Dopaminergic medication reduces interhemispheric hyper-synchronization in Parkinson's disease

Area of Science:

• Neuroscience
• Neurology
• Biomedical Engineering

Background:

• Parkinson's disease (PD) is characterized by dopamine deficiency.
• Previous research indicated heightened interhemispheric cortical hyper synchronization in PD patients.

Purpose of the Study:

• To investigate the hypothesis that increased interhemispheric cortical synchronization in PD is related to dopamine deficiency.
• To determine the correlation between cortical synchronization and motor function in PD.

Main Methods:

• Electroencephalography (EEG) was used to record brain activity in 20 PD participants.
• Interhemispheric phase synchronization (inter-PS) was analyzed in theta, alpha, beta, and gamma bands during medication OFF and ON states.
• Cortical synchronization was assessed during quiet standing and straight-line walking.

Main Results:

• Inter-PS was significantly higher in the OFF state compared to the ON state for theta, alpha, and beta bands during both standing and walking.
• Reduction in inter-PS from OFF to ON state correlated with improved mobility (Timed Up and Go test) and daily levodopa equivalent dose.
• Greater differences in inter-PS between OFF and ON states were observed in the occipital-parietal cortex.

Conclusions:

• PD patients exhibit increased interhemispheric cortical synchronization when OFF medication, which decreases upon medication intake.
• This synchronization is associated with clinical improvements in motor function, suggesting a link to dopamine levels.
• Findings support the role of asymmetric subcortical dopamine deficiency in altered cortical synchronization patterns in PD.