Two timescales of fronto-occipital theta coupling in meditation: slow-scale decoupling coexists with fast-scale coupling

Fronto-occipital theta coupling is often treated as a single quantity. Using two independent meditation EEG datasets (N=24 and N=93), we show that this coupling is scale-dependent. At the slow timescale (30-s power envelope), high spatial coverage is associated with decoupling (rho = -0.364, p = 0.0003). At the fast timescale (instantaneous phase), the same high-coverage states show positive coupling. This two-scale structure is consistent across four tasks and two datasets. It suggests that energy allocation and information transfer operate at different timescales in the human brain. Methods:- Datasets: ds001787 (N=24), ds003969 (N=93)- Slow timescale: 30-s windows, theta (4-8 Hz) power, frontal-occipital correlation- Fast timescale: band-pass 4-8 Hz, instantaneous phase correlation- Coverage: proportion of channels with double-peak theta structure- Statistics: Spearman correlation Results:- ds003969 med1breath (N=93): slow rho=-0.220 (p=0.034), fast rho=+0.081 (p=0.44)- ds003969 med2 (N=92): slow rho=-0.138 (p=0.19), fast rho=+0.094 (p=0.37)- ds003969 think1 (N=74): slow rho=-0.263 (p=0.023)- ds003969 think2 (N=73): slow rho=-0.217 (p=0.066)- ds001787 meditation (N=24): slow rho=-0.373 (p=0.072), fast rho=+0.179 (p=0.40)- Pooled (N=93): slow rho=-0.364 (p=0.0003), fast rho=+0.121 (p=0.25) Conclusion:Fronto-occipital theta coupling has at least two timescales with opposite dependence on spatial coverage. High coverage does not mean global synchronization; it means slow-scale independence with fast-scale dialogue.