0305 Degraded Fractal Activity Regulation Is Associated with Reduced Regional Cortical Gray Matter Volumes - Beyond the Brain Correlates of Sleep Fragmentation
Bibliographic record
Abstract
Human motor activity possesses fractal structures as characterized by similar fluctuation patterns across multiple time scales from seconds to hours. Such fractal regulation (FR) is robust in healthy young subjects and is degraded with aging. Evidence indicates a mechanistic link between fractal regulation and sleep/circadian control. Here, we tested whether FR degradation is associated with changes in brain structure and whether the FR brain correlates overlap with those for sleep disturbance in older adults. We examined motor activity recordings of 338 older non-demented adults (age: 81.5 ± 7.1 [SD]) in the Rush Memory and Aging Project. All participants underwent magnetic resonance imaging and actigraphy assessment (continuously recorded motor activity for 10 days) in the same year. Gray matter volumes of 34 cortical and 10 subcortical regions were obtained. To assess FR, temporal correlations in activity fluctuations at time scales ~0.1–1.5h were examined. We explored the associations between FR and gray matter volumes using bivariate Pearson correlation with Bonferroni correction. We confirmed the associations using linear regression models adjusted for age, sex, and years of education. Fractal activity correlations were positively associated with gray matter volumes in 14 cortical regions and 2 subcortical regions (Bonferroni corrected p<0.05). After adjustment for age, sex, and education, the associations remained in 13 cortical and 1 subcortical regions, including 7 regions that are known to be linked to Alzheimer’s disease pathology: lateral orbitofrontal, supra marginal, isthmus cingulate, superior temporal, fusiform, and accumbens area. Using the same database, we previously found that lower gray matter volumes in the lateral orbitofrontal cortex and inferior frontal gyrus pars orbitalis are associated with greater sleep fragmentation. Thus, FR degradation and sleep fragmentation involve certain common brain region in older adults (lateral orbitofrontal cortex), while FR degradation involves the decrease of gray matter volumes in more brain regions. This work was supported by NIH grants R01AG048108, R00HL102241, P01AG009975, R01AG017917, and R01NS078009.
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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 | 0.000 |
| 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 | 0.001 |
| 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 | 0.000 |
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 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".