Learning to Talk Begins in Early Infancy

Sept. 7, 2006 — -- Most parents will tell you that even though their infants can't talk, they understand what they hear.

These parents are right, according to a new study by French researchers published in the Proceedings of the National Academy of Sciences.

Researchers used a magnetic resonance imaging machine, or MRI, to look at brain activity while 3-month-old babies listened to a children's story read aloud. An MRI machine allows scientists to see what part of the brain is working the hardest at any given time, providing clues to how the brain works.

By looking at the areas of the babies' brains that "lit up" on the MRI, scientists could track the path of information through the brain.

Surprisingly, the researchers found that even though 3-month-old infants are a long way from learning to talk, their brains respond to the simple story just like an adult brain would respond.

The researchers saw the front of the brain, called the temporal lobe, light up first on the MRI. That means that the infants' temporal lobe was active, just as an adult's would be. The information then quickly moved to new regions of the brain, causing different areas to light up on the MRI.

Surprisingly, the researchers saw a part of the brain called Broca's area light up on the babies' MRIs. Broca's area is a part of the brain that puts sentences together.

This means that an infant's brain is working to fit words into sentences long before babies learn to talk.

"Babies' brains are little sponges, but we didn't realize how much they absorb," said Dr. Ari Brown, a pediatrician and author of the book "Baby 411."

Researchers also discovered that babies could identify a sentence when it is repeated. The second time a baby hears a sentence, its brain response is even stronger than the first time.

Pediatricians caution that these results should not be interpreted to mean that infants understand what is said.

"They can identify the difference between cat and rat," said Brown, "but they don't know what the sounds mean."