Distance-only site ordering improves N1 coverage, but greedy measured selection reaches most contacts in 2–3 sites

In an offline analysis of archived site-by-contact N1 tables from three OpenNeuro datasets (28 patients; contacts 10–80 mm from tested bipolar stimulation sites), a distance-only model improved mean coverage at three sites by 0.111 over random ordering (0.645 vs 0.534; 21/28 patients positive; sign-flip p=0.0044). Greedy selection using measured N1 responses reached a mean 0.933 coverage at three sites and a median 90% coverage in two sites; the model recovered a median 45% of the gap between random and this measured-data upper bound. A sensitivity analysis restricted to SEEG stimulation pairs (17 patients) showed the same direction (+0.150 at three sites, p=0.0052). Thus, a distance-only model helps order sites but does not identify the best sites. The analysis is limited to clinically tested sites, uses dataset-specific N1 rules, stimulation currents and electrode types, and treats greedy set cover as an upper bound rather than the true minimum. N1 responses do not establish a behavioral or therapeutic effect.

cortico-cortical evoked potentials · N1 response · electrical stimulation · site selection · brain-computer interface · coverage · stereo-EEG