Serotonin 2A Receptors and Visual Hallucinations in Parkinson Disease
Bibliographic record
Abstract
BACKGROUND: Complex visual hallucinations (VHs) occur in several pathologic conditions; however, the neural mechanisms underlying these symptoms remain unclear. Although dopamine may have a role, indirect evidence indicates that serotonin may also contribute to the pathogenesis of complex VHs, probably via involvement of the serotonin 2 receptor. OBJECTIVE: To examine for the first time in vivo changes in serotonin 2A receptor neurotransmission among patients having Parkinson disease (PD) with VHs. DESIGN: Case-control study. SETTING: Academic research. PATIENTS: Seven patients having PD with VHs and 7 age-matched patients having PD without VHs were recruited. MAIN OUTCOME MEASURES: We used the selective serotonin 2A receptor ligand setoperone F 18 during positron emission tomography among nondemented patients having PD with VHs. RESULTS: Patients having PD with VHs demonstrate increased serotonin 2A receptor binding in the ventral visual pathway (including the bilateral inferooccipital gyrus, right fusiform gyrus, and inferotemporal cortex) as well as the bilateral dorsolateral prefrontal cortex, medial orbitofrontal cortex, and insula. CONCLUSIONS: This pilot study provides the first in vivo evidence suggesting a role for serotonin 2A receptors in mediating VHs via the ventral visual pathway in PD. Treatment studies should be performed using selective serotonin 2A receptor antagonists, which have important implications for the clinical management of VHs and psychosis in PD.
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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 | 0.000 | 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) | 0.001 | 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".