Graph theory is increasingly used to study brain networks and find neural correlates of consciousness, especially in patients recovering from severe brain injury. A challenge is that researchers must arbitrarily set a threshold to keep the strongest connections equal across subjects, which risks including false connections, particularly in brain disorders. Resting-state data from 25 coma patients and 22 healthy subjects were compared. A fixed density threshold of 10% was chosen based on healthy subjects' significant connections. Coma patients had fewer significant connections, with about 50% not meeting the threshold. The remaining patients showed preserved connectivity but major whole-brain network reorganization, highlighting the need for careful connectome construction in disorders of consciousness.
Meditation produces a distinct, reversible mental state that reorganizes brain network hubs and connections without altering global network properties like small-worldness. Analyzing resting-state fMRI data from 18 Taoist meditators of varying expertise, the study found that during meditation, sensory cortex areas (primary visual and auditory cortices, temporopolar areas) showed decreased connectivity, while the thalamus and default mode network components (precuneus, posterior cingulate cortex) increased connectivity. Long-distance front-to-back connections increased, while right-left connections between homologous cortices decreased. These changes suggest that shifts in consciousness involve both topological and spatial reorganization of brain networks, with the anatomical pattern of integration being as important as its overall level.