Parkinson's Disease: Enhancing Physical Therapy With Brain Stimulation for Treating Postural Instability.

"Device: Transcranial Direct Current Stimulation (tDCS) Subjects will receive 20 minutes of either active or sham tDCS at intensity of 2mA. The anodal electrode will be placed over the primary motor cortex contralateral to the most painful side, and the cathodal electrode will be placed over the contralateral supraorbital area. In the sham group, the tDCS device will not be active for the full 20 minutes.~Device: Transcranial Ultrasound (TUS) Subjects will receive 20 minutes of either active or sham TUS. During active stimulation the ultrasound will be active for the full 20 minutes- however, during sham stimulation the ultrasound will not be active for the full 20 minutes."

"Device: SHAM Comparator Device: transcranial Direct Current Stimulation (tDCS) Subjects will receive 20 minutes of either active or sham tDCS at intensity of 2mA. The anodal electrode will be placed over the primary motor cortex contralateral to the most painful side, and the cathodal electrode will be placed over the contralateral supraorbital area. In the sham group, the tDCS device will not be active for the full 20 minutes.~Device: Transcranial Ultrasound (TUS) Subjects will receive 20 minutes of either active or sham TUS. During active stimulation the ultrasound will be active for the full 20 minutes- however, during sham stimulation the ultrasound will not be active for the full 20 minutes."

All subjects will enroll in a conventional PT balance and gait focused training program, and will receive PT 3x/week over the two weeks of stimulation for 45 minutes following the stimulation sessions when applicable. (And during the biweekly sessions for Phase II)