Near-death experiences and consciousness

randman,I couldn't find a link to the actual study, so I did a quick search. Turns out it's available free online.http://www.zarqon.co.uk/Lancet.pdf I agree that would be really nice evidence. Although there's always other hypotheses, so "proof positive" is a little strong. But itdefinitely would be nice evidence, and put some pressure on scientists to find evidence that might support another hypothesis.I'm interested to know how "brain inactivity" is operationally defined--that's a critical part in knowing if the study is being interpreted validly. Randman, do you know? If not, I'll try to make time to look through the study and find out. But if you know, that would be a huge help.BenThis message has been edited by Ben, Tuesday, 2005/11/29 07:51 AM

Looks like the last page of the study is the most relevant to "brain activity". You mentioned some.. there's one other section that seems relevant: Those studies may have more information about relating "brain activity" with the contents of this study. I don't have time to find refs or poke around in these other studies right now. Maybe tomorrow.Ben

If you could find any ref on this, that'd be great. It'd be surprising, as EEG is a pretty basic electrical signal. Certainly weak signals can be damped by the skull, and the amount of damping depends on the actual tools that they're using.But if that's the case, then we're talking semantics--the real information would simply not be measurable given the tools. "Brain death" would then just be defined not based on some unmeasurable measurement, but on a definition (i.e. can't be revived). So it just means the term wouldn't be useful for this discussion, I think.

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I do think your overall argument and evidence are pretty compelling, and that NDE can successfully be explained--as long as there's brain activity. Certainly the brain uses reconstructive processes all the time; NDE being "out of body" or "unrealistic" is not a problem at all. The same thing goes with "time compression" and all that. Not much problem explaining that either.So really, I think the interesting point is to focus on the claim of "no brain activity" and seeing how memory formation relates to such epochs.Ben

Do you think it's worthwhile to investigate what this means? It's looking a bit like, technically, this maybe can't be shown, but I don't know yet.If I suggest (after reviewing the evidence and explaining my reasons) that it can't be known that brain activity stops, are you going to be willing to address the technical arguments? Such a finding would simply mean that this NDE info is not evidence for biological or non-biological explanations of consciousness.Is that worthwhile to you? I'm willing to go ahead, read the references, and ask my colleagues (who do EEG stuff for a living) about what an EEG flat line does and does not mean.Ben

That's the same sense I got from reading (most of) the article. I would be absolutely shocked to see a scientist, especially at such an early stage of research with so many theoretical avenues wide open, make any equivocal statement at all. That was the take-home point I got from the Lancet article as well.Randman, I'll talk to some colleagues at work tomorrow and see if I can get some answers about the minimum level of brain activity which is detectable by EEGs, and thus what set of conditions could possibly show a flat EEG.Ben

randman,You've got it close, but not quite. You seem to be reading "medical factors" to be a broad term that is undefined here. However, it's not. It's defined in table 3: One of these factors is cognitive, but none of them are measurements of "brain activity."The authors are saying that no measured medical factors can account for NDEs. Thus, the unmeasured cognitive / brain factors (which they describe as "thus far assumed, but never proven") need to be rigorously studied in order to establish any scientific hypothesis of NDEs.To summarize again; the paper eliminates all "medical" hypotheses and makes a call for cognitive / brain research to be done on NDEs. They then summarize the extroadinarily limited literature on the cognitive side, and reiterate their call for cognitive research to be done, in order to put evidence where now there is only assumption.Hope that helps clear things up.Ben

There is only one claim of flat EEGs... so it's really hard to accept as scientific evidence. I think this point is best dropped; conscious processes ARE reconstructive all the time. Arach did a good job pointing out some instances. Another simple instance is during dreaming; we often take a viewpoint outside our own bodies.But it's not an important point. The important point is whether there's believable evidence of conscious activity happening without corresponding brain activity. The quality of the conscious experience doesn't matter at all. Sorry, I didn't catch what this means. Could you restate or point to a section in the paper? It was really helpful when you did that before. I totally agree that the "flat EEGs" are the interesting point. And thanks for your clarifying statement, I'm glad we can agree on that. But with only one anecdotal data point, you can't get at any scientific conclusion. It makes a suggestion that, in the author's words, "pushes at the limits of medical ideas about the range of human
consciousness and the mind-brain relation."But the paper is a call for further research. A statement that conflicting ideas and theories are out there, we have crappy data, and we've eliminated all other explanations. You cognitive guys, get off your asses and do some work.That's how I'm reading it. I see the whole final page as a "we have a bunch of flimsy data and theories. Hey yo, do some work!" I don't see that they give credence to the one data point for more than this type of "look, we can't make sense out of what you've said and the lacking data. We need more." That's why they say things like This is a criticism that the current theories lack data. They're really unimpressed with the lack of data behind the theories. They're puzzled. Some relation is there... but what could it be? Wish there was some data. Remember, they failed to reject the null hypothesis (that such factors caused NDEs). This doesn't mean the hypothesis is false, at all. It means that further studies need to be done. In other words, ... damn, it'd be nice to have some friggin data.By the way, sorry for the randomized ordering there. Sometimes I read sequences of paragraphs backwards, sometimes forwards. Helps me in reading the paper how they want me to read it, and also helps me parse the paper for my own interpretation (i.e. break the flow of their ideas, so I can capture the data and think about it on my own).

