SEEG band-power correlation had 13–18 mm median decay lengths across 3–140 Hz, with no supported frequency trend

We measured word-to-word correlations in bipolar SEEG band-power features from 19 patients during FR1 word encoding. Median spatial decay lengths were 13–18 mm across eight bands from 3 to 140 Hz; the planned test did not support a decrease in decay length with frequency (median Spearman rho −0.43; exact sign-flip p = 0.18). High-frequency power had a smaller local excess correlation at 140 Hz than at 3 Hz (median difference −0.076; Holm p = 0.006), and participation ratio was 0.26–0.28 of channel count at 40–140 Hz versus 0.17–0.18 at 5–13 Hz. Same-shaft pairs showed greater correlation in the planned comparison, but a post-hoc distance-matched check did not support a shaft effect. The results concern one task and a 0–1.6 s window, using bipolar channels and MNI coordinates; they do not test decoding directly.

SEEG · intracranial EEG · band power · spatial correlation · bipolar electrodes · word encoding · brain-computer interfaces · participation ratio