Near death experiences (NDE) first came
to public light in the 1970's with the publication of Raymond Moody's
book Life After Life. Patching together elements from
different accounts, Moody described an archetypal typical near-death
experience, while noting that most accounts include only some
elements in the described archetype. The archetype NDE included
elements such as a sensation of floating out of the body, feelings of
peace and joy, a life-review that occurs very quickly or in some
altered type of time, a passage through a tunnel, an encounter with a
being of light, and seeing deceased relatives.
A previous study on near-death experiences was published in the British medical journal The Lancet in 2001. The study interviewed 344 patients who had a close encounter with death, generally through cardiac arrest. 62 of those reported some kind of near-death experience. 15 reported an out-of-body experience, 19 reported moving through a tunnel, 18 reported observation of a celestial landscape, 20 reported meeting with deceased persons, and 35 reported positive emotions. More recently the AWARE study found some fascinating similar results, discussed here.
A previous study on near-death experiences was published in the British medical journal The Lancet in 2001. The study interviewed 344 patients who had a close encounter with death, generally through cardiac arrest. 62 of those reported some kind of near-death experience. 15 reported an out-of-body experience, 19 reported moving through a tunnel, 18 reported observation of a celestial landscape, 20 reported meeting with deceased persons, and 35 reported positive emotions. More recently the AWARE study found some fascinating similar results, discussed here.
Some scientists have done experiments
trying to shed light on near-death experiences. Back in 2014 we had
the paper “Surge
of neurophysiological coherence and connectivity in the dying brain,”
which was widely reported on by the press. But this was much ado
about nothing, for this skimpy little study really did nothing at all
to throw any light on near-death experiences.
The
study did not involve human subjects, but merely involved rats. The
scientists killed 9 rats who were connected to EEG machines that
measure brain waves. The results, as show below, were not at all
surprising: the brain waves quickly died out, reaching a very low
level at about 17 seconds, and flat lining entirely by 30 seconds.
Trying
to jazz up these dull-as-dishwater results, the scientists tried various minute
statistical analytics to extract something that would be relevant to
near-death experiences. Their data does not at all justify the title
of their paper. They did not at all discover a “surge of
neurophysiological coherence and connectivity in the dying brain.”
To the contrary, their data shows brain activity very quickly dying
out after the cardiac arrest of the rats they were studying, sharply
declining by 7 seconds after the cardiac arrest, declining to very
little at 17 seconds, and reaching nothing at 30 sec. They did not
detect, on average, any spike in brain waves following cardiac
arrest. An accurate title of their paper would have been Brain
Function Very Quickly Disappears When Rats Die.
I
may also note a few other points. First of all, it makes no sense to
claim that a few seconds of brain activity could somehow correspond
to what is reported in near-death experiences, since such accounts
are elaborate accounts corresponding to at least several minutes of
experience. Secondly, the sample size of the experiment was so small
that no reliable conclusion can be drawn from it, because they only
tested 9 rats. With a sample size that small, one can have little
confidence in any results (just as asking 9 pedestrians whether they
have cancer does not give a reliable indication as to how common
cancer is).
Recently
another study was released which has been touted as being relevant to
near-death experiences. It has been called a follow-up of the
previous study, but followed the same skimpy approach, using only
9 rats. Scientists killed 9 rats, and detected the release of more
than a dozen neurochemicals. This result is trivial. The brain is
releasing neurochemicals every minute.
But
still, a scientist insinuates this ridiculously skimpy rat study tells us something about near-death
experiences in humans:
This is a most dubious speculation, and
this claim of a “high likelihood” is unwarranted. There exists no
proof that a short-term surge in neurotransmitters causes
hallucinations, nor does there exist any evidence that any type of
trauma can cause a visual hallucination within a few seconds, as
would be required for hallucinations to produce near-death
experiences after a cardiac arrest. It is widely believed that the
electrical shock treatment called ECT produces a surge in
neurotransmitters, but such treatment does not produce
hallucinations.
What is the cause of hallucinations? Scientists don't understand this. As a medical doctor states here, "The cause of hallucinations is unknown."
What is the cause of hallucinations? Scientists don't understand this. As a medical doctor states here, "The cause of hallucinations is unknown."
The fact that neurotransmitters may
spike at death does nothing to suggest that such neurotransmitters
are causing hallucinations in conscious organisms. The brain can
continue to release neurotransmitters even after consciousness is
lost. A previous study found that neurotransmitters increase in sheep
which were killed by throat cutting. Evidently a spike in
neurotransmitters can occur in completely unconscious organisms. Would we have any sound basis for concluding that these sheep hallucinated when their throats were cut? No, we wouldn't. And to claim that such sheep had a "high likelihood" of near death experiences would be not merely unwarranted, but ridiculous.
There are two general reasons for
rejecting any hallucination hypothesis to explain near death
experiences, whether or not that hypothesis involves
neurotransmitters. The first reason is the time factor. Near-death
experiences often occur in people who undergo cardiac arrest,
something that should cause a quick loss of consciousness. In such
cases there simply is no time for a substantial hallucination. People
who have heart attacks don't go through a few minutes of raving that
might correspond to hallucinations, and then lose consciousness.
Instead they quickly have a heart attack and lose consciousness very
soon thereafter. The second reason is that
visual hallucinations produce random imagery, but the imagery in near death
experiences is typically not random. It tends to have a few common themes like
the themes mentioned at the top of this post. This common pattern is not what we would expect from hallucinations.
In the same vein of misguided experimentation, some scientists rigged up some elaborate
perceptual trick involving an MRI scanner and cameras to fool people
into thinking their body was located somewhere in the room elsewhere
than it was. They then found that a part of the brain called the
hippocampus lights up during such an experience. This silly study is
being trumpeted as an explanation for the out-of-body experiences
reported as part of near-death experiences (and in other cases also)
– “your hippocampus causes it.” But such a study shows nothing
of the sort, simply because you cannot explain a reported phenomenon
by creating some special experimental situation totally different
from the situation in which the phenomenon was reported. People having near death experiences and out-of-body experiences don't have them in anything like the weird hi-tech setup that was used in this experiment.
I may also point out the whole “this
brain part lights up when x occurs, so that brain part causes x”
line of reasoning is generally bunk, as pointed out in the book
Brainwashed: The Seductive Appeal of Mindless Neuroscience.
My suggestion to scientists who want to
learn more about near-death experiences is to actually work with the
people who have such experiences. Don't waste your time rigging up
goofy camera configurations that don't match actual human
experiences, and don't waste your time killing rats or cutting the throats of lambs.
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