October 24, 2020

Mean-field modeling of brain-scale dynamics for the evaluation of EEG source-space networks

Understanding the dynamics of brain-scale functional networks at rest and during cognitive tasks is the subject of intense research efforts to unveil fundamental principles of brain functions. To estimate these large-scale brain networks, the emergent method called electroencephalography (EEG) source connectivity has generated increasing interest in the network neuroscience community, due to its ability to identify cortical brain networks with good spatio-temporal resolution, while reducing mixing and volume conduction effects. However, the method is still immature and several methodological issues should be carefully accounted for to avoid pitfalls. Therefore, optimizing the EEG source connectivity pipelines is required, which involves the evaluation of several parameters. One key issue to address those evaluation aspects is the availability of a ground truth. In this paper, we show how a recently developed large-scale model of brain-scale activity, named COALIA, can provide to some extent such ground truth by providing realistic simulations (epileptiform activity) of source-level and scalp-level activity. Using a bottom-up approach, the model bridges cortical micro-circuitry and large-scale network dynamics. Here, we provide an example of the potential use of COALIA to analyze the effect of three key factors involved in the EEG source connectivity pipeline: (i) EEG sensors density, (ii) algorithm used to solve the inverse problem, and (iii) functional connectivity measure. Results show that a high electrode density (at least 64 channels) is needed to accurately estimate cortical networks. Regarding the inverse solution/connectivity measure combination, the best performance at high electrode density was obtained using the weighted minimum norm estimate (wMNE) combined with the weighted phase lag index (wPLI). The COALIA model and the simulations used in this paper are freely available and made accessible for the community. We believe that this model-based approach will help researchers to address some current and future cognitive and clinical neuroscience questions, and ultimately transform EEG brain network imaging into a mature technology.

 bioRxiv Subject Collection: Neuroscience

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