PERCEPTUAL CORRELATES OF CHANGES IN CORTICAL REPRESENTATION OF FINGERS IN BLIND MULTIFINGER BRAILLE READERS

The mature mammalian nervous system alters its functional organization in a use-dependent manner. Enhanced stimulation of a body part enlarg es its cortical representational zones and may change its topographic order. Little is known about the perceptual and behavioral relevance o f these plastic alterations in cortical organization. We used blind Br aille readers who use several fingers on each hand and who do so for m any hours each day as a model to investigate this issue. Magnetic sour ce imaging indicated that the cortical somatosensory representation of the fingers was frequently topographically disordered in these subjec ts; in addition, they frequently misperceived which of these fingers w as being touched by a light tactile stimulus. In contrast, neither the disordered representation nor mislocalizations were observed in sight ed controls. Blind non-teacher Braille readers who used only one finge r for reading were not significantly different from the sighted contro ls. Thus, use-dependent cortical reorganization can be associated with functionally relevant changes in the perceptual and behavioral capaci ties of the individual.