To calculate CFC, we used the modulation index (MI) (Tort et al., 2008) since it has been shown to be less affected by noisy data recorded at a lower sampling compared with other techniques (Hülsemann et al., 2019). Since MI is affected by small segments, we concatenated the 70 1-s epochs of EEG from each participant, thereby having one epoch of 70 s. The number of epochs was selected based on the largest number of epochs being included while excluding the least number of participants. First, raw data are filtered at the two frequency ranges using the pop_eegfiltnew function from EEGLAB (Delorme and Makeig, 2004). Afterward, the Hilbert transform was applied to extract the time series of the amplitude of the higher frequency band and the phase of the lower frequency band. The composite time series is then constructed, which gives the amplitude of the higher frequency band oscillation at each phase of the lower frequency band rhythm. Next, the phases of the lower band were binned into 18 frequency bins, and the mean of the amplitude of the higher
