Motor-cortical activity in tetraplegics.

Abstract

It may eventually be feasible to reconstruct voluntary motor activity in the paralysed. Paralysed patients may benefit from the development of an implantable brain–computer interface device that can bypass damaged motor pathways1,2,3. But it is unclear whether chronically de-efferented areas will still be sufficiently excitable to respond to motor attempts4,5 if the motor cortex has been extensively reorganized6,7, and, if they are, whether this excitability is somatotopically organized8,9. Here we use functional magnetic resonance imaging to study brain activity in subjects with spinal-cord injuries while they are executing, or attempting to execute, movements of different limbs. We show that their motor-cortical activation closely follows normal somatotopic organization in the primary and non-primary sensorimotor areas. Our results indicate that any reorganization of the motor system that does occur in these patients does not affect attempt-related activation, and that it should be possible to access voluntary control signals by using a cortical neuroprosthetic.