The out-of-body experience: It sounds like the stuff of science fiction, but researchers say that by scrambling visual and tactile signals in the brain, they can simulate and study the altered state with volunteers in labs.
British scientists reported yesterday that they used special goggles, connected to video cameras, to make subjects feel as if they were outside their bodies when they were tapped on the chest.
"I think it's a similar experience at least to being out of body. You feel that you are in a different place from where your physical body is," said Dr. Henrik Ehrsson, a neuroscientist who conducted the research at University College London.
Swiss researchers, meanwhile, say their virtual reality device can make volunteers feel like they're outside their bodies when a lab assistant strokes their backs.
Reports of out-of-body experiences have come from those who were hovering near death brought on by injuries, operations or illnesses.
The researchers say their results, published today in Science, don't prove or disprove anything about hints of an afterlife. But their experiments are intended to shed light on what happens in the brain.
"I think we've got some aspects of an out-of-body experience, but not the entire thing," said Dr. Olaf Blanke, a neurologist and researcher at the Ecole Federal Polytechnic of Lausanne. "We can, in a sense, trick people."
Experts not involved in the work say it could help scientists understand how the brain handles conflicting visual and tactile signals - an issue for some patients with neurological disorders such as epilepsy and schizophrenia.
"I think they're fascinating and really very clever investigations," said Dr. Kevin R. Nelson, a professor of neurology at the University of Kentucky College of Medicine, who also studies out of body experiences.
These episodes have been the focus of public and scientific curiosity for decades - reported by survivors of plane crashes, car accidents and others involved in near-death experiences, as well as by epileptics who suffer seizures.
Some experts attribute them to the misfiring of neurons when someone dying or experiencing a seizure has the flow of oxygen to the brain cut off. Others say they could be a kind of survival mechanism.
"When you're faced with a life-threatening situation, there may be a survival value to being able to leave yourself at some point," said Dr. Orrin Devinsky, an epilepsy expert at New York University Medical Center.
Exactly how many people have experienced out-of-body episodes is hard to determine. Descriptions of more than 1,200 experiences have been posted on the Web site www.nderf.org, set up in 1998 by Dr. Jeffrey P. Long, a radiation oncologist in Gallup, N.M.
Long, who has studied the phenomena since the 1980s, says the memories are too vivid and the details too striking to be caused by oxygen deprivation.
"They're absolutely medically inexplicable," he said. "It is a spiritual experience."
Bill Taylor, 65, a retired computer consultant from Clarksville, said he left his body when he went into cardiac arrest in 1979 while suffering from a viral infection that put him in the intensive care unit at Johns Hopkins Hospital.
"I was out there. I was out in space looking back on everything," he said.
Taylor now runs the Web site marylandiands.org and a support group in Columbia that attracts up to 40 people to its monthly meetings.
But many remain skeptical. Visions of white light, tunnels and feelings of warmth are common among those near death because of similarities in the experiences of people whose brains are being deprived of oxygen, said Michael Shermer, the publisher of Skeptic magazine, a journal that examines scientific theories.
"Our brains are structured in the same way, so we're going to experience the same things," he said.
Many clergy remain open minded about whether near-death experiences are spiritual events.
The Rev. Arthur Callaham, a curate at St. James Episcopal Church in Monkton, said it's difficult to say if these experiences are rooted in spirituality or in disrupted brain signals.
"The church is very keen on trying to validate the experiences of people, or at least deal with the experiences that people bring to us," Callaham said.
The most recent studies involved experiments intended to see what happens when conflicting visual and tactile signals are sent to the brain.
The London scientists sat volunteers in chairs and had them peer into goggles connected to video cameras that showed them live film of their backs. Researchers touched the volunteers chests with rods while also touching the chests of the illusory bodies behind them.
The volunteers felt themselves being touched, but also had the strange feeling that it was their body double, in the film, that was being touched. They also felt as though they were sitting behind their bodies and looking at them.
In the Swiss experiment, researchers put goggles on volunteers that gave 3-D views of either their own bodies, the body of a dummy or a simple object in front of them. The volunteers saw the back of the image being stroked with a brush while someone stroked their backs at the same time. After being blindfolded and backed up, they were told to return to their original position.
Volunteers whose backs were stroked simultaneously with the image of themselves or the dummies overshot their original position, moving to where the virtual image had been brushed.
For more information, go to www.marylandiands.org, www.iands.org and www.nderf.org.