In 51 FR1 SEEG patients, sex differences in the encoding memory effect and recall were not detected, but the confidence interval did not exclude a difference as large as the group effect

We asked whether female and male patients with stereoelectroencephalography (SEEG) differed in the word-encoding subsequent memory effect (SME) or delayed free-recall rate. We analyzed archived per-word log10 band-power features from 54 patients in the FR1, session 0 sample of OpenNeuro ds004789 v3.1.0; 51 patients (27 female, 24 male) met the requirement of at least 15 recalled and 15 not-recalled words. For each pair and band, we removed list and serial-position means and z-scored over words. We calculated Cohen’s d for recalled versus not-recalled words and averaged across pairs to obtain each patient’s SME. The female-minus-male difference in the primary tilt measure (z-scored 70–150 Hz minus z-scored 3–8 Hz power) was −0.006 d (95% CI −0.041 to +0.030; Holm-adjusted p = 1.0). Differences were also not detected for high-frequency activity (HFA; +0.008 d, p = 0.57) or theta (+0.017 d, p = 0.44). Recall rates were 0.276 in females and 0.270 in males (difference +0.006, 95% CI −0.050 to +0.063; p = 0.83). The pooled tilt SME was +0.022; its confidence interval spans −1.9 to +1.4 times that group effect, so these data do not exclude a sex difference as large as the group effect. The null result is not an equivalence result. Findings were similar after age adjustment and in a hippocampal-pair analysis. Limitations include 51 patients, one session, recorded biological sex only, differing electrode coverage, low split-half reliability of subject-level SME, and no medication, seizure-onset, or hormone data. The sample includes epilepsy patients only.

subsequent memory effect · word encoding · free recall · stereoelectroencephalography · sex differences · high-frequency activity · theta · hippocampus