Chuck Bednar for redOrbit.com – @BednarChuck
In the ongoing search for scientific explanations for out-of-body experiences that take place when a person is near-death, a team of researchers used an fMRI brain scanner and cameras to create the illusion that a person’s body was located in a different part of a room.
After creating the illusion, they examined brain activity to determine which areas of the brain were involved in forming the perception about where a person’s body was. They found that the conscious experience of body location was linked to the regions responsible for feelings of body ownership and those involved in spatial orientation, according to Discovery News.
Specifically, as the authors explained in a paper published in the journal Current Biology, their multisensory out-of-body illusion resulted in increased activity patterns in the hippocampus and the posterior cingulate, retrosplenial and intraparietal cortices (areas involved in the sense of self-location) as well as a spike in premotor-intraparietal activity (body ownership).
“The functional interplay between these two sets of areas was mediated by the posterior cingulate cortex,” they added. “These results extend our understanding of the role of the posterior parietal and medial temporal cortices in spatial cognition by demonstrating that these areas not only are important for ecological behaviors, such as navigation and perspective taking, but also support the perceptual representation of the bodily self in space.”
Shedding new light on how the brain perceives location
Furthermore, the research team said that their findings suggest that the posterior cingulate cortex plays a key role in integrating the neural representations of self-location and body ownership in a person’s mind. Previous research conducted using animals had revealed that these so-called GPS cells also play a vital role in navigation and memory, according to Discovery News.
Dr. Arvid Guterstam, a neuroscientist at the Karolinska Institutet in Sweden and co-author of the new study, explained to the website that he and his colleagues wanted to learn more about the brain mechanisms that underlie the “basic experience” that is the feeling of owning a body. They recruited participants and had they lay in an MRI scanner wearing a head-mounted display.
That display showed video from a set of cameras located in a different part of the room, and the cameras were positioned to look down on the body of a stranger while an image of the person in the MRI was visible in the background. To create the illusion, they used a rod to simultaneously stimulate the same part of both the volunteer’s body and the stranger’s body.
Cameras captured the entire experience, and the technique produces the illusion that the body of the participant is in a different part of the room than it really is, the researchers told the website. They then analyzed the brain activity in the temporal and parietal lobes of the participant, finding that the hippocampus (where the GPS cells are located) and the posterior cingulate cortex (which is home to the feeling of where the self is located) help create the perception of location.
The study authors believe that their research will ultimately improve our understanding of what happens in the brains of people suffering from conditions like schizophrenia and focal epilepsy, as well as the effects of the anesthetic Ketamine, which illegally used recreationally and can induce feelings of people removed from one’s own body, Guterstam added.
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