Activity in the human primary motor cortex related to ipsilateral hand movements.

In two studies with positron emission tomography (PET), we found that somatosensory discrimination of length activated the ipsilateral MI, but somatosensory discrimination of shape did not. This occurred even though both tasks required the exclusive use of distal finger and hand movements which were also very similar in both tasks. The activation of the ipsilateral MI was correlated with activations of the premotor cortex in the other hemisphere, the prefrontal cortex and the posterior cingulate cortex, indicating that these areas together with the ipsilateral MI constitute a task-related active network.