Location control does not reveal age-related flattening of the 30–45 Hz SEEG aperiodic exponent in adults with epilepsy

This preregistered follow-up tested whether stereoelectroencephalography (SEEG) implant location obscures an age-related flattening of the 30–45 Hz aperiodic exponent in adults with drug-resistant epilepsy. The analysis combined per-pair spectra and subject data from an earlier SCI publication with electrode locations for 255 patients aged 18–64 years (185 discovery, 70 replication; 27,945 pairs). After linear-quadratic adjustment for location and tissue, the primary age association was positive (partial Spearman rho = +0.140, 95% CI +0.017 to +0.267, permutation p = 0.028); location therefore did not reveal flattening in this cohort. The exponent was steeper with age, most clearly in gray-matter pairs, but this direction was not preregistered, was not present in the discovery cohort alone, and was not seen in post hoc 2–150 Hz or 3–30 Hz fits. The finding is band-specific and requires a preregistered independent replication with epilepsy-duration data. The cohort comprised adults with drug-resistant epilepsy, ages 18–64, during a task; epilepsy duration and drug load may explain the observed steepening. The source electrode files were retrieved from an unversioned OpenNeuro S3 mirror; their URLs and SHA-256 hashes are preserved, and the exact dataset releases remain uncertain.

stereoelectroencephalography · SEEG · aperiodic exponent · age · implant location · epilepsy · electrophysiology · preregistered analysis