This longitudinal study investigates early neurocognitive and behavioral predictors of speech development in infants with neurodiversity, including those at elevated likelihood (EL) for Autism Spectrum Disorder (ASD), preterm infants, and low-likelihood (LL) infants. Our ongoing efforts are building a comprehensive Neurodiversity Database by accumulating diverse neurocognitive, behavioral data, and speech from neonates to 3-year-olds. The first part of this presentation explores how maternal interaction with 6-month-old infants, specifically contingent responsiveness and the rhythmicity of maternal speech and movement, influences later speech development. The second part presents findings from functional Near-Infrared Spectroscopy (fNIRS) studies. One such study measured neural responses to maternal versus unfamiliar voices in 6-month-old infants, comparing EL and LL groups and assessing their impact on subsequent speech ability. Our results show that LL infants exclusively exhibited widespread cortical activation and robust functional connectivity, particularly in language areas and orbitofrontal cortices, indicative of a reward-driven language network. Crucially, brain activation and connectivity significantly predicted later language and social outcomes in LL infants. These findings underscore the critical role of socio-emotional motivation, particularly for human and familiar voices, as a driving factor in speech acquisition.
Yasuyo Minagawa (Wed,) studied this question.