Researchers at the University of Iowa have discovered a connection between a brain region and how humans redirect their thoughts and attention when distracted. This finding offers insights into the cognitive and behavioral side effects associated with a technique used to treat Parkinson's disease.
The study, published in Brain, focused on the subthalamic nucleus, a pea-sized brain region involved in the motor control system. In Parkinson's disease, this region is believed to exert too much influence, contributing to the characteristic tremors and motor deficiencies. To address this, clinicians have used deep brain stimulation, which involves implanting an electrode in the subthalamic nucleus to rhythmically generate electrical signals and loosen the "braking" effect.
While deep brain stimulation has been remarkably effective in improving motor function, some patients have experienced an inability to focus attention and impulsive thoughts, leading to risky behaviors. Researchers wondered if the subthalamic nucleus' role in movement also extended to thoughts and impulse control.
To investigate this, the researchers conducted an experiment with Parkinson's patients, monitoring their brain waves as they focused on a computer screen. Occasionally, a chirping sound was introduced to divert their attention. The study found that when deep brain stimulation was inactive, the Parkinson's patients diverted their attention from the visual to the auditory system, just as a control group had done. However, when deep brain stimulation was activated, the Parkinson's patients did not divert their visual attention, suggesting the subthalamic nucleus plays a role in how the brain communicates not only with movement, but also with thoughts and attention.
The researchers believe that while removing the subthalamic nucleus' inhibitory influence on the motor system is beneficial for treating Parkinson's, the same effect on non-motor systems, such as attention and cognition, can lead to adverse side effects. They are now working to understand how to fine-tune deep brain stimulation to maximize the benefits for motor function while minimizing potential cognitive and behavioral issues.