Neural encoding of auditory rhythm beyond cortical auditory areas before the age of term.

Rhythm experience begins in fetal life, shaping neural capacities critical for language, communication, and motor skills. While rhythm processing in adults involves distributed cortical networks, including premotor and supplementary motor regions, the mechanisms in the fetal brain remain unclear. We provide evidence that premature newborns encode rhythmic beats through cortical networks extending beyond the auditory cortex into premotor and sensorimotor regions. Using high-density functional near-infrared spectroscopy, we show that auditory beats trigger distinct cortical activation patterns, indicating early involvement of an auditory-motor network, despite the absence of coordinated motor activity. Our results highlight a fundamental role for these regions in rhythm perception, forming the basis for predictive timing mechanisms. This early engagement of sensorimotor regions reveals a neural framework supporting beat perception from the fetal stage onward. These findings advance understanding of the neural architecture for rhythm processing, showing that the premature brain is already wired for complex auditory-motor interactions.