Perceptual Correlates of Massive Cortical Reorganization

Abstract

Pons et al. (1) found cortical maps to be capable of an unexpectedly large degree of reorganization. After long-‐term (12years) deafferentation of one limb in adult primates, the cortical area of the brain corresponding to the limb became responsive to stimuli applied to the lower face region. This finding extended the previously recognized maximum area of cortical reorganization in adult primates from a mediolateral distance of 1 to 2mm to about 10 to 14mm. Because cells that originally received information from the arm can later receive information from the face, we wondered whether stimuli applied to the face would be mislocalized to the arm. To explore this, we have studied (2,3) localization of touch sensations in two human patients after amputation of one upper limb, and in another patient after amputation of one digit. We applied light touch or deep pressure to different points on the normal body surface. Stimulation of points even remote from the amputation line evoked precisely localized referred sensations in the phantom limb. We could plot "reference fields, " small regions of skin surface that evoked referred sensations in