Abstract
BackgroundAlthough focal epilepsies are increasingly recognized to affect multiple and remote neural systems, the underlying spatiotemporal pattern and the relationships between recurrent spontaneous seizures, global functional connectivity, and structural integrity remain largely unknown.Methodology/Principal FindingsHere we utilized serial resting-state functional MRI, graph-theoretical analysis of complex brain networks and diffusion tensor imaging to characterize the evolution of global network topology, functional connectivity and structural changes in the interictal brain in relation to focal epilepsy in a rat model. Epileptic networks exhibited a more regular functional topology than controls, indicated by a significant increase in shortest path length and clustering coefficient. Interhemispheric functional connectivity in epileptic brains decreased, while intrahemispheric functional connectivity increased. Widespread reductions of fractional anisotropy were found in white matter regions not restricted to the vicinity of the epileptic focus, including the corpus callosum.Conclusions/SignificanceOur longitudinal study on the pathogenesis of network dynamics in epileptic brains reveals that, despite the locality of the epileptogenic area, epileptic brains differ in their global network topology, connectivity and structural integrity from healthy brains.
Highlights
Widespread, bilateral structural and functional abnormalities have been reported in people with epilepsy, even when the epileptic syndrome is localization-related, idiopathic or cryptogenic, and the brain appears normal on conventional magnetic resonance imaging (MRI) [1,2]
Seizures occurred during onset of and recovery of anesthesia, which was confirmed by electroencephalography (EEG) recordings, showing high amplitude rhythmic spiking on EEG at 0% isoflurane anesthesia, not related to motion artifacts (Figure 1, right)
We applied serial rs-fMRI and diffusion tensor imaging (DTI) in a rat model of refractory focal neocortical epilepsy to longitudinally characterize functional connectivity, global network configuration and white matter integrity associated with chronic epilepsy
Summary
Widespread, bilateral structural and functional abnormalities have been reported in people with epilepsy, even when the epileptic syndrome is localization-related, idiopathic or cryptogenic, and the brain appears normal on conventional magnetic resonance imaging (MRI) [1,2] Such tissue damage distant from the epileptogenic zone has been observed in both white [2,3] and gray matter [4,5,6]. These subtle progressive changes in tissue integrity that are mostly undetectable with conventional MRI and extend outside the margins of the primary epileptogenic area [7], are presumed to be the result of recurrent seizure propagation [8] This is thought to play a crucial role in epilepsy as these changes may significantly modify the global structural and functional network topology [9]. Focal epilepsies are increasingly recognized to affect multiple and remote neural systems, the underlying spatiotemporal pattern and the relationships between recurrent spontaneous seizures, global functional connectivity, and structural integrity remain largely unknown
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
