Do you feel the beat, baby? Musical rhythm enhances sensorimotor neural responses and connectivity in infants

Rhythm perception, tracking temporal regularity at different hierarchical levels, is fundamental to processing music and speech. The sensorimotor network is proposed to be engaged for processing rhythm, where the motor system actively shapes auditory rhythm perception 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 the individual differences in its neural processing are associated with later speech and language skills. This MEG study examines how 7- and 11-month-old infants process two distinct musical rhythms: march (1,2,1,2,1,2) and waltz (1,2,3,1,2,3). Whole-brain analysis revealed increased neural responses in distributed brain networks that include the sensorimotor areas, auditory cortex, inferior frontal gyrus and basal ganglia for all rhythm types at both ages. Functional connectivities between sensorimotor and related areas were enhanced within the motor-related alpha and beta frequency bands as early as 7 months of age, predominantly in response to a relatively simple march rhythm. The strength of these connectivities during march rhythm perception at 7 months are positively related to their productive vocabulary size at 27 months. Our findings extend theories of rhythm perception from adulthood to infancy, suggesting that infants already recruit distributed motor-related brain regions for rhythm perception before they perform precise synchronization. These early neural responses underlying rhythm perception may serve as potential predictors for later language development, corroborating the literature regarding shared mechanisms between music and language processing.