Abstract
Introduction
The functional connectome is a complex network of interconnected communicating brain regions. Network development is governed by biological rules to make a trade-off between neural wiring cost and efficiency, resulting in small world topology to balance out efficient global communication and local organization. The last stages of pregnancy are a critical phase in brain development, and emerging evidence supports the notion that functional connectome formation and re-organization already starts as early as the second trimester. We aim to identify which first principles of functional connectome organization are already developed in utero.
Methods
We present new empirical data of functional complex network organization in a large fetal resting-state fMRI dataset. A sample of 105 women were scanned during pregnancy (fetal gestational age between 20 and 40 weeks) at Wayne State University, Detroit, MI. Brain regions were selected as cortical regions of the Freesurfer’s Desikan Killiany atlas constructed (including manual fine-tuning) on a fetal brain template (see Figure 1). Graph analysis and permutation testing were used to analyze weighted network characteristics. For a better interpretation of common functional resting-state networks, overlap with adult resting-state fMRI was examined.
Results
We observed efficient network features such as high clustering (1.20 times higher than in random networks, p < 0.001), average shortest path length (1.14 times higher than random networks, p < 0.001), and a small-world index larger than 1 (1.05 times higher than random networks, p < 0.001), common functional modules and rich club hubs in the group-averaged connectome. We also showed increasing global efficiency advancing with age in the prenatal connectome (r=0.206, p=0.034). In addition, we showed a 61.67% (Mantel test p < 0.001) overlap between the fetal and adult cortical modular organization.
Discussion
We conclude that key features of the functional connectome evolve in the second to third trimester of pregnancy. Within the fetal brain, most cortical regions tend to communicate with other regions within generally known functional modules. Rich club hubs can already be pointed out and have widely distributed communication paths across the cortex, and most likely, they have an important role in fetal information integration in the brain. By combining functional connectivity interpretations with later-life outcomes, the field could possibly stretch towards a fuller understanding of the developing brain.
Original language | English |
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Publication status | Published - 18 Jun 2018 |
Event | 2018 Organization of Human Brain Mapping Annual Meeting - Suntec Singapore, Singapore, Singapore Duration: 17 Jun 2018 → 21 Jun 2018 https://www.humanbrainmapping.org/i4a/pages/index.cfm?pageid=3821 |
Conference
Conference | 2018 Organization of Human Brain Mapping Annual Meeting |
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Abbreviated title | OHBM 2018 |
Country/Territory | Singapore |
City | Singapore |
Period | 17/06/18 → 21/06/18 |
Internet address |
Keywords
- fetal
- functional MRI
- connectome
- connectivity