During an out-of-body experience, you might first feel weightless, like you’re drifting away from the ground. Then, you might see your body from above, as if detaching from it into a phantom twin.
These startling sensations occur in an estimated 5 percent to 10 percent of the population and in many different cultures. An out-of-body experience can happen when someone goes under anesthesia for surgery, has a near-death experience or wakes up in the night temporarily unable to move or speak, a phenomenon called sleep paralysis.
Now, scientists have pinned down a part of the brain that may be going haywire during out-of-body experiences. The findings, published last month in the journal Neuron, hint at how the brain creates our everyday sense of reality and could point researchers toward new types of anesthesia in the future.
In 2019, an epilepsy patient visited Josef Parvizi, a neuroscientist at Stanford University and senior author of the recent study, and said he sometimes felt like he was floating, reports NPR’s Jon Hamilton. The patient felt “like an observer to conversations” going on in his mind, Parvizi tells the publication. The neuroscientist had a hunch that whichever brain area was undergoing unusual activity in the patient due to his epilepsy could also play a part in this altered state of consciousness.
Since that meeting, Parvizi and his team have tracked down a part of the brain that may be involved in out-of-body experiences. The culprit is a small sliver of tissue, buried deep within the fold running down the top of the brain, called the anterior precuneus.
During the study, stimulating this area with electricity resulted in unusual sensations in eight volunteers with epilepsy. (The patients already had electrodes inserted into their brains to help with monitoring before unrelated brain surgeries.) When scientists sent electric pulses to this chunk of the brain, the volunteers did not have true out-of-body experiences, but they felt like they were floating or falling. They also expressed feeling dizzy, dissociated and less focused.
“All of them reported something weird happening to their sense of physical self,” Parvizi tells Bruce Goldman of Scope, Stanford Medicine’s blog. “In fact, three of them reported a clear sense of depersonalization, similar to taking psychedelics.”
In this way, the anterior precuneus is likely the seat of a person’s physical sense of self, or the idea that experiences are happening to you, not to someone else. Disrupting this network in your brain could shift your point of view, making your place in the world seem unreal, the team found.
This understanding could point doctors toward potential treatments for people with trauma-related mental health problems that cause feelings of dissociation, Sahib Khalsa, a neuroscientist at the Laureate Institute for Brain Research who was not involved in the study, tells Scientific American’s Diana Kwon.
The “sausage-looking piece of brain,” as Parvizi calls it to NPR, might also act as a substitute for anesthetic drugs during medical procedures in the future. Stimulating this region in study participants created slow rhythms of brain activity. These brain waves and the feelings of dissociation resemble those created by the anesthetic drug ketamine, says Patrick Purdon, an anesthesia researcher at Harvard Medical School who was not involved in the new study, to NPR.
Most drugs for general anesthesia travel throughout the whole body and brain and carry some risks, since they slow heart rate and breathing. Purdon tells the publication that by sending electric pulses to this part of the brain, scientists might design new methods for anesthesia with fewer side effects.
“There’s an exciting array of studies that can be conducted based on this work,” Khalsa tells Scientific American.