BRAIN DEVELOPMENT AND FUNCTIONAL CONNECTIVITY
Human brain development during pregnancy and the perinatal period is characterized by a series of complex and interdependent mechanisms. The resulting macro- and microstructural changes are essential for the establishment of functional brain networks that underpin harmonious neurodevelopment. Recent advances in functional MRI (fMRI) and diffusion MRI (dMRI) have provided unprecedented access to the study of the brain in vivo during this critical period. Functional networks, characterized by coherent neuronal activity between different brain regions, have thus been observed as early as the third trimester of pregnancy. However, it remains to be understood whether the functional connections that are established between gray matter regions during early development are accompanied by maturation and microstructural changes, and whether a temporal link exists between these two characteristics.
WHAT ABOUT STRUCTURAL CONNECTIVITY ?
In this study, researchers investigated for the first time microstructural connectivity (MC) - that is, the microstructural profiles between gray matter brain regions - in order to assess whether this connectivity depends on or explains the development of functional connectivity (FC). The evolution of MC and FC was monitored after birth across a set of cortical and subcortical regions in 45 preterm infants who underwent longitudinal resting-state dMRI and fMRI as part of the developing Human Connectome Project (dHCP). The preterm infants were compared to 45 matched full-term newborns, using both direct comparisons of connection intensities and network-based analyses. The results reveal that prematurity affects the maturation of connectivity in both modalities, with a more pronounced reduction in FC. A significant positive correlation between FC and underlying MC was observed during development, a relationship that decreases with age and varies by type of connection. Despite this progressive maturational decoupling between MC and FC, the analyses suggest that a common network structure may underlie the developmental changes in these connectivities and explain the co-evolution of microstructural and functional systems.
This study provides new insight into the dynamic interaction between anatomical and functional brain development and highlights the potential of microstructural connectivity as a complementary tool to characterize the development of brain networks, as well as alterations caused by perinatal insults such as preterm birth.
Contact : Jessica Dubois (jessica.dubois@cea.fr or jessica.dubois@inserm.fr)
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The connectome is a comprehensive map of the connections within a brain.
Structural connectivity refers to the 'physical' connections between different brain regions (anatomical pathways formed by white matter axon bundles).
Functional connectivity, on the other hand, reflects the synchronization of spontaneous activity between regions. Explored for
the first time in infants, microstructural connectivity provides information about the similarity of microstructural profiles between brain regions.
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developing Human Connectome Project (dHCP), led by King's College London, Imperial College London, and the University of Oxford, aims to create the
first four-dimensional connectome during early infancy. The goal is to map the development of structural and functional brain connectivity from 18 to 42 weeks post-conception, integrating imaging, clinical, behavioral, and genetic data. The project also provides a scalable database and open-source computational tools.