A file photo of a human brain Photograph:( AFP )
"In the first few months, you can quantitatively measure language-skill improvement 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 findings of a new study show that acquiring a new language initially boosts brain activity, which then reduces as language skills improve. The study with first-time learners of Japanese measured how brain activity changes after just a few months of studying a new language.
"In the first few months, you can quantitatively measure language-skill improvement 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.
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 experience studying Japanese or travelling to Japan.
Volunteers took multiple-choice reading and listening tests after at least eight weeks of lessons and again six to fourteen weeks later. Researchers chose to assess only the 'passive' language skills of reading and listening because those can be more objectively scored than the 'active' skills of writing and speaking.
Volunteers were inside a magnetic resonance imaging (MRI) scanner while taking the tests so that researchers could measure local blood flow around their brain regions, an indicator of neuronal activity.
"In simple terms, there are four brain regions specialised for language. Even in a native, second or third language, the same regions are responsible," said Sakai.
Those four regions are the grammar centre and comprehension area in the left frontal lobe as well as the auditory processing and vocabulary areas in the temporoparietal lobe. Additionally, 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 while taking the tests.
During the initial reading and listening tests, those areas of volunteers' brains showed significant increases in blood flow, revealing that the volunteers were thinking hard to recognise the characters and sounds of the unfamiliar language.
Volunteers scored about 45 per cent accuracy on the reading tests and 75 per cent accuracy on the listening tests (random guessing on the multiple-choice tests would produce 25 per cent accuracy).
Researchers were able to distinguish between two subregions of the hippocampus during the listening tests. The observed activation pattern fits previously described roles for the anterior hippocampus in encoding new memories and for the posterior hippocampus in recalling stored information.
At the second test several weeks later, volunteers' reading test scores improved to an average of 55 per cent. Their accuracy on the listening tests was unchanged, but they were faster to choose 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 decreased brain activation in the grammar center and comprehension area during listening tests, as well as in the visual areas of the occipital lobes during the reading tests.
"We expect that brain activation goes down after successfully learning a language because it does not require so much energy to understand," said Sakai.
(With inputs from agencies)