Here is another arcticle that covers most of the issues brought up by Azazul, Lonewulf & Enzo. I bolded the part relevant to Enzo question on brain activity.
Tijn Touber
This article appeared in Ode issue: 29
Cardiologist Pim van Lommel did a monumental study of near-death experiences which raises fascinating questions about life after death, DNA, the collective unconscious, and everyone's karma.
When the The Lancet published his study of near-death experiences, Dutch cardiologist Pim van Lommel couldn't have known it would make him into one of the world's most-talked-about scientists. It seems everyone wants to know about the man who managed to get his study of this controversial topic published in one of the leading journals of medical research. Yet it's not really surprising that its publication in 2001 created a stir. Never before had such a systematic study been conducted into the experiences of people who were declared dead and then came back to life. And never before have we seen such a clear illustration of how these people's stories could affect our way of thinking about life and death. Van Lommel, 63, isn't one to seek name and fame. On this lovely summer day in his garden near the Dutch city of Arnhem, he displays more interest in what's going on at Ode magazine than in his own story. That same deep curiosity was at work 35 years ago when Van Lommel, working as a physician's assistant in a hospital, listened intently to a patient talk about her near-death experience. He was immediately fascinated. But it wasn't until years later, as he read the book Return from Tomorrow in which the American doctor George Ritchie describes his own near-death experience in detail, that Van Lommel wondered if there were many other people who had undergone similar experiences. Van Lommel decided from then on to ask all his patients whether they remembered anything that had happened during their cardiac arrests. "The answer was usually no but sometimes why? When I heard the latter, I extended the office visit." Over two years he heard stories from 12 patients and his scientific curiosity was piqued. Those stories were the beginning of a years-long study.
I was looking down at my own body from up above and saw doctors and nurses fighting for my life. I could hear what they were saying. Then I got a warm feeling and I was in a tunnel. At the end of that tunnel was a bright, warm, white, vibrating light. It was beautiful. It gave me a feeling of peace and confidence. I floated towards it. The warm feeling became stronger and stronger. I felt at home, loved, nearly ecstatic. I saw my life flash before me. Suddenly I felt the pain of the accident once again and shot back into my body. I was furious that the doctors had brought me back.
Just about every description of a near-death experience is this beautiful. People feel connected and supported. They grasp how the universe works. They experience unconditional love. They feel free of the pressing concerns of earthly existence. Who wouldn't want such an experience? "It sounds fantastic, doesn't it?" Van Lommel laughs. "But it's not always easy to deal with. When people come back, they often have the feeling they're being imprisoned. And it can take years before they are able or have the courage to integrate the insights they've gained into their everyday life."
Still, a majority of people who have had a near-death experience describe it as magnificent and say it enriched their lives. Van Lommel explains, "The most important thing people are left with is that they are no longer afraid of death. This is because they have experienced that their consciousness lives on, that there is continuity. Their life and their identity don't end when the body dies. They simply have the feeling they're taking off their coat." That may sound like it's coming from someone who's spent a little too much time hanging around New Age bookstores. But from what Van Lommel has seen, near-death experiences are not at all limited to members of the "spiritual" community. They are just as prevalent among people who were extremely skeptical about the topic beforehand.
I became detached from the body and hovered within and around it. It was possible to see the surrounding bedroom and my body even though my eyes were closed. I was suddenly able to think hundreds or thousands of times faster and with greater clarity than is humanly normal or possible. At this point I realized and accepted that I had died. It was time to move on. It was a feeling of total peace completely without fear or pain.
The most remarkable thing, Van Lommel says, is that his patients have such consciousness-expanding experiences while their brains register no activity. But that's impossible, according to the current level of medical knowledge. Because most scientists believe that consciousness occurs in the brain, this creates a mystery: How can people experience consciousness while they are unconscious during a cardiac arrest (a clinical death)?
After all those years of intensive study, Van Lommel still speaks with reverence about the miracle of the near-death experience. "At that moment these people are not only conscious; their consciousness is even more expansive than ever. They can think extremely clearly, have memories going back to their earliest childhood and experience an intense connection with everything and everyone around them. And yet the brain shows no activity at all!"
This has raised a number of large questions for Van Lommel: "What is consciousness and where is it located? What is my identity? Who is doing the observing when I see my body down there on the operating table? What is life? What is death?"
The body I observed laying in bed was mine, but I knew it wasn't time to leave. My time on earth wasn't up yet; there was still a purpose.
In order to convince his colleagues of the validity of these new insights, Van Lommel first had to demonstrate that this expansion of the consciousness occurred, in fact, during the period of brain death. It was not difficult to prove. Patients were often able to describe precisely what had happened during their cardiac arrest. They knew, for example, exactly where the nurse put their dentures or what doctors and family members had said. How would someone whose brain wasn't active know these things?
Nevertheless, some scientists continue to assert that these experiences must happen at a time when there is still some brain function going on. Van Lommel is crystal clear in his response: "When the heart stops beating, blood flow stops within a second. Then, 6.5 seconds later, EEG activity starts to change due to the shortage of oxygen. After 15 seconds there is a straight, flat line and the electrical activity in the cerebral cortex has disappeared completely. We cannot measure the brain stem, but testing on animals has demonstrated that activity has ceased there as well. Moreover, you can prove that the brain stem is no longer functioning because it regulates our basic reflexes, such as the pupil response and swallowing reflex, which no longer respond. So you can easily stick a tube down someone's throat. The respiratory centre also shuts down. If the individual is not reanimated within five to 10 minutes, their brain cells are irreversibly damaged."
