Conversations with my baby

Baby V woke up last Thursday with an amazing new skill: As her dad and I listened, she babbled away in her crib. “baBAbaba BA bababa,” she lilted in a sweet sing-song voice.

In her six months, Baby V has not been shy about using her vocal cords. She shows incredible range in both squealing and crying—the American Idol judges would love (O.K., hate) her long, exuberant runs. But until now, she has filled these pitchy discourses mostly with vowel sounds. This new sound is a bona fide word noise. You could ask Baby V what a sheep says and the girl would be dead on.

This new linguistic skill literally happened overnight. Bedtime on Wednesday night revealed nary a hint of “ba.” Baby V went to sleep as usual, and woke up to a world in which she could make this exciting new noise. At some point during the night, deep inside her snoozing brain, something clicked.

Maybe some long tendrils from growing neurons finally reached their target in the motor cortex, allowing Baby V’s lips to clamp in just the right way to form the “B” sound. Or some insulation finally shored up the bundle of neural fibers that help her recognize the sound in all of those Baa Baa Black Sheeps. Or some synapses in her cortex rearranged, sealing the memory of the “ba” sound into long-term storage.

I don’t know what went on in Baby V’s brain that night, but whatever it was, sleep probably helped it along. Every day, it seems, a new study reports another example of why sleep is so important for learning. So far, most of these studies have been on sleeping adults, but some have studied infants). Babies who napped right after hearing a made-up language were better at learning some of the rules than babies who stayed awake, for instance. And babies can learn even while they snooze, a skill that’s really handy to newborns who spend most of their hours asleep. 

Babies’ brains are the ultimate content aggregators, taking in every little piece of information about the world and trying to organize all of those pieces into something that makes sense. During sleep, when the outside world falls away, Baby V’s brain can turn inward and start to make sense of the jumble of new information.

Already in just a few days, Baby V’s repertoire has grown: yesterday she was hard at work making a weird “thhh” noise, which actually seems pretty tricky judging by her intense concentration and the way she hangs her entire tongue out of the left side of her mouth. “Da” and “ma” are also part of her new verbal rotation.

Now that she’s getting the hang of these single consonant-vowel syllables, Baby V will next start to string these sounds together to form more complicated words, like “BaDAmaDUH.” And these more complex sounds, called variegated babbling, get even closer to full-fledged words — and, oh what a thrill it will be to finally know what’s going on inside that sweet little head.   

So when Baby V cried out “maaaaa maaaaa” while her dad changed her this morning at 5:30, I was delighted to hear that mama was her first word. And then her dad told me that she was still asleep.

Laura Sanders is the neuroscience writer. She holds a Ph.D. in molecular biology from the University of Southern California.

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