Resting-state brain networks in neonatal hypoxic-ischemic brain damage: a functional near-infrared spectroscopy study

Abstract

Significance: There is an emerging need for convenient and continuous bedside monitoring of full-term newborns with hypoxic-ischemic brain damage (HIBD) to determine whether early intervention is required. Functional near-infrared spectroscopy (fNIRS)-based resting-state brain network analysis, which could provide an effective evaluation method, remains to be extensively studied. Aim: Our study aims to verify the feasibility of fNIRS-based resting-state brain networks for evaluating brain function in infants with HIBD to provide a new and effective means for clinical research in neonatal HIBD. Approach: Thirteen neonates with HIBD were scanned using fNIRS in the resting state. The brain network properties were explored to attempt to extract effective features as recognition indicators. Results: Compared with healthy controls, newborns with HIBD showed decreased brain functional connectivity. Specifically, there were severe losses of long-range functional connectivity of the contralateral parietal-temporal lobe, contralateral parietal-frontal lobe, and contralateral parietal lobe. The node degree showed a widespread decrease in the left frontal middle gyrus, left superior frontal gyrus dorsal, and right central posterior gyrus. However, newborns with HIBD showed a significantly higher local network efficiency (* $p<0.05$ ). Subsequently, network indicators based on small-worldness, local efficiency, modularity, and normalized clustering coefficient were extracted for HIBD identification with the accuracy observed as 79.17%. Conclusions: Our findings indicate that fNIRS-based resting-state brain network analysis could support early HIBD diagnosis.

Keywords: brain network; functional near-infrared spectroscopy; hypoxic-ischemic brain damage; infants; resting state.

Fig. 1

(a) Experimental settings. (b) Schematic illustration of the fNIRS layout (45 channels, 20 sources, and 16 detectors). The green lines represent channels, and the nodes represent optical probes. The arrangement covers the prefrontal, temporal, and parietal lobes.

Fig. 2

Grand-averaged correlation matrix: (a) infants with HIBD and (b) healthy infants. Axes represent the regions. Each channel with its correlation coefficient set at zero (the diagonal line). LPFC, left prefrontal cortex; LTL, left temporal lobe; LPL, left parietal lobe; RPFC, right prefrontal cortex; RTL, right temporal lobe; RPL, right parietal lobe. (c) The inter-group differences in actual channels. The dark blue lines represent connections with significant differences (*$p<0.05$) and the red lines represent connections with extremely significant difference (**$p<0.01$).

Fig. 3

The $p$ values of the inter-group $t$-test of functional connections between all ROIs. The dashed circles represent six ROIs. Red lines indicate significant inter-group differences in the regional connection ($0.01<*p\le 0.05$).

Fig. 4

The functional network metrics in the range of the sparsity thresholds (0.05 to 0.4). (a) The small-worldness, (b) the normalized clustering coefficient, (c) the modularity, (d) the local efficiency, and (e) the global efficiency. Red and blue curves with circles represent the HIBD and healthy control groups, respectively. The curves with an asterisk represent the mean and error bars of the matched random networks.

Fig. 5

The group differences in the global network metrics with the sparsity threshold at 0.3. (a) The small-worldness, (b) the normalized clustering coefficient, (c) the modularity, (d) the normalized local efficiency, and (e) the normalized global efficiency. Asterisk indicates a significant difference (*$p<0.05$).

Fig. 6

The ROC curves of small-worldness, normalized $Cp$, modularity, and normalized local efficiency, plotted in blue, red, green, and black, respectively. The AUC value for the four types of features is 0.74, 0.75, 0.76, and 0.75, correspondingly.

Fig. 7

Grand-averaged central node of the two groups at four thresholds.