Evoked responses to the cyclic sound motion

This work aims to study the event-related potentials (ERPs) during the cyclic movement of sound stimuli and to choose the optimal model for neuronal coding of azimuthal motion. The ERPs elicited by the cyclic motion of sound stimuli were investigated under conditions of dichotic stimulation. Stepwise or linear motion patterns were created by cyclic changes in the interaural time difference (ITD), which changed by 800 μs, and then returned to its initial value. Statistically significant ERPs were evoked by the motion onset and by the repeated changes of direction (sound turns) only in the case of a stepwise ITD pattern. The amplitude of the responses consistently depended on the angular position of the turning points relative to the head midline. These results support a two-channel model for encoding spatial information in the auditory cortex. ERPs evoked by motion offset indicated that spatial attention and sensory memory were involved in the preconscious perception of cyclic motion.