In 24 patients, bipolar SEEG coupling decayed more steeply from delta to beta, while HFA retained a distance-independent floor

We measured zero-lag coupling (r^2 minus a circular-shift null) between contacts on different shafts in 90-s interictal SEEG segments from OpenNeuro ds004100. We excluded SOZ contacts. The ratio Q = c(40-60 mm) / c(10-20 mm) was calculated per patient in 6 bands and in bipolar and referential montages. The plan was registered before the results. H1 (Q_delta > Q_HFA, from the synchrony view): the mean difference was negative (-2.28, p = 0.018), but only 11/24 patients had a positive difference, so the mean is not robust and H1 is not supported. H2 (monotonic trend of Q over 6 bands): not supported (mean rho -0.09, Holm p = 0.92). Q had a U shape: it decreased from delta (median 0.22) to beta (0.06) and increased in gamma and HFA, where far coupling stayed at a floor. H3 (Q_ref > Q_bip): the pre-registered mean test did not reject (p = 1.0) because of bipolar HFA outliers, but 22/24 patients had Q_ref > Q_bip (post-hoc sign test p = 3.6e-5). Limits: fsaverage distances, one segment, unknown sleep state, spikes not removed, Q unstable when near coupling is small. The package has code, edge-level data, provenance hashes and steps to reproduce.

SEEG · zero-lag coupling · distance decay · frequency bands · bipolar montage · volume conduction · epilepsy · OpenNeuro