Mastering to perfection the language of Shakespeare and that of Molière, and even more that of Shakespeare and that of Confucius, is a rare and envied ability. But how does the brain of bilingual people process both languages? “Languages are, by institution, arbitrary and convenient to peoples. There is the name and the thing. The name is a voice that notices and signifies the thing. (…) It is a foreign part, attached to the thing and outside of it”notes Montaigne in his Trials (1580).
A French team was therefore interested in how these written names, independently of things, are encoded by a bilingual brain in each of the two languages. The authors dissected the workings of reading in the brains of twenty-one English-French bilinguals and ten English-Chinese bilinguals. To do this, they used a precise scalpel: functional MRI at 7 Tesla from the NeuroSpin center at the CEA (Inserm-CNRS-Paris-Saclay University). Their work was published on April 5 in the journal Science Advances.
“Reading is a two-step processexplains Professor Laurent Cohen, neuroscientist at the Brain Institute in Paris (Pitié-Salpêtrière hospital, AP-HP), who coordinated this study with Stanislas Dehaene, director of NeuroSpin and professor at the College de France. In the first, the brain’s visual system recognizes letters and their order. In the second, these data are transmitted to the language system, which allows access to the meaning and sounds of the words read. »
Lobe temporal gauche
The researchers explored the first stage, which takes place in “the area of the visual form of letters and words”, a small area located in the left temporal lobe. “No bigger than a fingernail”explains Laurent Cohen, this area activates 150 to 200 milliseconds after a written word is presented. In the event of a cerebrovascular accident (CVA) located at this level, the patient loses his ability to read because he can no longer recognize the letters. Could this area have a finer specialization in the recognition of letters and sequences of letters in different languages, the authors wondered?
Lying in the tunnel of the high-resolution MRI machine, participants had to watch series of images on a screen. At the same time, the researchers scrutinized the small sub-regions activated by these visual stimuli, within this famous area. Occasionally, the participants had to press a button when they saw a star appear, just to keep their attention awake.
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