The bilingual brain

The bilingual brain thumbnail

Close your eyes and imagine that you can speak two languages. There are two words for every noun you can think about–object, feeling or place–whereas a monolingual brain only has one. Your brain must decide which word to use when speaking, reading, and writing. This task is on top of the language processing you already do.

Scientists believe that bilingual people have more practice with cognitive control by sorting through these extra words and switching between them. It is not known if bilingual brains are more neurologically different than monolingual ones.

Saima Malik-Moraleda, a fifth-year PhD student in the Harvard/MIT Program in Speech and Hearing Bioscience and Technology, is trying to help answer this question. She hopes to find ways to reduce the political and cultural tensions surrounding bilingualism, particularly in cultures where certain languages have different political connotations. As a member of the McGovern Institute lab of Ev Fedorenko, PhD ’07, who researches how brains create language, Malik-Moraleda is studying bilingual brains in a new way.

Neurobiologists usually focus on the relative involvement in bilingual activity of different brain regions. Malik-Moraleda takes this one step further by studying neural network–the specific pathways through which information travels in the head. Instead of simply looking at which brain regions are lit up during a particular activity she uses what’s called a localized approach. She tracks the reactions of specific sets or neurons between those regions.

Malik­Moraleda speaks Spanish, Catalan and English. She is also learning Arabic. She has always been aware of the cultural implications that bilingualism poses. Her mother is from Spain, and her father is from Kashmir. Kashmir is a disputed region in South Asia that is claimed both by India and Pakistan. She spent her school year in Girona in Spain’s Catalonia region and would travel with her father to Kashmir during summer vacations.

Splitting her year between these two places showed Malik-Moraleda the differences in how they treated bilingualism. Both regions are culturally distinct from the rest of the country and have historically fought to be independent. Residents often speak a different language than the primary language in the surrounding country or countries. Malik-Moraleda states that street signs in Barcelona state that “you’re going see Catalan first, Spanish then English,” While Catalonians prefer Catalan, and speak Spanish only when needed, Kashmiri parents discourage their children learning Kashmiri. They encourage them to speak English or Urdu, which are more common languages, to better prepare them for school and work.

As a polyglot, Malik-Moraleda was both sad and angry at her relatives’ neglect of Kashmiri as a child. She felt more than sadness or anger. She also felt confused. Why would anyone not learn two languages if they had the chance? She says, “It always blew me mind.” She decided to make a career out of discovering how bilingual brains work in order to show her community that bilingualism may have some benefits.

Saima Malik-Moraleda prepares a person to enter the MRI machine


Saima Malik-Moraleda at a computer viewing brain scans


Saima Malik-Moraleda prepares a lab colleague for an MRI imaging session and reviews brain images. She scans people while they listen to their native languages and any other languages.

She began in high school, writing a senior project about bilingual brains. After graduating from high school, she studied psychology at the Autonomous University of Barcelona. She spent her junior year at University of California in San Diego. While in San Diego, she attended a talk by MIT professor of brain and cognitive sciences Nancy Kanwisher ’80, PhD ’86, who mentioned the work of Fedorenko, a close collaborator and the Middleton Career Development Associate Professor of Neuroscience at MIT.

Malik–Moraleda was in New Delhi, after graduating from college, when she heard about the “Alice” project, which was a new effort by Fedorenko. The study, which has participants listen to translations of passages from Alice in Wonderland while in an MRI machine, aims to map the neural networks used for language processing in speakers of as many world languages as possible.

Because Malik–Moraleda had contact with speakers of languages such as Hindi, Telugu and Tamil in New Delhi she emailed Fedorenko asking for help. Fedorenko replied within one day and offered her coauthorship. She says, “It was crazy.” “That’s what led me to be like, ‘Yes, I really want to work with this person.'”

Malik-Moraleda’s work since she arrived at MIT–where she is also advised by professor of brain and cognitive sciences Ted Gibson–has formed the basis of a 2021 study with Fedorenko looking at executive function in bilingual people. Previous studies have not shown that bilingualism is associated with superior executive function. This may be due to the fact that bilingual people learn different languages at different ages, and are proficient in different languages. Fedorenko and Malik-Moraleda used data from the lab to scan people’s brains as they performed a task related spatial working memory. This involved identifying bilingual and monolingual subjects who were similar in their ability to remember where a sequence light flashes had appeared on an grid. They identified 55 bilingual and 54 monolingual subjects who were otherwise similar, and controlled for different kinds of bilingualism by including only bilingual people who had learned their second language before age six and reported a proficiency score of 4 or 5 on a scale of 1 to 5.

Previous studies were anatomy-based and focused on brain activity in areas associated with executive functions, such as the left forefrontal cortex. The left frontal cortex is linked to many networks, including the domain-general multi-demand (MD), network that supports executive function, as well as the language-selective (LSN), which does not. Fedorenko and Malik-Moraleda suspected that the anatomy-based studies produced contradicting results, as they didn’t attempt identify which network was being activated.

The boundaries of the MD network are not always the same for everyone and only a small portion of the left frontal cortex is affected. Instead of looking only for activity in the brain region, they looked at the MD network. They found that bilingual people had stronger neural responses to the flashing-light task than monolingual people. And they performed better.

Malik-Moraleda hadn’t expected the 2021 paper–which she thinks was the first to use the localized approach to study bilingual brains–to corroborate anatomy-based studies that had showed stronger executive function responses in bilingual brains. She had hoped it would show no difference.

But the results are very exciting and Malik-Moraleda believes there could be other reasons for the increase in MD network activity. Many bilingual people are either immigrants or children of immigrants who have had to face more challenges in their lives. She believes that executive functioning can be improved if there is more motivation and grit.

Under the umbrella of the Alice project, Malik-Moraleda has contributed to other high-impact language research, including a 2022 paper in Nature Neuroscience outlining the discovery of similarities in brain processing among speakers of diverse world languages. The team (on which she served as lead author with Dima Ayyash ’12, MCP ’13) reported that the language network of the brain responds similarly across 45 languages. It seems like the brain’s language network is designed to support all languages,” says Malik Moraleda.

One purpose of the research was to make it easier to study how language works in general–not just for English speakers, who have been the subjects of most studies to date. Other languages may not share the same features as English, such its conventions for word ordering. Establishing the properties of the language network over 45 different languages, though, lays the groundwork for future studies of linguistic elements that might be difficult to study in English speakers.

The researchers published all their fMRI data as well as recordings and other materials used in the study, and she hopes other neurobiologists will use them to improve methods of studying language and expand the number studied. She says, “It’s an opportunity for researchers who are located in an area [where people] use a language not usually researched to also use those tools.”

Her work helps build an inclusive and diverse language research community,” Fedorenko says. Fedorenko considers Malik-Moraleda a fearless researcher who is also a great colleague. Malik-Moraleda will use her research to address social and political issues after she has completed her PhD. Although she is now more aware of the science behind language processing than she thought, she hopes that her research will help people like her Kashmiri relatives to see that multilingualism is a gift.

Malik–Moraleda also wants to study whether certain languages are more conducive for cult-building due to the way they are structured. And she wants to study how the brain’s response to constructed languages–like Klingon from Star Trek or Dothraki from Game of Thrones–differs from its response to natural languages. She is committed to studying diverse languages to gain a better understanding of language processing.

“We have to look at as many languages as possible,” she says, “for us to be able to understand language processing in its entirety.”

Read More