NDEs and Neurology

So, Jerry Coyne over at “Why Evolution is True” linked to an article by Alex Lickerman on the Neurology of Near-Death Experiences.  Coyne likes it, but to me it strikes me as precisely illustrating the problem with neuroscience and psychology in general, and particularly when talking about these sorts of odd experiences.

The article is here:  http://www.happinessinthisworld.com/2011/05/15/the-neurology-of-near-death-experiences/#more-7165

Basically, Lickerman tries to use neurological results to support this theory about what NDEs are.  But you’ll that in the entire article he never actually says that.  What he does is list neurological results that he claims are evidence for NDEs not really being souls leaving the body at all, and slips in a few theories to try to claim that.  The problem is that, right out of the gate, we have an issue of competing theories that he isn’t addressing.

In addressing his article, I’m not going to rely on any sort of “soul” argument.  I am, however, going to put on a dualist cap and consider whether NDEs demonstrate that the mind and the body are not the same object, and whether they demonstrate that minds and bodies can become separate.  As a dualist, this isn’t that hard for me, but I don’t actually contend that mind and body being different objects entails that mind and body can be actually separated.  If I was doing a “soul” argument, I’d have to, but that’s theology to me and my views on philosophy of mind are not always in sync with my views on theology.  As those are separate fields, I think it quite appropriate to wall the two off so that I can consider the issues relatively independently, only integrating later.

Anyway, on to the article.  The first thing that Lickerman comments on is that people claiming to have experiences of NDEs doesn’t mean that they really had such an experience, or that it really is what it looks like:


“But just because millions of people have experienced NDEs doesn’t mean the most commonly believed explanation for them—that souls leave bodies and encounter God or some other evidence for the afterlife—is correct.  After all, people misinterpret their experience all the time (an optical illusion representing the most basic example).  ”


Absolutely.  But, in general, we trust our experiences unless we have good reason not to.  If someone had an experience where it really looks like their mind was out of their body, on what grounds would Lickerman suggest they doubt that experience?  Obviously, in the case of NDEs a claim can be made — and, of course, has been made — that the stresses the body is undergoing at the time would be cause for hallucinatory or at least inaccurate experiences.  Lickerman doesn’t bring that up as his starting point, and so one must wonder if it’s that “soul” thing that’s making Lickerman skeptical.  And if it is, then that’s him using mostly irrelevant beliefs to be skeptical about an experience.  Which is, of course, fair enough, but certainly isn’t scientific.

Ultimately, in general we do and must trust our experiences unless we have good reason to doubt them.  The same thing applies to our memories.  That both are fallible is not cause to judge them fallible in any case simply because you don’t like what they’re telling you, and one of the big issues in any of these discussions is that the people studying it go into the experiments skeptical, designing experiments in many ways simply to prove it wrong, without having a proper understanding of what the experience is and how hard it might be to prove right or wrong.  And we shall see this sort of reasoning in the rest of the article.

The first thing Lickerman talks about is REM intrusion often caused by low blood flow:


“Nelson further observes that when our blood pressure drops low and we faint, the vagus nerve (a large nerve that connects to the heart) tilts consciousness toward REM sleep—but interestingly in some people not all the way.  A number of subjects seem to be susceptible to what he calls “REM intrusion.”

Nelson found in his research that the functioning of the mechanism that flip-flops people between REM sleep and wakefulness tended to be different in people who reported NDEs.  In those people, he found the switch was more likely to “fragment and blend” those two states of consciousness (control of our state of consciousness is found in the brainstem and is tightly regulated), causing such people to simultaneously exhibit features of both.  During REM intrusion people have found themselves paralyzed (“sleep paralysis”), fully awake but experiencing light, out-of-body sensations, and stunningly vivid narratives.  During REM sleep, many of the brain’s pleasure centers are stimulated as well (animals that have had their REM regions injured lose all interest in food and even morphine), which may explain the feelings of peace and unity also reported during NDEs.”


So, he doesn’t actually say how this explains anything about NDEs, in general.  He mentions “out of body sensations”, but these do not have to be actual out of body experiences.  I’m not really sure what he means here, in fact, but let me describe an experience I’ve had that seems to be what he’s after.   When I get sick, quite often I experience states that I’ve considered to be “half-awake dreaming”, where I’m dreaming and yet still have some connection to my actual body.  The first time I really noticed this was one time when I had a cold and was having a hard time sleeping, and so would alternate between stages of watching television and sleeping.  The first time, I had just been watching Babylon 5, and so dreamed that I was flying around on my bed in space.  The second time, I had just been watching Jay Leno, and dreamed about a talk show while still knowing that I was on my bed.  Another time I recall dreaming that I was writing code with my mind at work because I obviously wasn’t in front of a computer typing.

