Behavior-relevant periodized neural representation of acoustic but not tactile rhythm in humans.

Abstract

Music makes people move. This human propensity to coordinate movement with musical rhythm requires multiscale temporal integration, allowing fast sensory events composing rhythmic input to be mapped onto slower, behavior-relevant, internal templates such as periodic beats. Relatedly, beat perception has been shown to involve an enhanced representation of the beat periodicities in neural activity. However, the extent to which this ability to move to the beat, and the related periodized neural representation, are shared across the senses beyond audition remains unknown. Here, we addressed this question by recording separately the electroencephalographic responses (EEG) and finger tapping to a rhythm conveyed either through acoustic or tactile inputs in healthy volunteers of either sex. The EEG responses to the acoustic rhythm, spanning a low-frequency range (below 15 Hz), showed enhanced representation of the perceived periodic beat, compatible with behavior. In contrast, the EEG responses to the tactile rhythm, spanning a broader frequency range (up to 25 Hz), did not show significant beat-related periodization, and yielded less stable tapping. Together, these findings suggest a preferential role of low-frequency neural activity in supporting neural representation of the beat. Most importantly, we show that this neural representation, as well as the ability to move to the beat, is not systematically shared across the senses. More generally, these results, highlighting multimodal differences in beat processing, reveal a process of multiscale temporal integration that allows the auditory system to go beyond mere tracking of onset timing and to support higher-level internal representation and motor entrainment to rhythm.Significance statement Integrating fast sensory events composing music into slower temporal units is a cornerstone of beat perception. This study shows that this ability relies critically on low frequency brain activity, below the sensory event rate, in response to acoustic rhythm. Conversely, brain responses elicited by the same tactile rhythm exhibit higher frequency activity corresponding to faithful tracking of the sensory event rate. Critically, the auditory-specific slow fluctuations feature an enhanced representation of the perceived periodic beat, compatible with behavior. This higher-level neural processing of rhythmic input could thus reflect internal representations of the beat that are not shared across senses, highlighting multimodal differences in beat processing. These results pave the way to explore high-level multimodal perception and motor entrainment in humans.