Parkinson's disease rigidity: relation to brain connectivity and motor performance
Nazanin Baradaran1, Sun Nee Tan, Aiping Liu
1Pacific Parkinson's Research Centre, University of British Columbia , Vancouver, BC , Canada.
Frontiers in Neurology
|June 14, 2013
Summary
Brain connectivity patterns in Parkinson's disease (PD) patients reveal a network associated with rigidity. Damping ratio, a motor performance metric, correlates with rigidity, offering a potential marker for motor deficits.
Area of Science:
- Neuroscience
- Neurology
- Biomedical Engineering
Background:
- Rigidity, a key symptom of Parkinson's disease (PD), involves resistance to passive movement and is exacerbated by contralateral limb activation.
- The precise relationship between clinical rigidity assessments and quantitative motor performance metrics in PD remains unclear.
- The involvement of a distributed brain network in PD rigidity is suggested by clinical observations.
Purpose of the Study:
- To identify the brain connectivity patterns linked to clinical rigidity scores in Parkinson's disease (PD).
- To investigate the correlation between clinically measured rigidity and quantitative motor performance indicators in PD patients.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was employed during a squeeze-bulb tracking task in 10 PD patients (off-medication) and 10 controls.
- Dynamic Bayesian Networks (DBNs) were used to analyze direct functional connectivity between defined brain regions.
- Linear Dynamical System (LDS) models quantified motor performance, and a cross-validated LASSO regression identified predictive connectivity networks for rigidity.
Main Results:
- A significant correlation was found between the damping ratio from LDS models and clinical rigidity scores (p=0.014).
- An fMRI-derived connectivity network encompassing subcortical and primary/premotor cortical regions accurately predicted clinical rigidity scores (p<10^-5).
Conclusions:
- A widespread cortical and subcortical network is associated with PD-related rigidity, highlighting the role of altered functional connectivity in PD pathophysiology.
- Higher rigidity scores in PD patients correlated with reduced overshoot in tracking tasks.
- The damping ratio emerges as a potential quantitative biomarker for the motor impact of increasing rigidity in Parkinson's disease.
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