Abstract
ObjectiveLate preterm birth confers increased risk of developmental delay, academic difficulties and social deficits. The late third trimester may represent a critical period of development of neural networks including the default mode network (DMN), which is essential to normal cognition. Our objective is to identify functional and structural connectivity differences in the posteromedial cortex related to late preterm birth.MethodsThirty-eight preadolescents (ages 9–13; 19 born in the late preterm period (≥32 weeks gestational age) and 19 at term) without access to advanced neonatal care were recruited from a low socioeconomic status community in Brazil. Participants underwent neurocognitive testing, 3-dimensional T1-weighted imaging, diffusion-weighted imaging and resting state functional MRI (RS-fMRI). Seed-based probabilistic diffusion tractography and RS-fMRI analyses were performed using unilateral seeds within the posterior DMN (posterior cingulate cortex, precuneus) and lateral parietal DMN (superior marginal and angular gyri).ResultsLate preterm children demonstrated increased functional connectivity within the posterior default mode networks and increased anti-correlation with the central-executive network when seeded from the posteromedial cortex (PMC). Key differences were demonstrated between PMC components with increased anti-correlation with the salience network seen only with posterior cingulate cortex seeding but not with precuneus seeding. Probabilistic tractography showed increased streamlines within the right inferior longitudinal fasciculus and inferior fronto-occipital fasciculus within late preterm children while decreased intrahemispheric streamlines were also observed. No significant differences in neurocognitive testing were demonstrated between groups.ConclusionLate preterm preadolescence is associated with altered functional connectivity from the PMC and lateral parietal cortex to known distributed functional cortical networks despite no significant executive neurocognitive differences. Selective increased structural connectivity was observed in the setting of decreased posterior interhemispheric connections. Future work is needed to determine if these findings represent a compensatory adaptation employing alternate neural circuitry or could reflect subtle pathology resulting in emotional processing deficits not seen with neurocognitive testing.
Highlights
IntroductionAdvances in perinatal care over the past few decades have increased the number of surviving preterm neonates
Clinical Importance of Prematurity on Brain DevelopmentAdvances in perinatal care over the past few decades have increased the number of surviving preterm neonates
Late preterm children demonstrated increased functional connectivity within the posterior default mode networks and increased anti-correlation with the central-executive network when seeded from the posteromedial cortex (PMC)
Summary
Advances in perinatal care over the past few decades have increased the number of surviving preterm neonates. The effects of increased risk for medical conditions, learning disabilities, and psychological problems among early preterm infants lasting into adulthood have a visible impact on developed societies [1, 2]. Preterm birth may be associated with serious neurodevelopmental impairments related to deficits in executive function and attention [3,4,5,6]. Prematurity significantly confers greater risk of autism spectrum disorders, and it is possible that these effects may be observed in later preterm births [7]. Developmental delay and increased academic difficulties are more common amongst even healthy children born late preterm with a risk of developmental delay approximately one-third higher than term infants [11, 12]
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