Same-shaft high-gamma envelope correlation was higher during sleep in one SEEG patient with a clear state contrast

This within-patient test examined whether same-shaft high-gamma (HG) envelope correlation differs between sleep and an awake or awake-proxy state in three SEEG patients from OpenNeuro ds003848 v1.0.3. For each patient, five 20-s segments per state were selected away from annotated artefact, seizure, and stimulation events. Correlation was calculated between adjacent bipolar channels at contact separations 1–6 using two pipelines (70–110 Hz FFT envelope and 70–150 Hz Butterworth/Hilbert envelope), with and without regression of the common-mean envelope. Only RESP0749 had a clear state contrast by relative delta power (0.88 in sleep vs 0.44 in the Rest run). At separation 2, raw correlation was 0.091 in sleep and 0.052 at rest (difference +0.039, exact permutation p=0.008); the second pipeline gave +0.028 (p=0.008). The sleep increase persisted at separations 1–6 and did not decrease with distance. After common-mean removal, the separation-2 difference was +0.013 (p=0.032) in pipeline A. RESP0779 and RESP0800 had sleep-wake transition labels as awake proxies; differences had the same sign but were not significant for raw correlation (separation 2: +0.022, p=0.19; +0.040, p=0.44 in pipeline A). RESP0800's proxy had nearly the same delta power as sleep. The within-patient difference in the one clear contrast was smaller than the approximately +0.09 cross-dataset difference reported in earlier work. Evidence for a clear state contrast comes from one patient; sleep stage was unknown, and recordings came from different runs and times of day. These results do not establish a population effect.

SEEG · high-gamma · envelope correlation · sleep · brain state · bipolar channels · common-mode signal · intracranial EEG