The neuroanatomy of bilingualism: how to turn a hazy view into the full picture

Abstract

Abstract:The neuroanatomical bases of bilingualism have recently received intensive attention.However, it is still a matter of debate how the brain structure changes due to bilingual experience since current findings are highly variable. The aim of this review is to examine these structural studies from a methodological perspective and to discuss two major methodological problems that could give rise to this variability. The first problem is sample selection, an issue directly related to the heterogeneous nature of bilingualism. The second problem is the inconsistency in the methods used for the analysis of brain imaging data. This review reveals that although structural changes related to bilingualism have been reported in regions comprising language/cognitive control and language processing, these results are not yet sufficiently numerous or consistent to allow important generalizations to be reached. Consequently, current evidence offers ambiguous support for neural models of bilingualism. This shortcoming in the field is exacerbated by critical methodological differences between studies that only further complicate the matter. We conclude by identifying issues that should be taken into consideration so that studies are more comparable and results are easier to aggregate and interpret. We also point out future directions that would allow for progress in the field.

Language experience and the brain: variability, neuroplasticity, and bilingualism

“…Such variables may have little to do with bilingualism per se, nor with particular measurement techniques. García-Pentón et al (2015) suggest that researchers adopt similar measurement techniques in order to promote more valid comparisons across studies. Clearly, this would represent an improvement in many respects, but would come with a cost as well.…”

“…Here, we consider what sort of framework is needed to begin to address the apparent inconsistencies in the evidence reviewed by García-Pentón et al (2015). We then consider the relationship of this work to the extensive body of research on the consequences of bilingualism for behaviour and ask what assumptions might need to be made to begin to understand the causal mechanisms that underlie these consequences.…”

“…Abutalebi et al, 2012;Bialystok, Craik, & Luk, 2012;Kroll, Dussias, Bice, & Perrotti, 2015). The article by García-Pentón, García, Costello, Duñabeita, and Carreiras (2015) asks what evidence exists to suggest that bilingualism imposes structural changes in the brain and what that evidence implies about whether the use of two or more languages confers cognitive advantages to bilingual speakers. Other recent reviews, notably Li, Legault, and Litckofsky (2014), have also evaluated the available structural data on the consequences of bilingualism.…”

“…The word "hazy" in the title of the García-Pentón et al (2015) paper suggests that there is a problem with the existing research on this topic and the paper is indeed oriented towards two problems. One is that the authors claim that the quality of the data on the consequences of bilingualism for neuroanatomical change is variable: studies are underpowered, use a range of analytic methods that may not be comparable, and anatomical results from similar studies lack convergence.…”

Sequential language learning versus language immersion in bilingualism: Diffusion MRI connectometry reveals microstructural evidence

“…The connectometry analysis results showed tracks with increased quantitative anisotropy in have learned second language, further complicates an answer to this question (11).…”