Abstract
Background:Lateralised representation of language in monolinguals is a well-established finding, but the situation is much less clear when there is more than one language. Studies to date have identified a number of factors that might influence the brain organisation of language in bilinguals. These include proficiency, age of acquisition and exposure to the second language. The question as to whether the cerebral lateralisation of first and second languages are the same or different is as yet unresolved. Methods:We used functional transcranial Doppler sonography (FTCD) to measure cerebral lateralisation in the first and second languages in 26 high proficiency bilinguals with German or French as their first language (L1) and English as their second language (L2). FTCD was used to measure task-dependent blood flow velocity changes in the left and right middle cerebral arteries during word generation cued by single letters. Language history measures and handedness were assessed through self-report questionnaires. Results:The majority of participants were significantly left lateralised for both L1 and L2, with no significant difference in the size of asymmetry indices between L1 and L2. Asymmetry indices for L1 and L2 were not related to language history, such as proficiency of the L2. Conclusion: In highly proficient bilinguals, there is strong concordance for cerebral lateralisation of first and second languages.
Highlights
Lateralised language processing is a well-established finding in monolinguals
functional transcranial Doppler sonography (FTCD) is not suitable for studying localisation of language within a hemisphere, we present evidence that it gives a reliable and sensitive measure of extent of lateralisation, that allows us to go beyond simple classification of language laterality as left or right, via a direct comparison of blood flow in the middle cerebral arteries
Study 2: Japanese-English bilinguals with moderate-high proficiency In Study 1 we found no difference in laterality patterns for L1 and L2 between French-English and German-English bilinguals, but it is possible that differences might be more apparent with languages that are more different from one another, in grammatical structure, lexical items and/or phonology
Summary
Lateralised language processing is a well-established finding in monolinguals. In bilinguals, studies using fMRI have typically found substantial regional overlap between the two languages, though results may be influenced by factors such as proficiency, age of acquisition and exposure to the second language. Methods: In Study 1, we used functional transcranial Doppler sonography (FTCD) to measure cerebral lateralisation in both languages in high proficiency bilinguals who varied in age of acquisition (AoA) of L2. They had German (N = 14) or French (N = 10) as their first language (L1) and English as their second language. Study 2 followed a similar format with 25 Japanese (L1) /English (L2) bilinguals, with proficiency in their second language ranging from basic to advanced, using phonological and semantic word generation tasks with overt speech production. Results: In Study 1, participants were significantly left lateralised for version 2
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
