A baby cries in the maternity room of the hospital in northern France. A study of crying mice could help explain some of the building blocks of human speech.
Philibert Huguen/AFP via Getty Images.
When baby mice cry, they do it to a beat that is synchronized to the rise and fall of their own breath. It's a pattern that could help explain why human infants cry at birth and how they learn to speak.
A group of cells in the brainstem of mice seem to coordinate the rhythms of breathing and vocalizations.
The ability to produce one or many syllables between each breath is an important building block for speech. The cells could explain why so many languages are spoken at the same time.
Kevin Yackle, the study's senior author and a researcher at the University of California, San Francisco, says that the study suggests that there is a hardwired network of neurons that is fundamental to speech.
Scientists who study human speech have debated how much of our ability is innate and how much is learned. The research adds to the evidence that human speech relies on biological building blocks that are present from birth, says David Poeppel, a professor of psychology and neural science at New York University who was not involved in the study.
There is a big difference between a mouse and a human brain. The human version of this building block may look different.
A rhythm emerges when baby mice cry.
The study came from research on the distress calls a newborn mouse makes when it is separated from its mother.
The ultimate goal is to have the mom find them and take them back to the nest.
The cries had similarities to the production of speech.
There could be multiple cries within a single breath, and they were recurring in a rhythm. Yackle says something. Can we find the origin of the cry rhythm?
The signals that control the muscles that produce the cries were traced by the team. They started looking for places in the brain where there was an overlap between vocalizing and breathing cells.
Yackle says there is only one area in the brain that overlaps. This is what brought us to this cluster of cells.
The team removed the cells from the newborn mice to make sure they found the right cluster. The animals were breathing normally. They stopped making cries that had a rhythm.
In other mice, the team tried to get the cluster of cells to grow. The animals began making loud noises.
A brain circuit that helps explain speech.
Yackle thinks that there is a similar cluster of cells in humans. It would explain why we are able to cry from birth and why our earliest cries are coordinated with breathing.
The presence of cells that act as a sort of metronome for human speech would explain why people say about three to six syllables per second, no matter what language you're speaking.
Some of the linguistic "LEGO blocks" we use to construct words and sentences could be provided by the cells.
He says that their words come out as a string of sound. You have to break it up. The study may show how the part is generated.
If that is the case, fluent speech would still require people to learn how to change their breathing and production of sounds.
He says you can say "bah" after inhaling deeply. That's one breath. You can inhale and go 'bah, bah, bah, bah, bah, bah, bah'.
Speech involves many other brain circuits and networks that are much more complicated. These allow us to do things like access a huge vocabulary and transform ideas into sounds that can be deciphered by another human brain.
