A series of questions by interview, questionnaires, and checklists will be collected. In addition, basic information (such as age, sex, race) and psychiatric, medical, and family history, physical and neurological exam that will include measuring vital signs (heart rate and blood pressure). There will be a "Falls Diary' to complete (an account of falling incidents and the details). Specific testing will be done to evaluate the gait and balance which will be repeated throughout the study. A psychiatric evaluation of mood and emotion will be performed including a detailed psychological testing, consisting of perception, learning, and memory. These psychological assessments will be repeated at every study visit. An MRI and a CT scan will be performed to make sure of the exact location of the DBS implant. The study will end in 24 months.