0044 Thalamocortical functional connectivity increases during REM sleep sawtooth waves
Bibliographic record
Abstract
Abstract Introduction Whereas sawtooth waves have been described as phasic bursts of slow oscillations in the scalp EEG during rapid-eye-movement (REM) sleep sixty years ago, little is known about their generators and functional role. Stereo-electroencephalography recordings (SEEG) performed for presurgical evaluation in drug-resistant focal epilepsy have allowed to demonstrate a peculiar slow activity in the thalamic medial pulvinar nucleus during REM sleep, contrasting with the fast desynchronized cortical activity. However, the link between this slow thalamic activity and sawtooth waves remains unexplored. Here, we used combined polysomnography and SEEG to investigate the dynamics of thalamic activity and thalamocortical functional connectivity at the time of scalp EEG sawtooth waves. Methods Night sleep recordings from six patients investigated with SEEG including thalamic recording in the Epilepsy Department of Lyon University Hospital were analyzed. Sawtooth waves were visually detected in the scalp EEG and compared with control segments selected in REM sleep. Thalamic SEEG and cortical EEG spectral power as well as thalamo-cortical functional connectivity assessed by the phase locking value were compared between sawtooth waves and control segments using paired t-tests. The effect size was assessed with Cohen’s d. Results A significant increase in the delta-theta (2-5 Hz, p< 0.003, d=0.31) and gamma (30-100 Hz, p< 0.003, d=0.31) power bands was found in posterior nuclei of the thalamus at the time of scalp-detected sawtooth waves. Functional thalamocortical connectivity in the 2-5 Hz band was enhanced during sawtooth waves as compared to control segments, with the thalamus driving the cortex (p< 0.001; d=0.84, average +/- SD time lag: 23 +/- 22 ms). Conclusion Our results provide evidence that sawtooth waves involve not only cortical areas but also the thalamus, suggesting a relation with ponto-geniculo-occipital waves. They may hence represent phasic brainstem-triggered short windows of an increased thalamocortical dialogue during REM sleep. Support (if any) B.F was supported by the Natural Sciences and Engineering Research Council of Canada RGPIN2020-04127 and RGPAS-2020-00021, and by the Fonds de Recherche du Québec–Santé 2021-2025 Salary Award “Chercheur-boursier clinicien Senior”. T.A. was supported by the “Healthy Brains, Healthy Lives initiative at McGill University” from the Canada First Research Excellence Fund and Fonds de recherche du Québec 2021-2022.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".