Subthalamic stimulation modulates working memory-related cortical dynamics in Parkinson’s disease

Subthalamic nucleus deep brain stimulation (STN-DBS) is a standard treatment for the motor symptoms of Parkinson's disease, but its impact on cognitive functions like working memory remains inconsistent. This study investigated whether cortical oscillatory dynamics, measured via electroencephalography (EEG), could serve as physiological markers for individual working memory outcomes following STN-DBS. Nineteen patients were evaluated in a prospective, randomized, double-blind, crossover trial comparing omnidirectional and directional stimulation modes 6 months after implantation. Researchers assessed verbal and visuospatial working memory performance alongside task-related EEG spectral power to identify neural signatures associated with cognitive trajectories.

At the group level, working memory performance remained stable regardless of the stimulation mode or comparison to baseline. However, significant individual-level associations emerged between cortical oscillations and cognitive outcomes. Higher baseline alpha and beta power in the sensorimotor cortex predicted slower reaction times in visuospatial working memory tasks at the 6-month follow-up. Furthermore, during stimulation, greater task-related desynchronization in the theta and beta frequency bands correlated with improved verbal working memory accuracy. These results suggest that while STN-DBS may not produce uniform cognitive effects across a population, specific oscillatory patterns reflect an individual's neural flexibility and capacity for cognitive processing under stimulation.

These findings highlight the potential of using task-related EEG as a tool to characterize cognitive variability in Parkinson's disease beyond traditional motor outcomes. By identifying physiological markers of individual cognitive responses to stimulation, this research provides a foundation for developing personalized, closed-loop DBS systems. Such systems could theoretically adjust stimulation parameters in real-time based on a patient's specific neural profile, potentially mitigating cognitive side effects or optimizing cognitive performance alongside motor symptom relief.