Infants born premature have reduced brain connectivity in regions linked to cognitive functioning, researchers from King’s College London found. They are also at higher risk of cerebral palsy, autism, ADHD, and other developmental conditions.
Preterm birth is the leading cause of neurological disability among children in the U.S., however there previously was little information available on why preterm babies have a higher risk of developing these neurodevelopmental problems.
Using fMRI, researchers sought to investigate the connectivity between the thalamus and cortex — which develops rapidly while preemies are in the care of neonatal units — of 66 infants, 47 of whom were born prior to 33 weeks (preterm) and 19 born between 37 and 42 weeks (full term).
Infants born at full term showed very similar brain structure to adults in the thalamus and cortex regions, confirming prior evidence that brain connectivity is fairly mature at time of birth. Conversely, infants born preterm had less connectivity between areas of the thalamus and regions of the cortex associated with cognitive functions. However, these preterm infants also showed greater connectivity between the thalamus and an area of the primary sensory cortex involved in processing signals from the face, lips, jaw, tongue, and throat.
“Notably, more extreme prematurity was associated with increased functional connectivity between thalamus and lateral primary sensory cortex but reduced connectivity between thalamus and cortex in the prefrontal, insular and anterior cingulate regions,” the authors wrote in the study, published in the Proceedings of the National Academy of Sciences. “This work suggests that, in early infancy, functional integration through thalamocortical connections depends on significant functional overlap in the topographic organization of the thalamus and that the experience of premature extrauterine life modulates network development, altering the maturation of networks thought to support salience, executive, integrative, and cognitive functions.”
The researchers suggested that the greater connectivity identified between the thalamus and primary sensory cortex is a result of the infants’ exposure to breast and bottlefeeding, while the lack of connectivity in other regions is attributable to a child’s developmental difficulties observed as they go through childhood.
“The next stage of our work will be to understand how these findings relate to the learning, concentration and social difficulties which many of these children experience as they grow older,” said study author Hilary Toulmin, MD, of the Centre for the Developing Brain at King’s College London.