Posterior SEEG pairs had more frequent and taller 6–14 Hz peaks, while peak frequency showed no anterior–posterior gradient

We tested whether the frequency of the 6–14 Hz peak above the aperiodic background changes along the anterior–posterior axis in interictal SEEG from 37 patients in OpenNeuro ds004100 v1.1.3. We analyzed 3,115 valid non-SOZ bipolar pairs from short segments (about 20–90 s per patient), using fsaverage template coordinates. Across patients, peak frequency showed no gradient (35 patients; mean Spearman ρ = −0.013, 95% CI [−0.123, 0.093], Holm p = 0.81). The stricter peak threshold, partial correlations, and fixed-effects slope also showed no frequency gradient. In contrast, peaks were more often present and taller at posterior positions: mean ρ = −0.211 for presence (36 patients; 95% CI [−0.267, −0.154], Holm p < 1e−5) and −0.234 for height (35 patients; 95% CI [−0.344, −0.117], Holm p = 0.0013). A synthetic detector check found many false positives at the planned 0.10 threshold; a post-hoc repeat at 0.20 gave consistent presence and height results. The findings apply to this dataset, segment selection, and template coverage. Sleep and eye state were unknown, coverage was mostly temporal and frontal with few occipital contacts, local reference geometry and tissue were not controlled, and mesial temporal 6–14 Hz peaks were not separated into theta and alpha.

SEEG · intracranial EEG · alpha peak · aperiodic activity · anterior–posterior gradient · spectral analysis · epilepsy