The feeling of leaving your body, seeing a bright light at the end of a tunnel, being in communion with other universes, watching your life flash before your eyes... These are all experiences reported by those who have had near-death experiences (NDEs). Is it Reality?  A hallucination? Researchers at the University of Liège are trying to understand the physiological and psychological processes that could provide an alternative to mystical explanations of these phenomena. In a study recently published in the open access journal PLoS One, the researchers showed that memories of NDEs clearly had the weight of real rather than imagined memories, whether in regards to sensations, emotions, or level of precision and the presence of self-referential details.  They also showed that their phenomenological characteristics (high precision, sensory and self-referential detail, etc.) are not due to constant recall. However, this doesn't necessarily prove the existence of the events that were described (out-of-body experiences, conversations with the deceased, etc.). In fact, physiological mechanisms appear to explain different NDE elements. These mechanisms may possibly "create" a perception that the subject perceives as external and real. In a sense, the individual's brain is lying to him/her, as it does during a hallucination.

Around 10% of people who have survived cardiac arrest report a near-death experience (NDE). But the number of cases may be underestimated. "Some patients may have forgotten this subjective experience, a bit like how we forget our dreams," explains Professor Steven Laureys, Research Director at FNRS and head of the Coma Science Group at the University of Liège Cyclotron Research Centre and Liège University Hospital. Moreover, some people report near-death experiences in the absence of cardiac or respiratory arrest. Their lives were never in danger nor did they ever fall into a coma.  "A very stressful situation may suffice," says Steven Laureys.

Furthermore, one hypothesis suggests that NDE memories may be imagined. Recent research by the Coma Science Group and ULg's Cognitive Psychology Unit published in PLoS One seems to confirm this hypothesis (see below). However, a Gordian knot remains: the cause of NDEs. Proponents of spiritual theories (in which the spirit or the soul - is regarded as immaterial and separate from the body) claim that out-of-body experiences (OBEs) described in about one third of NDEs confirm the validity of their beliefs. But then it was demonstrated that stimulating the right temporoparietal region of the brain could produce OBEs.

(1) Marie Thonnard* & Vanessa Charland-Verville*, Serge Brédart, Hedwige Dehon, Didier Ledoux, Steven Laureys, Audrey Vanhaudenhuyse, Characteristics of Near-Death Experience Memories as Compared to Real and Imagined Event Memories, PLoS One. * Authors contributed equally