NBS-SNI, an extension of the network-based statistic: Abnormal functional connections between important structural actors

TL;DR

This paper introduces NBS-SNI, a new method that improves the detection of brain connectivity abnormalities by combining structural and functional data in case-control studies.

Contribution

NBS-SNI extends the network-based statistic by incorporating node properties, offering improved statistical resolution in identifying abnormal connectivity.

Findings

NBS-SNI identified hypo- and hyperconnected subnetworks in autism and early psychosis case-control studies.

The method showed a 9 percentage point gain in prediction power over standard NBS.

NBS-SNI demonstrated versatility by incorporating anatomical measures like intrinsic curvature index and gray matter volume.

Abstract

Elucidating the coupling between the structure and the function of the brain and its development across maturation has attracted a lot of interest in the field of network neuroscience in the last 15 years. Mounting evidence supports the hypothesis that the onset of certain brain disorders is linked with the interplay between the structural architecture of the brain and its functional processes, often accompanied with unusual connectivity features. This paper introduces a method called the network-based statistic–simultaneous node investigation (NBS-SNI) that integrates both representations into a single framework, and identifies connectivity abnormalities in case-control studies. With this method, significance is given to the properties of the nodes, as well as to their connections. This approach builds on the well-established network-based statistic (NBS) proposed in 2010. We uncover and identify the regimes in which NBS-SNI offers a gain in statistical resolution to identify a contrast of interest using synthetic data. We also apply our method on two real case-control studies, one consisting of individuals diagnosed with autism and the other consisting of individuals diagnosed with early psychosis. Using NBS-SNI and node properties such as the closeness centrality and local information dimension, we found hypo- and hyperconnected subnetworks and show that our method can offer a 9 percentage points gain in prediction power over the standard NBS.

We propose an extension to the well-known network-based statistic (NBS) dubbed NBS-SNI, where the extension SNI stands for simultaneous node investigation. The goal of this approach is to integrate nodal properties such as centrality measures into the statistical network-based framework of NBS to probe for abnormal connectivity between important nodes in case-control studies. We expose the regimes where NBS-SNI offers greater statistical resolution for identifying a contrast of interest using synthetic data and test the approach with a real autism-healthy dataset that contains both the structural (DTI) and functional (fMRI) brain networks of each individual. We also tested our approach on a second dataset of individuals diagnosed with early psychosis. In the second case, our framework is supplemented by incorporating the anatomically derived measures of intrinsic curvature index and gray matter volume directly as a node property, rather than the structural networks, thereby illustrating the versatility of our approach.

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