In eight SEEG patients, N1 peak latency rose 0.23 ms/mm with distance, but distance explained little variance

We examined expert-checked N1 peak latencies after single-pulse electrical stimulation in eight SEEG patients from OpenNeuro ds005448 v1.0.0. Among 35,494 observations, 3,592 had an accepted N1; the core analysis included 2,891 first-run N1 peaks below 80 ms. The median per-patient Theil–Sen latency slope was 0.23 ms/mm (positive in 7/8 patients; exact sign-flip p = 0.031), corresponding to an apparent velocity of about 4 m/s. Distance explained little variance (median linear R² = 0.09; maximum 0.15) and reduced leave-one-patient-out mean absolute error from 8.4 to 8.1 ms. At fixed distance, same shaft, white-matter labels, and binary DTI connection showed no consistent effects in this sample. Larger N1 amplitudes were associated with earlier peaks; opposite-direction residual latencies had a weak positive association. In one patient, 2 mA produced more accepted N1 responses than 1 mA while paired latencies were similar (median difference −0.49 ms). Peaks at 80–100 ms clustered near the detector-window edge and increased ordinary least-squares slopes: median slope was 0.45 ms/mm using OLS on all N1 versus 0.23 ms/mm using Theil–Sen on the core set. A fixed 10–60 ms read window contained 97% of core N1 peaks and 85% of all accepted peaks. The findings are limited by one center, eight patients, peak rather than onset latency, a 9–100 ms detector window, Euclidean distance, and a current comparison in one patient; these data support measuring latency for each pathway rather than predicting it from anatomy.

SEEG · single-pulse electrical stimulation · N1 latency · evoked response · stereo-EEG · brain-computer interface · distance · DTI · reciprocity