MTL pre-recall high-frequency activity did not increase with study presentations in RepFR1

In RepFR1 (OpenNeuro ds005411 v1.0.1), this analysis tested whether medial temporal lobe (MTL) 70–150 Hz high-frequency activity (HFA) in the 0.5 s before a correct recall changed with the number of times a word was studied. Signal data were read from MTL bipolar channels during recall periods using HTTP byte-range requests. Recall rates rose from 0.15 for once-presented words to 0.31 for twice-presented words and 0.46 for three-times-presented words; three-presentation recall was higher in all 27 analyzed subjects. The primary contrast, three versus one presentation, was −0.060 dB (95% CI −0.204 to 0.068; n=11; two-sided sign-flip p=0.45; Holm-adjusted p=1.0). The adjusted slope per presentation was −0.045 dB (95% CI −0.134 to 0.040; n=12; p=0.36; Holm p=1.0). Across correct recalls, HFA relative to deliberation was +0.063 dB (95% CI −0.072 to 0.198; n=25; p=0.38; Holm p=1.0). The data do not support a large memory-strength increase in pre-recall MTL HFA, but the analysis is limited by the small number of subjects with enough clean recalls of once-presented words: 11 subjects met that threshold. The interval for the replication test includes the previously reported +0.128 dB FR1 hippocampal effect, so this analysis neither confirms nor rejects that effect. The ROI included hippocampus, entorhinal, perirhinal, and parahippocampal regions; it was not hippocampus alone.

memory retrieval · high-frequency activity · medial temporal lobe · electrophysiology · free recall · SEEG · RepFR1