When I was young, I remember first hearing the phrase “out-of-body experience” in reference to the Shirley Maclaine TV series “Out on a Limb.” At the time, I remember thinking of it as a mystical, mysterious state. Now, researchers know these experiences can happen through meditation, sensory deprivation, or when hearing death, but little is still understood about what happens when a person sees themselves and their environment from outside their own body. In a new study, cognitive neuroscientists used a novel virtual reality protocol to study what happens in the brain during these types of experiences.
“Out-of-body experiences are subjective experiences reflecting a complex perceptual distortion of the body image, due to a functional disturbance of the multisensory processing of body and self,” says Charlotte Martial of the University of Liège in Belgium, lead author of the study published in the Journal of Cognitive Neuroscience. Because of the varied contexts in which these experiences can occur, it’s critical to have a baseline understanding of the underlying science, she says.
Using virtual reality to simulate the conditions of an out-of-body experience in the lab, Martial and colleagues measured electrical activity in the brains of their subjects. Their EEG analysis showed a power shift that included a prominent role of delta activity, adding to other work showing this shift during particular conscious states.
I spoke to Martial about these findings, how she got started, and future work in this area.
CNS: How did you become personally interested in this research area?
Martial: To be honest, it was a pure coincidence. Indeed, I wanted to do neuroscience research on consciousness and I had the chance to meet the director of the Coma Science Group who was searching for someone working on the phenomenon of near-death experiences; this is one of the most common conditions in which individuals can experience an out-of-body experience. We obtained a grant which permitted us to set up different experiments on the topic. I’m now more than happy about this coincidence!
CNS: What were you most excited to find? Were any findings surprising?
Martial: We were very excited to observe the neural correlates associated with the subjective impression to leave the body. However, the experience was so tricky that not all participants had a subjective experience that we can compare to out-of-body experience. Indeed, most of the participants reported the feeling of floating in the air and of feeling high up in the virtual room at a strong intensity, but a relatively weak to moderate feeling of being out of their body.
Thanks to the analyses of my colleague Pablo Nùñez, we found that these subjective experiences were associated with a specific EEG signature, which was manifested notably in an increased relative power in the delta and a decreased relative power in the alpha band. These results are interesting, notably because they support a growing body of evidence revealing a prominent role of slow wave activity such as delta during particular conscious states, as for example the psychedelic literature has shown.
CNS: What was it like working with virtual reality?
Martial: We used virtual reality to try to induce a self distortion comparable to out-of-body experience because as researchers, we can’t be there when people experience a spontaneous out-of-body experience. It was very challenging, as it was new to us to work with such a technique. Thankfully, we were very well supported by our colleagues from the University of Barcelona who were experts in virtual reality technology. Just setting up the head-mounted-display on top of the EEG cap was quite complicated, but we were able to succeed.
CNS: What do you most want people to understand about this work and why it’s important?
Martial: Although some improvements can be made in our methodology, this study provides a proof-of-concept for studying the phenomenon of out-of-body experiences in laboratory settings. This is important because this type of subjective experience can be lived by anybody, and may sometimes be confusing, leading to subsequent consequences on a person’s life and the way they see themselves. Better understanding this phenomenon from a scientific perspective is essential.
CNS: What’s next for this line of work? And how best can these findings be applied to future studies?
Marital: I would like to continue in this direction, by using some other methods to induce out-of-body experience or near-death-like experience in laboratory settings, to better understand these fascinating phenomena. I’m actively trying to find financial support to use psilocybin in laboratory settings, because we have shown that this substance can induce a phenomenology very similar to near-death experience.
-Lisa M.P. Munoz
