Every year, thousands of people fall into a coma leading to a vegetative or a minimally conscious state. The distinction between these different clinical states is fundamental from the medical and ethical viewpoint because it directly impacts on the therapeutic follow up. However, assessing the state of consciousness remains extremely challenging. Recently, several research teams have tried to improve this evaluation by directly analyzing patients’ cerebral activity. Thanks to a novel experiment conducted in collaboration between the Neurospin imagery center (Stanislas Dehaene) and the “Institut du Cerveau et de la Moelle épinière” (Lionel Naccache), Jean-Remi King and Jacobo Sitt designed a novel measure of information sharing in the brain, termed wSMI (weighted Symbolic Mutual Information). The results obtained from 181 high density clinical EEG recordings show that wSMI systematically increases with patients’ state of consciousness. This measure of information sharing sharply distinguishes patients in vegetative, minimally conscious and conscious state. In addition to their important medical implications, these results support the current theories of consciousness that stipulate a major role of long-distant information sharing to consciousness, as described in the global workspace theory developed by Stanislas Dehaene, Jean-Pierre Changeux and Lionel Naccache in the last fifteen years.
Reference publication : King et al., Information sharing in the brain indexes Consciousness in noncommunicative patients
Figure legend: From left to right, the different conscious states of the patients: vegetative, minimally conscious, conscious and healthy. The 32 640 mutual information measures are represented by some archs. Their height is proportional to the distance separating the electrical source pairs and their colour indicates the mutual information amount (blue=minimal,red=maximum) Photo credits : Creative Commons / JR KING