 Testing will occur at three identical visits, with escalating stimulation intensity at each visit. Initial screening will be performed by telephone or in clinic and final screening will be performed and informed consent will be signed at the start of the first study visit. Initial set-up and calibration of the magnetic stimulation device will require 10-20 minutes. Theta-burst stimulation requires 40 seconds. Hand and arm function will be tested immediately before and during the one hour following the TBS. Therefore, each visit should occupy 90-120 minutes. Each visit will be at least 2 days after the previous visit and a telephone call will be placed one week after the third visit. 