Now, none of these are, in any way, similar to cases of NDEs.  However,  they do seem to be examples of REM intrusion.  And these examples do not map onto any sort of real-life situation at all, and aren’t actually out of body experiences.  So, we need to ask how often REM intrusions are actual out-of-body experiences and how often NDEs aren’t related to an actual experience at all.  In theory, you should get very odd experiences, and perhaps we do, but what has been impressive about NDEs is that they’ve been quite similar in their tunnel experience and such, despite the fact that associating that with death is, in fact, fairly shallow; most people have heard of those experiences but don’t seem to have directly internalized them.  But that internalization is, of course, psychologically studyable.

But there’s another issue here, which is that Lickerman is essentially arguing that because you can get out-of-body experiences another way, then it’s reasonable to believe that the claims of real out-of-body experiences are just this mechanism.  But even he admits that he doesn’t have enough evidence for this yet.  Philosophically, this argument is exceptionally poor because pretty much any possible experience can be generated artificially, but none of that in any way indicates that the experience was not real.  People on LSD have reported hallucinations of spiders, but that does not in any way cast doubt on spider experiences.  Again, it seems that without starting from a position that there really isn’t an experience there to be explained no one should consider this all that great evidence at all.  Sure, it is something that proponents of actual out-of-body experiences need to explain, but it isn’t all that hard to explain it, even as “similar but different mechanisms”.

The next explanation is of the experience of the “long tunnel”:


Neurophysiology can also explain the feeling of moving through a tunnel so commonly mentioned in NDEs.  People are well known to experience “tunnel vision” immediately before fainting.  Experiments with pilots spun around in giant centrifuges have reproduced the tunnel vision phenomena by increasing G-forces and decreasing blood flow to their retinas (the periphery of the retina is more susceptible to drops in blood pressure than its center, so that the visual field appears compressed, making scenes appear as if viewed through a tunnel).  When special goggles that generate suction were applied to the pilots’ eyes to counteract the blood pressure lowering effect of the centrifuge, the pilots lost consciousness without developing the tunnel vision effect—proving the experience of tunnel vision to be caused by decreased blood flow to the eye.”


Um, but isn’t it the case that most NDEs happen when someone is unconscious (or at least mostly so) and so have their eyes closed?  If they have their eyes closed, they aren’t getting their visual input from the eye.  It’s also certainly the case that in the long tunnel they aren’t generally describing things that they could see from the eye; they are, in fact, having experiences of loved ones that have died and are clearly not actually present and reflecting photons to their eyes.  So how can impacting the eye give them an experience of a tunnel when their visual experiences don’t seem to be generated, at least, from the eye itself?  Lickerman provides no more explanation than is given here, and this seems to me to be a rather obvious point, and I’m quite surprised he didn’t at least mention it, even in a “It’s a myth that the eyes are closed” kinda way.

So, so far the first set of evidence should not be all that convincing and the second seems unrelated to the phenomena under examination.  Next he starts on about out-of-body experiences more specifically, despite the fact that his first point was already basically about them (one hopes):


“Perhaps the most intriguing aspect of NDEs is how often they’re associated with out-of-body experiences.  This, too, however, turns out to be an illusion.  Evidence that out-of-body experiences have nothing to do with souls leaving bodies can be found in the observation that they’ve also been reported by people just awakening from sleep, recovering from anesthesia, while fainting, during seizures, during migraines, and while at high altitudes (there’s no reason to think the souls of people are leaving their bodies during any of those non-life-threatening situations). ”


First, you need more than some interesting evidence to conclude that it just turns out to be an illusion, especially since the association of NDEs with out-of-body experiences is clearly not one; it happens and he relies on it happening in his first point.  Second, asserting that there’s no reason to think that the mind is actually leaving the body in the more mundane cases doesn’t count as evidence or even as an argument, and is contradicted by the long posited — but not proven — theories about astral projection.  It may indeed be possible for the mind to separate itself from the body in mundane cases, and only by ignoring that — ie presuming it wrong — can that assertion make any headway.

