title: DTI reveals structural differences in white matter tracts between bilingual and monolingual children.
abstract: The impact of bilingualism on the microstructure of the white matter pathways related to language processing is assessed in elementary school children by magnetic resonance diffusion tensor imaging (MR-DTI). Forty children, 8-11 years old, subdivided into 3 different groups (15 simultaneous bilinguals, 15 sequential bilinguals and 10 monolinguals), were scanned. The hypothesis was that the starting age and the manner of second language acquisition would affect the characteristics of language circuitry. In each subject the mean fractional anisotropy (FA) was obtained for four major white matter pathways: 1 - the left arcuate fasciculus/superior longitudinal fasciculus (lAF/lSLF) that connects Broca's area in the opercular and triangular regions of the left inferior frontal gyrus to the posterior language zone, 2 - the left inferior occipitofrontal fasciculus (lIFOF), connecting anterior regions in the frontal lobe with posterior regions in the temporal occipital lobes, 3 - the bundle arising from the anterior part of the corpus callosum projecting to the orbital lobe (AC-OL) and 4 - the fibers emerging from the anterior midbody (AMB) of the corpus callosum that associate with the premotor and supplementary motor cortices (AMB-PMC). The three groups did not show significant differences in mean FA over the lAF/lSLF or AMB-PMC tracts. In simultaneous bilingual subjects the lIFOF tracts had higher mean FA value compared to monolinguals and also sequential bilinguals, whereas the comparison for the AC-OL fibers yielded a significantly lower mean FA value in simultaneous bilingual subjects compared to monolinguals. In both cases the FA value for sequential bilinguals was intermediate to that of the other two groups. To our knowledge, this study provides the first evidence of bilingualism related adaptation of white matter microstructure in the human brain.
authors.affiliation: Vrije Universiteit Brussel (VUB), Belgium. smohades@vub.ac.be
authors.forename: Seyede Ghazal
authors.initials: SG
authors.lastname: Mohades
authors.forename: Esli
authors.initials: E
authors.lastname: Struys
authors.forename: Peter
authors.initials: P
authors.lastname: Van Schuerbeek
authors.forename: Katrien
authors.initials: K
authors.lastname: Mondt
authors.forename: Piet
authors.initials: P
authors.lastname: Van De Craen
authors.forename: Robert
authors.initials: R
authors.lastname: Luypaert
mesh_terms: D000704:Analysis of Variance; D016880:Anisotropy; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D002648:Child; D056324:Diffusion Tensor Imaging; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008297:Male; D019303:Multilingualism; D009413:Nerve Fibers, Myelinated / Q000502:physiology*