Epilepsy and functional brain networks

Recent resting-state functional MRI (rs-fMRI) studies have demonstrated that the human brain is composed of several essential large-scale functional brain networks, including the "default-mode network". We analyzed electrocorticogram data from four patients with intractable focal epilepsy and compared the extent of these large-scale functional brain networks with propagation pathways of ictal discharge. We found that large-scale functional brain networks had markedly similar spatial patterns compared with multisite ictal fast activity, suggesting that some epileptic activity propagates along large-scale functional brain networks. Given that decreased functional connectivity in large-scale functional brain networks has been reported in patients with focal epilepsy, ictal propagation may lead to chronic alteration of normal functional networks in the brain.