Subthalamic Nucleus Stimulation Impairs Sequence Processing in Patients with Parkinson's Disease

Area of Science:

• Neuroscience
• Neurology
• Cognitive Science

Background:

• Sequence processing is crucial for language and memory.
• Parkinson's disease (PD) is linked to basal ganglia dysfunction and subthalamic nucleus (STN) hyperactivity.
• Impaired sequencing in PD suggests a role for STN in these cognitive functions.

Purpose of the Study:

• To investigate the effect of high-frequency STN deep brain stimulation (DBS) on sequence processing in Parkinson's disease.
• To determine if STN DBS impacts language and memory sequencing tasks.

Main Methods:

• Twenty-nine PD patients performed sentence comprehension and digit ordering tasks with STN DBS ON and OFF.
• Reaction times and ordering costs were measured for 'before/after' sentences and ordered/random digits.
• Volumes of tissue activated (VTAs) in the motor and associative STN were estimated.

Main Results:

• Patients were slower in sequence tasks with STN DBS ON compared to OFF, despite motor symptom improvement.
• Ordering-related reaction time costs increased with STN DBS ON, particularly in the 'before' sentence condition.
• Specific VTA sizes in the associative and motor STN, and dopaminergic medication, correlated with increased reaction time costs.

Conclusions:

• High-frequency STN DBS, especially in the associative region, may negatively impact sequence processing in PD.
• The findings suggest a potential trade-off between motor improvement and cognitive function with STN DBS.
• Further research is needed to optimize STN DBS parameters for both motor and cognitive benefits.