Authors:

PULVERMULLER, F.

Reference:

Year of publication:

2003

CBU number:

5877

Abstract:

The MMN is known to reflect the existence of memory traces for phonemes, and we recently reported that it reflects lexical processing as well. Its amplitude is enhanced to words as compared with pseudowords and its latency reflects word recognition. Now, the question becomes whether the enhanced MMN seen for words is, in part, related to word-specific activity that may even differentiate between individual lexical items. First results showed that MMN sources can reliably differ between individual spoken words. But would the activity patterns reflect word-specific features at the cognitive level, meaning for example? To investigate this, we looked at action words referring to movements carried out with different body parts and found differential activation along the motor strip to action related words from different semantic categories. This suggests that the MMN can be used to trace the cortical distribution of memory traces for individual words and, in particular, that it can provide a brain reflection of word meaning. If lexical and semantic factors can be traces using the MMN, only one linguistic domain is left: syntax. When comparing syntactically correct and deviant word strings, dynamics of the MMN were present that could be attributed to left-perisylvian sources in the language areas. A preliminary conclusion from these results is that the MMN reflects processing of phonological, lexical, semantic and syntactic information outside the focus of attention [1-4]. Since the MMN is to a large degree independent of attention being focussed on the stimuli, there are obvious implications for the automatic processing of words, meaning and syntax. Analysis of the spatio-temporal patterns of generator activations and deactivations underlying the MMN to words and word strings may be an important tool for investigating the brain dynamics of spoken language [5].[1] Pulvermüller, F., Kujala, T., Shtyrov, Y., Simola, J., Tiitinen, H., Alku, P., Alho, K., Martinkauppi, S., Ilmoniemi, R. J., and Näätänen, R. (2001). Memory traces for words as revealed by the mismatch negativity. Neuroimage 14, 607-616.[2] Pulvermüller, F., and Shtyrov, Y. (2003). Automatic processing of grammar in the human brain as revealed by the mismatch negativity. Neuroimage 20, 159-172.[3] Shtyrov, Y., Hauk, O., and Pulvermüller, F. (2004). Distributed neuronal networks for encoding category-specific semantic information: the mismatch negativity to action words. European Journal of Neuroscience, in press.[4] Shtyrov, Y., Pulvermüller, F., Näätänen, R., and Ilmoniemi, R. J. (2003). Grammar processing outside the focus of attention: an MEG study. Journal of Cognitive Neuroscience, in press.[5] Pulvermüller, F., Shtyrov, Y., and Ilmoniemi, R. J. (2003). Spatio-temporal patterns of neural language processing: an MEG study using Minimum-Norm Current Estimates. Neuroimage 20, 1020-1025.