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Objective: Human consciousness is thought to depend on information integration in the brain. How brain injuries affect the information content carried by signals of brain imaging modalities in patients with consciousness disorders has received little attention. Here we propose a novel approach to quantify changes of regional information content in the brain by assessing the entropy delineated by the principal components of regional voxel-based functional imaging signals in clinical MCS and UWS patients.Method: Resting-state functional imaging was performed in 23 MCS patients, 31 UWS patients, and 20 age-matched healthy individuals. Results: We show that, as the symptoms of DOC deepen from MCS to UWS, regional information content also was significantly reduced in that order in the sensory and memory systems of the brain. In contrast, with few exceptions, regional information content in high-order cognitive systems remained statistically at a level similar to those in healthy individuals in MCS patients and only showed a significant reduction in UWS patients. Conclusions and Significance: These findings provide, in the theoretical context of consciousness, novel evidence for a reduction of regional information content as a potential systems-level mechanism of consciousness disorder in MCS and UWS. Further, the findings reveal, for the first time, differential patterns of the reduction of information content in the sensory and memory compared with cognitive systems in MCS and UWS patients, consistent with the manifestations of clinical symptoms in the two DOC patient populations. |
