title: Identifying neural drivers with functional MRI: an electrophysiological validation.
abstract: Whether functional magnetic resonance imaging (fMRI) allows the identification of neural drivers remains an open question of particular importance to refine physiological and neuropsychological models of the brain, and/or to understand neurophysiopathology. Here, in a rat model of absence epilepsy showing spontaneous spike-and-wave discharges originating from the first somatosensory cortex (S1BF), we performed simultaneous electroencephalographic (EEG) and fMRI measurements, and subsequent intracerebral EEG (iEEG) recordings in regions strongly activated in fMRI (S1BF, thalamus, and striatum). fMRI connectivity was determined from fMRI time series directly and from hidden state variables using a measure of Granger causality and Dynamic Causal Modelling that relates synaptic activity to fMRI. fMRI connectivity was compared to directed functional coupling estimated from iEEG using asymmetry in generalised synchronisation metrics. The neural driver of spike-and-wave discharges was estimated in S1BF from iEEG, and from fMRI only when hemodynamic effects were explicitly removed. Functional connectivity analysis applied directly on fMRI signals failed because hemodynamics varied between regions, rendering temporal precedence irrelevant. This paper provides the first experimental substantiation of the theoretical possibility to improve interregional coupling estimation from hidden neural states of fMRI. As such, it has important implications for future studies on brain connectivity using functional neuroimaging.
authors.affiliation: INSERM, U836, Grenoble Institut des Neurosciences, Grenoble, France. odavid@ujf-grenoble.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: David
authors.forename: Isabelle
authors.initials: I
authors.lastname: Guillemain
authors.forename: Sandrine
authors.initials: S
authors.lastname: Saillet
authors.forename: Sebastien
authors.initials: S
authors.lastname: Reyt
authors.forename: Colin
authors.initials: C
authors.lastname: Deransart
authors.forename: Christoph
authors.initials: C
authors.lastname: Segebarth
authors.forename: Antoine
authors.initials: A
authors.lastname: Depaulis
mesh_terms: D000818:Animals; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology / Q000503:physiopathology; D004195:Disease Models, Animal; D004569:Electroencephalography; D004594:Electrophysiology; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008959:Models, Neurological; D009434:Neural Pathways / Q000502:physiology / Q000503:physiopathology; D051381:Rats; D013003:Somatosensory Cortex / Q000502:physiology / Q000503:physiopathology