Event-Related Potentials to Sound Stimuli with Delayed Onset of Motion in Conditions of Active and Passive Listening

The relationship between auditory event-related potentials (the N1, P2, cN1, and cP2 components) and the rate of motion of a sound stimulus was studied in humans in passive conditions (attention distracted from the stimulation) and during active localization of the beginning and end of the trajectory. Sound signals were presented dichotically and consisted of two fragments. Stimuli were initially stationary and located at the center of the head, after which they moved from the center of the head towards the right or left ear. Motion was created using a linear increase in the interaural time delay. As compared with passive listening, responses signal onset during active listening generated a greater-amplitude N1 component, while the P2 component had both greater amplitude and longer latency. In response to motion onset, the N1 and P2 components had greater amplitudes and latencies in active conditions. Monotonic relationships between N1 and P2 amplitude and latency on the one hand and stimulus movement speed on the other, were seen in both active and passive conditions. Contralateral asymmetry of responses to stimulus motion onset was seen only in the left hemisphere.