Study measures the development of language skills by monitoring brain activity

A study by Japanese learners for the first time has measured how brain activity changes after just a few months of studying a new language. The findings show that the acquisition of new language first strengthens brain activity, which in turn reduces how language skills improve.

“In the next few months, you can measure the development of language skills by monitoring brain activity,” said Dr. Kuniyoshi L. Sakai, a neuroscientist at the University of Tokyo and the first author of the research recently published in Boundaries in Ignorance of Behavior.

Researchers followed 15 volunteers as they moved to Tokyo and completed introductory Japanese classes for at least three hours each day. All volunteers were native speakers of European languages ​​in their 20s who had previously studied English as children or teenagers but had no prior knowledge of Japan or travel to Japan.

Volunteers took multiple reading and listening tests after at least eight weeks of lessons and again six to fourteen weeks thereafter. Researchers chose to assess only the “passive” language skills in reading and listening as these may be more rationally scored than the “active” skills in writing and speaking.

Volunteers were inside a magnetic resonance imaging (MRI) scanner while performing the tests so researchers could measure local blood flow around their brain regions, a sign of neuronal activity.

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

These four regions are the grammatical center and the comprehension area in the left frontal lobe as well as the auditory and lexical processing areas in the temporo-parietal lobe. In addition, the memory areas of the hippocampus and the visual fields of the brain, the occipital lobes, will also be active in supporting the four language-related regions during the tests.

During the initial reading and listening tests, these areas of the voluntary brain showed a marked increase in blood flow, indicating that the volunteers thought hard to familiarize themselves with the characters and sounds of the unfamiliar language. recognition.

Volunteers scored about 45% error on the reading tests and 75% accuracy on the listening tests (a random measurement of the multiple-choice tests would give 25% accuracy).

Researchers were able to differentiate between two subdivisions of the hippocampus during the hearing tests. The observed pattern of activation corresponds to previously described roles for the anterior hippocampus in coding new memories and for the posterior hippocampus in retrieving stored information.

At the second test several weeks later, voluntary reading test scores averaged 55%. Their accuracy of the listening tests was unchanged, but they were quicker to select an answer, which researchers interpret as improved comprehension.

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

“We expect brain activity to decline after we have successfully learned a language because it does not require as much energy to understand,” Sakai said.

Notably, during the second listening test, volunteers had performed a little more activity on the auditory processing area of ​​their temporal lobes, possibly as a result of an improved “mental voice” while listening.

“Beginners have not mastered the sound patterns of the new language, so they cannot remember and think well. They still expend a lot of energy to recognize the speech as opposed to letters or grammar rules, “Sakai said.

This pattern of altered brain activity – a dramatic initial increase in the level of learning and a decline as the new language is successfully acquired and consolidated – can be able to provide experts in language neurobiology with a biometric tool to evaluate curricula for language learners or people who may be regaining language skills lost after a stroke or other brain injury.

“In the future, we can measure brain activity to make a reasonable comparison between different ways to learn a language and choose a more effective way,” Sakai said.

To identify a unique method, researchers at UTokyo suggest acquiring language in a natural environment in an immersion style like learning abroad, or any way that implements the four language segments of the brain at at the same time.

This pattern of brain activation over time in individual volunteer brains mirrors results from a previous study (see Figure 3E in DOI Science: 10.1126 / science.1113530) where Sakai and his colleagues working with 13- and 19-year-old Japanese natives. learned English in ordinary Tokyo public school lessons.

Six years of study seemed to allow 19-year-olds to understand the second language well enough that brain activity levels decreased to levels similar to those of their native language.

The recent study confirmed this same pattern of brain activity changing over just a few months, not years, which may be a motivator for anyone wanting to learn a new language as an adult.

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