A neural substrate for nonpainful phantom limb phenomena

Activity in the cerebral cortex associated with non-painful phantom limb se nsation was studied in 14 upper extremity amputees. In four subjects, repet itive tactile stimulation of the digits or the lower corner of the mouth el icited non-painful phantom sensation in the amputated limb, in the remainin g 10 patients no sensation could be evoked. Neuroelectric source imaging re vealed significantly elevated activity in SI and posterior parietal cortex, and significantly decreased activity in ipsilateral SII cortex when referr ed sensations were present. However, nonpainful referred phantom sensations were not associated with a shift of the cortical representation of the mou th into the hand region, as previously suggested. Nonpainful phantom limb e xperiences seem to have widely distributed neural networks in multiple cort ical regions. NeuroReport 11:1407-1411 (C) 2000 Lippincott Williams & Wilki ns.