Patients with severe Parkinson's Disease can elect to undergo an invasive procedure where stimulating electrodes are surgically implanted deep in their brain.  The procedure, called Deep Brain Stimulation (DBS) is wildly successful in treating the motor symptoms of Parkinson's Disease. In graduate school, I conducted an experiment on patients undergoing DBS surgery.  In that research, we found that the stimulation protocol significantly improved motor symptoms, as expected, but also affected cognition.  This experience is what inspired me to seek noninvasive methods, like focused ultrasound, that might reach deep in the brain to treat brain disease, but without going through the trouble of surgery.