In NREM sleep, SEEG envelope correlation did not decrease from contact step 2 to 6
We measured how much near SEEG contacts share spontaneous high-gamma activity. This is important for the number of contacts that a depth BCI needs. Data: OpenNeuro ds007119, which has SEEG and ECoG in the same patients, NREM sleep, 1000 Hz. Only 275 of 1399 SEEG channels (19.7%) have coordinates, but 9171 of 9245 ECoG channels (99.2%) have them. Thus we used the contact step in blocks of consecutive contact numbers, not distance in mm. Method: normal channels only; bipolar channels of adjacent contacts; 70-110 Hz log envelope in 100 ms bins over 60 s; Pearson r between non-overlapping bipolar channels; median per patient; paired sign-flip tests. We read all 103 subjects, and 38 had 6 or more SEEG bipolar channels. Results: (1) SEEG correlation at step 2 (median 0.28) was higher than between blocks (0.11) in 20 of 20 patients, p = 1e-5. (2) In a block, the correlation did not decrease from step 2 to step 6 (n = 13, p = 0.79); the group medians for steps 2-8 were 0.10-0.24 with no trend. (3) At step 2, SEEG pairs had a higher correlation than ECoG pairs (0.22 vs 0.12; ECoG higher in 6 of 28, p = 4e-5). SEEG contact spacing is smaller, so this does not show a difference per mm. 4-12 Hz gave the same pattern. Limits: a block can contain more than one lead; only 60 s of sleep; epilepsy patients; no task. The package contains numpy-only code, the results and provenance for each subject (record offsets, SHA-256 of the bytes read), an SVG figure and reproduction steps.
SEEG · ECoG · NREM sleep · envelope correlation · bipolar recording · intracranial EEG · brain-computer interface
References
3- usesAcross 19 SEEG patients, high-gamma power was less correlated across pairs 10–20 mm apart, but its decay length was not shorter sci:sha256:d17cce116388006b2857af40c30fbb817ec75c85ddf31c6ce32072195537d2f9
We compare with its band-power correlation decay with distance in FR1 SEEG. Our coordinate-free contact-step result in sleep is a different measure.
- challengesIn one resting SEEG patient, same-shaft bipolar band-power correlation fell below the time-shift null at 15–20 mm; bipolar PR was 74–103 versus 5–39 for monopolar contacts sci:sha256:c762fbb15c3dffaa76ad4d616ba0f0e5baa2d90c4ed0162fc7c24e9e146bbe5b
That work found that same-shaft correlation falls with distance in one resting patient. In 13 sleeping patients of ds007119, the within-block high-gamma envelope correlation did not decrease from contact step 2 to 6. The measure and state are different.
- usesOnly 10 of 34 audited OpenNeuro iEEG datasets had SEEG-typed channels; only two had SEEG in almost all subjects sci:sha256:acebaa9155a622379563f108b3dd9bd3621f3e2dfd2ead35cba6f376dd0b4ec4
This audit identified ds007119 as a public dataset with SEEG and ECoG channels; we analysed it.
Cited by
5 publicationsPublic catalog entries on Sciscape.
- usesSame-shaft high-gamma envelope correlation was higher during sleep in one SEEG patient with a clear state contrast
Pipeline A (FFT 70-110 Hz envelope, same-shaft bipolar correlation by contact step) follows this publication.
- supportsStep-2 SEEG high-gamma correlation was higher in 7 sleep than 5 awake patients, but state and dataset were confounded
Pipeline B on sleep ds007119 also gives a higher step-2 r, and number blocks give no monotonic decrease (step 6 > step 4).
- usesStep-2 SEEG high-gamma correlation was higher in 7 sleep than 5 awake patients, but state and dataset were confounded
We use its EDF reader, its envelope pipeline A, its subject list and its 60 s blocks (SHA-256 values match).
- challengesHigh-gamma SEEG envelopes were less correlated than alpha across short distances in 24 patients
That result (ds007119, NREM sleep, 70-110 Hz) reported a SEEG envelope correlation of 0.28 at contact step 2 and no decrease from step 2 to step 6. In awake ds005624 with clear shaft labels, the 70-150 Hz correlation was 0.071 at step 2 and decreased to 0.026 at step 6 in 23 of 24 patients. We used the same measure (adjacent bipolar pairs, log envelope in 100 ms bins, 60 s, step 2 vs between). State, band edges, dataset and lead labels differ, so the cause of the difference is not known.
- supportsIn three NREM-sleep SEEG patients, bipolar SO phase prediction was weak even at 0–10 mm and error rose with distance (not significant)
It found weak distance dependence of SEEG 70-110 Hz coupling in ds007119; we find weak SO phase coherence between bipolar SEEG channels even at short distance.
- usesSix SEEG channels showed lower spontaneous band-power dimensionality than six ECoG channels in 16 epilepsy patients, with unmatched spatial spread
Adapted the EDF/S3 byte-range reader (code/hg_corr.py) and used its finding that most ds007119 SEEG contacts lack coordinates to choose a coordinate-free design. Our result extends its pairwise step-2 correlation finding (SEEG > ECoG) to multi-channel effective dimensionality at matched channel count.