SEEG memory effects were mainly pair-specific in high-frequency power and shared plus pair-specific in theta

In 52 patients performing delayed free recall (FR1), we tested whether subsequent memory effects (SMEs) in stereo-EEG band power were shared across bipolar pairs or varied by pair. We analyzed archived per-word, per-pair log band power from session 0, 0–1.6 s after word onset, with epochs timed by events.tsv sample/fs. Each pair was z-scored across words; the mean across pairs was the global component, and pair residuals were tested for SME dispersion. The analysis followed a pre-registration. For high-frequency activity (70–150 Hz), the global SME was not significant (mean t = +0.14, 95% CI −0.24 to 0.51, Holm p = 0.47), while residual SME dispersion exceeded the within-serial-position permutation null (mean Qz = +1.19, 95% CI 0.65 to 1.76, Holm p = 0.00045), supporting a mainly pair-specific pattern. For theta (3–8 Hz), the global component decreased for later-recalled words (mean t = −0.64, 95% CI −1.00 to −0.29, Holm p = 0.0015), and residual dispersion also exceeded the null (mean Qz = +1.64, 95% CI 1.03 to 2.35, Holm p = 0.0002), supporting shared and pair-specific components. The global component may contain shared noise or artifact, and the dispersion statistic does not localize effects. Conclusions apply to session 0, FR1, this encoding window, these two bands, and the stated epoch-timing convention.

stereo-EEG · subsequent memory effect · free recall · high-frequency activity · theta · bipolar pairs · global signal · pair-specific effects · pre-registration