Use of Transcranial Direct Current Stimulation (tDCS) Coupled With Constraint Induced Movement Therapy in Stroke Patient

In this 3 experiments study we will evaluate the effect of tDCS and constraint induced movement therapy (CIMT) in stroke patients (exp 1) as well as in healthy subjects (control population - exp 2). Finally we will investigate the effect of tACS - transcranial alternating current stimulation - as an alternative to tDCS, on motor function in healthy subjects (exp 3). The two experiments on tDCS are parallels (exp 1 & 2), while the experiment on tACS uses a crossover design (exp 3).

For stroke patients (Exp1), our primary outcome measure is a clinical scale (Jebsen-Taylor Hand Function Test), while for healthy subjects (Exp 2) we investigate the effect of tDCS and CIMIT on cortico-spinal excitability using TMS - transcranial magnetic stimulation. Finally, for the third experiment using tACS, our primary outcome is cortical oscillation, as measured by EEG - electroencephalogram.

Inclusion criteria

All subjects must be between the ages of 18-90 and must not be pregnant.

Additional Entry criteria for Stroke subject enrollment:

• First-time clinical ischemic or hemorrhagic cerebrovascular accident - evidenced by a radiological (or physician's) report;
• Weakness, defined as score of less than 55 (out of 66) on arm motor Fugl-Meyer (FM) scale
• Stroke onset >6 months prior to study enrollment.

Exclusion criteria

• Significant pre-stroke disability;
• Major depression, as defined by Hamilton Depression (HAM-D) scale grater then or equal 17 if needed (history of depression before the stroke);
• Any substantial decrease in alertness, language reception, or attention that might interfere with understanding instructions for motor testing;
• Excessive pain in any joint of the paretic extremity (not applicable to severe stroke subjects);
• Contraindications to single pulse Transcranial Magnetic Stimulation (TMS) (TMS will be used to measure cortical excitability) such as metal head implants

• history of seizures
• unexplained loss of consciousness
• metal in the head
• frequent or severe headaches or neck pain
• implanted brain medical devices.
• Contraindications to tDCS

• metal in the head
• implanted brain medical devices
• Advanced liver, kidney, cardiac, or pulmonary disease;
• A terminal medical diagnosis consistent with survival < 1 year;
• Coexistent major neurological or psychiatric disease as to decrease number of confounders;
• A history of significant alcohol or drug abuse in the prior 6 months;
• Use of carbamazepine and amitriptyline;
• Subjects may not be actively enrolled in a separate intervention study targeting stroke recovery and
• Subjects may not have already received constraint induced motor therapy and/or tDCS treatment for stroke;
• History of epilepsy before stroke (or episodes of seizures within the last six months).
• Subjects with global aphasia and deficits of comprehension
• Pregnancy