These authors contributed equally to this work.
Full-Length Original Research
Increased resting functional connectivity in spike-wave epilepsy in WAG/Rij rats
Article first published online: 1 JUL 2013
Wiley Periodicals, Inc. © 2013 International League Against Epilepsy
Volume 54, Issue 7, pages 1214–1222, July 2013
How to Cite
Mishra, A. M., Bai, X., Motelow, J. E., DeSalvo, M. N., Danielson, N., Sanganahalli, B. G., Hyder, F. and Blumenfeld, H. (2013), Increased resting functional connectivity in spike-wave epilepsy in WAG/Rij rats. Epilepsia, 54: 1214–1222. doi: 10.1111/epi.12227
- Issue published online: 1 JUL 2013
- Article first published online: 1 JUL 2013
- Manuscript Accepted: 23 APR 2013
- NIH. Grant Number: R01 NS049307
- Epilepsy Foundation Postdoctoral Research and Training Award. Grant Numbers: 123505, P30 NS052519
- Betsy and Jonathan Blattmachr family
- Resting functional connectivity;
- Spike-wave seizure;
- Functional magnetic resonance imaging;
Functional magnetic resonance imaging (fMRI)–based resting functional connectivity is well suited for measuring slow correlated activity throughout brain networks. Epilepsy involves chronic changes in normal brain networks, and recent work demonstrated enhanced resting fMRI connectivity between the hemispheres in childhood absence epilepsy. An animal model of this phenomenon would be valuable for investigating fundamental mechanisms and testing therapeutic interventions.
We used fMRI-based resting functional connectivity for studying brain networks involved in absence epilepsy. Wistar Albino Glaxo rats from Rijswijk (WAG/Rij) exhibit spontaneous episodes of staring and unresponsiveness accompanied by spike-wave discharges (SWDs) resembling human absence seizures in behavior and electroencephalography (EEG). Simultaneous EEG-fMRI data in epileptic WAG/Rij rats in comparison to nonepileptic Wistar controls were acquired at 9.4 T. Regions showing cortical fMRI increases during SWDs were used to define reference regions for connectivity analysis to investigate whether chronic seizure activity is associated with changes in network resting functional connectivity.
We observed high degrees of cortical–cortical correlations in all WAG/Rij rats at rest (when no SWDs were present), but not in nonepileptic controls. Strongest connectivity was seen between regions most intensely involved in seizures, mainly in the bilateral somatosensory and adjacent cortices. Group statistics revealed that resting interhemispheric cortical–cortical correlations were significantly higher in WAG/Rij rats compared to nonepileptic controls.
These findings suggest that activity-dependent plasticity may lead to long-term changes in epileptic networks even at rest. The results show a marked difference between the epileptic and nonepileptic animals in cortical–cortical connectivity, indicating that this may be a useful interictal biomarker associated with the epileptic state.