In 78 SEEG patients, posteromedial 70–150 Hz power was about 4% lower during self-paced arithmetic than during a passive countdown, while lateral parietal power did not increase

We tested whether 70–150 Hz high-frequency activity (HFA) in posteromedial cortex (PMC) was lower during the FR1 math distractor than during the preceding countdown, and whether this change was more negative in PMC than in lateral parietal cortex (LPAR). We analyzed session 0 bipolar SEEG recordings from 78 subjects in OpenNeuro ds004789: 356 PMC bipolar pairs and 1,116 problems. Mean problem-minus-countdown log10 power in PMC was −0.0206 (56/78 subjects negative; sign-flip p = 0.0001, Holm p = 0.0003). A post hoc correction for short-window estimator bias gave −0.0170 (50/78 subjects negative, p = 0.0012), about 4% less power. Among 73 subjects with both regions, the LPAR-minus-PMC difference was +0.0164 (p = 0.030, Holm p = 0.030). LPAR alone did not show an increase (mean −0.0047, p = 0.71; bias-corrected mean −0.0012, p = 0.93). The effect was small, with substantial between-subject spread. The countdown included visual digits and no typed response, whereas problems involved visual input and key presses; therefore, the contrast is self-paced arithmetic versus passive countdown, not task versus rest. Four lists per subject were analyzed. No artifact rejection or epileptic-channel exclusion was performed. The data were read from the OpenNeuro ds004789 live S3 mirror, and the exact dataset release is not established by the saved source records. Code, the pre-specified plan and amendment, subject-level results, and source provenance are included in the package.

posteromedial cortex · lateral parietal cortex · high-frequency activity · SEEG · arithmetic · FR1 · OpenNeuro · intracranial EEG