Brain lateralization for mismatch response to across- and within-category change of vowels

Differences in hemispheric predominance between across- and within-category change perception of vowels were assessed using a whole-head magnetoenceph alography. The magnetic mismatch responses (MMNm) to pure-tone and vowel wi thin-category changes were significantly predominant in the right hemispher e; on the other hand, vowel across-category MMNm did not differ in power be tween hemispheres. The results suggest that both hemispheres are symmetrica lly activated in the preattentive across-category change perception of vowe ls, while the within-category change of a vowel is analyzed as the change i n physical features of the stimuli, thus predominantly activating the right hemisphere. Thus, the relative contribution of the left auditory cortex in the preattentive speech processing may occur only at the level of percepti on of the vowel across-category change. NeuroReport 12:2467-2471 (C) 2001 L ippincott Williams & Wilkins.