Subthalamic Deep Brain Stimulation (DBS) in Parkinson's Disease
Subthalamic Deep Brain Stimulation (DBS) in Parkinson's Disease
The purpose of this study is to examine the brain changes in people with Parkinson's Disease
 (PD) after they get deep brain stimulation (DBS) surgery, compared with people who do not
 have Parkinson's Disease. Treatment of Parkinson's disease is often difficult and
 challenging. Deep brain stimulation is an established surgical treatment that is effective
 for the treatment of PD, but the details of why it helps are not known. In order to achieve
 maximum benefits from this treatment, it is important to understand how it changes the brain.
 Specifically, the investigators will study electrophysiology, which is the study of how the
 brain conducts electrical messages to the rest of the body. To do this, the investigators
 will use transcranial magnetic stimulation (TMS), which is a painless and non-invasive
 procedure. They will also conduct motor physiology experiments of the upper and lower limbs
 to collect data about skeletal muscle movement. The data from this study will help explain
 whether the electrical changes in the brain have any relation to the physical benefits
 patients with Parkinson's Disease sometimes receive from DBS surgery.
Screening evaluation: The Investigators will ask questions to see if the participant
 qualifies to be in the study. The screening visit will occur up to 4 months before the first
 study visit, and can be scheduled to occur on the same day as the first study visit. This
 evaluation will include a review of medical history and clinical findings related to
 Parkinson's Disease (if applicable). There may be a neurological exam (physical exam). Women
 of child bearing potential will take a urine pregnancy test. If applicable, the medications
 currently used to treat Parkinson's Disease symptoms will be reviewed and subjects will be
 asked to discontinue them for some hours on the days of the study visits. The investigators
 do not expect concerns or unwanted consequences arising either from discontinuing the
 Parkinson's Disease medications or turning off the DBS stimulator for the duration of time
 proposed in the study.

 Participants will be studied under 4 conditions, over a span of as few as two days to as long
 as two months. The four Conditions are : 1) The DBS stimulator will be turned OFF for both
 sides. 2) The DBS stimulator will be turned ON for the right side. 3) The DBS stimulator will
 be turned ON for the left side. 4) The DBS stimulator will be turned ON for both sides. The
 order of these conditions will be picked randomly.

 Participants will be asked not to take PD medications for approximately 12 hours prior to the
 scheduled visit time, and until after the physiological testing.

 Healthy controls will be studied on only one occasion, as they do not have DBS.

 Tests performed for each study condition:

 1. Parkinson's Participants Only: A neurological examination will be performed by
 administering several clinical scaled. These clinical scales include the Unified
 Parkinson's Disease Rating Scale (UPDRS), the self-report Parkinson's Disease Quality of
 life scale (PDQ-39), MMSE instrument for cognitive (or memory) testing, and Beck
 Depression Inventory (BDI II) for evaluation of mood and depressive symptoms. The
 PDQ-39, MMSE, and BDI will each only be administered once and therefore will not be
 repeated at every study visit.

 2. The investigators will determine individual motor evoked potential (MEP) thresholds
 before beginning the study treatment. MEP will be recorded from a muscle located between
 the right thumb and index finger, and then from the left thumb and index finger. MEP
 threshold refers to the amount of stimulation to the brain that is required to activate
 muscle cells enough to appear on an electromyography (EMG), which records electrical
 potential in muscle through electrodes placed on the skin.

 3. The investigators will use TMS to test motor cortex functions. For these tests,
 participants will sit in a chair that looks like the one at the dentist's office. A
 magnetic coil will be placed on the scalp on one side of the head, overlying the brain's
 motor cortex to stimulate the brain's output to the muscles in the opposite hand. A
 second magnetic coil will be placed on the scalp of opposite side. Recordings from both
 hands will be made using the magnetic coils placed on scalp.

 4. The investigators will collect data about the muscles of both the upper and lower limbs
 with a wireless EMG procedure. To do this, small wireless sensors will be placed on the
 skin over both arm and leg muscles. Participants will be asked to sit in a chair and
 perform movements with the upper and lower limbs while the EMG records measurements
 about movement activity. This procedure will be conducted separately for the upper and
 lower limbs.

 5. Participants who have provided consent will be videotaped during the visits.

 6. Side effects and adverse events pertaining to this study will be recorded at each visit.
Inclusion Criteria:

 -  Aged 18-80 years

 -  Diagnosis of Parkinson's Disease with bilateral subthalamic nucleus (STN) DBS

 Exclusion Criteria:

 -  Cardiac pacemakers

 -  Need for diathermy

 -  Repeat MRI scanning

 -  Anticoagulant therapy

 -  Previous neuro surgical procedure or ablative therapy

 -  Frank dementia according to cognitive screening

 -  History of seizures

 -  Pregnancy

 -  Presence of a terminal illness