FC29-05 - Season, sunlight, and brain serotonin function
Bibliographic record
Abstract
Introduction Many experience low mood and energy during winter. Brain serotonin is involved in the regulation of many physiologic and pathologic functions that vary with season. Seasonal variations in peripheral serotonergic markers have been described in clinical and nonclinical populations, and a postmortem study shows seasonal differences in hypothalamic serotonin concentration. Aim We investigated the molecular background of seasonal changes in serotonin function by conducting a series of studies on serotonin transporter (5-HTT) density and function in depression and health. Methods In a large study in drug-free patients with seasonal affective disorder (SAD) we aimed at detecting state-related alterations in 5-HTT-mediated inward and outward transport in platelets. Another study in healthy subjects aimed at detecting seasonal variations in 5-HTT binding in the living human brain using [ 11 C] DASB positron emission tomography. Regional 5-HTT binding, an index of 5-HTT density, was assessed in a large sample of drug-naïve healthy volunteers, and was related to meteorological and astronomical data. Results In patients with SAD we showed that the 5-HTT is in a hyperfunctional state during winter depression, and normalizes after light therapy and in natural summer remission. In healthy subjects, 5-HTT binding was higher in autumn/winter as compared to spring/summer. Regional 5-HTT binding correlated negatively with daily sunshine, such that higher values occurred at times of lesser light. Conclusions Since high 5-HTT density is associated with low synaptic serotonin levels, regulation of 5-HTT density and 5-HTT function by light is a mechanism that may explain seasonal changes in normal and pathologic behaviours.
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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 | 0.000 |
| 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".