The unstable bridge from stimulus processing to correct responding in Parkinson's disease

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Clinical Neurology

Background:

• The basal ganglia are hypothesized to link stimulus processing with motor responses.
• The P3b event-related potential component is proposed as a marker for stimulus-response (S-R) link integrity.

Purpose of the Study:

• To investigate S-R link integrity in Parkinson's disease (PD) using electroencephalography (EEG).
• To examine the role of basal ganglia in resolving response discrepancies.

Main Methods:

• Measured P3 complex (P3a and P3b) in EEG, time-locked to stimulus (S) and response (R) in healthy controls and PD patients.
• Compared P3b amplitudes in S-locked versus R-locked averages between groups.
• Analyzed error-negativity (NE)-type components in relation to response accuracy.

Main Results:

• Healthy participants exhibited similar P3b amplitudes in S- and R-locked averages.
• PD patients showed smaller P3b amplitudes in R-locked compared to S-locked averages.
• PD patients displayed an N(E)-type signal in both S- and R-locked averages during error trials, and a pre-response negativity in correct trials.

Conclusions:

• Findings support the basal ganglia's role in resolving signal discrepancies and competing responses.
• Altered P3b and N(E) components in PD patients suggest impaired S-R linking and potential response conflict.
• The overlap of P3b by N(E) components may represent a key pathophysiological feature in Parkinson's disease.