For each group, virtual channel data was reconstructed from central AAL-atlas nodes within the brain regions of significant group effect (Table 2, Manuscript). These data were then submitted to FFT analyses, focusing on 5 Hz bins between 30–90 Hz. Non-parametric, Monte-Carlo based permutation statistics, FDR corrected, were then used to find significant group differences within each 5 Hz bin, averaged across all significant regions. The results showed that spectral changes were broadband in nature, with increased gamma activity in CHR (CAARMS + SPI A group) participants between 35–90 Hz (0.006 < p < 0.031) and FEP group between 30–90 Hz (0.004 < p < 0.015), and decreased gamma-band activity in FEP patients and chronic SCZ patients between 30–90 Hz (FEP: 0.0001 < p < 0.006; SCZ: 0.0001 < p < 0.002). Significant bins are indicated with an asterisk in the Figure.