Information sharing in the brain indexes consciousness in noncommunicative patients.
Neuronal theories of conscious access tentatively relate conscious perception to the integration and global broadcasting of information across distant cortical and thalamic areas. Experiments contrasting visible and invisible stimuli support this view and suggest that global neuronal communication may be detectable using scalp electroencephalography (EEG). However, whether global information sharing across brain areas also provides a specific signature of conscious state in awake but noncommunicating patients remains an active topic of research. We designed a novel measure termed "weighted symbolic mutual information" (wSMI) and applied it to 181 high-density EEG recordings of awake patients recovering from coma and diagnosed in various states of consciousness. The results demonstrate that this measure of information sharing systematically increases with consciousness state, particularly across distant sites. This effect sharply distinguishes patients in vegetative state (VS), minimally conscious state (MCS), and conscious state (CS) and is observed regardless of etiology and delay since insult. The present findings support distributed theories of conscious processing and open up the possibility of an automatic detection of conscious states, which may be particularly important for the diagnosis of awake but noncommunicating patients.
Cognitive Neuroimaging Unit, Institut National de la Santé et de la Recherche Médicale, U992, 91191 Gif/Yvette, France; NeuroSpin Center, Institute of BioImaging Commissariat à l'Energie Atomique, 91191 Gif/Yvette, France; Institut du Cerveau et de la Moelle Épinière Research Center, Institut National de la Santé et de la Recherche Médicale, U975, 75013 Paris, France. Electronic address: jeanremi.king@gmail.com.
Jean-Rémi
JR
King
Jacobo D
JD
Sitt
Frédéric
F
Faugeras
Benjamin
B
Rohaut
Imen
I
El Karoui
Laurent
L
Cohen
Lionel
L
Naccache
Stanislas
S
Dehaene
D000328:Adult; D001921:Brain / Q000502:physiology* / Q000503:physiopathology; D001931:Brain Mapping; D003128:Coma / Q000503:physiopathology; D003243:Consciousness / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000503:physiopathology; D014851:Wakefulness / Q000502:physiology*