Learning a foreign language—before you’re born!

Can your brain attune itself to a foreign language before you’re even born? A team of neuropsychology researchers at the Université de Montréal has found that it can. The researchers discovered that just a few weeks of prenatal exposure to a new language is enough to rewire the language networks in a baby’s brain.

The foreign language heard in the womb is processed along the same neural pathways as the mother tongue. In contrast, a completely new foreign language is processed differently.

These findings were reported recently in an article published in Communications Biology. Lead authors Andréanne René and Laura Caron-Desrochers are doctoral students with the Université de Montréal’s Department of Psychology, supervised by Anne Gallagher. The study was funded by NSERC.

The team recruited 60 women with uncomplicated pregnancies who were native French speakers to participate in the study. Each was given an MP3 player with a recording of a short tale in 2 languages: French and either German or Hebrew. 

Why these specific languages? “We were looking for languages that were acoustically and phonologically different from French, but could be read by the same person to avoid voice bias,” René explains. “We were fortunate to find a trilingual speaker.”

When the women were in their 35th week of pregnancy, they placed the headphones on their stomachs while in a quiet environment with no music and played the recordings for their babies in both languages (French plus either German or Hebrew). Each baby heard the story an average of 25 times.

Then, around 10 to 78 hours after birth, the researchers played the same story again for the newborns, but this time in all 3 languages: their native French, the foreign language to which they had been exposed in utero, and a completely unfamiliar language. To measure the infants’ brain responses, the researchers used functional near-infrared spectroscopy (fNIRS), a non-invasive technique that records blood oxygenation in the cerebral cortex. 

“A device that looks like a swim cap lined with lights is placed on the baby’s head,” René explains. “Light close to the infrared spectrum passes through the tissue to the cortex, and sensors detect variations in blood oxygenation levels.”

Gallagher says when a region of the brain is activated, there is an increase in blood oxygenation because the brain needs energy. This is accompanied by a decrease in deoxygenated hemoglobin—the form of hemoglobin that has released its oxygen. Tracking it helps researchers see which parts of the brain are most active.

“We are able to measure these responses in the regions of the brain that process language,” she says. “We wanted to see whether modifying a baby’s linguistic environment in the womb can shape the brain’s language networks, so we compared brain activation in newborns when hearing 3 different languages: their mother tongue, a foreign language to which they had been exposed in utero, and another language they had never heard.”

When the babies heard French, their left temporal cortex was activated, as were other language regions, with a clear predominance in the left hemisphere—the same pattern seen in adults. A similar pattern was found when the babies heard the foreign language to which they had been exposed in utero.

But the third, completely unfamiliar foreign language triggered much less brain activity, with no strong predominance in either hemisphere. This indicates that babies just a few hours old process a foreign language heard in the womb differently than a completely unfamiliar one.

“We didn’t know if such brief exposure would have a measurable effect,” said Gallagher. “But we can clearly see that even a few minutes of listening per day for a few weeks is enough to modulate the organization of brain networks.”

These findings confirm the exceptional plasticity of the human brain before birth. “It shows how malleable language networks are,” Gallagher says. “But it also reminds us of their fragility: if a positive environment can have an effect, we can suppose that a negative environment would too.”

It is too early to say whether these prenatal stimuli have long-term impacts. “We are following the children over time,” says René. “Perhaps at 4 or 8 months of age, the effect will have disappeared. Or maybe it will persist.”

This study opens up exciting avenues for research that could improve our understanding of language development and potentially support early intervention.

“We’re not there yet,” Gallagher says. “But it is conceivable that some day, this approach could be used to support vulnerable children or children with developmental disorders.”

For now, 1 thing is clear: long before they utter their first word, babies—snug and warm in the womb—are already beginning to familiarize themselves with language.

This article was adapted and published with permission from the Université de Montréal.

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