The phase variables ϕx,y for different frequency bands were calculated using a wavelet-based approach (Torrence and Compo, 1998), with the center frequency and bandwidth of a continuous Morlet wavelet adapted to match conventional EEG bands, i.e., the δ (0.5–4 Hz), θ (4–8 Hz), α (8–13 Hz), β1 (13–20 Hz), β2 (20–30Hz), and γ1 (30–49 Hz) band, at full width half maximum (Osterhage et al., 2007): ϕband(t)=arctanIm Wband(t)Re Wband(t) where Wband(t) denotes the wavelet coefficient Wband(t)=∫−∞+∞μband(t−τ)s(τ)dτ of a Morlet wavelet μband(t)=(eiω0bandt−e− (ω0bandσband)22)e− 12(tσband)2 with σband=2πln2Δωband
