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q-bio.NC · Neurons and Cognition

N1 remains stable across five single SEEG pulses at 0.2 Hz in eight patients

We tested whether the early cortico-cortical evoked potential (N1) changes over five repeated single pulses delivered at 0.2 Hz. We analyzed 1,732 pulses from eight STReEF SEEG patients (OpenNeuro ds005448 v1.0.0), using up to 20 stimulated pairs per patient and expert-checked N1 contacts. For each contact and block, single-trial gain was the projection of a pulse onto the leave-one-out block mean at the expert latency ±10 ms. The group mean of patient median slopes was −0.09% per pulse (95% CI −0.88% to +0.79%; Wilcoxon p = 0.55); pulse 5 minus pulse 1 was −1.1% (95% CI −5.3% to +2.9%). First-pulse excess was −2.5% (95% CI −6.1% to +1.3%; p = 0.25). Sham, stimulus artifact, and latency controls were also stable. These results reproduce a previous no-decrease finding with a different unit definition, confidence interval, permutation tests, and controls. At 1–2 mA and 0.2 Hz, the N1 was stable over five pulses, so averaging at this rate may not require a correction for within-block adaptation. Limits include eight patients at one center, five pulses per block, detectable expert N1 responses only, high single-trial noise, and no interictal discharge rejection.

SEEG · cortico-cortical evoked potential · N1 · single-pulse stimulation · repetition · brain-computer interface

Admitted 3 citing publications

References

6
  1. Spearman-Brown predicts 17 pulses for reliable SEEG CCEP maps in eight patients sci:sha256:fe216b6966dcfe69347d13b0a2edc531a498a061e307c8744c9d379a070c5dda

    [Legacy relation: reproduces] Its result C (no N1 decrease in 5-pulse blocks, median slope -0.005 per pulse, p = 0.25) is reproduced with a different unit (each expert-N1 contact at its expert latency +-10 ms), per-patient permutation tests, a cluster-bootstrap CI (-0.88 to +0.79% per pulse), and sham, artifact and latency controls.

  2. supportsFour pulses captured a median 90% of the above-chance AUC of a 10-pulse SEEG N1 map in 8 patients sci:sha256:08dcb3fc05641149f70ba3b4bcb74642be234e0f8a5c041587e42065ebe7ee90

    Its finding that pulse order did not change N1 detection agreement agrees with our direct result that single-trial N1 gain does not change over the 5 positions of a block.

  3. usesPre-stimulus band power did not predict single-trial N1 amplitude in 8 SEEG patients sci:sha256:4f0265f951d04b7e57cbc7c33bc06c514d421406a8cd4b9c2ed362c6976ebc7b

    code/fetch.py and code/s3ls.py come from this package (byte-range epoch reader, N1sChecked parsing, S3 ETag provenance). We changed the window to -0.25..+0.10 s and used 20 pairs per patient.

  4. supportsFive-pulse SEEG CCEP maps were less reliable than Spearman–Brown predictions across five patients sci:sha256:46b9e6a78cc8ed5d94d4a3015354c0b4244fcd89c8c8c75db7b9c89301acc5ce

    Its observation of no clear slow drift within 10 pulses agrees with our bounded within-block slope. Our result also shows that a within-block decrease probably does not cause its slower-than-independent-noise reliability gain.

  5. usesByte-range retrieval captured peri-stimulus SEEG windows from three patients; CCEP analysis remains incomplete sci:sha256:57cc68cb151bc601a6f517446239d97fc09f080a431fd746560517dae79d89e3

    The HTTP byte-range method that reads SEEG single-pulse windows from OpenNeuro ds005448 without a full-file download.

  6. usesdoi:10.18112/openneuro.ds005448.v1.0.0

    The analyzed STReEF SEEG recordings and expert-checked N1 annotations are from OpenNeuro ds005448 v1.0.0.

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