Integrity of Cerebral Cortical Regions Involved in Core Cognitive Networks in Very Preterm Newborns
Open AccessVery preterm (VPT) infants (i.e., born before 32 weeks of gestation) are at increased risk for long-term socio-cognitive impairments. During the ex utero third trimester of VPT infants, critical interconnected neurobiological processes occur (e.g., dendritic arborization, synaptogenesis), thus VPT birth may alter the normal brain circuit formation. To minimize neurodevelopmental deficits, it is crucial to identify early biomarkers of socio-cognitive impairments. In this dissertation, we compared the microstructural and functional integrity of neurocognitive brain regions (i.e., areas known to be altered in neurodevelopmental disorders) between VPT infants at term-equivalent age (TEA) and healthy full-term newborns using multimodal 3T quantitative magnetic resonance imaging (MRI) techniques. First, using diffusion tensor imaging, we demonstrated reduced micro-architectural organization of the dorsolateral and medial prefrontal cortices, and posterior parietal cortex in VPT infants suggesting regional delayed microstructural maturation. Postnatal hydrocortisone treatment was associated with increased microstructural organization in the prefrontal cortex. Next, we evaluated cerebral blood flow (CBF) with arterial spin labeling MRI technique. Relative regional CBF was decreased in the insula and anterior cingulate cortex in VPT infants suggesting alterations in the normal functional maturational trajectory of these cortical areas. Additionally, the presence of brain injury and cardiac vasopressor treatment were related to lower regional perfusion in these two regions. Finally, using resting-state functional MRI and network analysis, global and regional functional connectivity was impaired following preterm birth. Complications related to chronic respiratory problems (e.g., chronic lung disease) were associated with lower global efficiency of brain networks. These results provide insight into the vulnerability of the brain regions involved in cognitive processing following preterm birth. Although correlations with neurobehavioral outcome remain to be established, this dissertation offers possible candidate biomarkers of impaired socio-cognitive functioning. Such biomarkers, previously unavailable, are crucial to implement therapeutic and rehabilitative strategies that will improve long-term outcome in VPT survivors.
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BouyssiKobar_gwu_0075A_14019.pdf | 2018-08-13 | Open Access |
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