Science Interviews


Thu, 15th Aug 2013

How do near-death experiences arise?

Jimo Borjigin, University of Michigin

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In past times, if your heart stopped beating, that probably meant that you Light at the end of a tunnelwouldn’t live to tell the tale. But modern medical techniques mean that many heart attack patients survive, and those who’ve been that near to death often say that they experience bright lights or other strange phenomena. Until now, doctors have struggled to understand why, but Jimo Borjigin looked into the question in a paper in PNAS this week.

Jimo - In the literature, what I find is 10% to 20% of cardiac arrest survivors had their near-death experiences. There are various kinds. They are not all identical, but there are some common threads such as seeing bright light. But I even think that that number is underestimation because a lot of people are afraid to speak up about their experiences. They're afraid to be ridiculed. They're not convinced this is really a supernatural, but yet, even science hasn’t provided any answers. I might be biased, but I think our study might be really the first attempt and then I'm sure, many more will follow.

Kate - How do you go about investigating near-death experiences because obviously, when a human is having a near-death experience, we’ve normally got other things to worry about than measuring their brain?

Jimo - That's right.  eah, if I know if somebody is about to have near-death experiences, first instinct is to save them rather than to stick electrodes in their brain. So, I think to do that kind of studies for individuals with a cardiac arrest is really tough. Unless you know somebody is going to have a pre-scheduled brain operation and we could perhaps give them EEG, electrode recording, just in case that patients, when they wake up, they'll report some kind of near-death experiences. I think those might be the kind of more feasible studies one could perform in the future, if there are sufficient number of patients who actually are available for neurosurgeons to gather data from.

Kate - So, until we can get those human subjects, what subjects did you use in this study and how did you go about looking at this phenomenon?

Jimo - Well, rodents are standard animal models for our studies, whether it’s rats and mice and that is just the reality of today’s scientific research. So, what we did was just give them anaesthetics and make sure they're not sensing any pain. We gave them lethal injection to the heart to stop the heart. During this whole time, we monitor their brain activity by placing 6 electrodes in distant parts of the brain and the results were all published in the paper.

Kate - And far from the brain going quiet after death, it actually became quite active.

Jimo -  Exactly. So, that's what we were actually really surprised to find measurable activities. We were predicting maybe something comparable to the levels we would see when an animal is awake. But what we were really surprised by is how high those activities were. In fact, they're 5 to 8 times higher during the near-death state than the waking state.

Then I really remember that in the human near-death experience, one of the very common description of experience, is they're realer than real, hyper vivid, hyper lucid. I mean, to the patients who experienced that, they seem to be extremely real. I think that realness of that perhaps is reflected by these measures that we provided and that is still not clearly confirmed. We need many scientists to get involved in these kind of studies, so we have a more advanced understanding of this phenomena.

Kate - Was any particular areas of the brain involved in this activity, like if someone saw a bright light, was the vision at the parts of our brain involved in this activity?

Jimo - Well initially, since we hear a lot about bright light, my first instinct was, “Their visual cortex must be highly activated.”  In fact, maybe visual cortex is the only part that is activated and that's what I thought naively initially. But I was surprised by how the entire brain seems to be participating in this amazing event, the electrical oscillation, not just occipital areas which is the visual cortex.

There is a unique sequence of events that every single animal demonstrates. There's different frequency at the different time period during this 30-second cardiac arrest. So initially, a very narrow band of high frequency activities and then eventually, it culminated really in the highly activated and not only in terms of the power density, but it’s also in the coherence which is the synchronised firing of distant parts of the brain, mainly in the gamma range. Gamma actually expand a huge range in this case, anywhere from 20 to 25 hertz, all the way up to 250 hertz that were investigated in our studies.

Kate - Does this activity tell us anything about why these near-death experiences might happen? Some of us might presume that if the brain is going without oxygen, it would just shut down very quietly. Do we know why?  s the brain having like a last hurrah or a last gasp before it runs out of oxygen?

Jimo - Yeah, I saw that comment, but I think perhaps since we see it in rats and I predict we’re going to see that in humans in the future, my guess, this is really brain’s built in defence against lack of oxygen, lack of glucose. We all know that a brain is very plastic. So, if you do something to damage the brain, to injure the brain, brain actually mounts a defence against that injury and insult. So, I think this is perhaps one built-in mechanism against external threats and if there's a lack of oxygen or glucose, maybe just one of the ultimate threat to brain survival.


