Brains of polyglots provide clues about how we process language – 03/11/2024 – Science

Although most people speak only one language or perhaps two, some are proficient in several. These people are called polyglots. And they are helping to provide information about how the brain handles language, the main method of human communication.

In a new study involving a group of polyglots — who spoke between five and 54 languages ​​— participants’ brain activity was monitored using a method called functional magnetic resonance imaging while they listened to excerpts in several languages.

With one intriguing exception, activity increased in areas of the cerebral cortex involved in the brain’s language processing network when these polyglots listened to languages ​​in which they were most proficient, compared to those in which they were less fluent.

“We believe this is because when you process a language you know well, you can trigger the entire set of linguistic operations — the operations that your brain’s linguistic system supports,” said neuroscientist Evelina Fedorenko of MIT (Massachusetts Institute of Technology). ), member of the McGovern Institute for Brain Research at MIT and senior author of the study published this Monday (11) in the journal Cerebral Cortex.

“You can access all word meanings from memory, construct phrases and sentences from individual words, and access complex sentence-level meanings,” Fedorenko added.

One exception, however, caught the attention of researchers. In many of the participants, listening to their native language elicited a smaller brain response compared to listening to other languages ​​they knew — on average, a drop of about 25%. And in the case of some polyglots, hearing their native language activated only part of the brain’s language network, not all of it.

“Polyglots become experts in their native language from the standpoint of the efficiency of the neural processes required to process it. Therefore, the language network in the brain is not activated in the same way as it is when they process the native language versus the non-native,” said neuroscientist and study co-author Olessia Jouravlev, from Carleton University, Canada.

“A person’s native language may have a privileged status, at least in this population,” Fedorenko added, referring to the study’s multilingual participants.

The brain’s language network involves some areas located in the frontal and temporal lobes.

“The language network supports comprehension and production in all forms of language — spoken, written, symbolic, etc. — and helps us encode our thoughts in sequences of words and decode the thoughts of others from their utterances,” said Fedorenko.

Study co-author Saima Malik-Moraleda, a doctoral student in the Harvard/MIT Speech and Hearing Bioscience and Technology Program, said the findings suggest that the distillation of meaning governs the brain’s response to language.

“The more meaning you can extract from the linguistic input you are receiving, the greater the response in linguistic regions — except in the native language, probably because the speaker is more efficient at extracting meaning from linguistic input,” Malik-Moraleda said.

The ages of the 34 study participants, 20 men and 14 women, ranged from 19 to 71 years old. Twenty-one were native speakers of English, and the remainder were native speakers of French, Russian, Spanish, Dutch, German, Hungarian, and Mandarin.

Brain activity was monitored as they listened to recordings of passages in eight languages: their native language, three others in which they were highly proficient, moderately proficient and minimally proficient, and four that they did not know. Half listened to recordings of Lewis Carroll’s “Alice in Wonderland.” The other half listened to recordings of Bible stories.

The smaller brain response to listening to the native language was more pronounced among study participants who heard the biblical stories — linguistically simpler, according to Fedorenko, than Carroll’s writing.

Fedorenko said that “much of the work in language research has focused on individuals with language difficulties — developmental or acquired.”

“But we can also learn a lot about the cognitive and neural infrastructure of some function by observing individuals who are ‘experts’ in that function. Polyglots are a type of language ‘expert’,” he said.