Resting state connectivity (RSC) measures synchronous hemodynamic signals between cerebral areas that are spatially distinct in the absence of any cognitive tasks. RSC is a useful measure to explore the brain's functional organization by assessing correlations across functionally related brain regions. These correlations have been chiefly measured with functional magnetic resonance imaging (fMRI) uncovering the functional architecture of the human adult brain. Functional near-infrared spectroscopy (fNIRS) can better be employed to measure RSC in young populations, owing to its higher temporal resolution than fMRI, and its portability allowing use in multiple settings. The present study used fNIRS to examine the functional cerebral network of developing brains and elucidate differences depending on postnatal age (PNA) and gestational age (GA) in infants. We obtained RSC data from 80 infants. They were further grouped according to GA into very preterm group (N = 20, GA under 30 weeks, mean PNA = 77 days), preterm group (N = 33, GA = 30-36 weeks, mean PNA = 22 days) and term group (N = 27, mean PNA = 4.4 days). Using 46 channels, we measured changes in hemoglobin concentration in the frontal and temporal areas during sleep. The results revealed stronger RSC in the preterm group than in the term and very preterm group. Short range connectivity was generally stronger than long range connectivity. Analysis of variance with factors of group and connectivity type supported these results by showing main effects for both factors without any interaction. Then, PNA, gestational weight and post menstrual age were correlated with the connectivity data and PNA was found to be the most critical factor that explains connectivity amplitude. However, how PNA impacts on the brain network was different depending on the group. Namely, long range connectivity develops rapidly as a function of PNA in the term and preterm groups in contrast to the very preterm group who exhibited rather slow development. These results suggest that GA before 30 weeks may change the developmental trajectory of the cerebral functional organization.

研究助成：Research funds : KAKENHI JP15H01691