Summary: In a study of speakers of 45 languages, researchers found similar patterns of brain activity and language selectivity.
Over several decades, neuroscientists have created a well-defined map of the brain’s “linguistic network,” or regions of the brain that specialize in language processing. Found primarily in the left hemisphere, this network includes regions in Broca’s area, as well as other parts of the frontal and temporal lobes.
However, the vast majority of these cartographic studies were carried out on English speakers while they listened to or read texts in English. MIT neuroscientists have now performed brain imaging studies on speakers of 45 different languages. The results show that the language networks of speakers appear to be essentially the same as those of native English speakers.
The results, while not surprising, establish that the location and key properties of the language network appear to be universal. The work also lays the groundwork for future studies of linguistic elements that would be difficult or impossible to study in English speakers because English lacks these characteristics.
“This study is very fundamental, extending some findings from English to a wide range of languages,” says Evelina Fedorenko, Frederick A. and Carole J. Middleton Career Development Associate Professor of Neuroscience at MIT and a member of the McGovern Institute for Brain of the MIT. To research.
“The hope is that now that we see that the basic properties seem to be general across all languages, we can ask about potential differences between languages and language families in how they are implemented in the brain, and we can study phenomena that don’t really exist in English.
Fedorenko is the lead author of the study, which appears today in Natural neuroscience. Saima Malik-Moraleda, a doctoral student in Harvard University’s Speech and Hearing Bioscience and Technology program, and Dima Ayyash, a former research assistant, are the lead authors of the paper.
Map linguistic networks
The precise locations and shapes of language areas differ from individual to individual. To find the language network, researchers ask each person to perform a language task while scanning their brain with functional magnetic resonance imaging (fMRI). Listening to or reading sentences in one’s native language should activate the language network.
To distinguish this network from other brain regions, the researchers also ask participants to perform tasks that should not activate it, such as listening to an unfamiliar language or solving math problems.
Several years ago, Fedorenko started designing these “localization” tasks for speakers of languages other than English. While most language network studies have used English speakers as subjects, English does not include many features commonly seen in other languages. For example, in English word order tends to be fixed, while in other languages there is more flexibility in word order. Many of these languages instead use the addition of morphemes, or word segments, to convey additional meaning and relationships between words.
“There has been a growing awareness for many years of the need to look at more languages, if you want to make statements about how language works, as opposed to how English works,” says Fedorenko.
“We thought it would be useful to develop tools to allow people to rigorously study language processing in the brain in other parts of the world. There is now access to brain imaging technologies in many countries, but the basic paradigms you would need to find the language sensitive areas in a person just aren’t there.
For the new study, the researchers performed brain imaging of two speakers of 45 different languages, representing 12 different language families. Their goal was to see if key properties of the language network, such as location, left-lateralization, and selectivity, were the same in these participants as in people whose first language is English.
The researchers decided to use “Alice in Wonderland” as the text that everyone would listen to, because it is one of the most translated works of fiction in the world. They selected 24 short passages and three long passages, each of which was recorded by a native speaker of the language. Each participant also heard nonsense passages, which should not activate the language network, and were asked to perform a variety of other cognitive tasks that should not activate it.
The team found that the language networks of the participants in this study were in approximately the same brain regions and had the same selectivity as those of native English speakers.
“Linguistic areas are selective,” says Malik-Moraleda. “They shouldn’t respond during other tasks such as a spatial working memory task, and that’s what we found in the speakers of 45 languages we tested.”
Additionally, language regions that are typically activated together in English speakers, such as frontal language areas and temporal language areas, were similarly synchronized in speakers of other languages.
The researchers also showed that across all subjects, the small amount of variation they saw between individuals who spoke different languages was the same as the amount of variation that would typically be seen between native English speakers.
Similarities and differences
Although the results suggest that the overall language network architecture is similar between speakers of different languages, that doesn’t mean there’s no difference, Fedorenko says. For example, researchers could now look for differences between speakers of languages that primarily use morphemes, rather than word order, to help determine the meaning of a sentence.
“There are all sorts of interesting questions you can ask about morphological processing that don’t really make sense to ask in English, because it has a lot less morphology,” says Fedorenko.
Another possibility is to investigate whether speakers of languages that use pitch differences to convey different word meanings would have a language network with stronger ties to auditory brain regions that encode pitch.
Currently, Fedorenko’s lab is working on a study in which they compare the “temporal receptive fields” of speakers of six typologically different languages, including Turkish, Mandarin and Finnish. The temporal receptive field is a measure of how many words the language processing system can handle at once, and for English it has been shown to be six to eight words long.
“The language system seems to work on chunks of only a few words, and we’re trying to see if this constraint is universal in these other languages we’re testing,” Fedorenko says.
Researchers are also working on creating language localization tasks and finding study participants representing additional languages beyond the 45 in this study.
Funding: The research was supported by the National Institutes of Health and research funds from MIT’s Department of Brain and Cognitive Sciences, the McGovern Institute and the Simons Center for the Social Brain. Malik-Moraleda was funded by a la Caixa scholarship and a Friends of McGovern scholarship.
About this language and news in neuroscience research
Author: Anne Trafton
Contact: Anne Trafton – MIT
Image: Image credited to Christine Daniloff, MIT
Original research: Access closed.
“A Survey of 45 Languages and 12 Language Families Reveals a Universal Language Network” by Evelina Fedorenko et al. Natural neuroscience
A survey of 45 languages and 12 language families reveals a universal language network
To understand the architecture of human language, it is essential to examine various languages; however, most cognitive neuroscience research has focused on only a handful of primarily Indo-European languages.
Here we report an investigation of the fronto-temporo-parietal linguistic network in 45 languages and establish the robustness to cross-linguistic variation of its topography and key functional properties, including left lateralization, strong functional integration between its brain regions. and functional selectivity for language processing.