- DBS treatment. Patients are randomly assigned to have electrodes implanted in either the Gpi or STN area of the basal ganglia. The electrodes are what stimulate the brain in DBS therapy. Before surgery, a frame is secured to the patient's head, and an MRI scan is done. DBS involves making two small incisions and two small holes in the skull, opening the lining around the brain, locating the Gpi or STN, securing the electrodes in place, and connecting them to the pulse generator that is placed under the skin below the collar bone. In addition, during the surgery, the patient is asked to move certain muscles. The muscle activity is recorded to gain a better understanding of the physiology of movement. After surgery, MRI scans are done to confirm placement of the electrodes.