The 30–50 Hz aperiodic exponent did not discriminate seizure-onset-zone contacts in 35 SEEG patients

We assessed whether interictal spectral features distinguish clinician-marked seizure-onset-zone (SOZ) contacts in stereoelectroencephalography (SEEG). The analysis used 30 s from the first interictal run in 36 of 37 subjects in the HUP iEEG Epilepsy Dataset (OpenNeuro ds004100 v1.1.3); one recording failed to download. For each patient, channel features were compared between SOZ and non-SOZ contacts in bipolar and common-average montages, and patient-level AUCs were tested by sign-flip permutation. The fixed 30–50 Hz aperiodic exponent did not discriminate SOZ contacts (mean AUC 0.48, p=0.57 bipolar; 0.46, p=0.26 common average). Absolute 1–30 Hz power (AUC 0.69–0.70), 65–115 Hz power (0.64–0.67), and line length (0.59–0.65) were higher in SOZ contacts (p≤0.013); relative high-gamma power was lower in the bipolar montage (AUC 0.40, p=0.003). SOZ AUCs did not differ between Engel 1 (n=19) and Engel 2–4 (n=16) patients. No feature reached p<0.05 for resected versus non-resected contacts among Engel 1 patients. There were 24 group tests without table-wide correction; power and line-length SOZ effects with p<5×10⁻⁵ survive Bonferroni correction. Limits include one 30 s clip per patient, no artifact or spike rejection, no gray/white-matter covariate, clinical SOZ labels, and a fixed exponent fit without a knee or peak model. Tissue type may partly explain power differences.

stereoelectroencephalography · epilepsy · seizure onset zone · interictal · aperiodic exponent · spectral power · AUC