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Speech rhythm entrainment in 6-month-old infants: frequency specificity, voice familiarity, and language foundations
Poster Session E, Friday, October 2, 11:00 am - 1:00 pm, Wangari Maathai
Isabelle Rambosson1,2, Damien Benis3, Leonardo Ceravolo1,2, Manuela Filippa1,2,3, Didier Grandjean1,2; 1Neuroscience of Emotion and Affective Dynamics Lab, Department of Psychology, University of Geneva, Geneva, Switzerland, 2Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland, 3Division of Development and growth, Department of Women, child and adolescent medicine, University Hospital of Geneva, Switzerland
Early language acquisition relies on the brain's ability to extract temporal regularities from speech. Infant-directed speech primarily falls within the delta frequency range (~0.5–3.5 Hz), a phylogenetically conserved tempo of biological communication. Neural entrainment to this timescale is thought to be a key mechanism through which the developing brain generates temporal predictions, a critical foundation for speech segmentation and language learning. Yet the underlying mechanisms of auditory temporal prediction remain poorly studied in young infants. Forty-seven 6-month-old infants (30 term and 17 preterm; age corrected for prematurity) were recorded with high-density EEG while exposed to trains of rhythmic syllables produced by their mother or a stranger at delta (2 Hz) or theta (4 Hz) rates, alongside a non-rhythmic control condition. Rhythmic sequences also included violations of the expected pattern. Auditory temporal regularity elicited a broad frontotemporal entrainment response. In term infants, delta-band entrainment was frequency-specific across frontal and temporal clusters, with right frontal selectivity progressively strengthening throughout the entrainment period, while no theta-band tuning was observed. Beyond frequency specificity, voice familiarity asymmetrically shaped delta entrainment across hemispheres: the right frontal cluster responded selectively to the stranger’s voice, whereas the left temporal cortex showed selective entrainment to the mother’s voice. However, in preterm infants, frontal delta entrainment failed to strengthen over the session and persistent left-temporal theta responses were observed. These findings reveal a neural architecture for temporal prediction already in place by 6 months in term-born infants, with the right frontal cortex emerging as a higher-order, experience-tunable node. Critically, preterm birth disrupts this trajectory, with potential long-term consequences for language acquisition.
Topic Areas: Language Development/Acquisition, Disorders: Developmental