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Looking for neuronal currents using MRI: an EEG-fMRI investigation of fast MR signal changes time-locked to frequent focal epileptic discharges
|Published in||NeuroImage. 2010, vol. 50, no. 3, p. 1109-1117|
|Abstract||RATIONALE: Reproducible direct measurement of neuronal electrical activity using MRI signal changes due to local magnetic field perturbations would represent a step change in neuroimaging methods. While some previous studies using experiments based on evoked and spontaneous activity provided encouraging results no clear demonstration of neuronal current-related MR changes in the human brain has emerged to date. The availability of simultaneously acquired EEG-fMRI in patients with frequent interictal epileptic discharges (IED), which have significantly greater amplitude than evoked potentials, offers the opportunity to further investigate the phenomenon. METHODS: We re-analysed simultaneously acquired EEG-fMRI data in 6 epilepsy patients with very frequent focal IED and a well-localised generator. A model of MRI signal changes due to fast activity and BOLD signal changes was used to identify fast MR signal changes, potentially directly reflecting neuronal activity. Simultaneously-acquired EEG allowed the comparison of electrical source localisation (ESI), clinical epilepsy localisation and BOLD signal changes with the fast MR signal changes. RESULTS: Clusters of IED-related fast MR signal change were observed in all cases. Spatial correspondence between the IED-related fast MR, BOLD, ESI clusters and irritative zone (IZ) was observed in one slice of a single dataset. The other IED-related fast MR clusters were remote from electro-clinically determined generators of interictal activity. The sign and magnitude of the fast MR signal changes varied across regions and subjects. CONCLUSION: The observed fast MR changes cannot be confidently attributed to the direct effect of neuronal currents due to lack of spatial concordance with generators of interictal activity, IED-related BOLD clusters and ESI estimates.|
|Keywords||Adolescent — Adult — Brain/blood supply/*physiopathology — Child — Electroencephalography/*methods — Epilepsy/*physiopathology — Humans — Magnetic Resonance Imaging/*methods — Male — Models, Neurological — Oxygen/blood — Signal Processing, Computer-Assisted — Synaptic Transmission/*physiology — Time Factors|
|Research group||Organisation et plasticité des réseaux neuronaux cérébraux (148)|
|RODIONOV, Roman et al. Looking for neuronal currents using MRI: an EEG-fMRI investigation of fast MR signal changes time-locked to frequent focal epileptic discharges. In: NeuroImage, 2010, vol. 50, n° 3, p. 1109-1117. https://archive-ouverte.unige.ch/unige:21261|