Fig. 5

Time–frequency analysis of IRP signals. All IRP spectral values are expressed in dB with respect to the pre-stimulus period (− 0.1 to 0). A Grand-averaged time–frequency representations of the IRP in PPI condition. B Grand-averaged time–frequency representations of the IRP in PPF condition. C Pixel-by-pixel difference between PPF and PPI. From C, PPF is greater than PPI responses in two distinct frequency bands (3.8–12.6 Hz and 25.3–31.2 Hz) during the N100/P200 time-windows. D Grand-averaged IRP spectral power values in PPI condition for both CTL and BDD groups. The gray-shaded area indicates the frequency band of significant group differences. E Grand-averaged IRP spectral power values in PPF condition for both CTL and BDD groups. The IRP spectrum was computed in the 0.6–0.26 s time-window for both D and E