Resting-State and Task-Related fMRI Correlates of Working Memory Performance in Parkinson's Disease, on and off Dopamine Replacement Therapy (P4.107)
Bibliographic record
Abstract
Background Executive dysfunction is a frequent feature of Parkinson’s disease (PD), even in its early stages, but its neural basis is debated. Objective One possibility is that dopamine depletion in the striatum impairs information processing in cortico-striatal circuits. Design/Methods We tested this hypothesis by examining working memory performance with a letter 2-back task, task-related fMRI signal, and caudate connectivity in the resting state in 19 patients with mild-moderate PD and 20 demographically matched controls. PD patients were tested off their usual dopamine replacement therapy (DRT), and again after a standard dose of l-dopa/carbidopa. Results PD patients off DRT showed poorer working memory compared to controls. Administration of l-dopa significantly improved performance, tested within-subject, and eliminated the group difference. FMRI showed that PD patients and controls engaged a similar set of frontal, parietal and subcortical regions during the 2-back task, but the extent of frontal and parietal activations was significantly reduced in the PD group. There was no difference in the pattern of activation in the PD group on compared to off DRT. When working memory performance was included as a regressor, we found that better performance was associated with greater activation of right dorsolateral prefrontal cortex (PFC) in PD patients off DRT compared to controls, and that greater left ventrolateral PFC activation was associated with better performance in the PD group on, compared to off DRT. Finally, DRT led to a significant increase in caudate-parietal functional connectivity at rest, and this connectivity predicted better performance in PD patients on and off DRT, and healthy controls. Conclusions These findings show that working memory impairment in PD is remediated by l-dopa, and elucidate the effects of both PD and l-dopa on the neural correlates of this behavior. Resting-state findings argue that a DRT-sensitive cortical-caudate network is related to working memory performance.
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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".