Valyear K

Animal models reveal that deafferenting injuries precipitate reorganisation in both contralateral and ipsilateral somatosensory cortices. The functional significance and duration of these effects are unknown, and it is unclear whether they also occur in humans. We delivered cutaneous stimulation during fMRI to map the sensory cortical representation of the intact hand and lower face in a group of chronic, unilateral, upper extremity amputees (N = 19) and healthy matched controls (N = 29). Our findings reveal greater activity in amputees than controls within the deafferented former sensory hand territory (S1f) during stimulation of the intact hand, but not the lower face. Despite this cortical reorganisation, amputees do not differ from controls in tactile acuity on their intact hand, nor are these changes related to tactile acuity, pain, prosthesis use, or time since amputation. We conclude that S1f becomes atypically responsive to cutaneous stimulation of the intact hand of amputees, and that these reorganisational changes persist for many years, if not indefinitely. The functional relevance of these changes, if any, remains unknown.