Word-specific cortical activity as revealed by the mismatch negativity
Psychophysiology, 41 (1):
106--12 (2004)DOI: 10.1111/j.1469-8986.2003.00135.x
Zusammenfassung
Neurophysiological brain activity evoked by individual spoken words
and pseudowords was recorded and the mismatch negativity (MMN), an
automatic index of experience-dependent auditory memory traces, was
calculated. Consistent with earlier reported results, the MMN response
to word-final syllables was enhanced compared with that elicited
by the same syllables placed in a pseudoword context. Here we now
demonstrate that the enhancement of the MMN elicited by two individual
words showed different scalp topographies. The early word-specific
brain activity is consistent with the assumption that the memory
traces activated by individual words are carried by large neuronal
ensembles that differ in their distributions over the cortex. Current
source estimates localized the between-word differences in the right
hemisphere and in parieto-occipital left-hemispheric areas. The differential
brain responses to individual words appeared as early as approximately
100 ms after the recognition points of the words, suggesting that
their specific memory traces become active almost immediately after
the information in the acoustic input is sufficient for word identification.