The purpose of this research study is to determine if DBS is a safe and effective therapy for severe freezing of gait in patients with Parkinson's Disease. Freezing of gait (FOG) is a particularly debilitating motor deficit seen in a subset of patients with Parkinson's Disease (PD).

Inclusion:

1. Confirmed Parkinson's Disease according to movement disorder neurologist with documented exclusion of other disorders such as fronto-temporal dementia (FTD)/ frontal gait disorder/normal pressure hydrocephalus (NPH)/progressive supranuclear palsy (PSP)
2. PD stage3 ON medication, with severe gait dysfunction and predominant axial symptoms: Movement Disorder Society-Unified Parkinson's Disease Rating Scale Tremor Dominant (MDS-UPDRS TD), Postural Instability Gait Difficulty (PIGD) ratio ≤ 0.90 and Freezing Of Gait Questionnaire (FOGQ) score > 12.
3. Age 40-75 with good response to Levodopa (defined as greater than 20% improvement in UPDRS score)
4. FOG refractory to LEVODOPA>600 mg
5. 6. Minimal tremor, bradykinesia, and rigidity symptoms, or well controlled with Levodopa and/or with already implanted STN/GPi DBS.
6. a) Poor candidate for STN or GPi DBS due to good control of tremor, bradykinesia, and rigidity symptoms with Levodopa b) or Post-operative STN/GPi DBS PD patients with significant residual non-levodopa responsive postural and gait instability
7. Must agree to full 6-month participation in study.

Exclusion:

1. Individuals with major executive dysfunction
2. Individuals with dementia, as defined by the Mattis Dementia Rating Scale-2 (DRS-2) score ≤ 130
3. Individuals with other neurocognitive impairments
4. Individuals who have depression, as defined for example by the Beck Depression Inventory II (BDI-II) > 25
5. Presence of major medical co-morbidities and other surgical contra-indications such as coagulopathy
6. Individuals who require diathermy, transcranial magnetic stimulation (TMS), or electroconvulsive therapy (ECT)
7. Individuals with a history of prior intracranial surgery
8. Individuals with a metallic implant in their head that is not MRI compatible (e.g., aneurysm clip, cochlear implant)
9. Individuals with active implantable devices anywhere in the body (e.g. cardiac pacemaker, defibrillator, spinal cord stimulator, implanted medication pump)
10. Individuals who are pregnancy or desire to become pregnant during the study
11. Individuals who are breastfeeding12.
12. Individuals who are on investigational drugs and any other intervention (not part of the guidelines for management of Parkinson's Disease) known to have a potential impact on outcome
13. Subjects utilizing recreational drugs at the time of screening will be excluded from the study with the exception of medicinal marijuana