Functional characterization of the language network of polyglots and hyperpolyglots with precision fMRI.

A small fraction of the world’s population master five or more languages. How do such polyglots represent and process their different languages, and more generally, what can this unique population tell us about the language system? We identified the language network in each of 25 polyglots (including 16 hyperpolyglots with knowledge of 10+ languages) and examined its response to the native language, languages of varying proficiency, and unfamiliar languages. We found that all languages elicit a response reliably above the perceptually matched control condition in all areas of the language network. The response magnitude across languages generally scaled with comprehension level: aside from the native language, which elicited a relatively low response, languages that were more comprehensible to the participant elicited stronger responses. This pattern held for both familiar (studied) languages, and unfamiliar languages (cognate languages of high-proficiency languages elicited a stronger response than non-cognate languages). We also replicated a prior finding of weaker responses during native language processing in polyglots compared to non-polyglots. These results contribute to our understanding of how multiple languages co-exist within a single brain and provide new evidence that the language-selective network responds more strongly to stimuli from which more linguistic meaning can be extracted.