Positive Potentials Evoked by the First Syllable of Spoken Words in Right- and Left-Handers

Andrea Cobianchi and Salvatore Giaquinto

Published: 13 April 1998

Eighteen right-handed and 18 left-handed young volunteers were invited to listen to digitized Italian 5-letter words. Signals from 16 electrodes were averaged and displayed both as traces and maps. When the same word was delivered repetitively to a subject, a positive component was recorded following the N100-P200 complex at a mean latency of 340 msec. By applying multivariate analysis to the groups, inter-hemispheric differences were significant. This potential was automatic, phonologically driven, independent of habituation, specific for verbal material and significantly lateralized to the language areas. Conversely, a 500-Hz tone having the same duration and the same intensity failed to evoke a lateralized potential. Multivariate analysis showed a clear difference between word and tone stimulation. There is evidence suggesting that inheritance may be linked to a right-sided language representation more than handedness itself, as assessed by Edinburgh test. The results indicate the utility of event-related potentials in studying language processing. Spoken words appear to be an appropriate tool, because they permit the study of EEG changes on a millisecond-to-millisecond basis.

Keywords: language, event-related potentials, speech processing, cerebral dominance, left-handedness