Injury-induced reorganization in adult auditory cortex and its perceptual consequences

Restricted cochlear lesions in adult animals result in a reorganization of auditory cortex such that the cortical region deprived of its normal input by the lesion is occupied by expanded representations of adjacent cochlear loci, and thus of the frequencies represented at those loci. Analogous inju ry-induced reorganization is seen in somatosensory, visual and motor cortic es Of adult animals after restricted peripheral lesions. The occurrence of such reorganization in a wide range of species (including simian primates), and across different sensory systems and forms of peripheral lesion, sugge sts that it would also occur in humans with similar lesions. Direct evidenc e in support of this suggestion is provided by a small body of functional i maging evidence in the somatosensory and auditory systems. Although such re organization does not seem to have a compensatory function, such a profound change in the pattern of cortical activation produced by stimuli exciting peri-lesion parts of the receptor epithelium would be expected to have perc eptual consequences. However, there is only limited psychophysical evidence for perceptual effects that might be attributable to injury-induced cortic al reorganization, and very little direct evidence for the correlation betw een the perceptual phenomena and the occurrence of reorganization. (C) 2000 Elsevier Science B.V. All rights reserved.