EVENT-RELATED POTENTIALS TO ITALIAN SPOKEN WORDS

Forty-four right-handed volunteers were invited to listen to Italian 5 -letter words of different kinds, including non-words, digitally recor ded. Signals from 16 electrodes were averaged and displayed both as tr aces and maps. When the same word was monotonously delivered to the su bject, a positive component at 340 ms was recorded following the N100- P200 complex. This potential was automatic, phonologically driven, ind ependent of habituation, specific for verbal material and lateralized to the left side. By contrast, semantic tasks evoked bilateral N400, b y using the oddball paradigm with different kinds of target stimuli, i ncluding non-words. The N400 duration was related to the task complexi ty. The late positive component was locked-in-time with the end of the words. Therefore, N400 reached its peak before the word completion. A t that time the probability of recognition was 60%, progressively reac hing 100% at the time of the late positive component. Intra- and inter individual variance was low. The findings indicates two different lang uage processings: one is confined to the perisylvian regions of the le ft hemisphere in right-handed subjects and appears earlier, reflecting phonological processing, whereas the other one is bilateral and takes places when semantic judgments are going on. Event-related potentials during language processing appear to be a very useful tool, especiall y when EEG maps are displayed, giving us the information on both tempo ral and spatial events. (C) 1997 Elsevier Science Ltd.