Magnetic auditory evoked fields: interhemispheric asymmetry.

Magnetic auditory evoked fields (MAEFs) were recorded from the right (11 subjects) and the left (7 subjects) hemisphere following 128 click stimuli delivered to contralateral, ipsilateral and both (bilateral) ears. Right hemisphere MAEFs were of higher amplitude following contralateral, compared to ipsilateral, stimulation in 9 of 11 subjects; mean contralateral response amplitude was 135 +/- 33% (S.D) of ipsilateral response amplitude. Left hemisphere MAEFs were of higher amplitude following contralateral stimulation in 7 of 7 subjects; mean contralateral response amplitude was 145 +/- 44% of ipsilateral response amplitude. These observations are compatible with evidence that a majority of centripetal auditory input is crossed, and/or that contralateral auditory stimulation activates a larger area of cortex than does ipsilateral stimulation.