[Topography of the Event-Related Brain Responses during Discrimination of Auditory Motion in Humans]

The present study investigates the hemispheric asymmetry of auditory event-related potentials (ERPs) and mismatch negativity (MMN) during passive discrimination of the moving sound stimuli presented according to the oddball paradigm. The sound movement to the left/right from the head midline was produced by linear changes of the interaural time delay (ITD). It was found that the right-hemispheric N1 and P2 responses were more prominent than the left-hemispheric ones, especially in the fronto-lateral region. On the contrary, N250 and MMN responses demonstrated contralateral dominance in the fronto-lateral and fronto-medial regions. Direction of sound motion had no significant effect on the ERP or MMN topography. The right-hemispheric asymmetry of N1 increased with sound velocity. Maximal asymmetry of P2 was obtained with short stimulus trajectories. The contralateral bias of N250 and MMN increased with the spatial difference between standard and deviant stimuli. The results showed different type of hemispheric asymmetry for the early and late ERP components which could reflect the activity of distinct neural populations involved in the sensory and cognitive processing of the auditory input.