Brainwaves: What happens between life and death?

This is the fourth episode in 'Brainwaves: Mysteries of the human brain.'

A tunnel. A bright light. Reuniting with deceased loved ones. Many people who have near-death experiences have remarkably similar stories. Why?

Charlotte Martial, neuroscientist at the University of Liège in Belgium.

Jimo Borjigin, professor of neuroscience at the Shenzhen University of Advanced Technology in China. Adjunct associate professor of Molecular and Integrative Physiology at the University of Michigan.

Joan Pavlinsky, had a near-death experience in 1996.

Peter Panagore, had two near-death experiences, one in 1980 and the other in 2015.

The version of our broadcast available at the top of this page and via podcast apps is a condensed version of the full show. You can listen to the full, unedited broadcast here:

Part I

MEGHNA CHAKRABARTI: In 1996, Joan Pavlinsky was riding her bike along a path in Eastham on Cape Cod, Massachusetts, and then suddenly she was somewhere else.

JOAN PAVLINSKY: I woke up floating above the trees. It was blue, blue, blue, bluebird sky, no wind.

It was just gorgeous. Very peaceful, very peaceful.

CHAKRABARTI: Joan says right next to her was her dad.

PAVLINSKY: He is sitting in the tree in a lotus position and I'm up there with him and he had on a turquoise blue Navy jacket that my mom had sewed for all seven of us in the '60s. I just thought it was odd. Even at that point I knew he was dead and he'd been dead for 10 years.

I didn't say, what are you doing here? But it was more like, what am I doing here? I kept saying, this is so beautiful. I had this incredible feeling of bliss. I never had a feeling like this before. And he kept saying that I had to go back, but I was arguing, saying, no, it's so beautiful here. I really want to stay.

And I looked down and I saw from the tree a bicycle and a woman who was tangled up in the bicycle. I didn't recognize it as me. And then the next thing I recall was the sound of the emergency room staff debriding my face with water, getting all of the pavement out of my face, basically.

CHAKRABARTI: Basically, Joan had been in a terrible bike accident, a bungee cord she kept on the back of her bike, had slipped off and tangled in the rear tire, and that catapulted Joan off the bike.

Joan was alone when the accident happened. She doesn't know who found her and called an ambulance. Doctors later told her she was unconscious for about 15 minutes.

PAVLINSKY: So I was missing three teeth. I had the whole left side of my face torn off. They told me I had a closed head injury. And I was kept overnight, but the neurosurgeon just said, a helmet saved your life. They did all of the scans that they needed to do and said that there was no brain bleed. So I was able to go home.

CHAKRABARTI: The official diagnosis was a traumatic brain injury, a high-grade concussion with loss of consciousness. For several months, Joan struggled with short-term memory loss. She doesn't know how close she was to actually dying, but traumatic brain injuries like hers can cause what are referred to as near death experiences.

Many people who have these near-death experiences report seemingly mystical things like seeing a bright light or a tunnel or having an out of body experience like Joan did, and Joan says she still thinks about that beautiful place above the trees, sitting with her father and the way it made her feel.

PAVLINSKY: It's a feeling that, like I said, I don't think I've ever had before. I don't think I've had it since. It wasn't scary at all. It was just peculiar for me, initially, I talked about people going through a tunnel, darkness, and I don't call it any of that, but the idea that are these an amalgam of memories that we've had.

Was it real? Did it really happen? Hard to say.

CHAKRABARTI: Hard to say. Just like it's hard to say what is actually happening in the brain near death. That's what we're going to talk about today. And joining us now is Charlotte Martial. She's a neuroscientist at the University of Liège in Belgium. Charlotte, welcome to On Point.

CHARLOTTE MARTIAL: Hi everyone. Thank you.

CHAKRABARTI: So you study what happens in the brain during near death experiences. First of all, what attracted you to this area of research?

MARTIAL: Oh, actually it was by chance. I wanted to work on neuroscience. I was interested by consciousness topic, and actually my supervisor or TA supervisor suggested me these topics saying that actually the current literature is very limited.

And so we have plenty things to discover. So I was directly attracted by the topic. And now I am happy to have chosen this topic.

CHAKRABARTI: Okay. So there was a great opportunity there to expand our understanding.

MARTIAL: Exactly.

CHAKRABARTI: Yeah. Okay. So you heard Joan's story there about sort what she experienced and saw and felt during those, that long period of unconsciousness and her traumatic brain injury.

What would you describe or how would you define what a near death experience actually is? So we can put a border around the experience we're talking about.

MARTIAL: Near death experience can be defined as an episode of disconnected consciousness, meaning that it's an ... experience in the absence of awareness of sensory environment. And of course, this happen when we are close to death and the particularity of the phenomenon is that there are recurring prototypical features such as out of body experience, meeting entity, seeing a bright light or an intense feeling of peacefulness or bliss as Joan just described. This is --

CHAKRABARTI: So forgive me for interrupting Charlotte. So this a period of disconnected consciousness, which often happens close to death. Can this, can the same type of disconnected consciousness be experienced when you're actually not close to death? Because again, Joan doesn't know if she actually was close to dying.

MARTIAL: Exactly. We now know that it is possible to experience such an experience when we are in a situation where there is no threat to life. We can also experience that when we are disconnected from our body and simply experience, for example, high fever or high level of anxiety. So I'm not surprised that here she did experience the phenomenon even if she was maybe not in a severe physiological crisis.

CHAKRABARTI: I see. And forgive me for asking for so many definitions, but this is something that we've learned throughout the course of this week, talking about the brain, is that it can be the lines around an area of conversation can be very blurry, right? Because the brain is so complicated.

