Central sulcus is a barrier to causal propagation in epileptic networks.

Abstract

the functional interactions of different brain regions are dependent of their underlying structural connectivity. These interactions are important for normal brain activity as well as in epileptic disorders where spontaneous epileptic discharges are generated. To understand the effects of brain topography on both normal and epileptic functional networks, we evaluated propagation frequency with respect to geodesic distance and the specific role of sulcal patterns in modulating these functional connections. We implemented a multimodal approach combining Electrocorticography (ECoG) and magnetic resonance imaging (MRI) to evaluate the relationships between epileptic and non-epileptic networks as they are related to structural connectivity in the human brain. We analyzed interictal ECoG along with MRI 3D reconstructions from seven epileptic patients and found that interictal full-dataset network propagations travel to both nearby and distant cortical locations, however with longer distance the propagations occurrence attenuates dramatically. We also discovered that the central sulcus acts as a strong barrier allowing only 30% of the propagation to cross central sulcus whereas the rest of the 70% propagations are observed on the same side of the sulcus. Epileptic spike propagations, however, were more highly localized with significantly less distant spread and had further reduction in spread across sulci. This is a novel approach to explore the structural influence of brain topography on the functional network and would help understand the interaction of different brain regions and how these are altered in patients with epilepsy. This approach could assist physician decision making during epilepsy surgery by revealing an appropriate brain network and cortical interactions.