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I guess what it comes down to is believing that no scientist would make a conclusion based on a single data point. Instead, they would want more data. Maybe that's where our interpretations diverge?Ben

I didn't feel that the author tied this fact with the data they measured explicitly. That bothers me. But it's an important point. That's the point that I marked as "investigate further." I'll try tonight, when I need a break from my research stuff. Well at this point I think we've extracted the relevant issue (how prevalent are flat EEGs) and question further investigation (what does a flat EEG mean for brain activity?) out of the paper, so I'm willing to drop the discussion of "what the authors meant" as irrelevant at this point.If the connection can be made above that you're making, then the viewpoint that you're stating is much more plausible. I'd be surprised if the authors were using that point, because they didn't make the deduction that many EEGs were flat explictly. But I've been surprised many times, so ... let's simply do the fact-checking ourselves, and see if that is a valid deduction!Talk to you later. Thanks for being very clear about what points you extracted from the article and what quotes you got that from; it made your POV very accessible. I appreciate it!BenThis message has been edited by Ben, Tuesday, 2005/11/29 04:10 PM

Thanks. I learned about some really interesting developmental problems, like anencephaly. Oh right, and about brain death. Flat EEGs are a little harder to track down well... working on that. I'm not familiar with research in this area. Mind if I ask for more links?Aw, hell.Can you provide some links to the kind of research you have in mind for "filling in" ?AbE: I got WK's link to Elizabeth Loftus' work. "Funny" enough, I actually met her (and her husband) while I was studying at the University of Washington psych department for a bit. Maybe. But, how could you falsify this hypothesis?BenThis message has been edited by Ben, Tuesday, 2005/11/29 07:02 PM

Cortical and thalamic cellular correlates of electroencephalographic burst-suppression - PubMed

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At variance with cortical neurons, only 60-70% of thalamic cells ceased firing before overt EEG burst-suppression and were completely silent during flat periods of EEG activity. The remaining 30-40% of thalamic cells discharged rhythmic (1-4 Hz) spike bursts during periods of EEG silence.

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You can get a flat EEG with thalamic firing (in cats). I'd really like to know what a flat EEG means electrophysically. It would really help. There's all sorts of reconstructive processes in the mind; I don't know any that would particularly fit this scenario. Elizabeth Loftus' stuff looks interesting, but seems a bit removed from this to me. Why would you assume that's what I mean? Of course that's not what I mean, that's not falsification of your hypothesis at all. I mean, how would you design an experiment to show whether that hypothesis was true?Here's your hypothesis again: For example, why isn't it due to brain activity after EEG activity resumes? Or is there another biological process, besides electrical activity, that either causes false memories to form or supports consciousness?If the theory's not testable, it's not really helpful in enlightening us anything about the nature of consciousness. That's all.Ben

randman,I agree with the other posters. It IS anecdotal. The question is just, what do we do with it. Where does it fit in with the research and hypotheses that we have?Those are always the questions you ask. If you struggle to fit it in, then you ask, DOES it fit in? If not, how do we proceed? In some sense, I don't see any problem of bias. NDE is very anecdotal. So are other interesting things, like missing limbs, etc. Some people get really interested to study them, and if they come up with well-reasoned, well-supported hypotheses that are useful beyond their own domain, other people start to listen. Ramachandran makes a living off of this stuff; he's great.NDE are interesting, but hard to study and anecdotal. Most people avoid such subjects because... the scientific methodology just doesn't work without ways to gather reliable evidence....On the other hand, of course science is always going to be biased to finding hypotheses that operate within the natural world. That's the way the method works. "Can I explain this phenomenon naturalistically?"Faith hosted a thread which was all about the statement "Just because you can explain it naturalistically doesn't mean you're right." I'm sympathetic to that claim. There's an infinite number of theories that can explain any set of phenomena. As you can see from other threads, I tend to take science as an exploration in finding the most "useful" theories.I think further discussion of this kind of topic is best taken somewhere else. I wanted to at least answer your complaint, so that we can proceed in this thread in good faith.Ben

Sure, thanks schraf. I am aware that, well really, all of cognition is constructive. Right. As far as I know, usually this happens on a much smaller scale than what's being reported here. It depends how you define "easy". I read a summary of Loftus' work, and the method of choice there was basically using family cohorts to convince someone that something was true. Even then, the percent of people who were able to "swallow the lie" varied greatly with the actual false memory.It's a possibility that NDE are simply highly constructed memories (in the sense that there was very little "original" processing), but by no means does it seem to be a slam dunk to me. That's a pretty big hole, a lot of information. And seems like there's a fair number of claims that suggest there's sensory data for the time of the NDE being incorporated. It's possible that it's the incorporation of generic knowledge, pre/post NDE knowledge, or something like that. But again, that's only a possibility.Without more compelling information about memory reconstruction or evidence from NDE studies, I think it's dismissive to suggest that no conscious processes are happening during a flat EEG. I think the best we can do is to say, "yes, we don't know. Not enough data to find an adequate explanation."

Sure. The same argument goes for ANY theory, though, physiological or not. So I don't feel this argument carries ANY weight at all in any direction.Especially not in cognition. Too many possible factors for individual differences, and so little understanding of what those factors might be, or how to measure them. That'd be interesting. So would putting the people through Loftus' "familial informant false narrative procedure", or "lost-in-the-mall" technique of implanting false memories, or tests for susceptibility to suggestion. Also would be interesting to try to correlate beliefs or exposure to such things (difficult, but you can operationalize this to some believable extend) and see what correlations (if any) fall out.I think those are the starts to having a cognitive science of NDEs.Ben