Smith, Keith. (2017). Accounting for the Complex Hierarchical Topology of EEG Functional Connectivity in Network Binarisation, 2017 [software]. University of Edinburgh. School of Engineering. Institute for Digital Communications. https://doi.org/10.7488/ds/2109.
Herein are the network adjacency matrices, scripts and MATLAB functions used to provide the results in "Accounting for the complex hierarchical topology of EEG functional connectivity in network binarisation". Research into binary network analysis of brain function faces a methodological challenge in selecting an appropriate threshold to binarise edge weights. For EEG, such binarisation should take into account the complex hierarchical structure found in functional connectivity. We explore the density range suitable for such structure and provide a comparison of state-of-the-art binarisation techniques, the recently proposed Cluster-Span Threshold (CST), minimum spanning trees, efficiency-cost optimisation and union of shortest path graphs, with arbitrary proportional thresholds and weighted networks. We test these techniques on weighted complex hierarchy models by contrasting model realisations with small parametric differences. We also test the robustness of these techniques to random and targeted topological attacks. We reveal that complex hierarchical topology requires a medium-density range binarisation solution, such as the CST which proves near maximal for distinguishing differences when compared with arbitrary proportional thresholding. Simulated results are validated with the analysis of three relevant EEG datasets: eyes open and closed resting states; visual short-term memory tasks; and resting state Alzheimer's disease with a healthy control group. The CST consistently outperforms other state-of-the-art binarisation methods for topological accuracy and robustness in both synthetic and real data. We provide insights into how the complex hierarchical structure of functional networks is best revealed in medium density ranges and how it safeguards against targeted attacks.
The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336, VAT Registration Number GB 592 9507 00, and is acknowledged by the UK authorities as a “Recognised body” which has been granted degree awarding powers.