Linguistics

Cognitive psychology

Philosophy

Neuroscience

Phonology

Functional neuroimaging

Functional imaging

Grammar

Functional magnetic resonance imaging

Computer science

Semantics (computer science)

Psychology

Politics

Political science

Meta-analysis

Internal medicine

Artificial intelligence

Representation (politics)

Medicine

Programming language

Audiology

Neuroscience of multilingualism

Neuroimaging

Neuroscience & Biobehavioral Reviews

Notwithstanding rising interest, a coherent picture of the brain’s representation of two languages has not yet been achieved. In the present meta-analysis we analysed a large number of functional neuroimaging studies focusing on language processing in bilinguals. We used activation likelihood estimation (ALE) to enucleate activation areas involved in bilingual processing and control of different types of linguistic knowledge – lexico-semantics, grammar, phonology – in L1 and L2. Results show that surprisingly, compared to L2, lexico-semantic processing in L1 involves a widespread system of cortico-subcortical regions, especially when L2 is acquired later in life. By contrast, L2 processing recruits regions exceeding the L1 semantic network and relating to executive control processes. Only few regions displayed selective activation for grammar and phonology. Analyses of language switching highlight a functional overlap between domain-general and bilingual language control networks. Collectively, our findings point to a shared neural network for L1 and L2 with few differences depending on the linguistic level. The emerging picture identifies under-investigated issues, offering clear directions for future research.

Bilingual language processing: A meta-analysis of functional neuroimaging studies