Stimulating brain region elicits illusion often attributed to the paranormal.
Activity in one region of the brain could explain out-of-body experiences. Researchers in Switzerland have triggered the phenomenon using electrodes1.
People describe out-of-body experiences as feeling that their consciousness becomes detached from their body, often floating above it. Because these lucid states are popularly linked to the paranormal, "a lot of people are reluctant to talk about them", says neurologist Olaf Blanke of Geneva University Hospital in Switzerland.
Blanke found that electrically stimulating one brain region ? the right angular gyrus ? repeatedly triggers out-of-body experiences. Blanke and his team were using electrodes to excite the brain of a woman being treated for epilepsy.
The right angular gyrus integrates visual information ? the sight of your body ? and information that creates the mind's representation of your body. This is based on balance and feedback from your limbs about their position in space.
"It makes perfect sense," agrees Peter Brugger of University Hospital, Zurich, in Switzerland, who studies the phenomenon. "We have representations of our entire body that can be dissociated from our real body," he says. But this is an isolated case, he points out.
With gentle stimulation, the woman, who could speak during the operation, felt she was falling or growing lighter. As the intensity increased she told them: "I see myself lying in bed, from above."
When asked to look at her raised arm, she thought it was coming to punch her. This observation suggests that 'alien hand syndrome' ? when people feel that a limb is foreign ? or 'phantom' limbs that people can feel after amputations could be related to out-of-body experiences, says Blanke.
Out-of-body experiences are incredibly common, says clinical neurologist John Marshall of the Radcliffe Infirmary in Oxford, UK. Some are part of near-death experiences.
Some believe that the events have religious or spiritual causes, or that a person really leaves their physical body behind. They may, for example, interpret them as evidence that the physical and spiritual body can separate again after death.
The new experiments cannot disprove such ideas, says Marshall: "It doesn't show that people with paranormal beliefs are wrong" - it simply demonstrates one way that the experience can be stimulated. Nevertheless, "I think it would give great comfort to patients" who, he says, frequently question their own sanity.
Thrill-seekers will be hard-pushed to artificially create their own out-of-body experiences, adds Brugger. "You can't stimulate that precisely without opening up the skull," he says.
Blanke, O., Ortigue, S., Landis, T., Seeck, M. Stimulating own-body perceptions. Nature, 419, 269 - 270, (2002).