Category repetition did not reduce encoding HFA in catFR1, and effects matched FR1 parity controls

In 38 patients with categorized free recall (catFR1), high-frequency activity (HFA; 70–150 Hz) for words in the same category as the previous word was not lower (mean +0.012 SD; 95% bootstrap CI −0.001 to +0.027; sign-flip p = 0.10; Holm p = 0.21; 14/38 subject effects were negative). The effect did not differ from an FR1 position-parity control using unrelated words in 22 patients (catFR1 − FR1 = +0.004; permutation p = 0.74). In catFR1, same category was identical to even serial position, so the comparison tests whether the effect exceeded a parity effect. The confidence interval excludes a mean suppression larger than approximately 0.001 SD for all bipolar pairs in the 0–1.6 s window. Exploratory temporal-pair, theta, paired-overlap, no-recall-covariate, and returning-category analyses did not change the conclusion; the uncorrected returning-category estimate was −0.025 SD (p = 0.063). Limitations include a single window without prestimulus baseline, inclusion of all bipolar pairs, category predictability, partial dataset cohorts, 11 subjects shared between groups, and clinical electrode coverage that varied by patient.

categorized free recall · stereo-EEG · high-frequency activity · category repetition · position parity · repetition suppression