Christophe Grova McGill, Associate Professor
Physics Dpt and PERFORM Centre, Concordia University, Montreal, Canada
Adjunct Prof in Biomedical Eng., and Neurology and Neurosurgery Dpt, McGill University
Montreal Neurological Institute - Epilepsy group | ''The importance of connector hubs reorganizations in focal epilepsy: a multimodal investigation using MEG and fMRI''
Thursday 25 April. 2019 – 14:00, INS Seminar Room, Campus Timone, Red Wing, 5th Floor.
Abstract : Within brain networks, connector hubs are brain regions participating in inter-network connectivity promoting long-range communications. Hubs are often identified using the hubness metrics in graph theory, such as degree centrality, counting the number of all pairwise significant correlations between voxels up to several thousands. To address the inherent problem of multicollinearity, we developed a “SParsity-based Analysis of Reliable K-hubness (SPARK)” (Lee et al Neuroimage 2016) to study connector hubs using resting state functional MRI (fMRI). SPARK proposes a new measure of hubness by counting a sparse number (k) of networks involved in each voxel (k-hubness), featuring the unique ability to identify which networks are actually involved in each hub. We applied SPARK to investigate the reorganization of connector hubs in Temporal Lobe Epilepsy patients, showing specific patterns of hubs disruption and hubs emergence in left versus right TLE patients (Lee et al Neuroimage Clinical 2018). In the second part of the presentation, we will investigate ongoing resting state fluctuations in Magneto-EncephaloGraphy (MEG). Localizing slow amplitude fluctuations within the alpha band using Maximum Entropy on the Mean, our results are suggesting that network properties characterizing long range connections with the presumed focus, even in absence of any detectable epileptic discharges, could predict the seizure outcome. Finally, we will present a mutimodal study assessing the concordance between connector hubs using fMRI and resting state MEG patterns in focal epilepsy.
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