0649 STRUCTURAL BRAIN ABNORMALITIES IN IDIOPATHIC HYPERSOMNIA
Bibliographic record
Abstract
Idiopathic hypersomnia (IH) is characterized by excessive daytime sleepiness but, in contrast with narcolepsy, does not involve cataplexy, rapid REM sleep onset (at the multiple sleep latency test, MSLT), or any consistent hypocretin-1 deficiency. The pathophysiological mechanisms of IH remain unclear, and no neuroimaging study has been conducted in IH. We hypothesize that IH is characterized by cortical alterations within networks involved in alertness. We conducted magnetic resonance imaging (MRI) on a 3T scanner in 12 participants with IH (mean age 33, range 22–59 years, 6 males, 10 females) and 16 good sleepers (mean age 31, range 22–53 years, 3 males, 9 females). High-resolution T1-weighted anatomical images were used to perform voxel-based morphometry (VBM) to measure regional volume and cortical thickness analyses. Daytime mean sleep latency from MSLT and Epworth sleepiness score were collected to measure respectively objective and self-reported scores of daytime sleepiness. Student t-tests were used to compare groups, and regression analyses were conducted on sleepiness scores, controlling for total intracranial volume (only for VBM), age and sex (threshold T>2.5, equivalent to p<0.01). Participants with IH had thicker and larger cortical structures, mainly within the default-mode network, compared to good sleepers: the anterior cingulate cortex, precuneus extending to posterior cingulate cortex, lateral parietal cortex bilaterally, and right premotor cortex were larger in IH. These larger volumes and thickness in IH were correlated with increased levels of subjective daytime sleepiness. The present results show that IH is associated with structural brain alterations, mainly located within the default-mode network and changing in proportion of clinical severity. Larger volume and thickness in these structures might reflect compensatory changes to chronic daytime sleepiness. Supported by the Sleep Research Society Foundation, the Canadian Institutes of Health Research (CIHR), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Fonds de Recherche du Québec - Santé (FRQ-S), and the Canada Foundation for Innovation (CFI).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.005 | 0.000 |
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 source (direct Gemma or distilled Codex), 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".