Perceptual correlates of massive cortical reorganization

Following long-term deafferentation of one upper limb in adult primates, the cortical areas corresponding to that limb become responsive to stimuli applied to the face. To explore this phenomenon, we studied some patients after upper limb amputation. In patient VQ, stimuli applied to the lower face or 7 cm above the stump evoked precisely localized referred sensations in individual digits which were often modality specific. Similarly, in another patient, WK several complete somatotopic representations of the phantom limb were found, on the face, chest and axilla, indicating the emergence of such maps in regions remote from the stump. These effects may be a direct perceptual correlate of the physiological observations of Merzenick et al (1984), Wall (1977) and Pons et al (1991).