Abstract
Auditory-motor synchronization tasks (such as tapping to a beat) involve both auditory and sensorimotor neural networks. Electrophysiologically-recorded steady-state evoked potentials have shown enhanced amplitudes at specific stimulus frequencies during listening and tapping to external rhythms. We attempted to distinguish neural responses to percepts and actions during an auditory synchronization task, and to compare them with behavioral synchronization measures. Neural responses during Synchronization were compared with those during Listen-only (no movement, same stimulus) and Motor-only (no stimulus, same movement) tasks.
Twenty-five right-handed musicians tapped to a rhythmically regular stimulus as their electroencephalogram (EEG) was recorded.
The Synchronization stimuli varied in rhythmic complexity from low complexity (stimulus-to-tap ratio of 1:1) to moderate (1:2) and high complexity (3:2); thus, the tapping frequency was held constant while the stimulus rate varied. Participants synchronized with the stimulus (Synchronize), listened to the same stimulus rhythms (Listen-only) and detected occasional missing beats, or tapped at the same rate (Motor-only).
As the rhythmic complexity increased across conditions, behavioral asynchrony (measured as tap onset minus stimulus onset times) increased, and peak amplitudes in the EEG power spectra at tap frequencies decreased. The Synchronize condition elicited greater ssEP peak amplitudes than Listen-only and Motor-only conditions at both stimulus and tap frequencies. Individuals’ entrainment strength in low complexity (1:1) was predictive of their entrainment in high complexity (1:2, 2:3) rhythms.
An additional ssEP component emerged in the 3:2 condition at unique frequency where stimulus and taps aligned, suggesting neural interactions between auditory and sensorimotor networks during auditory-motor synchronization
