How Does a Bilingual Speaker's Brain Process Two Languages? New Research Suggests That Both Rely on the Same Neural Wiring

Scientists have long wondered whether different neural mechanisms govern each language within a bilingual speaker’s brain. A recent study of people who speak both English and Spanish hints at a single “grammatical engine” The new work contributes to a broader shift in bilingualism research, which is moving toward the view that grammar is supported by a shared, flexible brain mechanism that operates across all languages. Paula Sierra via Getty Images Language allows humans to express an infinite range of meanings with remarkably small changes to a word. By modifying a term’s form, speakers can indicate whether they’re referring to one or many things, the past or the present, or other grammatical distinctions. Add -s as a suffix to the English word book, for example, and it becomes the plural books. But the rules that govern grammar can vary widely between languages. An Arabic speaker would modify the internal vowel pattern for the word kitāb, which means book, to change it to the plural form kutub. Neuroscientists have long wondered whether bilingual speakers navigate these different systems with different parts of the brain. Now, a study published in the July 1 issue of the Journal of Neuroscience suggests that the brain uses the same underlying neural machinery across different languages. “Our research suggests that brains have a single ‘grammatical engine’ that fuels all of the languages we speak—rather than separate engines for each one,” says study co-author Esti Blanco-Elorrieta, a neuroscientist at New York University, in a statement. The findings, he adds, hint that human language “may be built from neural computations that transcend any one language.” To understand the underpinnings of grammar in bilingual brains, Blanco-Elorrieta and NYU neuroscientist Xuanyi “Jessica” Chen recruited 23 highly proficient speakers of both English and Spanish. They mapped the participants’ neural activity using a non-invasive technique called magnetoencephalography (MEG), which measures the tiny magnetic fields produced when nerve cells send electrical signals to one another. MEG imaging tracked the bilingual speakers’ brains millisecond by millisecond as participants were asked to produce singular and plural noun forms in both languages, like one boat versus two boats. They also tested cognates—words in different languages that share a common meaning, spelling and pronunciation because of a similar origin—as well as made-up words, like “paple.” The pseudowords allowed the researchers to investigate whether the brain can apply grammatical rules independently of a word’s lexical status or belonging to a particular language. Similar patterns of brain activity emerged when both languages were used in each test, the team found. Cognates didn’t enhance the overlap, and novel pseudowords didn’t impair it. “That makes it harder to explain the effect as simply reflecting shared vocabulary and suggests the brain may be representing the grammatical operation itself,” Blanco-Elorrieta tells K.R. Callaway at the New York Times. The findings are “highly informative” and offer strong evidence that one brain mechanism drives both languages, Mirjana Bozic, a cognitive neuroscientist at the University of Cambridge in England who wasn’t involved in the study, tells the outlet. Still, the results are not too surprising, she notes, given that they’re in line with other initial results in this research field. Another study involving English-Spanish speakers, published on June 24 in the journal Cell, for example, found that the brain might store concepts in a “language-independent format.” Did you know? Linguistic golden age Today, humans around the globe speak roughly 7,500 languages. But according to a study published this month in the journal Science, people may have talked in 20,000 to 75,000 different tongues around three millennia ago. Still, researchers aren’t sure how the findings about the single grammatical engine might generalize to language pairs that differ more substantially than English and Spanish, Bozic tells the Times. Future research should pursue this avenue, the study authors note in the paper. Additionally, the discovery contributes to a broader shift in bilingualism research. Rather than viewing each language as relying on its own grammatical processing system, the field is moving toward models in which grammar is supported by a shared, flexible mechanism that operates across languages, the study authors write. The findings could also have practical implications for aspiring polyglots, since they suggest that the brain doesn’t need to build each new language system from scratch. “From the perspective of language learning, if it is true that there is one universal mechanism for language, then it follows that it may be easier for you to learn new languages” if you already know one, Blanco-Elorrieta says in a separate statement. You Might Also Like Get the latest stories in your inbox every weekday. More about: Brain Cognition Language Neuroscience Psychology