Topography of Activity Evoked in the Human Brain during Discrimination of Moving Sound Stimuli

Abstract

The aim of the present work was to assess interhemisphere asymmetry of the N1, P2, and N250 components of auditory event-related potentials (ERP) and mismatch negativity (MMN) in passive discrimination between moving sound stimuli in an oddball paradigm. Stimulus movement was created using a linear increase in the interaural time delay ΔT in dichotically presented signals. The amplitudes of the N1 and P2 components were greater in the right hemisphere, this being particularly clear in the frontolateral area. The amplitude of the N250 component in the frontolateral and frontomedial areas was greater in the hemisphere contralateral to the sound stimulus. The direction of movement of sound stimuli had no effect on the asymmetry of ERP and MMN components. The right-hemisphere asymmetry of N1 increased with increases in stimulus speed, while asymmetry of P2 was maximal for short movement trajectories. Asymmetry of N250 and MMN was identified in terms of differences between standards and deviants, i.e., a higher-order feature. Thus, these studies demonstrated differences in the nature of interhemisphere asymmetry for the early and late ERP components, reflecting differences in the neural structures supporting primary analysis of the stimulus and higher cognitive processes.