Neural substrates for motor imagery in severe hemiparesis.

Background: The beneficial effects of imagined movements on motor learning and performance suggest that motor imagery is functionally close to preparatory and executive motor processes.

Objective: The purpose of this study was to examine the cortical processes associated with imagery of movement of the wrist in subjects with severe hemiparesis.

Methods: During fMRI, subjects with stroke performed alternating blocks of imagining wrist-tracking movements with the hemiparetic hand, active wrist-tracking movements with the unaffected hand, and resting.