Changes of Dynamic Functional Connectivity Associated With Maturity in Late Preterm Infants.

Objective: To investigate the changes of dynamic functional connectivity (DFC) in late preterm infants, and assess whether these changes are associated with the indicators measuring the maturity of neonates. Methods: Resting-state fMRI (rs-fMRI) data of eligible neonates was acquired with a 3.0-T MRI scanner in the Department of Radiology, Daping Hospital, Army Medical University (Chongqing, China). After the selection of functional connectivity networks obtained by independent component analysis (ICA), a sliding-window approach was used to cluster all the windows into different states. Then the differences of temporal properties of DFC between groups were compared, and the association between these temporal properties and the degree of maturity was also explored in each state. Results: Eventually, 34 late preterm and 37 term neonates were included in the final analysis. Based on their data, 5 components were located in 5 networks: default-mode (DMN), dorsal attention (DAN), auditory (AUD), sensorimotor (SMN), and visual (VN). Then four reoccurring state patterns of functional connectivity were identified with the k-means clustering method. The late preterm group dwelled significantly longer in State III (late preterm: 33.57 ± 37.64 s, term: 18.50 ± 11.71 s; P = 0.03), which was characterized by general weaker connectivity between networks. Also, the correlation analysis shows the degree of maturity is negatively correlated to the dwell time and fractional windows in State III. Conclusion: Our findings suggested that compared with term infants, late preterm infants preferred to stay in a state with general weak connectivity between networks, but this preference declined as maturity increased.

Functional thalamocortical connectivity development and alterations in preterm infants during the neonatal period.

The thalamus is one of the most commonly affected brain regions in preterm infants, particularly in infants with white matter lesions (WML). The aim of this paper is to explore the development and alterations of the functional thalamocortical connectivity in preterm infants with and without punctate white matter lesions (PWMLs) during the period before term equivalent age (TEA). In this study, twenty-two normal preterm infants (NP), twenty-two preterm infants with PWMLs and thirty-one full-term control infants (FT) were enrolled. Thalamus parcellation was performed based on partial correlation between the thalamus and seven well-recognized infant networks obtained from independent component analysis (ICA), and thalamocortical connectivity was further reconstructed between the defined thalamus clusters and the whole brain. Thalamo-salience (SA) and thalamo-sensorimotor (SM) connectivity were predominantly identified, while other types of thalamocortical connectivity remained largely limited during the neonatal period. Both preterm groups exhibited prominent development in thalamo-SA and thalamo-SM connectivity during this period. Compared with NP infants, PWML infants demonstrated increased connectivity in the parietal area in thalamo-SA connectivity but no significant differences in thalamo-SM connectivity. Our results reveal that compared with NP infants, PWML infants exhibit slightly altered thalamo-SA connectivity, and this alteration is deduced to be functional compensations for inefficient thalamocortical processing due to PWMLs.

Frequency of Spontaneous BOLD Signal Differences between Moderate and Late Preterm Newborns and Term Newborns.

Little is known about the frequency features of spontaneous neural activity in the brains of moderate and late preterm (MLPT) newborns. We used resting-state functional magnetic resonance imaging (rs-fMRI) and the amplitude of low-frequency fluctuation (ALFF) method to investigate the frequency properties of spontaneous blood oxygen level-dependent (BOLD) signals in 26 MLPT and 35 term newborns. Two frequency bands, slow-4 (0.027-0.073 Hz) and slow-5 (0.01-0.027 Hz), were analyzed. Our results showed widespread differences in ALFF between the two bands; differences occurred mainly in the primary sensory and motor cortices and to a lesser extent in association cortices and subcortical areas. Compared with term newborns, MLPT newborns showed significantly altered neural activity predominantly in the primary sensory and motor cortices and in the posterior cingulate gyrus/precuneus. In addition, a significant interaction between frequency bands and groups was observed in the primary somatosensory cortex. Intriguingly, these primary sensory and motor regions have been proven to be the major cortical hubs during the neonatal period. Our results revealed the frequency of spontaneous BOLD signal differences between MLPT and term newborns, which contribute to the understanding of regional development of spontaneous brain rhythms of MLPT newborns.

Efficacy of surfactant at different gestational ages for infants with respiratory distress syndrome.

Since exogenous surfactant replacement therapy was first used to prevent respiratory distress syndrome (RDS), it has become the main method for treatment of RDS. However, in some infants, death is inevitable despite intensive care and surfactant replacement therapy, especially in near-term and term infants. The main purpose of this study was to compare the therapeutic effect of pulmonary surfactant for infants at different gestational ages and to investigate whether exogenous surfactant replacement therapy is effective for all newborns with RDS. Data on surfactant replacement therapy, including blood gas, oxygenation function parameters and therapy results, were collected from 135 infants who were diagnosed with RDS during three years at a tertiary neonatal intensive care unit. According to gestational age, the subjects were classified into three groups as follows: group 1: gestational age <35 weeks (n=54); group 2: 35 weeks ≤ gestational age <37 weeks (n=35); group 3: gestational age ≥37 weeks (n=46). Six hours after surfactant was given, there were significantly better blood gas results in group 1 and worse results in groups 2 and 3. Similar oxygenation function parameter results were observed in the three groups. In addition, there was a trend toward an increased rate of repeated surfactant administration with increasing gestational age. For near-term and term infants, the efficacy of surfactant therapy was not as good as it was for preterm infants. The causes of RDS in near-term and term infants might be different from those in preterm infants and should be studied further.