Study to Characterize Acute and Chronic Directional Aspects of Deep Brain Stimulation

Key Inclusion Criteria: * Diagnosis of bilateral idiopathic PD with the presence of rigidity and at least one (1) of the following: resting tremor or bradykinesia. * UPDRS III score of \>25 in the meds OFF condition * Medication must improve PD symptoms by ≥30%, as measured by UPDRS subset III score Key Exclusion Criteria: * Any significant psychiatric problems, including unrelated clinically significant depression as determined by the investigator * Any current drug or alcohol abuse as determined by the investigator * Any history of recurrent or unprovoked seizures * Any significant medical condition that is likely to interfere with study procedures or likely to confound evaluation of study endpoints, including any terminal illness with survival \<12 months