Participants were asked to relax with eyes closed for 5 min while listening to soft white noise. EEG was recorded from the vertex of the head (Cz), referenced to the two ears, and from two bipolar derivations: O1-P7 and O2-P8. Power in the alpha, beta, theta and delta frequency bands were obtained from a fast Fourier transform of EEG recorded at the Cz electrode. Alpha power and peak frequency were also obtained for the two bipolar leads and averaged together. Schizophrenia is robustly associated with increased low-frequency power in particular (Kam et al. 2013; Narayanan et al. 2014), a finding that is also observed in their relatives (Narayanan et al. 2014).
