Neurocomputational Emergentism as a Framework for Language Development

Large-scale investigation of white matter structural differences in bilingual and monolingual children: An adolescent brain cognitive development data study

Emerging research has provided valuable insights into the structural characteristics of the bilingual brain from studies of bilingual adults; however, there is a dearth of evidence examining brain structural alterations in childhood associated with the bilingual experience. This study examined the associations between bilingualism and white matter organization in bilingual children compared to monolingual peers leveraging the large-scale data from the Adolescent Brain Cognitive Development (ABCD) Study. Then, 446 bilingual children (ages 9-10) were identified from the participants in the ABCD data and rigorously matched to a group of 446 monolingual peers. Multiple regression models for selected language and cognitive control white matter pathways were used to compare white matter fractional anisotropy (FA) values between bilinguals and monolinguals, controlling for demographic and environmental factors as covariates in the models. Results revealed significantly lower FA values in bilinguals compared to monolinguals across established dorsal and ventral language network pathways bilaterally (i.e., the superior longitudinal fasciculus and inferior frontal-occipital fasciculus) and right-hemispheric pathways in areas related to cognitive control and short-term memory (i.e., cingulum and parahippocampal cingulum). In contrast to the enhanced FA values observed in adult bilinguals relative to monolinguals, our findings of lower FA in bilingual children relative to monolinguals may suggest a protracted development of white matter pathways associated with language and cognitive control resulting from dual language learning in childhood. Further, these findings underscore the need for large-scale longitudinal investigation of white matter development in bilingual children to understand neuroplasticity associated with the bilingual experience during this period of heightened language learning.

Bilingual effects on lexical selection: A neurodevelopmental perspective

When a listener hears a word, multiple lexical items may come to mind; for instance, /kæn/ may activate concepts with similar phonological onsets such as candy and candle. Acquisition of two lexicons may increase such linguistic competition. Using functional Near-Infrared Spectroscopy neuroimaging, we investigate whether bilingualism impacts word processing in the child's brain. Bilingual and monolingual children (N = 52; ages 7-10) completed a lexical selection task in English, where participants adjudicated phonological competitors (e.g., car/cat vs. car/pen). Children were less accurate and responded more slowly during competing than non-competing items. In doing so, children engaged top-down fronto-parietal regions associated with cognitive control. In comparison to bilinguals, monolinguals showed greater activity in left frontal regions, a difference possibly due to bilinguals' adaptation for dual-lexicons. These differences provide insight to theories aiming to explain the role of experience on children's emerging neural networks for lexical selection and language processing.