Auditory cortex evoked magnetic fields and lateralization of speech processing

Potential use of different auditory evoked brain responses for determining cerebral lateralization of speech function was evaluated. Cortical magnetic fields elicited by plosive syllables or complex non-speech sounds analogou s to them were recorded with 122-channel magnetometer. We estimated paramet ers of magnetic PI, NI and P2 responses to both stimuli in the Mo hemispher es and found no hemispheric asymmetry for any of the responses. No correlat ion between the right-ear advantage, determined with dichotic listening tes t. and any of asymmetry indexes, calculated for the speech-elicited respons es, was observed. These results suggest that PI, NI and P2 responses to spe ech signals do not indicate lateralization of speech function in the brain. The results are discussed in relation to previous studies suggesting that the mismatch negativity (MMN) seems to be the only early auditory cortex re sponse sensitive to the lateralization of speech function. NeuroReport 11:2 893-2896 (C) 2000 Lippincott Williams & Wilkins.