By Meeri Kim, The Washington Post
Babies start with simple vowel sounds - oohs and aahs. A mere months
later, the cooing turns into babbling - "bababa" - showing off a
newfound grasp of consonants.
A new study has found that a key part of the brain involved in
forming speech is firing away in babies as they listen to voices around
them. This may represent a sort of mental rehearsal leading up to the
true milestone that occurs after only a year of life: baby's first
Any parent knows how fast babies learn how to comprehend and use
language. The skill develops so rapidly and seemingly without much
effort, but how do they do it?
Researchers at the University of Washington are a step closer to
unraveling the mystery of how babies learn how to speak. They had a
group of 7- and 11-month-old infants listen to a series of syllables
while sitting in a brain scanner.
Not only did the auditory areas of their brains light up as expected
but so did a region crucial to forming higher-level speech, called
These findings may suggest that even before babies utter their first
words, they may be mentally exercising the pivotal parts of their brains
Study author and neuroscientist Patricia Kuhl says that her results
reinforce the belief that talking and reading to babies from birth is
beneficial for their language development, along with exaggerated speech
and mouth movements ("Hiii cuuutie! How are youuuuu?").
"Understand that they want to talk with you - serve and volley - so give them a chance to talk back," she said.
Kuhl and her colleagues also threw a non-native language into the mix
to see how babies' perception of speech sounds change as they grow.
They looked at brain activation of the infants, all from
English-only-speaking homes, while listening to a series of Spanish
As expected, a 7-month-old's brain reacted the same way when hearing both English and Spanish.
"That's why I call them citizens of the world," Kuhl said. "Then by
11 to 12 months, they have become more like adults in their
Adults have trouble distinguishing sounds that they didn't grow up
hearing or speaking, which is one reason why learning a new language is
"When you take French class in high school and you can't tell apart
'blanc' and 'blond,' that's because you didn't learn those vowels when
you were a child," psychologist Daniel Swingley, of the University of
Pennsylvania, wrote in an e-mail. "But you can tell 'sheep' from 'ship,'
which your Parisian counterparts have the same problem with," said
Swingley, who was not involved with the study.
The older infants studied were more stimulated by their native
language for the auditory regions of the brain - kind of like perking up
your ears when you hear your name in a noisy crowd. At only 11 months,
the babies developed this kind of activation pattern seen in adults.
"Between 6 and 12 months, infants get better at telling apart the
sounds their language uses, and worse at telling apart the sounds their
language doesn't use," Swingley said.
The increase in language precision that occurs during the first year
of life also means that older babies can't distinguish those foreign
sounds as well anymore. They are now native speakers, to whom non-native
languages now seem a bit odd.
"They lose the ability because they don't get exposed to those
differences, so they unlearn them," said psychologist Richard Aslin, of
the University of Rochester, who was not involved in the study. "The
process of learning is really unlearning."
Using a technique called magnetoencephalography, or MEG, Kuhl and her
colleagues were able to measure tiny magnetic fields generated by the
firing of neurons in each baby's brain. Because the signals are so
faint, the MEG machine uses liquid-helium-cooled superconducting sensors
and requires extensive shielding from any outside magnetic activity,
including the Earth's magnetic field.
"It looks like a hair dryer from Mars," Kuhl said of the multi-million-dollar system.
In a second experiment with MEG, she used Finnish-learning infants
with Mandarin Chinese as the non-native language. Her results were
similar to the -English-Spanish study.
The engagement of Broca's area at such an early age is intriguing to
Aslin, since it has been known to play a role in the motor coordination
of speech in adults.
An individual with damage to Broca's area through stroke or tumor can
still comprehend language but typically talks very slowly and uses
short phrases. It is named after French surgeon Pierre Paul Broca, who
in 1861 described a 51-year-old patient of his who could only utter a
single word: tan. He became known by the name Tan throughout the
hospital, and after he died, an autopsy revealed a lesion on his left
frontal lobe - now known as Broca's area.
But no piece of the brain is an island, and Aslin notes that sensory areas of the brain can be entwined.
For instance, previous studies have shown that what we hear can be influenced by what we are looking at.
"I'm sure there's going to be some subtleties here about how these
motor areas are actually connected with perceptual parts of the brain,"
Kim is a freelance science journalist based in Philadelphia.
Image: Getty Images