  Severe traumatic brain injury can lead to disorders of consciousness (DOC)
characterized by deficit in conscious awareness and cognitive impairment
including coma, vegetative state, minimally consciousness, and lock-in
syndrome. Of crucial importance is to find objective markers that can account
for the large-scale disturbances of brain function to help the diagnosis and
prognosis of DOC patients and eventually the prediction of the coma outcome.
Following recent studies suggesting that the functional organization of brain
networks can be altered in comatose patients, this work analyzes brain
functional connectivity (FC) networks obtained from resting-state functional
magnetic resonance imaging (rs-fMRI). Two approaches are used to estimate the
FC: the Partial Correlation (PC) and the Transfer Entropy (TE). Both the PC and
the TE show significant statistical differences between the group of patients
and control subjects; in brief, the inter-hemispheric PC and the
intra-hemispheric TE account for such differences. Overall, these results
suggest two possible rs-fMRI markers useful to design new strategies for the
management and neuropsychological rehabilitation of DOC patients.
