Neuro-cognitive development of semantic and syntactic bootstrapping in 7- to 9-year-old children.

We examined longitudinal relations of brain and behavior assessing semantic and syntactic language bootstrapping in children from ages 7- to 10.5-years-old. This study is a direct extension of our earlier investigation on 5- to -7-year-old children (Wagley & Booth, 2021). In a series of preregistered and exploratory analyses, we tested how semantic and syntactic knowledge may influence the development of left hemisphere brain regions implicated in these processes, i.e., inferior frontal gyrus pars opercularis (IFGop) and pars triangulairs (IFGtri), posterior superior temporal gyrus (pSTG), and posterior middle temporal gyrus (pMTG). We also tested how engagement of these brain regions may influence the development of children's semantic and syntactic knowledge. Participants were 7-8.5 years old at Time 1 and 9-10.5 years old at Time 2 of data collection. Hierarchical regression analyses included data from N = 53 participants for the semantic task and N = 41 for the syntax task, controlling for baseline effects. In line with our previous study, we found that early behavior predicted later brain activation but that earlier brain activation did not predict later behavior. Across the analyses, there was weak evidence of semantic bootstrapping in the pSTG but strong evidence in support of syntactic bootstrapping in the IFGtri. We observed no support of either semantic or syntactic bootstrapping in IFGop or pMTG. These results complement prior behavioral models of language suggesting close relations between lexical and grammatical development in older elementary school age children, as well as neurocognitive models that highlight the importance of semantic and syntactic integration for language comprehension.