Differential impact of thalamic versus subthalamic deep brain stimulation on lexical processing

Area of Science:

• Neuroscience
• Cognitive Science
• Neurology

Background:

• Subcortical structures' roles in language processing remain unclear.
• Deep Brain Stimulation (DBS) targeting basal ganglia and thalamus may affect lexical abilities.

Purpose of the Study:

• To investigate the impact of thalamic versus subthalamic DBS on word processing.
• To differentiate the neurophysiological effects of DBS on lexical tasks.

Main Methods:

• Compared word processing in essential tremor patients (thalamic DBS) and Parkinson's disease patients (subthalamic DBS) ON and OFF stimulation.
• Utilized an acoustic Lexical Decision Task and analyzed event-related potentials (ERPs), including N400.
• Included age-matched healthy controls for comparison.

Main Results:

• Thalamic DBS prolonged word decision times and reduced N400 amplitudes.
• No significant ON-OFF stimulation effects were observed in patients with subthalamic DBS.
• Patients with subthalamic DBS exhibited low N400 amplitudes regardless of stimulation status.

Conclusions:

• Word processing speed and N400 are modulated by thalamic DBS, suggesting thalamo-cortical involvement in lexical processing.
• Subthalamic DBS did not show comparable effects on these measures.
• Findings highlight target-specific cognitive consequences of DBS.