Multilingual babies use more cognitive control
You may believe that you have forgotten the Chinese you spoke as a child, but your brain hasn't. Moreover, that "forgotten" first language may well influence what goes on in your brain when you speak English or French today. New research demonstrates our brain's plasticity and ability to adapt to new language environments.
In a paper published today in Nature Communications, researchers from McGill University and the Montreal Neurological Institute describe their discovery that even brief, early exposure to a language influences how the brain processes sounds from a second language later in life. Even when the first language learned is no longer spoken.
It is an important finding because this research tells scientists both about how the brain becomes wired for language, but also about how that hardwiring can change and adapt over time in response to new language environments.
The research has implications for our understanding of how brain plasticity functions, and may also be important information about creating educational practices geared to different types of learners.
Researchers asked three groups of children (aged 10 - 17) with very different linguistic backgrounds to identify French pseudo-words (such as vapagne and chansette).
One group of children was born and raised in unilingual French-speaking families. The second group were adopted from China into a French-speaking family before age three, stopped speaking Chinese, and from that point on heard and used only French. The third group were fluently bilingual in Chinese and French.
As the children responded to the words they heard, the researchers used functional magnetic resonance imaging (fMRI) to look at which parts of their brains were being activated.
Although all groups performed the tasks equally well, the areas of the brain that were activated differed between groups.
In monolingual French children without exposure to Chinese, the left inferior frontal gyrus and anterior insula areas of the brain, expected to be involved in processing language-associated sounds were activated.
However, children who are bilingual (Chinese/French) and those who had been exposed to Chinese as young infants but stopped speaking it, use additional areas: the right middle frontal gyrus, left medial frontal cortexand bilateral superior temporal gyrus are all active.
It appears early language sounds leave brain traces.
Researchers found that the Chinese children who had been adopted into unilingual French families and no longer spoke Chinese, were functionally unilingual at the time of testing, but still had brains that processed language in a way similar to bilingual children.
"During the first year of life, a first step in language development in an infants' brain is to collect and store "important sounds" relative to what is said around them," said Lara Pierce, a doctoral student at McGill and the first author on the article.
"What we discovered from children adopted into French-language families - who no longer spoke Chinese, they like bilingual children, showed brain activation in areas known to be involved in working memory and cognitive control during language tests.
"These results suggest children exposed to Chinese as infants process French in a different manner to monolingual French children."
Researchers believe their findings speak to the unique and lasting influence of early language experience on later brain organization.
Pierce: "Adopted children we tested have an interesting background as they were exposed to one language from birth, but completely discontinued that language when adopted into families who speak a new language.
"This is very interesting from a language development perspective because it allows us to compare just that very early language development on later language processing."
Future research will be directed at whether similar areas of the brain are active if languages that had been "lost" and "gained" through adoption are more similar to each other — such as with French and Spanish.
Early experiences may establish a foundation for later learning, however, influences of early language experience on later neural processing are unknown. We investigated whether maintenance of neural templates from early language experience influences subsequent language processing. Using fMRI, we scanned the following three groups performing a French phonological working memory (PWM) task: (1) monolingual French children; (2) children adopted from China before age 3 who discontinued Chinese and spoke only French; (3) Chinese-speaking children who learned French as a second language but maintained Chinese. Although all groups perform this task equally well, brain activation differs. French monolinguals activate typical PWM brain regions, while both Chinese-exposed groups also activate regions implicated in cognitive control, even the adoptees who were monolingual French speakers at testing. Early exposure to a language, and/or delayed exposure to a subsequent language, continues to influence the neural processing of subsequently learned language sounds years later even in highly proficient, early-exposed users.
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Dec 29, 2015 Fetal Timeline Maternal Timeline News News Archive
Imaging slices are shown overlapping in the axial plane to demonstrate
the similarity between brains of bilingual and internationally adopted children.
The left hemisphere is on the left side, bilinguals (RED), international adoptees
(BLUE), and monolinguals (GREEN). Bilingual children, showed brain activation
in areas known to be involved in working memory and cognitive control.
Lara J. Pierce, Jen-Kai Chen, Audrey Delcenserie,
Fred Genesee & Denise Klein