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Increased resting functional connectivity in spike‐wave epilepsy in WAG / R ij rats
Author(s) -
Mishra Asht M.,
Bai Xiaoxiao,
Motelow Joshua E.,
DeSalvo Matthew N.,
Danielson Nathan,
Sanganahalli Basavaraju G.,
Hyder Fahmeed,
Blumenfeld Hal
Publication year - 2013
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.12227
Subject(s) - neuroscience , epilepsy , functional connectivity , resting state fmri , somatosensory system , psychology , electroencephalography , neuroplasticity , medicine
Summary Purpose Functional magnetic resonance imaging (f MRI )–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 f MRI 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. Methods We used f MRI ‐based resting functional connectivity for studying brain networks involved in absence epilepsy. W istar A lbino G laxo rats from R ijswijk ( WAG / R ij) 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 / R ij rats in comparison to nonepileptic W istar controls were acquired at 9.4 T . Regions showing cortical f MRI increases during SWD s were used to define reference regions for connectivity analysis to investigate whether chronic seizure activity is associated with changes in network resting functional connectivity. Key Findings We observed high degrees of cortical–cortical correlations in all WAG / R ij rats at rest (when no SWD s 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 / R ij rats compared to nonepileptic controls. Significance 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.