<qa>  What is the primary outcome measure?The purpose of this protocol is to investigate the changes in interhemispheric inhibition IHI between human motor cortices with learning of performance of an accurate motor task pinch force control. Performing a simple motor task is associated with activation in the contralateral motor areas. Activation of the ipsilateral motorpremotor cortex might be elicited by performing more challenging and difficult unimanual motor tasks. However, the functional role played by this ipsilateral activation has been controversial, and is felt to be more prominent with more complex tasks. Several studies using paired-pulse transcranial magnetic stimulation TMS revealed a significant IHI from the active upon the non-active hemisphere. Together these results suggested IHI between motor cortical areas may play a critical role in motor control and could influence manual dexterity. Taking these into account, it raises the interesting question of whether the IHI balance between both motor cortices is progressively modified during the learning phase of an accurate motor task. We hypothesize that learning to perform a tracking motor task requiring accurate control of pinch force generation Tracking accurate, will increase IHI from the learning to the non-learning hemisphere to a larger extent than learning to perform a less precise tracking motor task Tracking non-accurate. The primary outcome measure will be the amount of changes in IHI from the learning to the non-learning hemisphere as a function of learning both motor tasks. 