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The researchers might try hooking up their electrodes, etc. to patients undergoing shock therapy for psychiatric reasons. These patients experience a near death experience during which their brain gives up its delusions in a scramble to find a way to survive. Not politically correct in many areas, which may be a disservice to the patient who is denied treatment. grizelda, Wed, 21st Aug 2013

I'm not entirely convinced by Jimo's speculative explanation, in the interview, for the observed hyperactivity. He says:

However, in cases of local oxygen deprivation (such as in stroke), or mechanical brain damage, the brain response to the injury is itself damaging. For this reason, the latest emergency services systems include means to rapidly cool the brain so as to minimize this damaging response.

If the activity resulting in NDE's really is a positive defence against brain injury and insult, and not simply a direct physiological result of oxygen deficit (causing neuronal hypersensitivity?), it would be interesting to know how this burst of activity defends the brain, and why it contrasts with the damaging response to local brain injury. dlorde, Thu, 22nd Aug 2013

Some professional scientists, neurosurgeons and such like, without bias say, that when blood stops flowing into the brain or when the brain is at 12 centigrade or when there is an infection, that there is no brain activity and should be no perception and consciousness... Europan Ocean, Wed, 18th Sep 2013

The question here is how are they measuring brain activity? EEG can be flat while there is still brain activity.

Clearly if blood stops flowing for long enough, activity will cease because the cells will die, but this won't be true of an NDE because death doesn't occur.

Another question is when the NDE actually occurs - can we be certain it doesn't happen prior to or after the period of minimal brain activity? The subject's sense of time may not be accurate. dlorde, Wed, 18th Sep 2013

May be relevant to this discussion: New Brain Activity State Exists In 'Flat Line' Coma Patients, Scans Suggest

I've often wondered, the last thoughts in the moments before death in a way last for eternity from the point of view of the person dying. I view it as release of consciousness from all the physical concerns of the universe, in particular time and space, I won't need a timepiece or map. If during the process I'm thinking of heaven (or whatever), will I experience it forever? I mean that from my point of view, not a third party like the universe that may go on for trillions of years or more.

Another question, if/when it is possible to "freeze" an organ like the brain and "thaw" to revive it will the person be considered dead while in suspended animation? If all chemical processes are stopped I can not see how there would be any perception/consciousness, would this be considered a near death experience? I'm not saying this is possible now, maybe not ever, there are enormous technical difficulties, but I do not see any known physical laws to prevent it. Wouldn't be the first time science caused a redefinition of biological status. distimpson, Thu, 19th Sep 2013

I'd expect it to be more like falling asleep - your consciousness becoming fragmented, then ceasing.

I think a reasonable definition of 'death' would be irreversible cessation of brain activity. Some circumstances considered diagnostic of death today almost certainly won't be death in the future.

If there's no perception or consciousness, doesn't seem likely there will be any experience. The question is, can you generate the perception or experience of an NDE from events in the brain immediately prior to unconsciousness that might be remembered, or immediately following resuscitation as the initially random neural activity becomes synchronised again?

Some people have gambled a lot of money that contemporary cryogenic storage will be reversible sometime in the future. I suspect they're a bit premature, but I wouldn't bet against it being possible for future cryogenic subjects. dlorde, Thu, 19th Sep 2013

Agreed, thanks for the clarification, read my post again, it seemed like I was treating non-existence as an existential state, not the intention just poor wording on my part. distimpson, Fri, 20th Sep 2013

Near death experiences arise from such events as which cause heart failure that is later fixed. When brain activity has to pause due to no blood flow.

Some of the experiences, or sights are long and detailed, minutes, more than an hour, days, or even weeks long if induced by Ketamine anesthesia.

How can can one say as above that this is an evolutionary development that aids survival?

NDEs usually result in a change of heart towards less aggression and more empathy. Europan Ocean, Fri, 27th Sep 2013

Sounds reasonable, point is the most dangerous position.

I've been trying to do some research on the Native American "vision quest". Haven't had much luck finding out if the visions are similar to the those experienced with cardiac arrest. I'm not sure if this qualifies for near-death but in some cases it seems to be pushing the limits of human survival.

Another ritual involves a sweat lodge, I'm not clear here if this is actually supposed to be a near death experience or some events have just gone very wrong perhaps causing cardiac arrest. Anyway my very limited understanding is that the rituals are an attempt to reach a different level of consciousness to give insight, clarity of one's life. Do patients that experience NDE believe they have benefited psychologically from the experience? (as you say "less aggression and more empathy" perhaps a more satisfying life?).

Last but not least, the movie "Flatliners" comes to mind, Hollywood's interpretation of the experience. Interesting topic. Sorry for the ramble, I had a pseudo NDE last week, shook me up a bit. distimpson, Sun, 6th Oct 2013

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