Do You Feel the Beat, Baby? MEG Reveals Motor Brain Activity during Rhythm Processing in Infants and Its Links to Later Language Skills

Rhythm processing, the ability to track temporal regularities across multiple hierarchical levels, is fundamental in music and speech perception. The sensorimotor network is proposed to support rhythm processing, with the motor system actively shaping auditory processing through temporal prediction and action simulation, based on adult studies. However, it remains unclear whether and how the sensorimotor network is engaged in rhythm perception in infants, and whether individual differences in its neural activity are associated with later speech and language skills. Using magnetoencephalography (MEG), we examined how 7-month-old infants process two distinct musical rhythms: march (1,2,1,2,1,2) and waltz (1,2,3,1,2,3). Source analysis revealed increased neural responses in distributed brain networks encompassing sensorimotor areas, auditory cortex and basal ganglia for both rhythm types. Functional connectivity between sensorimotor and related areas was enhanced within the motor-related alpha and beta frequency bands, predominantly in response to the relatively simpler march rhythm. Notably, connectivity strength during march rhythm perception at 7 months was positively associated with productive vocabulary size at 27 months. These findings extend theories of rhythm processing from adults to infants, suggesting that motor-related brain regions are already recruited for rhythm processing before the emergence of precise movement synchronization. These early neural responses to nonlinguistic rhythms may serve as potential predictors of later language development, corroborating the literature regarding shared mechanisms between music and language processing.