Abstract
Bilingualism is of great interest to the neuroscience of language, and understanding the anatomical changes associated with second language learning help inform theories of bilingual advantage across the lifespan. While the literature on structural differences between bilinguals and monolinguals is robust, relatively few studies of gray matter (GM) have directly compared bilinguals with monolinguals in a whole-brain analysis. Overall, this and heterogeneity of study samples and methodology have led to a lack of clear anatomical support for major theories. Here, we engage in an activation likelihood estimate (ALE) meta-analysis of voxel-based morphometry (VBM) studies of GM for cases that directly compare bilingual and monolingual subjects in a whole-brain analysis. The analysis (sixteen foci, from ten contrasts across eight studies) resulted in one cluster located primarily within the anterior lobe of the right cerebellum. However, when the one pediatric study was removed, the analysis revealed no consistent results across the studies included in this meta-analysis. This suggests that for VBM studies of bilingual and monolingual adults there is considerable heterogeneity of results that complicate the understanding of the bilingual brain. Future studies will need to include larger, more well-defined samples and interrogate more fine-grained anatomical features such as cortical thickness and surface area in order to more fully examine the anatomical changes associated with bilingualism across the lifespan.
Highlights
Bilingualism continues to be a topic of intense interest, providing a unique lens into the study of the neuroscience of language
The same analysis was repeated, but removing foci from contrasts that were not corrected for multiple comparisons, which included thirteen foci from the ten contrasts. For this activation likelihood estimate (ALE) analysis, again one cluster where bilinguals showed greater gray matter (GM) than monolinguals was identified with two peaks: (18, –44, –20) and (12, – 58, –8)
The neuroanatomy of bilingualism continues to be of great interest for the neuroscience of language and in understanding the potential cognitive and brain advantages of learning multiple languages (Baum and Titone, 2014; Li et al, 2014; Bialystok et al, 2016; Grundy et al, 2017)
Summary
Bilingualism continues to be a topic of intense interest, providing a unique lens into the study of the neuroscience of language. Along with the importance of understanding the potential benefits of multi-language learning comes the concern of heterogeneity of samples in studies of bilingualism and the brain due to the roles of factors such as age of acquisition and how the second language is learned. As such Garcia-Penton et al (2016), has outlined how the variability in sample selection and methodology have led to a lack of generalizability of results across studies, and relatively little neuroanatomical support for major theories of bilingualism.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
