Words in the Brain as Reflected by the Mismatch Negativity and Mismatch Field

Abstract:
Abstract: The mismatch negativity (MMN) and its magnetic correlate, the mismatch field (MMF), are well-known indicators of novelty detection. It has recently been shown by Näätänen et al. (1997) that prototypical speech sounds elicit greater mismatch responses than speech-like sounds lacking a corresponding phoneme in one's language. This fostered the view that the existence of a permanent neuronal memory trace for an incoming stimulus is reflected in the MMN and MMF, at least at the level of language sounds. We show here that this view can be extended to the higher linguistic level of word processing. Word-final syllables evoked greater MMNs and MMFs compared to physically identical stimuli placed in a pseudoword context. The main generator of the word-evoked MMF could be localized in the left superior temporal lobe. Furthermore, individual words were found to elicit mismatch responses with different cortical topographies. We conclude that the existence of cortical memory traces for words is reflected in the MMF and MMN, and that the present experimental strategy makes it possible to investigate neurocognitive processes triggered by individual lexical items.