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Inside a newborn’s brain: what babies know about language

by Margaret Polanyi Dec 22 / 12
When we hold a newborn, our attention is usually drawn to the delicate features, the tiny fingers and toes, the soft burbling.

But there’s much more going on than meets the eye. The latest research shows that from the moment they are born, babies are picking up on language in the most extraordinary ways.

“They are primed for language and have already started learning about their native language at birth,” says Dr. Janet Werker, a CIFAR Fellow and professor of psychology at the University of British Columbia. Dr. Werker studies the factors that help a child acquire language, especially in the first two years of life. She’s widely respected for her dazzling insights into how finely tuned the infant brain is to language.

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But until now, few researchers had ever tested newborns aged zero to three days to see what’s actually going on in their brains as they listen to language. In a fascinating study published online in Frontiers in Psychology in September 2011, Dr. Werker and her collaborators did just that. They wanted to see how speech heard by babies in the womb might shape their brain’s response to language in the first few days of life.

The team looked at the neural response of 20 newborns of English-speaking mothers when the infants were exposed to both English and an unfamiliar language. The researchers measured changes in the oxygen levels of neural blood as they shone an infrared light at the baby’s head while the infant was asleep or at rest in a bassinet. Intriguingly, when newborns listened to familiar and unfamiliar language, there was a clear difference in brain response.

“These results show that even prior to birth, the human brain is tuning to the language environment,” says Dr. Werker. “The fact that brain activity was greatest when babies heard their native language suggests that prenatal experience – in addition to biological programming – seems to have an impact at this early stage of life.”

It’s amazing to think that babies experience language in utero. How does this work? The peripheral auditory system (the outer, middle and inner ear) is developed by 26 weeks gestation. “The mother speaks and the sound goes to the belly and makes the amniotic fluid vibrate and that hits the ear drum,” explains Dr. Werker. The fetus is also exposed to the mother’s speech through bone conduction. The rhythmical properties of language come through most strongly, says Dr. Werker. Meanwhile, the brain is developing and organizing. “It’s more developed at 40 weeks than it is at 26 weeks. Some of this is probably determined by the maturation process, but there is also an opportunity for auditory input to have a role in organizing the area of the brain that processes language.”

Understanding prenatal language experience is not easy, considering the study subjects. “The problem with babies is that they do not listen to instructions,” Dr. Werker says with a laugh. Babies get irritable and distracted. They get hiccups and gas. A lot of wriggling can throw off sensitive equipment. Even so, Dr. Werker’s team is learning new things every day – including about the roots of bilingualism.

Her team has shown that infants just zero to five days old and born to monolingual English mothers prefer only English. By contrast, babies of bilingual English-Tagalog mothers show a preference – by sucking more intensely on their pacifiers – for both English and Tagalog. “Babies who are exposed to two languages even in utero are already responding to both of their native languages within hours of birth,” says Dr. Werker. (Interestingly, without continued exposure to both languages, babies will later lose interest in the less used language.)

“I don’t want the message to be that prenatal listening experience is entirely responsible for driving language acquisition – because I think the brain has to be prepared for the input it’s going to receive – but clearly experience can start having an effect as soon as the information is coming in.”

So should women be reciting Shakespeare to their pregnant bellies to enhance the auditory experience inside the womb? Dr. Werker thinks not. “In most cases, babies are getting enough input naturally.” But she’s intensely interested in learning how much prenatal language experience is enough to shape the neural response to language.

Another question: what happens to language development when pregnant women take certain medications? At the 2012 AAAS meeting, Dr. Werker, with CIFAR’s Dr. Takao Hensch of Harvard University, will present important new findings from a study that examined the effect on prenatal language development when pregnant women took common anti-depressants. Dr. Werker is chairing a AAAS symposium centred on the effects of early experience on lifelong functioning – a key area of inquiry for CIFAR’s Experience-based Brain and Biological Development program, to which Drs. Werker and Hensch belong.

“As a human species, language is one of our most quintessential capabilities. My interest is in understanding the critical periods in language acquisition, the role experience plays in organizing the brain, and the lasting effects.”