Independent contact shifts retain a positive mean fourth-order beta power term on shared bipolar edges in eight SEEG recordings

We compared two contact control models in public SEEG data from eight patients. Each patient supplied six fixed 20-second samples. On shared-contact bipolar edges, independent time shifts gave a mean normalized cross fourth cumulant of 0.128. Independent Fourier phases gave -0.002. The mean patient contrast was 0.131, with a descriptive bootstrap 95% interval of [0.086, 0.182]. All eight contrasts were positive. The exact two-sided sign-flip P value was 0.00781, under independent patient effects and sign symmetry at zero. A fourth-moment formula predicted the pooled control draws. Time shifts preserve contact burst shapes; independent phases change those shapes. Thus, a shared contact can retain a fourth-order power term under an independent-contact model. This benchmark does not identify neural coupling. The package contains code, spectra, source versions, hashes, results, and reproduction instructions.

SEEG · power correlation · fourth cumulant · beta band · bipolar montage · contact time shifts · Fourier phase controls · signal mixing