
pmid: 28194612
For the first time in research in humans, we used simultaneous icEEG-fMRI to examine the link between connectivity in haemodynamic signals during the resting-state (rs) and connectivity derived from electrophysiological activity in terms of the inter-modal connectivity correlation (IMCC). We quantified IMCC in nine patients with drug-resistant epilepsy (i) within brain networks in 'healthy' non-involved cortical zones (NIZ) and (ii) within brain networks involved in generating seizures and interictal spikes (IZ1) or solely spikes (IZ2). Functional connectivity (h 2 ) estimates for 10 min of resting-state data were obtained between each pair of electrodes within each clinical zone for both icEEG and fMRI. A sliding window approach allowed us to quantify the variability over time of h 2 (vh 2) as an indicator of connectivity dynamics. We observe significant positive IMCC for h 2 and vh 2, for multiple bands in the NIZ only, with the strongest effect in the lower icEEG frequencies. Similarly, intra-modal h 2 and vh 2 were found to be differently modified as a function of different epileptic processes: compared to NIZ, [Formula: see text] was higher in IZ1, but lower in IZ2, while [Formula: see text] showed the inverse pattern. This corroborates previous observations of inter-modal connectivity discrepancies in pathological cortices, while providing the first direct invasive and simultaneous comparison in humans. We also studied time-resolved FC variability multimodally for the first time, finding that IZ1 shows both elevated internal [Formula: see text] and less rich dynamical variability, suggesting that its chronic role in epileptogenesis may be linked to greater homogeneity in self-sustaining pathological oscillatory states.
focal epilepsy, Adult, Male, 616.8, Electroencephalography/methods, multimodal imaging, dynamic connectivity, Multimodal Imaging, Magnetic Resonance Imaging/methods, Resting-state, Young Adult, resting-state, Seizures, Multimodal imaging, 616, Humans, Seizures/diagnostic imaging/physiopathology, [SPI.SIGNAL] Engineering Sciences [physics]/Signal and Image processing, [SDV.IB] Life Sciences [q-bio]/Bioengineering, Connectivity, Brain Mapping, Epilepsy, Nerve Net/diagnostic imaging/physiopathology, Brain, Focal epilepsy, Electroencephalography, Magnetic Resonance Imaging, Dynamic connectivity, Brain/diagnostic imaging/physiopathology, Epilepsy/diagnostic imaging/physiopathology, connectivity, Female, Nerve Net, ddc: ddc:616.8
focal epilepsy, Adult, Male, 616.8, Electroencephalography/methods, multimodal imaging, dynamic connectivity, Multimodal Imaging, Magnetic Resonance Imaging/methods, Resting-state, Young Adult, resting-state, Seizures, Multimodal imaging, 616, Humans, Seizures/diagnostic imaging/physiopathology, [SPI.SIGNAL] Engineering Sciences [physics]/Signal and Image processing, [SDV.IB] Life Sciences [q-bio]/Bioengineering, Connectivity, Brain Mapping, Epilepsy, Nerve Net/diagnostic imaging/physiopathology, Brain, Focal epilepsy, Electroencephalography, Magnetic Resonance Imaging, Dynamic connectivity, Brain/diagnostic imaging/physiopathology, Epilepsy/diagnostic imaging/physiopathology, connectivity, Female, Nerve Net, ddc: ddc:616.8
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