And one can even make an objective theory about it.  If mind and body are separate and separable, there’s likely a mechanism for determining when the mind should separate.  This would, of course, be triggered by actions in the brain the indicate that the brain is dying and the mind should leave.  As Lickerman already described, many of the mundane cases do involve issues with blood flow and cases where the brain is at best not functioning properly and at worst actually is in some sense shutting down.  So this mechanism triggers because it misfires, and the mind tries to separate from the body since it thinks the brain is dying.

It gets better.  Note that this mechanism itself need not be the mechanism that actually tethers the mind to the brain.  This may simply be a mechanism that tells the mind that this separation is occurring, and that it must prepare and start to vacate the brain.  But if it’s still connected, the mind and brain would not actually separate and so the mind could indeed return to the brain.  In the mundane cases, that would always occur because the separation would never have actually taken place.  In NDEs where revival occurs things would reset before real separation could occur.

We can also explain, then, how some people have different REM intrusions which makes them more likely to have NDEs.  REM intrusions might rely on similar mechanisms to this separation detection mechanism, and so people who are more likely to enter REM intrusion might also be prone to misfires of this mechanism.

Now, this is an alternate theory that also fits the evidence.  Other than Lickerman appealing to parsimony, there’s really no reason to consider his theroy better evidenced than the one I just provided at this point.  So now we turn to temporoparietal activations:


“One patient suffered from temporal lobe seizures and when Penfield stimulated the temporoparietal region of his brain, he reported leaving his body.  When the stimulation stopped, he “returned,” and when Penfield stimulated the temporoparietal region again, he left his body once more.”


Well, it should be obvious that this evidence doesn’t in any way impact the theory I just advanced; if that theory is right, then all Penfield did was find that mechanism.  And the other examples don’t support his theory better either because we all know that we can have phantom experiences — see, for example, phantom limbs — and artificially generated experiences, but none of those mean that there are never real experiences of that type, as was pointed out above.  So this is interesting and NDE theories have to account for it, but it’s not that impressive.

Which leads to:


“Further evidence that this phenomenon is an illusion comes from experiments in which people who’ve had out-of-body experiences when transitioning from sleep to wakefulness were unable to identify objects placed in the room after they’d fallen asleep, strongly suggesting the picture they viewed of themselves sleeping in their beds was reconstructed from memory.  ”


Which ignores the fact that all memory is, in fact, reconstruction, and is potentially prone to making those sorts of mistakes.  To test this properly, what we’d need is:

– Artificially generated cases where the subject is looking for the new object (to make it memorable).

– A memorable object.

– A way to make certain that these artificial cases are really the same as NDE cases.

Remember, Lickerman has already linked the sleep to wake case as a case of REM intrusion.  But REM intrusion might not be the same mechanism, as there are differences between them.  Maybe the out-of-body experiences in REM intrusions aren’t real out-of-body experiences at all, which is why you can’t identify new objects.  Or maybe there are memory issues.  In order to settle some of these, we need to define what an out-of-body experience is and what it has to have.   Lickerman asserts that they should remember but doesn’t have the evidence or even conceptual analysis to demonstrate that they really should.  It’s something, again, that out-of-body proponents need to address, but it doesn’t count as any sort of mass evidence for Lickerman’s theory and against OOB theory.


“In sum then, though far from proven, as an explanation for what actually explains near-death experiences, the REM intrusion hypothesis has far more evidence to support it than does the idea that we actually do leave our bodies when death looms near.”


No … no, it doesn’t.  OOB theory is compatible with most of the evidence presented or can be made such with minor adjusetments.  That’s hardly “far more evidence”, by any standard.

The problem here is that Lickerman isn’t treating OOB as a competing hypothesis.  He’s treating it as, at best, a folk explanation not worthy of real consideration.  That’s why he can completely ignore all considerations about what OOB actually entails and simply toss out things that he thinks the theory in its most basic form can’t explain.  But all scientific theories in all of the cases we’ve had previously were able to change their theories on the basis of new evidence without having to be thrown away because of one thing that doesn’t seem right, and I see no reason why OOB should be any different.  Eventually, some did go away — like caloric and phlogiston — but it isn’t clear what the line for that actually is; how much you can change a scientific theory before it stops being the same theory is not well-defined.  What Lickerman does here is find any issue that his preferred theory does better and declares that that means OOB is much less evidenced even if OOB could easily accommodate it.  Once we eliminated all the cases where OOB can accommodate the evidence, the evidence gap is far less than Lickerman posits.

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