Transcranial Direct Current Stimulation to Improve Hand Movement in Stroke Patients

This study will examine whether hand movement in stroke patients can be improved by applying electrical stimulation to the side of the brain affected by the stroke. It will compare the effects of similar brain stimulations in stroke patients and healthy volunteers. Healthy, right-handed normal volunteers and stroke patients between 18 and 80 years of age may be eligible for this study. Patients' stroke must have occurred at least 3 months before entering the study and affect one side of the brain only. Candidates are screened with a medical history, brain MRI, and evaluation of memory and attention span. Pregnant women are excluded from the study. The study involves seven 2-day sessions over the course of about 8 weeks, with each session separated by at least 1 week. During each session participants practice a pattern of hand movements and their accuracy in performing the movements is evaluated before and after brain electrical stimulation. The movements include a complex finger sequence, a simple finger sequence, a peg test (placing wooden pegs in holes on a board), a hand function test (turning over cards, picking up small objects with one hand and placing them in a can, picking up small objects with a spoon and placing them in a can, stacking checkers, moving light cans, and moving heavy cans), and a box and block test (picking up and moving blocks from one box to another). The first day of each 2-day session lasts about 5 hours and includes the following:

• TMS measurements: A wire coil is held on the scalp, and a brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. The stimulation may cause a twitch in muscles of the face, arm, or leg, and the subject may hear a click and feel a pulling sensation on the skin under the coil.
• tDCS: Small, wet sponge electrodes are applied to the head - one above the eye and the other on the back of the head. A small electrical current is passed between them. The subject may feel an itching or tingling sensation under the electrodes or see light flashes. Some sessions are done with sham tDCS.
• Motor learning under tDCS: tDCS is repeated while the subject performs different finger movements. A new pattern of finger movements is taught each session.
• Surface electromyography: Electrodes are filed with a conductive gel and taped to the skin over one small hand muscle to measure the electrical activity of muscles.
• Behavioral measurements: Evaluation of learned movement tasks
• Questionnaires to evaluate the subject's attention, fatigue and mood before and after testing The second day of each session lasts about 2 hours and includes the TMS measurements and behavior measurements.