Memory traces for words as revealed by the mismatch negativity

Brain responses to the same spoken syllable completing a Finnish word or a pseudo-word were studied. Native Finnish-speaking subjects were instructed to ignore the sound stimuli and watch a silent movie while the mismatch neg ativity (MMN), an automatic index of experience-dependent auditory memory t races, was recorded. The MMN to each syllable was larger when it completed a word than when it completed a pseudo-word. This enhancement, reaching its maximum amplitude at about 150 ms after the word's recognition point, did not occur in foreign subjects who did not know any Finnish. These results p rovide the first demonstration of the presence of memory traces for individ ual spoken words in the human brain. Using whole-head magnetoencephalograph y, the major intracranial source of this word-related MMN was found in the left superior temporal lobe. (C) 2001 Academic Press.