A systematic review and meta-analysis of language and cognition in the developing bilingual brain: From infancy to adolescence

Research investigating the neural mechanisms of language and cognition in bilingual children is steadily growing. We reviewed functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) studies to identify brain regions engaged during linguistic and cognitive tasks of bilingual compared to monolingual children. Out of 26 eligible studies, six fMRI studies were included into an exploratory coordinate-based meta-analysis, whereas fNIRS papers lacked sufficient statistical and methodological data for meta-analysis. However, the small number of studies, combined with considerable heterogeneity in participant characteristics, task paradigms, and underlying brain organization, limits the generalizability and interpretability of the current findings. Results suggest that: (1) bilinguals’ neural correlates of language and cognition revealed clusters across classic language areas (as well as additional domain-general executive regions as supported by supplementary probabilistic atlas analyses); (2) comparisons considering bilingual age of acquisition groups and age-matched monolinguals revealed differences in activation within the IFG – the sole area identified in the fMRI meta-analysis – among other regions across the frontal, temporal, and parietal lobes. While findings should be interpreted cautiously given the early and heterogenous nature of this literature, activation patterns in bilingual children were consistent with those of bilingual adult studies, highlighting involvement of key frontal and temporal regions in language and cognition. Our findings also underscore the urgent need for standardized reporting practices, especially in fNIRS research, including detailed documentation of acquisition parameters and processing methods to facilitate future meta-analyses and improve reproducibility.