Left-hemisphere dominance for processing of vowels: a whole-scalp neuromagnetic study

BRAIN-activation of 11 healthy right-handed subjects was studied with magnetoencephalography to estimate individual hemispheric dominance for speech sounds. The auditory stimuli comprised binaurally presented Finnish:vowels, tones, and piano notes in groups of two or four stimuli. The subjects were required to detect whether the first and the last item in a group were the same. In the left hemisphere, vowels evoked significantly,stronger (37-79%)responses than notes and tones,whereas in the right hemisphere the responses to different:stimuli did not differ significantly. Specifically, in the two-stimulus task, all 11 subjects showed left-hemisphere dominance in the vowel ss tone comparision. This simple paradigm may be helpful in noninvasive evaluation of language lateralization. (C) 1999 Lippincott Williams & Wilkins.