 Motor training is an important part of recovery after stroke. During motor training, stroke patients practice performing a movement and become better at performing the trained movement over time. Repetitive transcranial magnetic stimulation rTMS, which uses magnetism to excite neurons near the surface of the brain, may further improve performance. Healthy adults made larger training-related improvements in their motor performance when they received rTMS over the primary motor cortex during motor training. There is evidence that the premotor cortex may be a more effective target than the primary motor cortex for rTMS for some stroke survivors. In the current study, the investigator will determine the effect of rTMS over the premotor cortex on training-related improvements in motor performance in healthy adults. 