A 26-patient catFR1 extension found no increase in hippocampal high-frequency power before correct recall

This planned extension tested 65 person-independent patients who were not tried in an earlier time-limited RAM catFR1 fetch. The same fetch and analysis code was used. Thirty patients had hippocampal bipolar pairs, and 26 met the threshold of at least 10 correct recalls. In the primary analysis, hippocampal 70–150 Hz power in the 0.5 s before correct recall differed from the deliberation baseline by +0.052 dB (95% CI −0.079 to +0.183; two-sided sign-flip p = 0.45), so the pre-specified hypothesis of an increase was not supported. Pooling these 26 patients with 46 archived values gave +0.011 dB (95% CI −0.095 to +0.112; n = 72). This pooled interval did not include the earlier FR1 estimate of +0.128 dB, but that descriptive comparison was not pre-specified and does not include uncertainty in the FR1 estimate. Descriptive contrasts showed higher power before correct recalls than before intrusions (+0.198 dB, n = 14, p = 0.030) or non-word vocalizations (+0.168 dB, n = 18, p = 0.013); these results were not corrected under this plan. Same-category minus category-switch power was +0.093 dB (n = 15, p = 0.36), while the earlier sample had the opposite sign. The interpretation that correct-recall contrasts reflect lower power before intrusions and vocalizations, rather than a rise before correct recall, is post hoc. Limits include the sample size, atlas-field-only hippocampal labels without image checking, and exclusion of people who completed both FR1 and catFR1. The source was read from the OpenNeuro ds004809 S3 URL; recorded byte offsets and SHA-256 hashes identify the analyzed files, but the source does not establish an exact dataset release.

categorized free recall · hippocampus · high-frequency activity · 70–150 Hz · stereo-EEG · intracranial EEG · memory retrieval · RAM dataset