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How does the adult brain react to learning a new language?

Spanish researchers recently highlighted the differential specialization of brain areas when learning a new language in adulthood. This research thus shows the plasticity of the cerebral language systems.

A different contribution from the two hemispheres

Human language is a unique ability. However, this requires a certain balance between cerebral plasticity and neuronal specialization. These are two principles at the base of the organization of the brain . By studying language learning, experts can therefore learn more about these principles in the human brain. In a study published in the Journal of Neuroscience on November 9, 2020, researchers from the Basque Center on Cognition, Brain and Language (BCBL) focused on learning a new language in adulthood. According to this research, the two hemispheres of the brain do not contribute in the same way than when an individual learns a language from birth.

In general, language activates the fronto-temporo-parietal network of the brain. Nevertheless, the cognitive functions are not the subject of an equal distribution in the two hemispheres. As far as language is concerned, the areas of the brain taken into account are located on the left side for 95% of the population . As for the right hemisphere, it acts more as a support, since it is able to take over in the event of deterioration of the left hemisphere.

However, the study leaders showed that the right hemisphere is able to come into play when learning a new language in adults. By performing functional magnetic resonance imaging (fMRI), the researchers were able to observe activity in both hemispheres in adults learning a new language. The subjects read and spoke in their mother tongue as well as in the language to be learned. According to the results, the two languages ​​initially manifest themselves quite similarly in the brain. Then these same languages ​​stand out more and more.

A "softer" understanding

The left hemisphere mobilizes when we speak, regardless of whether it is the mother tongue or the language being learned. On the other hand, there is a difference with regard to the understanding of the language (listening, reading). Indeed, the understanding of the mother tongue takes place in the left hemisphere while that of the language being learned, in the right hemisphere.

The results of the study therefore suggest that language production is rooted in the left hemisphere . However, his understanding is more flexible. Thus, the study provides additional details to explain why it is more difficult to learn to speak a language while its understanding poses less problems . In addition, this research makes it possible more generally to feed – with new principles – the debate on the cerebral organization of language.