The motor and visual networks in preterm infants: An fMRI and DTI study

• Visual and motor functional connectivity are evident at termequivalent age in infants .
• Functional visual and motor connectivity are related to white-matter maturation.
• Corpus callosum maturation level at term possibly predicts outcome at 1 and 2 years.
• Brain development may be affected by the extra-uterine environment and experience.

Knowledge regarding the association between functional connectivity and white-matter (WM) maturation of motor and visual networks in preterm infants at term equivalent age (TEA) and their association with behavioral outcome is currently limited. Thirty-two preterm infants born <34 weeks gestational-age without major brain abnormalities were included in this study, underwent resting-state fMRI at TEA. Thirteen infants also underwent diffusion tensor imaging (DTI). Neurobehavioral assessments were performed at one and two years corrected age using the Griffiths Mental Developmental Scales. Functional connectivity between homolog motor and visual regions were detected, which may reflect that a level of organization in these domains is present already at TEA. DTI parameters of WM tracts at TEA demonstrated spatial-temporal variability, with the splenium of the corpus-callosum (CC) found to be the most mature fiber bundle. Correlations between DTI parameters, functional connectivity and behavioral outcome were detected, yet did not show the same pattern of diffusivity changes in the different networks. Visual functional connectivity was negatively correlated with radial-diffusivity (RD) in the optic radiation, while motor functional connectivity was positively correlated with RD in the splenium. In addition, axial-diffusivity (AD) and RD in the genu and midbody of the CC were positively correlated with neurobehavioral outcome at one and 2 years of age. This study highlights the importance of understanding the spatial-temporal changes occurring during this sensitive period of development and the potential effect of extrauterine exposure on the microstructural changes as measured by DTI; their correlation with functional connectivity; and their long term relationship with neuro-behavioral development.

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