Figure 2.

Time-frequency spectrograms. Grand- (far left) and group-averaged (middle and right) time-frequency spectrograms from a representative parieto-occipital MEG sensor. Time is shown on the x-axis in seconds, and frequency is shown on the y-axis in Hz. The colors reflect power increases (red) and decreases (blue) relative to the baseline, with the scale bar shown to the far right. Time-frequency windows for source imaging (beamforming) were derived from statistical analysis of the sensor-level spectrogram data across all participants. Thus, the separate group-level spectrograms are provided for visualization purposes only. Weaker low alpha responses in patients can be discerned throughout most of the maintenance phase.