Abstracts

Rationale: Mesial temporal lobe epilepsy (mTLE) is the most common form of drug-resistant epilepsy (DRE). The clinical application of non-invasively mapped networks using resting-state functional magnetic resonance imaging (rsfMRI) in humans has been rather limited due to heterogeneity of the patients. We employed a status epilepticus (kainic acid) rodent model of TLE to measure the extent of functional network disruptions using rsfMRI. Methods: The functional and anatomical scans were acquired using a high-field Varian 9.4T scanner. Functional connectivity was determined by temporal correlation of the resting-state Blood Oxygen Level Dependent (BOLD) signals between two brain regions during 1.5% and 2% isoflurane, and analyzed as networks in epileptic (n=8) and control (n=7) rats. Results: Graph theoretical analysis revealed a significant (p < 0.05) increase in functional connectivity between brain areas in epileptic than control rats, and the connected brain areas could be categorized as a limbic network and a default mode network (DMN). The limbic network includes the hippocampus, amygdala, piriform cortex, nucleus accumbens, and mediodorsal thalamus, whereas DMN involves the medial prefrontal cortex, anterior and posterior cingulate cortex, auditory and temporal association cortex, and posterior parietal cortex. Conclusions: These results suggest extensive disruptions in the functional brain networks, which may be the basis of altered cognitive, emotional and psychiatric symptoms in TLE. Funding: This research was financially supported by operating grants from the Natural Sciences and Engineering Research Council (NSERC) of Canada, Canadian Institutes of Health Research (CIHR), and Ontario Brain Institute (EpLink project).