For each subject, the realigned MEG data were transformed into individual frequency power spectra by applying a Fast Fourier Transformation (FFT) to 2000 ms data epochs. The output of this procedure was the mean (averaged over the 90 trials) power for each frequency bin in the range of 0.5–100 Hz (with a 0.5 Hz frequency resolution, resulting in 200 frequency bins), for each of the 148 channels. Power values were normalized by calculating the mean power from all sensors and frequencies for each individual subject. Subsequently, each separate sample (frequency × sensor power estimate) was divided by the subject's mean power.
