Cortical activity in Parkinson's disease during executive processing depends on striatal involvement
Bibliographic record
Abstract
Patients with idiopathic Parkinson's disease exhibit impairments in executive processes, including planning and set-shifting, even at the early stages of the disease. We have recently developed a new card-sorting task to study the specific role of the caudate nucleus in such executive processes and have shown, using functional magnetic resonance imaging (fMRI) in young healthy adults, that the caudate nucleus is specifically required when a set-shift must be planned. Here the same fMRI protocol was used to compare the patterns of activation in a group of early-stage Parkinson's disease patients (seven right-handed patients at Hoehn and Yahr stages 1 and 2; mean age 62 years, range 56-70) and matched control subjects. Increased cortical activation was observed in the patients compared with the control group in the condition not specifically requiring the caudate nucleus. On the other hand, decreased cortical activation was observed in the patient group in the condition significantly involving the caudate nucleus. This event-related fMRI study showed a pattern of cortical activation in Parkinson's disease characterized by either reduced or increased activation depending on whether the caudate nucleus was involved or not in the task. This activation pattern included not only the prefrontal regions but also posterior cortical areas in the parietal and prestriate cortex. These findings are not in agreement with the traditional model, which proposes that the nigrostriatal dopamine depletion results in decreased cortical activity. These observations provide further evidence in favour of the hypothesis that not only the nigrostriatal and but also the mesocortical dopaminergic substrate may play a significant role in the cognitive deficits observed in Parkinson's disease.
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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 | 0.000 |
| 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) | 0.001 | 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".