In 8 ds005448 SEEG patients, white-matter-only contacts had no N1 labels; boundary and gray-matter contacts showed no consistent difference

We examined whether SEEG recording contacts in or near white matter (WM) differ from gray-matter (GM) contacts in expert-checked N1 cortico-cortical evoked potentials (CCEPs), using OpenNeuro ds005448 v1.0.0 (STReEF): 8 patients, 11 runs, and clinical single pulses at 1–2 mA. Dataset tissue flags classified contacts as WM only, GM only, both (MIX; gray-white boundary), or neither (NONE). All 219 WM-only depth contacts were excluded for every stimulated pair in all 8 patients and 11 runs (9,253/9,253 entries), so this dataset has no N1 labels at WM-only recording contacts. At distances of at least 10 mm, the comparison therefore used MIX as a proxy for near-WM contacts, not as WM contacts, and GM contacts: 17,712 units, including 4,056 MIX units and 357 stimulated pairs. In 6 patients with sufficient data, the mean MIX-minus-GM N1 log-odds was +0.19 (95% CI −0.31 to +0.69; 3/6 positive; exact sign-flip p=0.34). Among N1 units, the log-amplitude difference was −0.02 (95% CI −0.13 to +0.09) and the log-latency difference was +0.06 (95% CI −0.04 to +0.15). Sensitivity analyses at 15–50 mm and without stimulated-pair fixed effects gave similar results. Per-patient effects differed in sign; the confidence interval does not exclude odds ratios of 0.74 or 1.99. Tissue classes are dataset flags, the N1 detection reference montage is unknown, volume conduction may make GM and MIX contacts similar, and the group analysis includes only 6 patients. The reason WM-only contacts were excluded is unknown; a dataset-pipeline choice is a probable but untested explanation.

SEEG · cortico-cortical evoked potentials · N1 · white matter · gray matter · electrode contacts · epilepsy · OpenNeuro · STReEF