How Exactly Do Infant Brains Wire Themselves For Speech, Anyway?

We seem to have a plethora of posts pertaining to Pure Pedantry's penchant for peroratory punditry. I found a recent press release that I fear will only encourage him.

Using magnetoenephalography, this group tracked how the brains of newborns, 6 month olds, and one year olds work when speaking. They specifically looked at cross-talk between Broca's Area, which is responsible for comprehending speech, areas responsible for audition in general, and other areas responsible for generating it.

The babies were exposed to three kinds of sounds through earphones -- pure tones that do not resemble speech like notes played on a piano, a three-tone harmonic chord that resembles speech and two Finnish syllables, "pa" and "ta." The researchers collected magnetic data only from the left hemisphere of the brain among the newborns because they cannot sit up and the magnetoencephalography cap was too big to securely fit their heads.

At all three ages the infants showed activation in the temporal part of the brain, Broca's area, that is responsible for listening and understanding speech, showing they were able to detect sound changes for all three stimuli. But the pure perception of sound did not activate the areas of the brain responsible for speaking. However, researchers began seeing some activation in Broca's area when the 6-month-old infants heard the syllables or harmonic chords. By the time the infants were one-year old, the speech stimuli activated Broca's area simultaneously with the auditory areas, indicating "cross-talk" between the area of the brain that hears language and the area that produces language, according to Kuhl.

So what we're basically looking at is the time it takes for connections between primary/secondary auditory cortices, Wiernicke's Area, and Broca's Area to establish themselves. That some children may not form these connections until later than one year should come as little surprise, and does not necessarily indicate that there is anything wrong with the child's development. It seems likely that practice has some role in the formation of connections, but there are likely some developmental signals that induce formation of the pathways themselves; if these signals are delayed, then practice won't necessarily help. Which is why parents shouldn't needlessly blame themselves if their kid starts talking late.

But if all you've been doing is locking them in the basement with no lights and doping them with cough syrup, you might want to kick yourself.

More like this

Any ideas for how to help my little one (1 year old) speak - he had multiple strokes at 3 mos old and sign is too hard for him. He understands cause and effect, he knows people and can identify them if I say their name but I havent heard a single consonant. Are there books? or an online resource?

Have him evaluated by a speech-language pathologist. These services are free through your public school.

By Linda Bowers (not verified) on 22 Jun 2007 #permalink