Figure 1.

Experimental design, example data of pre-TMS oscillatory activity (EEG/EMG) and MEP. (A) Experiment consisted of 8 blocks; 10 TMS pulses were applied within each block, with intervals of ~2 s between consecutive pulses, and ~ 1 min breaks between blocks. (B) Example of pre-TMS EEG/EMG signals. (C) Response was quantified by the peak-to-peak amplitude of the TMS-evoked motor potential (MEP). (D) Group data of the distribution of the phase after Fourier decomposition of the EEG (C4 channel, 17 Hz; near-threshold intensity). Circle segments illustrate the phase binning, and the colors signify phase in the same way as in E and F. (E) Mean peak-to-peak MEP amplitudes as a function of the pre-TMS phase of the EEG. The dashed line is a least-squares fitted cosine function. The MEP (as a function of phase) modulation was quantified by the fitted cosine function called modulation depth (denoted by the symbol D). (F) Same as (E) but for average EEG power. (G) Coefficient of variation of the MEP amplitude (y-axis) was estimated for each subject (represented by a circle) and intensity (x-axis). (H) Same as G but for EEG phase; each diamond represents 1 frequency (between 6 to 30 Hz).