Interhemisphere asymmetry of auditory evoked potentials in humans and mismatch negativity during sound source localization.

Results of studies in humans of long-latency auditory evoked potentials and mismatch negativity in conditions of dichotic stimulation during presentation of deviant stimuli producing instantaneous changes in stimulus azimuth from the null to +22.5 degrees or movement at rates of 11.25-112.5 degrees/sec from the midline of the head across the left and right hemispheres towards each ear are presented. These studies showed that the total amplitude of the components of the N1-P2 complex of auditory evoked potentials in the frontal lead of the right hemisphere was greater than that in the left hemisphere. Mismatch negativity parameters showed significant relationships with the spatial position of the sound source, namely, its displacement into the right hemisphere from the position of the sound image of the standard signal. Questions of the involvement of the right hemisphere in discriminating the spatial characteristics of sound sources are discussed.