There is good evidence that single rTMS trains can produce plastic changes that outlast the rTMS for several minutes up to several hours. These plastic changes depend on the stimulation frequency, stimulation intensity and the duration of the rTMS train. To address the question of cumulative rTMS effects we currently study responses to repeated rTMS trains. To examine network responses we use rTMS over the premotor area and measure cortical responses in the motor cortex, thus studying plastic changes in the premotor-motor network. The reasons for this are threefold. First, motor cortex excitability can be measured directly and non-invasively using single and paired pulse TMS techniques. Second, anatomical and functional connections between premotor and motor cortex are dense. Third, we and others have previously shown that premotor rTMS can change the excitability of circuits intrinsic to the motor cortex