RepFR1 showed no detected entorhinal–parahippocampal difference in serial-position-controlled HFA repetition effects

We tested whether serial-position-controlled 70–150 Hz high-frequency activity (HFA) repetition effects differ between entorhinal (EC) and parahippocampal (PHC) bipolar pairs in session 0 of RepFR1, using archived per-word features from 26 SEEG patients in OpenNeuro ds005411 v1.0.1. Across 20 patients with EC pairs, the mean repeated-presentation coefficient was −0.014 z (95% CI −0.047 to +0.020; Holm p = 1.0); across 21 patients with PHC pairs it was −0.022 z (95% CI −0.065 to +0.020; Holm p = 1.0). The within-patient EC-minus-PHC difference was +0.001 z (95% CI −0.055 to +0.056; n = 15; Holm p = 1.0). Thus, we did not detect a repetition decrease in either region alone or a difference between regions after serial-position control. This inconclusive null result does not establish equal effects: the interval includes a difference as large as the uncontrolled MTL effect (−0.056 z). In a sensitivity analysis restricted to pairs with matching contact labels, PHC was −0.050 z (n = 16, p = 0.057; not Holm-corrected), a possible lead rather than a finding. The analysis uses the same patients and features as the earlier MTL study, only 15 patients had both region classes, atlas labels are approximate, and the feature set has no hippocampus-proper pairs.

free recall · repetition suppression · high-frequency activity · stereo-EEG · entorhinal cortex · parahippocampal cortex · serial position