Motion-induced disturbance of auditory-motor synchronization and its modulation by transcranial direct current stimulation.

The timing of personal movement with respect to external events has previously been investigated using a synchronized finger-tapping task with a sequence of auditory or visual stimuli. While visuomotor synchronization is more accurate with moving stimuli than with stationary stimuli, it remains unclear whether the same principle holds true in the auditory domain. Although the right inferior-superior parietal lobe (IPL/SPL), a center of auditory motion processing, is expected to be involved in auditory-motor synchronization with moving sounds, its functional relevance has not yet been investigated. The aim of the present study was thus to clarify whether horizontal auditory motion affects the accuracy of finger-tapping synchronized with sounds, as well as whether the application of transcranial direct current stimulation (tDCS) to the right IPL/SPL affects this. Nineteen healthy right-handed participants performed a task in which tapping was synchronized with both stationary sounds and sounds that created apparent horizontal motion. This task was performed before and during anodal, cathodal and sham tDCS application to the right IPL/SPL in separate sessions. The time difference between the onset of the sounds and tapping was larger with apparently moving sounds than with stationary sounds. Cathodal tDCS decreased this difference, anodal tDCS increased the variance of the difference and sham stimulation had no effect. These results supported the hypothesis that auditory motion disturbs efficient auditory-motor synchronization and that the right IPL/SPL plays an important role in tapping in synchrony with moving sounds via auditory motion processing.