Pathophysiology
Chronic stimulation of the STN, called deep brain stimulation (DBS), is used to treat patients with Parkinson disease. The first to be stimulated are the terminal arborisations of afferent axons, which modify the activity of subthalamic neurons. However, it has been shown in thalamic slices from mice, that the stimulus also causes nearby astrocytes to release Adenosine Triphosphate (ATP), a precursor to adenosine (through a catabolic process). In turn, adenosine A1 receptor activation depresses excitatory transmission in the thalamus, thus mimicking ablation of the subthalamic nucleus.
Unilateral destruction or disruption of the subthalamic nucleus – which can commonly occur via a small vessel stroke in patients with diabetes, hypertension, or a history of smoking – produces hemiballismus.
As one of the STN's suspected functions is in impulse control, dysfunction in this region has been implicated in Obsessive–compulsive disorder. Artificially stimulating the STN has shown some promise in correcting severe implusive behavior and may later be used as an alternative treatment for the disorder.
Read more about this topic: Subthalamic Nucleus