From sounds to movement and back: how movement shapes internal representation of musical rhythms

The perception of beat and meter when listening to musical rhythms is an extremely commonability that allows people to synchronize to music. The rhythms are spontaneously structuredby the listener into beat and meter, i.e., multiple periodic levels, even if the acoustic input isnot strictly periodic. However, how musical rhythms are embodied in brain structures remainsunclear. Using EEG to record beat- and meter-related steady-state evoked potentials, we inves-tigated how body movements involving motor, proprioceptive and vestibular systems shape theinternal representation of an ambiguous polyrhythm (i.e. a rhythm that can be perceived in dif-ferent meters). We recorded the EEGwhile participants listened to such ambiguous polyrhythm,before and after a body movement training session aiming to disambiguate the perception ofthis rhythm by favoring the ternary meter. We found that brain activities recorded beforethe movement session faithfully followed the structure of the sound envelope, with no selectiveenhancement at specific frequencies. In contrast, the steady-state evoked potentials recordedduring the listening session performed after the body movement training were significantly en-hanced at frequencies corresponding to the ternary metric interpretation to which they movedduring the movement training. These results provide evidence that movement shapes selectivelythe perception and neural representations of rhythm as captured with EEG. Moreover, theseresults help to progress in our understanding of the neural dynamics underlying auditorymotorintegration, as captured in the context of musical rhythm