Effects Of Transcranial Direct Current Stimulation On Brain Network Characteristics In Patients With Focal Epilepsy

Epilepsy is a common chronic neurological disorder characterized by recurrent seizures.The mechanism of seizures is still unclear,and the treatment need to be further explored.Transcranial direct current stimulation as a noninvasive neuromodulation has been explored in scientific research and applied in clinical in the treatment of epilepsy.In recent years,more and more people have approved that epilepsy is a network-level disease.Therefore,it is of great significance to study the regulation of brain activity by transcranial direct current stimulation at network level in epileptic patients.Based on the EEG signals of focal epileptic patients before and after receiving transcranial direct current stimulation,we used synchronization likelihood to establish brain network,and explored the modulation of transcranial direct current stimulation on the brain network of focal epileptic patients.The main contents include three parts:First,we investigated the changes of five characteristics of brain network in patients with focal epilepsy before and after active and sham transcranial direct current stimulation,and found that there were significant differences between active and sham groups.After active stimulation,the mean clustering coefficient decreased in ? band and increased in ? band,while the characteristic path length in the ? band decreased and the small-worldness decreased in ? and ? band significantly.At the same time,we found that after active stimulation,the degree of nodes corresponding to stimulation sites in the ? and ? band brain networks increased significantly,and the betweeness centrality of corresponding nodes in ?,? and ? band brain networks increased significantly.The results above indicated that transcranial direct current stimulation can regulate the brain network of patients with focal epilepsy and change the characteristics of the brain network.Secondly,we investigated the changes of brain network in patients with focal epilepsy before and after transcranial direct current stimulation in the effective group and the uneffective group,and found that transcranial direct current stimulation significantly reduced the small-worldness of the patients' ? band brain network,and significantly increased the degree of nodes corresponding to stimulation site in ? and ? brain network.The betweeness centrality of the nodes corresponding to stimulation site in the ?,? and ? band brain networks were significantly increased.These results suggested that transcranial direct current stimulation in effective group regulated the brain network of patients with focal epilepsy effectively,and these regulatory effects are related to its antiepileptic effect.In the last,by comparing the characteristics of the baseline brain network before stimulation between the effective group and the uneffective group,we found that the mean clustering coefficient,the characteristic path length and the small-world of the effective group were significantly higher than those of the uneffective group in the ? and ? bands,which indicated that the brain network of the effective group and the ineffective group were different before stimulation.For patients with high mean clustering coefficient,characteristic path length and small-worldness,transcranial direct current stimulation had a better therapeutic effect.In summary,this study showed that transcranial direct current stimulation can effectively regulate the brain network of patients with focal epilepsy,change the local and global characteristics of these patients' brain network,and have a better antiepileptic effect on patients with high mean clustering coefficient,characteristic path length and small-worldness.