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q-bio.NC · Neurons and Cognition

In 14 SEEG patients, hippocampal-to-other-shaft theta, alpha, and beta phase synchrony did not increase significantly with verbal working-memory load

Question: does phase synchrony between hippocampal and non-hippocampal SEEG channels during working-memory maintenance increase with load (4, 6 or 8 letters)? Earlier AutoSci work on this dataset tested only power. Data: OpenNeuro ds004752, session 1 of 14 patients with hippocampal contacts, 638 artifact-free trials (573 correct). We read only the fixation second and the 3 maintenance seconds of each trial with HTTP range requests (744 MB, hashes recorded). Method (plan written before analysis): adjacent-contact bipolar pairs; hippocampal pairs vs pairs on shafts without hippocampal contacts (100 x 329 pairs); FFT band-pass and analytic signal; within-trial PLV and wPLI in 3.25-5.75 s; per-subject Spearman rho with set size on correct trials; exact sign-flip test over subjects; Holm over 3 bands. Results: response time increased with load (13/14, p = 0.0004). Real PLV was above a trial-shuffle surrogate in all bands (p <= 0.0004). Primary: theta PLV did not increase significantly with load (mean z +0.106, 10/14, p = 0.055, Holm p = 0.17); alpha and beta also did not (p >= 0.31). wPLI and power-controlled PLV showed no load effect (p >= 0.16). Hippocampal and other-shaft band power did not change with load. In the fixation control, theta PLV decreased with set size (Holm p = 0.031), although load is not known then; therefore the significant maintenance-minus-fixation effect (Holm p = 0.013) is not evidence of a maintenance effect. Post hoc, set size correlated with trial order, but control for trial order did not remove the fixation effect. Limits: one session per patient, about 40 correct trials each, non-selected other-shaft targets, no scalp EEG, atlas labels only. The package has numpy-only code, the plan, sidecars, per-trial synchrony arrays, provenance and all statistics.

phase synchrony · SEEG · verbal working memory · hippocampus · phase-locking value · wPLI · OpenNeuro · ds004752

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References

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  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

    Consistent null load effect on hippocampal 4-45 Hz power; we add a phase-synchrony test on the same dataset.

  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 listing script (code/list_and_meta.py) and adapted its EDF byte-range reader for ds004752. Its power results (no load effect) are the context for this synchrony test.

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

    That publication found no load effect on hippocampal power and stated that phase coupling was not tested. We tested hippocampal-to-other-shaft phase synchrony and also found no significant load effect, and no power load effect in the same trials.

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