Study Of EEG Based Default Mode Network In Temporal Lobe Epilepsy Rat Model

Epilepsy is a dangerous neurological disease causing serious harm to human health, with more than 30% of patients still continuing to seizures after surgery, and the reason remains unclear. Neuroimaging evidence suggests that epilepsy is a result of pathological changes of brain network, rather than caused by any single brain area. Accordingly, the identification of the brain network characteristics of patients with epilepsy, can provide prediction of seizure and indentification of core brain area during seizure.Recent studies based on fMRI found that the brains of rodents and non- human primates possess default mode network. But the behaviour of DMN topology during seizure is not yet been fully study. Therefore, this research study the dynamic changes of DMN during seizure with the animal model of temporal lobe epilepsy via multichannel intracranial electrophysiological recording.The research shows that:1. The default mode network of normal rats was divided into two network modules, consistent with the results found in MRI.2. The brain network clustering coefficient and the shortest path length were changed significantly during seizure. All frequency band’s network parameters were increased during grand mal seizures, and decreace in the end of seizure. In the delta band, brain network efficiency reach it’s peak at the time of seizure onset, while alpha and beta band network efficiency reach their peaks at the time of grand mal seizures.3. The small-world network of DMN had changed significantly during seizure. The brain networks shift to a random network during the seizure onset and seizure propagation, and then shift to regular network during the end of seizure.4. The brain network topology is also changed significantly during seizure. Presenting a characteristic change of hypoconnectivity between the two system of DMN. Different frequency band shows different change in the network topology during seizure. The theta band shows increasing connectivity before seizure, the delta band shows increasing connectivity during seizure onset and the alpha, beta band increaseconnectivity during grand mal seizures.Our result shows that the brain network properties, small-world property and brain network topology are all changed significantly during seizure. During stages of seizure onset and propagation, the network properties’ efficiency enhanced and the brain network increase connectivity between two system of DMN. In addition, different components of EEG frequency bands may play different role during seizure. The theta and delta bands may play a role during seizure onset, since these two bands shows significant increased network efficiency and connetivity before grand mal seizure. While the alpha and beta bands may play a role during grand mal seizure.