Why otherwise healthy
babies born prematurely face higher risk of developmental delays has still remained a mystery.
Babies born prematurely don't use their expectations about the world
to shape their brains as babies born at full term do, important evidence
that this neural process is important to development.
‘Babies born prematurely don't use their expectations about the world to shape their brains as babies born at full term do. This is possibly one of the reasons for developmental delay in infants born early but healthy.’
The study by researchers at Princeton University, the University
of Rochester Medical Center and the University of Rochester,, appears in the journal Current Biology
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, an assistant
professor of psychology at Princeton. But babies born prematurely don't
demonstrate that type of brain response to expectations, known as
"This helps bring together the picture that this type of processing
is important for neural development," Emberson said. "This also gives us
insights into what might be going wrong in the case of prematurity. We
believe this inability for learning to shape the brain is possibly one
of the reasons."
The researchers 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.
The babies 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. The researchers used functional near-infrared
spectroscopy, a technology that measures oxygenation in regions of the
brain using light, to assess the babies' brain activity.
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. The brains of premature babies didn't show this
Emberson said this research sets the stage for continued work to
understand how top-down processing helps babies learn better and how the
lack of top-down processing relates to later developmental delays in
the babies born prematurely. For example, the first sign of a
developmental delay for a child might come when they aren't using any
words at age two.
"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."
Charles Nelson, professor of pediatrics and neuroscience at Harvard
Medical School and professor of education at Harvard University, said
the research highlights the importance of examining such potential links
between early brain development and later learning difficulties.
"This work has important implications for the thousands of infants
born early but healthy, a group that does not typically receive a great
deal of attention," Nelson said.