Children’s brains change in unexpected ways as they develop language, according to a new study conducted by researchers from the University and King’s College in London.
The study was published in the Journal of Neuroscience Oct. 9.
The researchers focused on the development of myelin, the fatty material that forms an insulating sheath around nerves, helping them conduct electrical signals. Because structures that support language ability are usually on the left side of the brain, the researchers expected to find increasingly asymmetrical levels of myelin in children developing language, with more myelin development on the left side, according to the study. They also expected the difference in myelin levels between the left and right sides of the brain to increase with the development of language skills.
The researchers hypothesized that the asymmetry of myelin would increase in children between the ages of 2 and 4, when there is enormous growth in language skills. But contrary to their hypothesis, the researchers found that the asymmetry of myelin in the brain was present as early as the age of 1 and remained steady as children acquired language.
Though there are many studies on myelin asymmetry, “there is a significant gap in the imaging literature with respect to children aged between 1 and 6 years,” the authors wrote in the paper.
Jonathan O’Muircheartaigh, lead author of the study and visiting scientist at the School of Engineering, said this is because “they won’t go to sleep and they’ll cry and they’ll be upset” in the scanner, moving too much for researchers to collect usable data.
To test their hypothesis, the researchers performed cognitive assessments and magnetic resonance imaging scans on 108 infants and children between 1 and 6 years of age. In order to avoid the problems that other researchers encountered when attempting to scan young children, researchers scanned children under 4 years of age while they were asleep and children over 4 while they watched a movie, O’Muircheartaigh said.
The lab in which the study was conducted, the Advanced Baby Imaging Lab, has two family rooms where families sit with their children until they fall asleep and can be scanned, O’Muircheartaigh said.
For the cognitive assessments, researchers administered a battery of tests to measure receptive language, expressive language, gross motor skills, fine motor skills and visual reception, according to the study.
To determine the myelin levels in different parts of the brain, researchers used a technique called “multicomponent relaxometry.” O’Muicheartaigh said, “The signal you get out of MRI all comes from water. And by collecting different variants of images, you’re able to decompose that water into water that’s associated with different tissue pools.”
Sean Deoni, the principal investigator of the study and an assistant professor in the School of Engineering, wrote in an email to The Herald that, “by isolating that signal, we can quantify it, and obtain an indirect measure of myelin content.”
The researchers are now examining how environment may impact language development, as previous animal studies show that “the degree of myelination changes in response to environment and neuronal activity,” the authors wrote in the study. In particular, the researchers will study whether the pattern of their results remains as subjects continue to return for more scanning.
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