Brain activation for actual and imagined hand movement following bilateral hand transplantation

Abstract

Hand transplantation has been successful in restoring function in a select group of people, but the mechanisms by which the central nervous system integrates a new hand are unknown. We used event-related functional magnetic resonance imaging (fMRI) to assess brain activation related to actual and imagined hand movement, for a recipient (female, 60 years of age) of bilateral hand transplants. Investigation of a patient-specific network of sensorimotor cortical regions was conducted at a preoperative session, as well as at three assessments conducted over a 16-month, post-transplantation period. We detected significant activation for both actual and imagined hand movement, relative to a rest baseline, for both transplanted hands, at all three postoperative sessions. Activation was higher for actual movement than for imagined movement. Across the postoperative period, movement-related activation decreased in magnitude, relative to an imagined-movement baseline. Movement-related activation also became more focused, postoperatively, on hand-related brain regions, in contralateral sensorimotor cortex. Some movement-related brain activation was relatively stronger for the right hand, postoperatively, consistent with the fact that the patient had been right-handed, preoperatively. To our knowledge, this is the first hand-transplant recipient to exhibit more pronounced brain activation, post-transplantation, for actual movement relative to imagined movement. Overall, the findings suggest that, following hand transplantation, sensorimotor cortex returns to a more canonical functional organization, similar to that of healthy individuals.