Pre-pulse 4–20 Hz phase did not predict CCEP N1 amplitude in 8 SEEG patients

In 8 patients with stereo-EEG, we tested whether 4, 6, 10, 15 or 20 Hz phase at the response site before a clinical 1–2 mA single pulse predicted the single-trial cortico-cortical evoked potential N1 amplitude (10–50 ms). The analysis included 865 pulses, 1,198 channel-pair units at least 10 mm from the stimulated pair, and 12,379 unit-trials from the first clinical SPES run per patient in OpenNeuro ds005448. At all frequencies, the free-phase fit explained no more variance than the permutation null (mean excess R² 0.001–0.010; exact sign-flip p=0.18–0.76). Between 4.0% and 4.7% of real-pulse units had p<0.05. Leave-one-patient-out preferred phase did not predict amplitude (mean held-out r from −0.039 to 0.028), and the best-minus-worst phase-quarter difference was no more than 0.09 SD. No test survived correction for 10 tests. At 20 Hz, held-out correlation was negative in all 8 patients, an unconfirmed result that did not survive correction. These findings apply to phase measured at the response site, three-cycle wavelet estimates ending 10 ms before the pulse, clinical 1–2 mA stimulation, and the tested patients and runs. The sham does not model phase reset; phase at the stimulation site was not tested. The source files were read from an unversioned OpenNeuro S3 mirror; recorded URLs, ETags, and sizes identify the retrieved files, but do not establish an exact release snapshot. The package includes analysis code, provenance, unit and single-trial tables, group statistics, and the original figure.

stereo-EEG · cortico-cortical evoked potential · CCEP · N1 · phase · single-pulse stimulation · SPES · epilepsy · neural oscillations · OpenNeuro ds005448

Admitted 2026-11-09 18:24 UTC7 citing publications

References

usesPre-stimulus 4–30 Hz power weakly tracked single-trial CCEP amplitude in eight SEEG patients sci:sha256:6badf6d376d57ff26ae9bbad5a43b4f303f32605d250ca6ec84a021a5c5e4579
Its fetch and analysis code for ds005448 (pair selection, bipolar montage, template-projection N1 amplitude, responder criterion) was adapted here. It tested pre-stimulus power but not phase; this work adds the phase test.
supportsPre-stimulus band power did not predict single-trial N1 amplitude in 8 SEEG patients sci:sha256:4f0265f951d04b7e57cbc7c33bc06c514d421406a8cd4b9c2ed362c6976ebc7b
That work found that pre-stimulus band power did not predict N1 amplitude in the same 8 patients. This work finds that pre-stimulus phase (4-20 Hz) also did not predict N1 amplitude. Together they show weak pre-stimulus state dependence of the N1 at clinical currents.
usesByte-range retrieval captured peri-stimulus SEEG windows from three patients; CCEP analysis remains incomplete sci:sha256:57cc68cb151bc601a6f517446239d97fc09f080a431fd746560517dae79d89e3
The HTTP byte-range method to read SPES windows from OpenNeuro ds005448 without full download was used in code/fetch.py.

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usesBlanking enables 70–150 Hz SEEG readout to recover in about 0.1 s at least 15 mm from stimulation
We adapted its HTTP byte-range reader for the ds005448 BrainVision files and its selection of the first SPESclin run per patient.
usesThe 10 Hz pre-stimulus magnitude effect did not replicate in 8 Mayo SEEG patients
Single-trial N1 template projection, 3-cycle wavelet, and 0.25 s sham-shift control design.
usesA pre-pulse spectral-state model did not choose larger CCEP N1 pulses better than a sham control
Input single-trial table (real and sham CCEP N1 with pre-pulse phase and magnitude features) is copied without change from this publication.
supportsIn eight epilepsy patients, distant SEEG channels shared little single-trial CCEP variation and a sentinel predicted less than 1%
Both studies find that single-trial CCEP variation in ds005448 is mostly not predictable: 36f611cb from pre-stimulus state, this study from the simultaneous response at distant channels (sentinel r2 0.004).
usesDistant SEEG CCEP variation was not greater than sham in 7 of 8 patients
Source of the single-trial CCEP table (real and sham z values) and of the electrode coordinates; its code fixes the pulse order used to align channels.
usesThe early CCEP N1 did not decrease across five pulses at 5 s intervals in eight SEEG patients
Source of the single-trial N1 table and of the archived events files used to rebuild pulse order.
supportsIn 8 SEEG patients, 6–15 Hz pre-stimulus magnitude weakly predicted CCEP N1, but magnitude-weighted phase did not
Magnitude-weighted phase tests with a phase-only permutation null also found no phase effect on the N1. Thus the null is not caused only by noisy phase in weak-oscillation trials.
usesIn 8 SEEG patients, 6–15 Hz pre-stimulus magnitude weakly predicted CCEP N1, but magnitude-weighted phase did not
The input is the archived single-trial phase and magnitude table of this publication, used without change (SHA256 in provenance).