This study will determine: 1) whether learning a task with the dominant hand is accompanied by changes in the area of the brain that controls hand movement, and 2) how the brain is able to make these changes. Previous studies have shown that practicing a motor task can change brain excitability, but it is not known how well brain excitabilities are changed during motor learning. This study will measure changes in activity of the part of the brain that controls hand movement before, during, and after exercising the hand on a response pad.