In 169 patients with epilepsy, SEEG alpha peaks were stronger posteriorly, but peak frequency showed no monotonic anterior-posterior gradient

We tested whether the alpha peak frequency (PAF) of SEEG pairs increases from anterior to posterior cortex in each patient. MEG studies report this gradient. We used the spectra of 21,525 bipolar SEEG pairs from 204 RAM patients (AutoSci dc146f0e). We added MNI coordinates from the OpenNeuro electrodes.tsv files. We wrote and hashed the plan before we joined the coordinates. The primary test used 169 patients with 10 or more valid peaks and a y range of 20 mm or more. The within-patient Spearman rho between MNI y and PAF had a mean of -0.04 (95% CI -0.09 to +0.003; sign-flip p = 0.07). The linear slope was +0.009 Hz per 10 mm (95% CI -0.03 to +0.05). Thus the data do not support a monotonic anterior-posterior PAF gradient larger than approximately 0.05 Hz per 10 mm. Other properties of the peak had strong gradients. Valid alpha peaks were more frequent in posterior pairs (mean rho -0.23, 145 of 177 patients negative, Holm p = 0.0002). Peak height also decreased toward anterior pairs (mean rho -0.22, Holm p = 0.0002). PAF increased with MNI z (mean rho +0.12, Holm p = 0.0002). The y effect was 0 after we adjusted for z and |x|. An exploratory profile of subject-centred PAF had a U shape: +0.4 Hz at y -90 to -70 mm, -0.1 Hz at y -30 to +10 mm (mostly temporal pairs), and +0.15 Hz at y +10 to +50 mm. Thus the SEEG PAF topography is not a single posterior-to-anterior axis. The sample of contacts is mostly temporal. The data are from patients with epilepsy and from 60 s of task data only.

SEEG · alpha peak frequency · electrophysiology · spatial gradient · epilepsy · RAM dataset · within-patient analysis