Scalp T3/T4 alpha-envelope coupling increased with lateral position within SEEG shafts in 10 patients

This analysis tested whether lateral bipolar pairs within a stereoelectroencephalography (SEEG) shaft had stronger alpha-band (8–12 Hz) envelope correlation with the ipsilateral temporal scalp channel than mesial pairs. It used session 1, run 1 from 15 participants in OpenNeuro ds004752; 10 had usable T3/T4 channels, yielding 49 shafts and 340 bipolar pairs. Across subjects, mean Spearman rho between absolute template-space x position and correlation was +0.214 (median +0.295); 8 of 10 subject values were positive. The Wilcoxon test (p = 0.020) and sign-flip permutation (p = 0.025) were below 0.05, while the exact sign test was not (p = 0.11). Thirty-six of 49 shafts had positive rho. Thirty-seven percent of pairs exceeded their 95% circular-shift null, and 7 of 10 subjects exceeded the 5% expected fraction after Holm correction (p_holm ≤ 0.0021). Exploratory theta and beta results showed no gradient. An exploratory C3/C4 reference across all 15 participants gave a weaker, nonsignificant alpha gradient (mean rho +0.12; Wilcoxon p = 0.12; sign-flip p = 0.13). Evidence for a lateral gradient is moderate: two of three planned tests were below 0.05, but the sign test was not. Absolute template-space x is only a proxy for scalp distance; the analysis cannot distinguish volume conduction from stronger lateral temporal alpha that co-varies with scalp alpha. Continuous data include task-locked co-modulation, segments are short, and scalp-SEEG alignment is assumed from equal EDF record counts despite start times differing by about four hours. The analyzed EDF prefixes and S3 version identifiers and hashes are recorded in original/provenance_s3.tsv; the exact OpenNeuro release represented by the live-mirror source is uncertain.

stereoelectroencephalography · scalp EEG · alpha envelope · amplitude-envelope correlation · temporal cortex · within-shaft gradient · OpenNeuro ds004752