Altered brain functional connectivity in vegetative state and minimally conscious state

Abstract

ObjectivesThe pathological mechanism for a disorder of consciousness (DoC) is still not fully understood. Based on traditional behavioral scales, there is a high rate of misdiagnosis for subtypes of DoC. We aimed to explore whether topological characterization may explain the pathological mechanisms of DoC and be effective in diagnosing the subtypes of DoC.MethodsUsing resting-state functional magnetic resonance imaging data, the weighted brain functional networks for normal control subjects and patients with vegetative state (VS) and minimally conscious state (MCS) were constructed. Global and local network characteristics of each group were analyzed. A support vector machine was employed to identify MCS and VS patients.ResultsThe average connection strength was reduced in DoC patients and roughly equivalent in MCS and VS groups. Global efficiency, local efficiency, and clustering coefficients were reduced, and characteristic path length was increased in DoC patients (p < 0.05). For patients of both groups, global network measures were not significantly different (p > 0.05). Nodal efficiency, nodal local efficiency, and nodal clustering coefficient were reduced in frontoparietal brain areas, limbic structures, and occipital and temporal brain areas (p < 0.05). The comparison of nodal centrality suggested that DoC causes reorganization of the network structure on a large scale, especially the thalamus. Lobal network measures emphasized that the differences between the two groups of patients mainly involved frontoparietal brain areas. The accuracy, sensitivity, and specificity of the classifier for identifying MCS and VS patients were 89.83, 78.95, and 95%, respectively.ConclusionThere is an association between altered network structures and clinical symptoms of DoC. With the help of network metrics, it is feasible to differentiate MCS and VS patients.

Re-awakening the brain: Forcing transitions in disorders of consciousness by external in silico perturbation

“…In this context, increased inhibition and decreased excitatory output of the thalamus have been identified as a hallmark in DoC [124,125], with the highest relevance in the thalamofrontal connection [126,127]. Interestingly, a study revealed an increased degree of centrality of the thalamus in DoC patients compared to controls associating it to compensatory mechanisms and a reorganization of network structure [128]. This higher coupling and communication of the thalamus with other brain areas might explain the broadcasting of the local stimulation in the thalamus at the global level dynamics, as revealed in our results.…”