To examine the extent to which specific low-frequency phase and high-frequency amplitude values were coupled, we calculated circular-linear correlations using phase frequencies between 2 and 16 Hz in 2-Hz increments and amplitude frequencies between 18 and 120 Hz in 4-Hz increments, collapsed across trials and time within each trial, for each subject, block, stimulation condition, and electrode. The correlation coefficients were normalized using the standard Fisher r-to-z transformation. Of note, similar PAC results were obtained using a narrower range of amplitude frequencies from 18 to 58 in 4-Hz increments.
