Study measures improvement in language skills by tracking brain activity

A study of new Japanese learners measured how brain activity changes after just a few months of studying a new language. The results show that acquiring a new language initially stimulates brain activity, which then declines as language skills improve.

“In the first few months, you can quantitatively measure improvement in language skills by tracking brain activations,” said Professor Kuniyoshi L. Sakai, a neuroscientist at the University of Tokyo and first author of the research recently published in Frontiers in Behavioral Neuroscience.

The researchers followed 15 volunteers as they moved to Tokyo and took introductory Japanese classes for at least three hours a day. All of the volunteers were native speakers of European languages ​​in their 20s who had previously studied English as children or adolescents but had no previous experience studying Japanese or traveling to Japan.

The volunteers took multiple-choice reading and listening tests after at least eight weeks of class and again six to fourteen weeks later. The researchers chose to assess only “passive” reading and listening language skills, as these can be scored more objectively than “active” writing and speaking skills.

The volunteers were inside a magnetic resonance imaging (MRI) scanner during testing so the researchers could measure local blood flow around their brain regions, an indicator of neuronal activity.

“Simply put, there are four regions of the brain specialized for language. Even in a native, second or third language, the same regions are responsible,” Sakai said.

These four regions are the grammar center and the comprehension area in the left frontal lobe as well as the auditory processing and vocabulary areas in the temporoparietal lobe. In addition, the memory areas of the hippocampus and the visual areas of the brain, the occipital lobes, also become active to support the four language-related regions during testing.

During the initial reading and listening tests, these areas of the volunteers’ brains showed significant increases in blood flow, revealing that the volunteers were thinking hard to recognize the characters and sounds of the unfamiliar language.

Volunteers scored about 45% accuracy on reading tests and 75% accuracy on listening tests (a random estimate on multiple-choice tests would produce 25% accuracy).

The researchers were able to distinguish two sub-regions of the hippocampus during listening tests. The observed activation pattern corresponds to the roles previously described for the anterior hippocampus in encoding new memories and for the posterior hippocampus in recalling stored information.

On the second test several weeks later, the volunteers’ reading test scores improved to an average of 55%. Their accuracy on listening tests remained unchanged, but they were quicker to pick an answer, which the researchers interpret as better comprehension.

By comparing the results of the first tests to the second tests, after additional weeks of study, the researchers found a decrease in brain activation in the grammar center and the comprehension area during listening tests, as well as in visual areas of the occipital lobes during reading tests.

“We would expect brain activation to decrease after successfully learning a language because it doesn’t require as much energy to understand it,” Sakai said.

Notably, during the second listening test, volunteers had slightly increased activation of the auditory processing area of ​​their temporal lobes, possibly due to an improvement in the “voice of the mind” when hearing. .

“Beginners do not master the sound patterns of the new language, so they cannot remember them and imagine them correctly. They still spend a lot of energy on recognizing speech unlike letters or grammar rules,” he said. Sakai said.

This pattern of changes in brain activation – a dramatic initial increase during the learning phase and a decline when the new language is acquired and successfully consolidated – may give experts in the neurobiology of language a biometric tool to evaluate programs for them. language learners or potentially for people who regain lost language skills after a stroke or other brain injury.

“In the future, we will be able to measure brain activations to objectively compare different methods of learning a language and select a more efficient technique,” ​​Sakai said.

Until an ideal method can be identified, UTokyo researchers recommend acquiring a language in a natural immersion-like environment such as studying abroad, or in any way that simultaneously activates the four language regions of the brain.

This pattern of cerebral activation over time in the brains of individual volunteers mirrors the results of previous research (see Figure 3E in Science DOI: 10.1126 / science.1113530) where Sakai and colleagues worked with young people aged 13 and 19. years of Japanese language. who learned English in standard Tokyo Public School lessons.

Six years of study appeared to enable 19-year-olds to understand the second language well enough that brain activation levels were reduced to levels similar to their native tongue.

The recent study confirmed this same pattern of brain activation changes within months, not years, which could encourage anyone looking to learn a new language as adults.

“We all have the same human brain, so we can learn any natural language. We should try to exchange ideas in multiple languages ​​to develop better communication skills, but also to better understand the world – to broaden our view of other people and about future society, ”said Sakai.