Continued:
However:
Quote:Not everyone is convinced. Greyson maintains that the protocol for Nelson's survey - recruiting NDE subjects on the internet - could have artificially elevated the frequency of REM intrusion in that group. "Those who report their NDEs on the internet may be more likely to admit to unusual things happening to them," he says.
Greyson also questions the conclusion that more REM intrusion in people who have had an NDE means that the phenomenon causes NDE. "It may be more plausible," he says, "that NDEs played a role in subsequent REM intrusion." It is known, for example, that people with post-traumatic stress disorder subsequently have more frequent REM intrusion - maybe because they sleep less soundly. But "if NDE enhances subsequent REM intrusion," responds Nelson, "then that would tell me that NDE and REM are related." He believes this is a testable hypothesis and encourages other researchers to investigate.
But is it all settled?
Quote:The definitive scientific explanation for NDEs may be a little way off, but if, as Nelson's work suggests, many of us are in line for a talk with the man in white, perhaps we should make use of the time we have left to come up with some really good questions.
I continue to follow the studies and debates with interest, though I do feel there are still too many unexplained areas. When members of IANDS admit that science has established a biological cause, then most of us can rest assured that it's a purely material phenomenon. The NDE has taken on an almost religious-like status for many, and I don't this this is helpful. On the other hand, some skeptics dismiss it all way too simplistically.
Consider this from
Time:
Quote:"There's nothing mysterious about NDEs," says Mark Mahowald, director of the Minnesota Regional Sleep Disorders Center. "Many people want it to be a religious, paranormal or supernatural phenomenon. The fact that NDEs can be explained scientifically detracts from the mystique."
The second camp is as adamant that no theory based purely on the workings of the brain can account for all elements of an NDE, and that we should consider the mind-bending possibility that consciousness can exist independent of a functioning brain, or at least that consciousness is more complex than we suppose. Though NDEs are driven in part by neurochemistry and psychology, says Auckland psychiatrist Karl Jansen, it has "underlying mechanisms in more mysterious realms that cannot currently be described."
http://www.time.com/time/magazine/article/0,9171,1657919-1,00.html Quote:Meanwhile, University of Kentucky neurophysiologist Kevin Nelson theorizes that NDEs are what can happen when a particular sleep state intrudes on the imperiled brain. "I wouldn't say it's definitive," says Nelson. "But it's an intriguing hypothesis that answers a great deal."
Here is one of those "loopholes" inadequately explained which I mentioned:
Quote:So what's so baffling about NDEs? We know that when a person's heart stops, the decline in brain function caused by a cut in blood supply is steep. Simultaneous recording of heart rate and brain output shows that within 11 to 20 secs. of the heart failing, the brain waves go flat. A flat electroencephalogram (EEG) recording doesn't suggest mere impairment. It points to the brain having shut down. Longtime NDE researcher Pim van Lommel, a retired Dutch cardiologist, has likened the brain in this state to a "computer with its power source unplugged and its circuits detached. It couldn't hallucinate. It couldn't do anything at all." Yet it's in this period, between switch-off and resuscitation, that many researchers believe NDEs occur.
But Nelson had another theory:
Quote:Nelson's theory goes some way toward explaining how NDEs can seem to occur when the brain is down. The sleep/wake switch is in the brainstem, which helps control the body's most basic functions and stays active for longer than the higher brain in cardiac arrest. "It's likely that the transition to brain death is, in fact, gradual," says Mahowald, "and NDEs occur during this transition." As for people reporting accurately on events that went on around them while they were apparently unconscious, Nelson says "they may be seemingly out of it but still processing in a very aberrant way."
But:
Quote:Of the thousands of NDEs reported, none has done more to convince some researchers that the phenomenon's explanation must lie outside the square than the case of Pam Reynolds, an American who underwent brain surgery for an aneurysm in 1991. Preparation for Reynolds' operation included taping her eyes shut, blocking her ears and monitoring her EEG to ensure her brain was functioning at only the most basic level. Yet after coming around, Reynolds described not only a full-blown NDE but the bone saw that had been used to cut her skull.
"Aberrant"? More from Nelson:
Quote:Happy to concede that "the brain deals with crisis in ways we don't fully understand," Nelson is keen to test his theory some more. He won't go into details, but it's believed he wants to monitor REM activity in subjects he would expect to have NDE-like symptoms in certain conditions.