Cortical Mechanisms of Mirror Activation during Maximal and Submaximal Finger Contractions in Parkinson's Disease
Bibliographic record
Abstract
BACKGROUND: Mirror movements are often reported in the early stages of Parkinson's disease (PD) and have been attributed to bilateral activation of the primary motor cortex; however, the precise cortical mechanisms are still unclear. Subclinical mirror activation (MA) that accompanies mirror movement has also been reported in healthy aging adults. OBJECTIVE: To characterize mirror activation and determine the cortical mechanisms of MA in individuals with PD who demonstrate mirror movements. HYPOTHESIS: 5 Hz rTMS to the supplementary motor area (SMA) will reduce MA by increasing interhemispheric inhibition (IHI) of the ipsilateral motor cortex. METHODS: MA was assessed using surface electromyography during maximal and submaximal unimanual contractions of the first dorsal interosseous in 7 individuals with PD with mirror movements (PD-MM: 70.9 ± 13.9 years; UPDRS III: 28.0 ± 8.2), 7 individuals with PD without mirror movements (PD-NM: 71 ± 10.1 years; UPDRS III: 27.8 ± 6.7) and 7 healthy controls (74.4 ± 6.0 years). IHI of the ipsilateral motor cortex was assessed using paired-pulse transcranial magnetic stimulation. RESULTS: MA was enhanced in both PD groups during submaximal contractions, with the latest onset of activation in PD-NM. Ipsilateral motor cortex excitability was the highest in PDMM; however, IHI did not differ between PD and controls. 5 Hz rTMS to the SMA reduced IHI in PD-NM; however, did not affect MA. CONCLUSIONS: IHI may not be the sole contributor to the expression of overt mirror movements in PD. Expression of overt mirror movement may be due to the combination of enhanced ipsilateral motor cortex excitability and an earlier onset of electromyographic activation in the mirror hand (mirror activation) in PDMM.
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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".