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

Fronto-occipital theta coupling is treated as a single quantity. We show it decomposes into two timescales with opposite behavior. At the slow timescale (30-s theta power envelope), high spatial coverage correlates with decoupling (rho = -0.252, p = 0.015, N = 93). At the fast timescale (instantaneous phase), the correlation is positive (rho = +0.100, p = 0.34). Across four tasks and two datasets, the two timescales behave oppositely. Applying the same analysis to sleep EEG (N = 69, five stages) separates wakefulness, meditation, and sleep into three distinct regimes: - Wakefulness: positive coupling on both scales- Meditation: slow-scale decoupling with maintained fast-scale coupling- Sleep: slow-scale coupling with fast-scale anti-phase locking The two-dimensional (slow, fast) representation distinguishes states that are indistinguishable on a single synchrony axis.