Enhancement of synchronizability in chronic migraine patients related to the increase of connectome interhemispheric connectivity

Abstract The structure of the brain can be characterized as a set of interconnected regions, using the concept of connectome . It has been shown that the connectome is altered in patients with migraine, presenting a series of structural connections differences with respect to healthy subjects. Relating these structural alterations to the specific characteristics of migraine is a difficult task. One approach is to study the effects of these alterations on the dynamic processes that can take place in the connectome. An ubiquitous process in brain networks is the synchronization of neuronal populations. It depends not only on the network but also on the properties of the units being synchronized. Fortunately, the contribution of the network structure can be calculated independently, thus defining the network synchronizability . Connectome synchronizability and structural connectivity were assessed using diffusion-weighted magnetic resonance imaging data from 56 female patients with episodic migraine, 60 female patients with chronic migraine (CM) and 39 female healthy controls (HC). We found that whole-brain synchronizability was significantly larger in CM than in HC. The analysis of the synchronizability of subnetworks showed that differences between CM and HC were larger for subnetworks involving regions from different hemispheres. Moreover, the number of interhemispheric streamlines was significantly larger in CM than in HC, whereas no such difference appeared between intrahemispheric streamlines. The largest contributions to these differences come from the interhemispheric connections from three regions: left superior frontal gyrus, right precentral cortex, and right caudate.