Babies born prematurely do not use their expectations about the world to shape their brains as babies born at full term do. This finding offers clues to the mystery of why otherwise healthy babies born prematurely face higher risk of developmental delays as they grow, researchers say.
"In six-month-old babies born at-term, the portions of the brain responsible for visual processing respond not just to what the baby sees but also to what the baby expects to see. That's a sign babies are learning from their experiences," said Lauren Emberson, Assistant Professor at Princeton University in New Jersey, US.
But babies born prematurely do not demonstrate that type of brain response to expectations, known as top-down processing — important for neural development.
This inability for learning to shape the brain may possibly be one of the reasons for prematurity, Emberson added.
For the study, appearing in the journal Current Biology, the team tested 100 babies, split between those born at full term and those born prematurely.
The babies were tested at six months of age, based on their conception and were exposed to a pattern that included a sound — like a honk from a clown horn or a rattle — followed by an image of a red cartoon smiley face.
After exposing the infants to the sound-and-image pattern, the researchers began omitting the image sometimes.
In the full-term infants, brain activity was detected in the visual areas of the brain even when the image didn't appear as expected, a sign of this top-down sensory prediction.
However, the brains of premature babies did not express this activity.
"Developmental sciences knows these missed milestones don't happen in the moment. They're happening in the months and years leading up to that," Emberson said.
"By looking much earlier and being able to show that are these differences in how learning is shaping the brain, maybe we can know much sooner which babies are likely to have problems," Emberson noted.