This study will test whether DC electrical polarization of the brain can temporarily improve hand function in patients with corticobasal syndrome (CBS). In this degenerative disorder of the brain, nerve cells die over time, causing a progressive decline in the patient's ability to use their hands. This is always worse on one side. Other symptoms include arm or leg stiffness, tremor, gait unsteadiness, and speech difficulty. Some patients also have some decline in thinking ability, such as loss of skilled activities, poor problem solving abilities poor concentration, problems with language, and forgetfulness,. DC electrical polarization of the brain involves placing sponge electrodes on the head and passing a very weak current between them. DC polarization can temporarily improve the ability of healthy people to make word lists and may improve symptoms in some brain diseases.