By Tanya Lewis via LiveScience
SAN DIEGO — The human mind effortlessly constructs the feeling of inhabiting a body, and now scientists are figuring out how the brain produces that experience.
Recent studies have shown that the brain incorporates information from multiple senses and the first-person visual perspective to create a sense of body ownership. But it’s still unclear how the brain perceives the body’s location in space.
In the study, which has not yet been published in a scientific journal, participants lay inside an MRI scanner while wearing a head-mounted display that showed a first-person camera view of another person’s body lying in a corner of the scanner room, with their head either parallel to a wall or perpendicular to it. Researchers from the Karolinska Institutet in Sweden repeatedly touched each participant with an object while simultaneously touching the body shown in the camera view. This gave participants the illusion that the body in the camera view belonged to them.
To heighten the illusion, the researchers used . . .
By J. Francis Wolfe via Listverse
There is very good reason for all of humanity to have a healthy curiosity relating to near-death experiences. Death is the one experience we are all guaranteed to ultimately share. The field of science has therefore made numerous attempts to explain the near-death phenomena that so many people have independently described.
10 • The Temporoparietal Junction May Be Responsible For Out-Of-Body Experiences
Among the more common elements of near-death experiences is the distinct feeling of an individual having left their worldly body. Those who have had an “out-of-body” experience often report floating above themselves while being able to see their body and the people surrounding them. There have even been a few reports in which those who have had an out-of-body experience can identify objects and events occurring during times in which they were considered clinically dead, but there have also been studies demonstrating that this all could be due to damage in the temporoparietal junction of the brain.
The temporoparietal junction is responsible for assembling the data collected by the body’s senses and organs to form the perception of an individual’s body. When this part of the brain is damaged, it is possible that this results in the “out-of-body” experience that so many people have reported.
Though the experience may appear to be incredibly vivid and real, scientific studies have been able to reproduce this phenomenon without bringing the subject close to death, simply by electrically stimulating the temporoparietal junction of the brain.
9 • Excess Carbon Dioxide May Create The Tunnel And White Light
Nearly every individual who has had a near-death experience discusses the existence of a bright, white light and a tunnel that seems to lead to the afterlife. The white light seems to take on an otherworldly quality and is often accompanied by an overwhelming sense of peacefulness and welcoming.
A 2010 study of patients who had heart attacks revealed that there may be a correlation between this type of near-death experience and the level of CO2 in the blood. Out of the 52 cardiac patients studied, 11 reported a near-death experience. The levels of CO2 in the blood of those 11 patients were significantly higher than the patients who did not report having a near-death experience.
The feeling among researchers is that the excess CO2 in the bloodstream can have a significant effect on vision, which leads to patients seeing the tunnel and the bright light.
8 • Lack Of Oxygen To The Brain Causes Hallucinations
Many near-death experiences include the presence of long-dead friends and relatives appearing and perhaps even guiding the individual as they pass from the world of the living to the afterlife. Memories from every part of life are recalled in rapid succession, and there is an overwhelming sense of comfort, yet it appears that scientific research has provided an explanation for this phenomenon as well.
While excess CO2 has an effect on vision during a near-death experience, a lack of oxygen to the brain also plays a contributing role. It is well known that oxygen deprivation can lead to hallucinations and may even contribute to the feeling of euphoria that is often reported. While the sample size available to researchers is limited, studies have indicated that individuals who reported a near-death experience during cardiac arrest also had lower levels of oxygen.
Researchers believe that oxygen deprivation could well result in people “seeing their lives flash before their eyes” or being transported to a place where they are surrounded by friends and relatives who have long since passed on. This remains just a theory, however, as the other available research seems to indicate that multiple factors contribute to the near-death experience, which include the aforementioned CO2 levels as well. It makes sense in this regard that near-death experiences are commonly reported by those resuscitated following a heart attack, as a heart attack occurs when blood is blocked from reaching the brain.
Researchers use virtual reality gear to mess with subjects’ perspective
If you think about it, memory is an astounding thing. At will, our brains can dig back through the archives and pull out the sights, sounds, smells, sensations, and emotions from a day long gone. All those memories have one pretty obvious thing in common—everything about an experience is recorded from a first-person perspective. But what happens if your memory is not in first-person.
Some people go through what is commonly referred to as “out-of-body experiences,” where they feel a sense of detachment from their body as if they were somehow floating above it. This and related “dissociative” phenomena can be a part of posttraumatic stress disorder or schizophrenia, for example. The people who have out-of-body experiences often seem to have difficulty recalling these experiences with the usual amount of detail. That could be a clue about how our memories work, but how could you design an experiment to test the possibilities?
Loretxu Bergouignan and Henrik Ehrsson of Sweden’s Karolinska Institute and Umeå University’s Lars Nyberg have an answer. They utilized a setup that simulates the feeling of an out-of-body experience by transporting a subject’s perception of sight and sound across the room. (Science writer Ed Yong has first-hand knowledge of this non-first-person experience.) Subjects wear a virtual-reality-like display connected to stereo cameras and microphones that can be placed elsewhere. Under controlled conditions (holding still, etc.) the illusion can be quite profound.
In order to test the effect this has on memory, the researchers staged situations intended to be memorable. The participants—64 university students—were given some reading materials on several topics and told they would be given an oral exam. After they studied up, they donned the virtual reality gear. The cameras were placed in a few different configurations: either just above and behind the student’s head to match a normal perspective, on the opposite side of the room pointing back at themselves, or a few feet to their right. To reinforce the out-of-body illusion, one person walked up to the cameras and repeatedly extended a rod toward a point below them while another poked the student’s actual chest synchronously.
At this point, a professional actor playing the role of an “eccentric professor” entered the room, sat in a chair facing the student, and began to . . .