Enhancing functional recovery after stroke: Identifying neuro-stimulation targets

Neuro-stimulation has been used in treatment of several brain diseases from the replacement of affected circuits to the re-training of remaining circuits using invasive and non-invasive stimulations. Neuro-stimulation can benefit from brain network information to enhance functional recovery after stroke. Connectome-guided approaches have been used recently and demonstrated post-stroke connectivity changes and possible interventions.

The process where remaining brain regions can partially or fully take over functions of the lesioned brain areas is known as vicariation of function. A challenge is to find the regions that would facilitate functional compensation and whose reorganization after a stroke could be facilitated by brain stimulation. These regions might be some of the adjacent regions to the affected tissue but often it could be remote cortical regions within the same hemisphere or regions in the opposite hemisphere. Therefore, we need a more optimised search scheme to find better candidate regions for stimulation that would also assess distant areas which are involved over cortical fibre tracts or through subcortical reorganization.

Here, we present a proof of concept study to find candidate brain regions or circuits for neuro-stimulation to restore the lost function after stroke. Possible candidates for functional recovery can be areas with similar incoming and outgoing connections. We evaluate how similar the connectivity of a potential target region is to the connectivity of the lesioned area by stroke. First, we use the matching index (or Jaccard coefficient) and non-metric multi-dimensional scaling (NMDS) to measure similarity of the connectivity between regions. Second, we look at the similarity of indirect neighbours. Third, we consider how close a candidate region is to the lesioned area in the hierarchical structure of the network. We hypothesize that the connectivity of the region involved in functional recovery will be similar to the stroke-affected area. We test our hypothesis using data from an animal study in which we could identify the location of the region that showed evidence of functionally compensation. We show that our approach to find optimal target regions for neuro-stimulation using connectome information could be used to enhance the recovery of stroke patients.