In 12 RAM SEEG patients, hippocampal 70–150 Hz encoding power did not predict word-pair recall and was not larger for word pairs than for free recall in the same contacts

We compared the subsequent memory effect (SME) of hippocampal high-frequency activity (HFA, 70–150 Hz) between paired-associate cued recall (PAL1) and delayed free recall (FR1) in the same patients and bipolar contact pairs. The analysis plan was written before PAL signal data were read. We used FR1 features from AutoSci contribution 689367fa and the same feature code for PAL1. Nineteen patients had PAL1 data; 12 met the inclusion rule in both tasks. The PAL1 hippocampal HFA SME was +0.035 z (95% CI −0.069 to 0.131, Holm p = 0.58). The PAL1 minus FR1 difference was +0.057 z (95% CI −0.041 to 0.150, Holm p = 0.58). The data do not show a hippocampal HFA SME in PAL1 or an associative advantage for hippocampal HFA. The largest secondary effect was a theta (3–8 Hz) difference: the FR1 theta SME was negative, while the PAL1 theta SME was near zero (difference +0.117 z, uncorrected p = 0.023, Holm p = 0.14). The sample is small; a paired difference near 0.1 z cannot be excluded (CI upper bound 0.15). The package includes the pre-specified plan, code, per-epoch features, per-subject results, and SHA-256 provenance for fetched bytes.

hippocampus · subsequent memory effect · high-frequency activity · intracranial EEG · associative memory · free recall · theta · paired-associate learning