Neural Oscillatory Mechanisms of Speech Processing in Newborns

Language acquisition begins even before birth, as the fetal auditory system becomes functional in the third trimester and is exposed to the rhythmic and prosodic patterns of the native language through intrauterine sound transmission. This dissertation examines whether cortical oscillations in the delta and theta frequency bands are attuned and calibrated to the rhythmic structure of the native language by prenatal experiences, or whether enhanced neonatal oscillatory responses reflect the intrinsic acoustic properties of certain language types, independent of prior exposure. The study replicates the paradigm of Ortiz-Barajas et al. (2023), which demonstrated that newborns exposed to French exhibit stronger delta and theta responses to the syllable-rhythmic French and Spanish languages than to the stress-rhythmic English, with a sample of 20 Canadian newborns from monolingual English-speaking families. Electroencephalographic activity was recorded during rest and while listening to naturally spoken English, French, and Spanish sentences. The results show a numerical trend toward stronger delta-band oscillatory responses to English at the frontal electrodes, which is consistent with the predicted inverse of the French pattern, although this did not reach global statistical significance. No reliable theta effects were observed, and no oscillatory differences were found between French and Spanish, which is consistent with the rhythmic class hypothesis. These preliminary results tentatively support the theory of prenatal attunement and are consistent with an integrated view of language acquisition, according to which a biologically prepared oscillatory infrastructure is gradually attuned to the rhythmic properties of the native language through prenatal acoustic experiences.