodic (i.e., oscillatory) and aperiodic (i.e., non-oscillatory) components. While both contribute to conventional measures of power within the frequencies that compose EEG recordings, the periodic aspect characterizes true oscillations, the speed of which is thought to be critical to efficient functioning of neural systems. Given evidence of EEG power abnormalities in schizophrenia (SCZ), we sought to determine whether the periodic aspect of EEG was aberrant in people with SCZ and could serve as a general measure of brain efficiency. Methods: Resting-state EEGs were gathered from 104 participants with SCZ and 105 healthy control participants. We used the FOOOF toolbox to remove aperiodic neural activity. We computed the cross-correlation between power spectra for individual participants and the mean power spectrum for all participants to quantify the relative speed of neural oscillations. Results: Periodic activity in SCZ was shifted toward lower frequencies than control participants during eyes-closed rest. On average, participants with SCZ had a 0.55-Hz shift toward oscillatory slowing across the frequency spectrum that predicted worse perceptual reasoning. Conclusions: Slowed periodic activity at rest is evident in SCZ and may represent inefficient functioning of neural circuits as reflected in worse perceptual reasoning. A slower pace of neural oscillations may be a general limitation on the transmission of information within the brain.