Assessing the impact of brain gliomas on effective connectivity gradients

Spatial macroscale gradients have proved useful for understanding the relationship between specific cortical regions and function, by mapping brain connectivity matrices on a low-dimensional representational hierarchy that encodes increasingly abstract levels of cognition. While this approach is well-established with functional connectivity, it has never been applied to whole-brain effective connectivity, which accounts for the direction of propagating information. In addition, the study of EC has rarely been applied in brain pathology. In this work, we identified the so-called “gradients” of brain organization from effective connectivity matrices. In neuroscience “gradients of brain organization” is referring to the use of the Laplacian matrix to study spatial modularity and transitions of brain network structure. The aim was to assess the impact of glioma with respect to healthy controls on whole-brain effective connectivity gradients by accounting for the signaling directionality of the information flow. The results showed more differences between controls and tumour subjects in left-hemisphere networks, and in incoming links with respect to outgoing ones. These findings suggest that glioma has a different impact depending on the directionality of connections