Cortical Thickness Is Related to Variability in Heritage Bilingual Language Proficiency

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Posted on August 24, 2023 by childrenslearninginstitute


August 2023 (online) and December 2023 (print)


Translational Issues in Psychological Science

CLI Author:

Kelly A. Vaughn, PhD


Research suggests that bilingual experience is associated with gray matter changes, such that initial language gains are associated with expansion and language expertise is associated with renormalization. Previous studies on language proficiency development primarily focused on between-subjects, quasiexperimental comparisons of monolinguals and bilinguals. This study proposes a new paradigm to examine language expertise and cortical thickness within heritage bilinguals (n = 215), as well as between bilinguals and monolinguals (n = 145), using data combined from eight previous magnetic resonance imaging studies. In general, results highlight variability within bilinguals, finding relationships between cortical thickness and English proficiency that are relatively consistent within monolinguals, but inconsistent within bilinguals. In all participants, higher levels of proficiency in English—monolinguals’ only language and bilinguals’ second but stronger language—were negatively related to cortical thickness. In bilinguals, higher proficiency in the weaker, albeit first learned, language was positively related to cortical thickness. Moreover, there was an interaction between language group and English proficiency in predicting cortical thickness, such that the relationship between proficiency and thickness was stronger in monolinguals than in bilinguals. Findings also demonstrate that the regions associated with language expertise differ between bilinguals and monolinguals. Future directions for cognitive-developmental neuroscience research in bilinguals are suggested, particularly the longitudinal examination of cortical changes in relation to bilingual experiences.

Impact Statement:

This study highlights neural variability among bilinguals, their difference from monolinguals, as well as the dynamic nature of language system organization/cortical representation by examining the relationship between language proficiency and cortical thickness. Notably, proficiency in the first-learn but weaker language positively correlated to cortical thickness. Future research is needed to understand how these complex relationships between bilingual experience and neural structure develop. (PsycInfo Database Record (c) 2023 APA, all rights reserved)


Nguyen, M. V. H., Vaughn, K. A., Claussenius-Kalman, H., Archila-Suerte, P., & Hernandez, A. E. (2023). Cortical thickness is related to variability in heritage bilingual language proficiency.Translational Issues in Psychological Science, 9(4), 364–379.