SignificanceThis study sheds new light on the neuroanatomical adaptations resulting from bilingual language exposure and use, providing crucial insights into untangling the variability of findings in the existing literature. Our results demonstrate that differences in bilingual language experiences confer a range of systematic outcomes in terms of brain/mind adaptations. In doing so, our findings strongly support a shift away from traditional designs with bilingual vs. monolingual comparisons and toward an approach of modeling the experiences within bilingualism that give rise to neurocognitive adaptations. Crucially, we maintain that experience-based factors should be accounted for in all future studies investigating the effects of bilingualism on the brain and cognition.

Research on the effects of bi- and multi-lingualism on brain structure has so far yielded variable patterns. Although it cannot be disputed that learning and using additional languages restructures grey (cortical, subcortical and cerebellar) and white matter in the brain, both increases and reductions in regional volume and diffusivity have been reported. This paper revisits the available evidence from simultaneous and sequential bilinguals, multilinguals, interpreters, bimodal bilinguals, children, patients and healthy older adults from the perspective of experience-based neuroplasticity. The Dynamic Restructuring Model (DRM) is then presented: a three-stage model accounting for, and reinterpreting, all the available evidence by proposing a time-course for the reported structural adaptations, and by suggesting that these adaptations are dynamic and depend on the quantity and quality of the language learning and switching experience. This is followed by suggestions for future directions for the emerging field of bilingualism-induced neuroplasticity.

Numerous studies in psychology, cognitive neuroscience and psycholinguistics have used pictures of objects as stimulus materials. Currently, authors engaged in cross-linguistic work or wishing to run parallel studies at multiple sites where different languages are spoken must rely on rather small sets of black-and-white or colored line drawings. These sets are increasingly experienced as being too limited. Therefore, we constructed a new set of 750 colored pictures of concrete concepts. This set, MultiPic, constitutes a new valuable tool for cognitive scientists investigating language, visual perception, memory and/or attention in monolingual or multilingual populations. Importantly, the MultiPic databank has been normed in six different European languages (British English, Spanish, French, Dutch, Italian and German). All stimuli and norms are freely available at http://www.bcbl.eu/databases/multipic .

Recent studies suggest that learning and using a second language (L2) can affect brain structure, including the structure of white matter (WM) tracts. This observation comes from research looking at early and older bilingual individuals who have been using both their first and second languages on an everyday basis for many years. This study investigated whether young, highly immersed late bilinguals would also show structural effects in the WM that can be attributed to everyday L2 use, irrespective of critical periods or the length of L2 learning. Our Tract-Based Spatial Statistics analysis revealed higher fractional anisotropy values for bilinguals vs. monolinguals in several WM tracts that have been linked to language processing and in a pattern closely resembling the results reported for older and early bilinguals. We propose that learning and actively using an L2 after childhood can have rapid dynamic effects on WM structure, which in turn may assist in preserving WM integrity in older age.bilingualism | immersion | white matter | second language acquisition | TBSS