SEEG CCEP reciprocity is mostly explained by distance and site effects; the reverse response adds no held-out prediction (OpenNeuro ds005448, 8 patients)

In eight patients with SEEG data from OpenNeuro ds005448 v1.0.0, we tested whether cortico-cortical evoked potential (CCEP) N1 responses are reciprocal beyond distance, shaft, and site effects, and whether the reverse response improves prediction. Among 7,368 unordered stimulation-pair combinations at least 10 mm apart, raw reciprocity was strong (median odds ratio 5.8), but jointly responding pairs (465) were close to the 470 expected from distance alone. After adjustment, median reciprocity was gamma = 0.29 (median OR 1.34); it exceeded the simulated independence null in four of eight patients, while the exact sign-flip test was not significant (p = 0.14). Site effects raised median held-out AUC from 0.874 to 0.965. Adding the reverse response changed AUC by a median of +0.0001 (sign-flip p = 0.48). Sender and receiver effects did not correlate (median r = -0.08). The results suggest that the reverse CCEP adds almost no predictive information once distance and site effects are known. Inference is limited to eight patients, expert-checked N1 labels, and new pairs of already observed sites; the latency and white-matter analyses have additional limitations, and the white-matter analysis was exploratory.

SEEG · CCEP · N1 response · reciprocity · brain connectivity · epilepsy · site effects · stimulation · held-out prediction