Comparison of Different Non-invasive Electrical Stimulation Protocols to Facilitate Rehabilitation in Parkinson's Disease Subjects With Postural Instability and Gait Disorders

"Two cycles of dual-task gait/balance training consisting of action observation training (AOT) and motor imagery (MI) combined with practicing the observed-imagined exercises.~Three 1-hour sessions per week for 6 weeks. Cycle repeated after 8-week washout period."

SHAM stimulation will be performed using the same montage used for transcranial and spinal stimulation, however an initial current is delivered and programmed to fade off in a brief period of time.

Anodic tDCS with the anode placed on the of the left DorsoLateral Prefrontal Cortex. Patients will undergo 30 minutes tDCS session preceding rehabilitation

Anodic spinal cervical stimulation with anode electrode placed on the spinous process of C3 vertebra and cathode placed on T3. Patients will undergo 30 minutes stimulation session preceding rehabilitation during the first cycle (6 weeks)

Anodic spinal cervical stimulation with anode electrode placed on the spinous process of C3 vertebra and cathode placed on T3. Patients will undergo 30 minutes stimulation session preceding rehabilitation during the second cycle (6 weeks after 8-week washout)

SHAM stimulation will have the same montage as tsDCS but run in SHAM more with an initial stimulation at standard intensity, followed by a programmed fade off after a brief time period. Patients will undergo 30 minutes of SHAM stimulation session preceding rehabilitation during the first cycle (6 weeks)

SHAM stimulation will have the same montage as tsDCS but run in SHAM more with an initial stimulation at standard intensity, followed by a programmed fade off after a brief time period. Patients will undergo 30 minutes of SHAM stimulation session preceding rehabilitation during the second cycle (6 weeks after 8-week washout)

SHAM stimulation will have the same montage as tsDCS but run in SHAM more with an initial stimulation at standard intensity, followed by a programmed fade off after a brief time period. Patients will undergo 30 minutes of SHAM stimulation session preceding rehabilitation