The role of the Frontal Aslant tract in bilingual language control

Abstract

In the present study the microstructural properties of the right and left Frontal Aslant tract (FAT) have been investigated in relation to bilingualism and to language modality by comparing a group of unimodal bilinguals (i.e., bilinguals of two spoken languages) and a group of bimodal bilinguals (i.e., bilinguals of a spoken and a signed language). The microstructural properties of the left FAT correlated with performance in picture naming and semantic fluency in L2 for both groups of bilinguals. The microstructural properties of the both the right and left FAT correlated with picture naming performance in L1 for bimodal bilinguals. No significant correlations were found with performance in a language comprehension task. Overall, the results suggest that the FAT plays a relevant role in language control in bilinguals. While the left FAT seems to be mainly involved in the suppression of the spoken native language (L1) during the use of the spoken or signed L2, both the right and the left FAT seem to be involved in the suppression of sign language (L2) during speaking in L1.