Testing a new electrode during brain stimulation surgery

Inclusion criteria: 1. Diagnosis of idiopathic Parkinson's disease; 2. Clinical indication for STN DBS with MER; 3. Age > 18 years; 4. Subject is a male or non-pregnant female; 5. Ability to comply with the study assignments; 6. Ability to give informed consent. Exclusion criteria: 1. Parkinson's disease graded according to Hoehn and Yahr stage 5; 2. Score on MATTIS dementia rating scale <120; 3. Psychiatric contraindications to STN DBS; 4. General contraindications for stereotactic surgery and general anaesthesia (e.g. severe hypertension, blood coagulation disorder); 5. Subject has factors that would put the subject at an additional risk for intra-operative or postoperative bleeding. This includes underlying disorders of the coagulation cascade (eg, hemophilia), disorders that affect platelet count or function (eg, Von Willebrand's disease), as well as administration of any anti-platelet or anti-coagulant medication in the 7 days prior to surgery, or any history of anticoagulant or aspirin use or history of hemorrhagic stroke, that in the view of the neurosurgeon or neurologist would place the subject at an increased risk for intra-operative or postoperative bleeding; 6. Subject has a diagnosis of acute myocardial infarction or cardiac arrest less than or equal to 6 months prior to the screening testing; 7. Subject has a history of a seizure disorder; 8. Subject requires short surgery time due to general health issues, as determined by the investigator; 9. Subject is a woman who is pregnant or planning to become pregnant, or a woman of child-bearing potential, who is not using a medically-acceptable method of birth control. Women of child-bearing potential must undergo a pregnancy test, with a clear negative result, no more than 7 days prior to the investigational procedure visit.