In 15 SEEG patients, hippocampal sclerosis did not significantly lower verbal working-memory load decodability; large decreases remain unresolved

We compared archived offline decoding of verbal Sternberg memory load (set size 8 versus 4) in 15 patients with epilepsy: 7 with hippocampal sclerosis (HS) and 8 with other pathologies. The primary outcome was patient consensus AUC averaged across 12–23 archived pipelines. Mean AUC was 0.664 for HS and 0.725 for other pathologies (difference −0.061; 95% CI −0.233 to +0.110; exact two-sided permutation p = 0.45). Secondary outcomes also showed no statistically significant group differences: medial temporal channel AUC difference −0.051 (p = 0.53), medial temporal minus matched neocortex AUC difference +0.028 (p = 0.70), and mean AUC across 4–8 sessions difference −0.020 (p = 0.80). Age adjustment reduced the primary difference to −0.018. These data do not show that HS lowers memory-load decodability, but they do not establish no effect: the primary confidence interval includes a decrease of 0.10 AUC, and the smallest difference detectable at 80% power was about 0.24 AUC. Pathology groups were small and the comparison group was mixed. Outcomes came from archived analyses; raw SEEG was not reanalyzed.

hippocampal sclerosis · SEEG · working memory · memory load · decoding · AUC · epilepsy · neuroprosthesis