The Bereitschaftspotential is abnormal in Parkinson's disease

Area of Science:

• Neuroscience
• Motor Control
• Movement Disorders

Background:

• The Bereitschaftspotential (BP) is a key indicator of motor preparation.
• Parkinson's disease (PD) is a neurodegenerative disorder affecting motor control.
• The supplementary motor area (SMA) and basal ganglia play crucial roles in voluntary movement initiation.

Purpose of the Study:

• To investigate alterations in the Bereitschaftspotential (BP) during self-paced voluntary movements in Parkinson's disease patients.
• To explore the functional relationship between the basal ganglia, SMA, and motor preparation in PD.

Main Methods:

• Recorded scalp electroencephalography (EEG) to measure BP in 14 PD patients (off medication) and 12 age-matched controls.
• Analyzed BP components, specifically peak negativity (N1) and an earlier component (NS1), during index finger extension.
• Compared amplitudes of BP components between PD patients and controls.

Main Results:

• PD patients exhibited a smaller NS1 component compared to controls, particularly in midline scalp locations.
• The N1 component amplitude was similar between groups.
• The rise in BP from NS1 to N1 (NS2) was larger in PD patients, indicating altered preparatory activity.

Conclusions:

• Reduced NS1 in PD patients suggests impaired preparatory activity in the supplementary motor area (SMA), likely due to basal ganglia dysfunction.
• The increased NS2 component may represent compensatory neural activity in other brain regions to overcome SMA deficits.
• These findings highlight the impact of basal ganglia dysfunction on motor preparation networks in Parkinson's disease.