Fig. 5

Individual subject results for 40 Hz audiovisual stimulation. (A) PSD comparison between 40 Hz audiovisual stimulation (blue) and baseline (grey). Shaded areas represent the standard error of the mean and full lines the mean power spectral density across trials. (B) Phase difference polar plots for selected electrodes (FCz, Cz, Oz, POz) comparing baseline and stimulation periods. The polar histograms show the distribution of instantaneous phase differences across multiple trials in 12 bins from -π to π. Top row displays baseline period phase distributions (grey), while bottom row shows stimulation period phase distributions (blue). Red dashed lines indicate circular means of phase angles. (C) Joint visualization of time-frequency power changes and corresponding topographical distributions during 40 Hz stimulation. Top row shows topographical maps of power distribution at five time points relative to stimulation onset. The topographic map uses a color scale ranging from -0.3 (blue) to 1.5 (red), representing log-ratio power changes relative to baseline, with white indicating no change (0). The main panel shows the time-frequency representation of power changes across the epoch (-5 to 5s), with horizontal dashed lines indicating the gamma band of interest (38–42 Hz) and vertical dash-dotted line marking stimulation onset (0s). (D) Inter-trial phase coherence during audio-visual stimulation for four selected EEG channels (FCz, Cz, Oz, POz). Time-frequency representations show ITPC computed using Stockwell transform (1–85 Hz). The data is baseline corrected and displayed in z-scores using a red colormap (0 to 10). Grey dashed lines indicate the frequency band of interest (38–42 Hz). Higher ITPC values (darker red) represent stronger phase consistency across trials at specific time-frequency points.