 Theta-burst stimulation will be performed according to the standard protocols developed by Rothwell and co-workers with NIH and European consortium safety guidelines stringently enforced. Active motor threshold and resting motor threshold will be determined by single-pulse stimulation while monitoring electromyographic EMG activity at the first dorsal interosseus FDI muscle according to standard published protocols using commercially available surface EMG electrodes DelSys Inc.. Stimulation will be performed using the commercially-available Magstim Rapid 2 Magstim, Inc., Wales UK with a standard figure-eight coil held by a member of the research team. Biphasic stimulation pulses will be given according to the standard included driver software. Single pulse, paired pulse, and theta-burst rapid stimulation protocols are directly available through standard user options on this device. 