Oscillatory timing of neural responses to rhythm from 2 months linked to individual differences in language from 12 to 24 months

The phase alignment of low-frequency neural oscillations to amplitude-modulation driven rhythm patterns during the cortical tracking of speech is a key mechanism regarding linguistic encoding, and is active in the infant brain from birth. Atypical timing of these phase-related neural mechanisms when processing rhythm is characteristic of children with dyslexia, a linguistic developmental disorder involving phonological impairments. Atypical oscillatory timing of neural responses to rhythm may thus affect various domains of language acquisition from infancy. Here we examined whether low-frequency phase alignment in response to slow rhythmic speech and non-speech input between 2 and 9 months of age related to subsequent measures of language acquisition in a community sample of 122 infants. During longitudinal EEG recordings at 2, 6 and 9 months, infants were played drumbeats and syllables repeated at 2Hz. At the population level, the phase of infants’ neural oscillations aligned consistently to the rhythmic inputs, indexing cortical tracking. Group-level convergence towards a common preferred phase was found for all stimuli. At the level of the individual infant, the phase angle and consistency of the oscillatory 2Hz response related to individual differences in infant-led and parent-reported measures of communication, vocabulary and phonological processing taken from 12-24 months. Accordingly, individual differences in early language acquisition may be related to the neural timing of cortical tracking responses to auditory and audiovisual rhythmic input. Using oscillatory timing differences to simple rhythm to identify infants at risk for language difficulties could allow for intervention at the earliest stages of development.