The researchers recorded mothers reading a chapter of Paddington Beara children’s book that has been translated into many languages. Each mother made a recording for her baby in her native language.
The babies were randomly assigned to the treatment group (who heard their moms’ voice recordings) or the control group (who did not). For babies in the treatment group, the recordings were played during the night in 10-minute periods, for a total of 160 minutes each night. By playing the recordings at night, the researchers prevented the parents from knowing which group their babies were in, ensuring that the parents’ behavior wouldn’t affect the results. The recordings did not appear to interfere with babies’ sleep, the researchers said, noting that fetuses at the same stage of development often sleep while their mothers are awake and talking.
The babies received MRI scans of their brains as part of the usual health checks given before hospital discharge. The scans included imaging of the arcuate fasciculus tracts on both sides of the brain, which contain large bundles of nerve fibers that help process and understand sound. The left arcuate fasciculus is specialized for language processing.
Changes in a key language pathway
On brain scans, the researchers saw a significant difference in the white matter in the left arcuate fasciculus: This language-processing pathway was more mature in babies in the treatment group than those in the control group. The right arcuate fasciculus was less affected by the treatment, which is consistent with known differences in how the two hemispheres of the brain process speech, the scientists said.
“I was surprised by how strong the effect was,” Travis said. “That we can detect differences in brain development this early suggests what we’re doing in the hospital matters. Speech exposure matters for brain development.”
The researchers are planning new studies to test whether the benefits extend to babies with medical complications, and they are exploring in more detail how the voice recordings exert their effects. Scala also leads a team at Packard Children’s that is creating customized plans for patients so that the sounds that preemies hear in the hospital’s NICU are most conducive to promoting brain development.
Encouragement for parents
Parents of preemies often experience stress during their baby’s hospitalization, including feelings of helplessness or frustration that they cannot spend as much time with their babies as they want to.
“We’ll always support parents visiting and talking to their babies in person as much as they can,” Scala said, noting that in-person visits also offer opportunities for parents to hold their babies skin to skin, which confers its own neurodevelopmental benefits.
She also hopes parents will feel encouraged to learn that voice recordings can supplement in-person visits.
“This is a way that — even if they can’t be there as much as they want to — the baby is still hearing them and still knows that they’re there,” she said. “And the parents are still contributing to the baby’s brain development.”
The research was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (grants 5R00-HD84749 and 2R01-HD069150).
