STN-DBS affects language processing differentially in Parkinson's disease: Multiple-case MEG study.

Area of Science:

• Neuroscience
• Neurolinguistics
• Biomedical Engineering

Background:

• Parkinson's disease (PD) affects motor and non-motor functions, including speech and language.
• Deep brain stimulation of the subthalamic nucleus (STN-DBS) is a common treatment for PD, but its effects on cognitive functions like language are not fully understood.
• Investigating neural responses during language processing can elucidate the impact of STN-DBS.

Purpose of the Study:

• To investigate the effects of bilateral and unilateral STN-DBS on neural responses during spoken language processing in PD patients.
• To examine how STN-DBS influences the processing of action-related verb semantics and morphosyntactic information.
• To determine if different stimulation parameters (bilateral vs. unilateral) have differential effects on language processing.

Main Methods:

• Magnetoencephalography (MEG) was used to record neural responses in three PD patients.
• Patients were studied under four conditions: no STN-DBS, left unilateral STN-DBS, right unilateral STN-DBS, and bilateral STN-DBS.
• Linguistic contrasts included action vs. abstract verbs and correct vs. incorrect morphosyntactic inflections, presented passively.

Main Results:

• Bilateral and right unilateral STN-DBS showed significant differences in processing action vs. abstract verbs, with enhanced responses for action verbs compared to the DBS-off state.
• Left unilateral STN-DBS demonstrated significant differences in morphosyntax processing, showing greater neuromagnetic responses to incorrect inflections than correct ones.
• These findings indicate dissociable effects of STN-DBS on different aspects of spoken language comprehension.

Conclusions:

• Unilateral and bilateral STN-DBS have differential impacts on neuromagnetic responses during spoken language processing in PD.
• Specific linguistic information processing in PD patients is modulated differently by STN-DBS.
• These results highlight the complexity of STN-DBS effects on cognitive functions beyond motor control.