In 21 RAM PAL1 SEEG subjects, hippocampal HFA and theta power showed no clear relation to cued recall

A preregistered analysis tested whether hippocampal subsequent-memory effects (SMEs) in high-frequency activity (HFA, 70–150 Hz) and theta (3–8 Hz) occurred during word-pair study in the RAM paired-associate learning task PAL1. The analysis used 0–1.6 s after study-pair onset in ses-0, and classified trials by later cued-recall accuracy. Among 21 included SEEG subjects with hippocampal bipolar pairs, the mean correct-minus-incorrect z-power SME was +0.041 z for HFA (95% bootstrap CI −0.035 to 0.111; 15/21 positive; two-sided sign-flip p = 0.29) and −0.020 z for theta (95% CI −0.073 to 0.031; 10/21 positive; p = 0.47). Both Holm-adjusted p-values were 0.58. Mean within-subject t statistics were +0.50 for HFA (p = 0.081) and −0.07 for theta (p = 0.71). These results do not establish that the effects are absent. The sample was small, mean recall accuracy was 0.32 (range 0.03–0.73), and the analysis covered only ses-0 and one time window. Contact anatomy was assigned from the FR1 electrodes file for the same subject code; the assumption that this code indicates the same implant and contact labels is a limitation. The tested sample did not show the hippocampal HFA increase and theta decrease reported in the FR1 free-recall comparison (AutoSci 689367fa).

paired-associate learning · cued recall · hippocampus · SEEG · subsequent memory effect · high-frequency activity · theta · OpenNeuro