The subthalamic nucleus is a small, oval, section of the subthalamus in the brain, made of gray matter (uninsulated nerve fibers). Functionally, it is part of the basal ganglia system.
As the name suggests ("sub"), it is located on the underside of the thalamus, which lies near the center of the brain. The subthalamic nucleus impacts motor control and may also have a role in psychological processes.
People with lesions on the subthalamic nucleus have shown increased impulsiveness and behavioral issues. Research indicates that the subthalamic nucleus may be involved with issues like hyperactivity disorders or addictive behaviors.
Several studies have shown that creating lesions on the subthalamic nucleus can actually help with symptoms of Parkinson's disease, especially with motor functions. Less conclusive results were found on mood issues related to Parkinson's.
Other studies have shown that stimulation of the subthalamic nucleus can help with severe obsessive-compulsive disorder, although researchers in this study stated that more results are needed because of possible new obsessive-compulsive disorder symptoms or return of severe symptoms.