ELECTROPHYSIOLOGICAL EVIDENCE FOR CROSS-MODAL PLASTICITY IN HUMANS WITH EARLY-ONSET AND LATE-ONSET BLINDNESS

It is commonly believed that sensory deprivation can lead to cross-mod al reorganization in an immature but not in a mature brain. The result s of the present study suggest, however, that plasticity between senso ry modalities is possible even in adults: activity indicating involvem ent of parietal or occipital brain areas in pitch-change discriminatio n was found in individuals blinded after childhood. Event-related brai n potentials of early blinded (before the age of 2 years), late-blinde d (12-28 years of age), and sighted adults were recorded to stimulus s equences consisting of standard tones occasionally replaced by deviant tones. Even when participants were not attending to auditory stimuli, the deviant tones elicited the mismatch negativity (MMN) in each grou p. There were no significant MMN front-back scalp distribution differe nces among the groups. However, when participants were detecting devia nt stimuli, these stimuli elicited N2 and P3 waves that were posterior in distribution in both groups of blind participants relative to thos e of the sighted participants. These results suggest that cross-modal reorganization may occur even in the mature human brain.