Time frequency representations of oscillatory activity.

Top: evoked activity from a single representative participant. Middle: evoked activity averaged across all participants. Bottom: total activity averaged across all participants. Note, how averaging of evoked activity smeares the relatively focal activity of single participants (black boxes in top and middle display). These data have been obtained by averaging time frequency planes from the posterior ROI. Stimulus onset is at 0 ms. Amplitudes are in dB relative to a baseline 200 up to 100 ms before stimulus onset.