Task-free functional connectivity changes before and after hyper- and hypoglycemia in very preterm neonates.

Significance: Very preterm infants are prone to large fluctuations in their blood glucose concentration (BGC), i.e., they can experience episodes of hyper- and hypoglycemia, due to impaired glucose control. To date, the relationship among how specific regions of the brain respond to glycemic events has not been fully explored, and characterizing how glucose fluctuations affect region-specific functional connectivity at birth may provide insight into neurodevelopment and could help identify early biomarkers of brain vulnerability in very preterm infants. Aim: The aim is to evaluate whether the differences in task-free functional connectivity (tfFC) patterns before and after experiencing several days of BGC fluctuations were correlated with changes in the glucose profile during this time interval. Approach: We continuously monitored both glucose concentration with a continuous glucose monitoring device and brain hemodynamics with diffuse optical tomography in a group of very preterm newborns to conduct tfFC analysis ( Results: Changes in tfFC patterns between the left frontal and left parietal regions were found to be correlated with the standard deviation of the glucose profile, whereas changes between the central prefrontal cortex and the right prefrontal region were found to be correlated with the maximum value of glucose concentration. Conclusions: We suggest that changes in the coupling of these brain areas during rest are dependent on and occur during exposures to glycemic changes in the preterm brain.