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Poster Session C, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall

Early brain changes while learning a second language - Relearning how to listen, read, and learn, from words to sentences

Tomás Goucha1, Helyne Adamson1, Alfred Anwander1, Matthias Schwendemann1, Angela D. Friederici1;1Max Planck Institute for Human Cognitive and Brain Sciences

Second language (L2) acquisition has repeatedly been considered a puzzle in recent years, especially in terms of brain plastic changes (1). This is mainly due to the reported involvement of a multitude of brain regions inconsistently across different studies in different phases of learning (2) and an inherent difficulty to attribute these changes to specific functions, in particular in cross-sectional studies. Here, we observed changes in white matter microstructure along the first three months of learning German as a second language in an intensive course administered to Arabic native speakers (N=54), in an immersive context. Concurrently, we acquired measures of language learning together with well-established measures of language aptitude (3), and executive function (e.g., cognitive control). Finally, the participants also took part in an fMRI experiment on word and sentence-level processing. In this first phase of second language acquisition, the participants start by learning in an item-based fashion, by chunks, only acquiring more creative skills including the internalisation of productive rules towards the end. This phase is rarely taught in an immersive environment so that frequently no strong changes are observed. Another often ignored aspect in the initial phase of second language learning that is rarely observable at later periods is the acquisition of a new sound system, and the re-acquisition of word chunking in speech as well as of reading and writing in a foreign language (which was particularly important in this study due to the change of script). Concerning longitudinal effects in the first three months of L2 learning, we find changes in cortical regions and underlying white matter, in subcortical grey matter structures, and in the brain stem, with a predominance of the right hemisphere. We find both changes in typical language areas and their right hemisphere homologues, but also in primary sensory and motor areas. In agreement with these results, the fMRI task also presents less lateralised brain activations than in typical L1 processing. We also found changes in areas responsible for cognitive control, shown mainly for early bilinguals or bilinguals in immersion, together with more basal areas in the auditory and visual pathways, as well as dopaminergic regions involved in reward learning. When considering the behavioural measures and their correlations with brain plastic changes, we observed that already speaking a previous language fluently was associated with higher word learning skills, being a good predictor of learning success. Results converged to show the preponderance of this type of learning in this early phase. We finally pinpoint that more naturalistic measures of the spontaneous language production of the participants were the best indicators of brain changes, especially in typical language-related brain regions. References: (1) García-Pentón, L., et al. (2016). The neuroanatomy of bilingualism: how to turn a hazy view into the full picture. Language, Cognition and Neuroscience; (2) Pliatsikas, C. (2019). Understanding structural plasticity in the bilingual brain: The Dynamic Restructuring Model. Bilingualism: Language and Cognition; (3) Rogers, V., et al. (2017). Examining the LLAMA aptitude tests. Journal of the European Second Language Association.

Themes: Multilingualism, Control, Selection, and Executive Processes
Method: White Matter Imaging (dMRI, DSI, DKI)