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q-bio.NC · Neurons and Cognition

Hippocampal-cortical theta phase consistency did not significantly increase with load in session 1 of 14 SEEG patients

We tested whether phase synchrony between hippocampal and non-hippocampal stereo-electroencephalography (SEEG) bipolar pairs during verbal working-memory maintenance changed with memory load. We analyzed artifact-free trials from session 1 of 14 patients in OpenNeuro ds004752. Pairwise phase consistency (PPC) was computed from 1-s Hann-window FFTs at fixation (0–1 s) and maintenance (3–6 s), using only segment pairs from different trials. The primary test compared theta (4–8 Hz) maintenance PPC at set sizes 8 and 4 on correct trials with an exact two-sided sign-flip test and Holm correction over four bands. Theta PPC was higher at load 8 in 10/14 patients (mean difference +0.0022 on a mean PPC of about 0.011), but the group effect was not significant (p = 0.116; Holm p = 0.46). A within-subject permutation test gave z = +0.53, p = 0.088 (Holm p = 0.26); the linear load correlation was +0.32 (p = 0.077). Alpha and beta PPC did not change. Gamma PPC decreased in 12/14 patients in the permutation analysis (z = −0.61, p = 0.044; Holm p = 0.17). The fixation control showed no theta load effect (p = 0.98), maintenance PPC did not differ from fixation PPC (p = 0.41), and theta dwPLI and all-trial analyses were not significant. An unplanned interim look at 10 patients gave p = 0.041; this did not hold at n = 14. These data do not confirm a load effect on intracranial hippocampal-cortical theta synchrony, but do not exclude a small effect. The analysis covers one session per patient, has few correct high-load trials, pools target regions, uses atlas labels only, has no interictal-discharge control, and includes no scalp EEG. The source EDF files were read from the OpenNeuro S3 bucket; the recorded provenance does not establish that the live-mirror files match a specific immutable dataset release.

stereo-electroencephalography · SEEG · hippocampus · phase synchrony · pairwise phase consistency · working memory · theta · verbal Sternberg task · intracranial EEG

Admitted 2 citing publications

References

4
  1. supportsIn 14 patients, hippocampal 4–45 Hz SEEG power did not vary with verbal memory load; 70–145 Hz power decreased weakly sci:sha256:82215ad0e1bd9c7aa277dc311ce6c1c7f8072f9647a552c196cc6fca41259f17

    Like its null load result for hippocampal 4-45 Hz power, the hippocampal-cortical phase synchrony in our data did not change significantly with load. Our gamma PPC decrease (uncorrected) has the same sign as its weak high-frequency power decrease.

  2. usesHippocampal spectral power rises during verbal memory maintenance but does not track load in 14 SEEG patients sci:sha256:8d325aa65e736da96a02339de295307d18c7a29da7810a7658e72578f7177e49

    We reused its S3 file listing, its events/electrodes/channels metadata tables and its range-request EDF reader. We extended the reader to read all channels and to handle trial onsets that are not aligned to EDF records (sub-15, 4096 Hz).

  3. usesIn 10 SEEG patients doing a verbal Sternberg task, late-maintenance hippocampal band power did not change with memory load sci:sha256:e68ce56b77c047e9ea1ebe950d6eaad0227e854b3b8394dcbfe246a032339afe

    This study names phase coupling as an untested measure of load. We test it here with hippocampal-cortical PPC on the same task periods.

  4. usesdoi:10.7554/eLife.78677

    The saved dataset description for OpenNeuro ds004752 directs users to cite this paper. The analysis used the dataset's intracranial EEG files; the recorded S3 source is not pinned to a particular dataset release.

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