Authors:

SHTYROV, Y. & PULVERMULLER, F.

Reference:

Year of publication:

2001

CBU number:

5254

Abstract:

Recently demonstrated enhanced mismatch negativity (MMN) responses for word stimuli indicated the existence of acoustic memory traces for words (Pulverm¸ller et al, NeuroImage, in press). It has been, however, argued that this enhancement may be explained merely by differences in the lexical status between the frequent (standard) and infrequent (deviant) stimuli. We have explored this issue by recording MMN elicited by identical phonemic contrast incorporated into three sets of spoken monosyllabic stimuli: (I) deviant (16%) word presented among repetitive words, (II) deviant word presented among pseudowords, (III) deviant pseudoword among words. Standard and deviant stimuli were within each set identical up to the divergence point, which was their last phoneme. They were acoustically presented in a passive oddball paradigm to native English speakers whose brain activity was simultaneously recorded using 64-channel EEG set-up. The MMNs elicited by word deviants (conditions I & II) were larger than that elicited by pseudoword (condition III), thus replicating our earlier result. The largest MMN could be elicited in critical for this investigation condition I, in which both deviant and standard stimuli were words, i.e. there was no lexical status difference between the stimuli. Thus, our results indicate the existence of the word-related MMN enhancement, which can reflect the presence of a memory trace for a spoken word, and is largely independent of the lexical status of the deviant stimulus.