Tactile Learning in Stroke Patients

Study Summary

This study will determine if stimulation of the stroke-injured side of the brain combined with stimulation to the paralyzed hand can temporarily improve the sense of touch in stroke patients. Healthy normal volunteers and people who have had a single stroke within 3 months of entering the study that affected one side of the brain may be eligible for this study. All participants must be between 18 and 90 years old and must be right-handed. Candidates are screened with a medical history, neurological examination and magnetic resonance imaging (MRI) of the brain if one has not been done within 1 year of entering the study. Participants undergo the following tests and procedures during four 2-day sessions over about 6 weeks: * Peripheral high-frequency stimulation: Small loudspeakers are taped to the fingertips and simple tactile pulses are passed through the skin. Stimulation may be sham or real. * Transcranial direct current stimulation: Two small rubber electrodes are taped to the head - one above the eye and the other on the back of the head. A current is passed between the two electrodes. Stimulation may be sham or real. * MRI: The subject lies in the scanner, a metal cylinder surrounded by a magnetic field, for about 40 minutes, lying still for up to 40 minutes at a time. An electrical stimulation is applied to the fingers of the right and left hand in separate sessions. Earplugs are worn to muffle the loud noises during the scanning. Functional MRI measures blood flow changes in the brain during the performance of specific tasks. * Behavioral measurements: * Grating orientation task: The subject responds as quickly as possible to a touch stimulus to the finger by saying whether the direction of the stimulus is vertical or horizontal. * Haptic object recognition task: The subject is given five categories of unfamiliar objects in the shape of cubes. During the task, identical objects are hidden in a sack. With eyes closed, the subject is asked to identify a