Resilience in Brain Networks After Stroke

Abstract

How do brain networks anticipate, endure, respond, and adapt to limit the consequences of a stroke? Recent studies suggest that understanding the whole process of resilience of brain networks may create new opportunities in the management of patients. The first step of resilience relates to the architecture of brain networks even before the stroke has occurred. In healthy subjects, brain networks seem to be organized to limit the impact of a lesion. Indeed, the anatomic location and the position of strategic nodes prevent major desorganization of brain architecture when these hubs suffer from a targeted attack. The second step in the process of resilience reflects how the brain endures the impact of stroke. Widespread changes in the organization of brain networks are triggered by the lesion. This effect can be understood as “connectional” diaschisis or “connectomal” diaschisis, defined, respectively, as the changes in coupling between two nodes of a specific network or in the whole brain connections. Clinically, the reduction in interhemispheric coupling after stroke seems to be particularly relevant. Further steps in the process of resilience include response and adaptation to the initial lesion. Recent evidence points to the importance of changes in network configuration during recovery. However, recent studies show that network changes during recovery not only aim at restoring brain architecture that prevailed before stroke but also at developing network configuration that limits the impact of further attacks. Based on the concept of resilience, further studies are needed to determine how therapeutic strategies (transcranial magnetic stimulation, transcranial direct current stimulation) based on brain connectivity could help restore function but also promote a brain architecture that would limit the consequences of further attacks.