When we talk about death as a definitive moment. First of all, it seems like science is showing that it's not actually a single definitive moment. But is the area of research that you are interested in something where like cardiac death has to be close or could you consider, do you also look at times when maybe the body is actually still functioning, but the brain itself is not, how do you define death specifically?

MARTIAL: Yeah. It's very important actually to be clear with the definition of death. So it's important to distinguish two types of condition we have, when we talk about this, we talk about brain death, so meaning here that there is no more brain activity in the brain. But next to that, there is also this condition that we call clinical death. And so here it's a severe physiological crisis where the earth and breathing stops. However, this condition can be actually reversible. And so the prototypical example is a cardiac arrest.

Where actually the person can be conscious when, sorry, if she's reanimated properly. So it's very important to distinguish those two condition. And of course, when we talk about near death experience, we talk about patient who were able after the accident to recall such an experience.

So they were not properly death. They were clinical death condition or another severe physiological crisis.

CHAKRABARTI: Okay. Thank you for that. Because it's very important to understand. So in the context of this conversation, we're talking about people who experienced temporary clinical death, but were resuscitated.

MARTIAL: Exactly.

CHAKRABARTI: Okay. Okay. So heart and breathing stops. So this is very interesting. So you were saying a little bit earlier, what are some of the common reports that people have of what they experienced in that moment where they were technically clinically dead.

MARTIAL: So I would say that each testimony is very unique because, of course, each person has his own interpretation of the experience, but the particularity of the phenomenon is that there are recurring features that we can find that most of them, we can find them in the testimony.

And so in term of the most frequently reported ones, there are out of body experience, an intense feeling of peacefulness, wellbeing, or bliss. There is also the sensation of harmony, unity, also meeting entity, be it a simple sensation of a presence or whether someone we know and who may be deceased.

There is also this vision of a tunnel, et cetera. And so in total, I would say that we can find about 20 prototypical features that we can find in most of the testimony.

CHAKRABARTI: How much do we know if these are culturally influenced experiences? Do people report similar things around the world, I guess is a better way of answering it.

Of asking it.

MARTIAL: Yeah. That's a good question. To be honest, today it's difficult to respond properly to that question, because there is very limited research on that question specifically. However, what has been shown so far in some case report, et cetera, is that our culture may have an influence at least on the interpretation of the phenomenon.

And so a prototypical example is this impression of being at a frontier at a point of no return. Like a gateway, experience it, which is actually reported in Europe and North America as a tunnel while for example in Asia, they report it as a river. And we know that in this culture, the river as a particular spiritual importance.

Part II

CHAKRABARTI: Charlotte, we got some stories from listeners, which actually don't fall within that typical pattern that you were talking about. So this is Jim in Sioux City, Iowa. He's a college professor, and he told us a story about once, how his heart stopped.

This is about 14 years ago when he was out on a field trip with his students.

JIM: I was walking up a hill and all of a sudden, I said, guys, I have to stop for a moment. The next thing I know, the students were standing around me asking me if I was okay. Evidently, I had been laying on the ground for almost two minutes, and it came to find out that my heart had stopped.

I have cardiomyopathy. By some miracle, my heart started beating again. I didn't experience anything. It felt like I just had went to sleep. And I had woken up and two minutes of my life had disappeared.

CHAKRABARTI: That's Jim in Sioux City, Iowa. Charlotte, have you had reports similar to Jim's where there's no transcendent experience, just a complete cessation of awareness?

MARTIAL: Yeah, sure. Sure. Actually, if we look at the cardiac arrest survivor it's only, it's a lot, but it's only one out of five survivor that will report a typical near-death experience.

CHAKRABARTI: Only one out of five. Okay. And the other four, are they just atypical or are they just like Jim, they just don't remember anything.

MARTIAL: Yeah, exactly. No memory.

CHAKRABARTI: Okay. That's interesting. Now, I guess I should ask you how many of these NDEs, if we can call them that, have you documented?

MARTIAL: Actually, now it's, I think I have a database of more than 2,000 near-death experience that we collected for 11 years.

CHAKRABARTI: 2,000. Okay.

And what exactly are the data that you're getting from people? Is it just this narrative data of what they tell you they experienced or is there more in these files of the patients?

MARTIAL: It depends, I would say, but generally we have a clear and detailed description of what happened.

So we have a fully express, write a narrative. Plus, we ask the person to fill in several kind of questionnaire, which permit to quantify the phenomenon. And also its subsequent memory. So we also analyze the way the memory is recalled, et cetera.

And next to that, so this is about like the retrospective database, we call it like that, because those people experience the experience like years or even decades ago. And next to that we also have in hospital prospective study where we follow patient in intensive care or emergency department.

CHAKRABARTI: Tell me more about that.

MARTIAL: So basically, the idea is here to follow survivor of critical situation and to be there just upon awakening. And so there we administrate a series of question where basically the idea is to detect those people who experience near-death experience. And then we follow them for months to see to what extent, for example, this experience can have an impact on their life, their belief, et cetera.

And next to that, we also are conducting study where we also studied the neurophysiological mechanism of this phenomenon where we are using, for example, EEG in the resuscitation room of our hospital in order to record EEG activity during near-death experience.

CHAKRABARTI: Okay. Charlotte, if you'll just hang on for just a moment. We did get so many interesting stories from listeners in advance of today's conversation. Here's another one. This is Nancy. She's in Portland, Oregon. She's a retired physician and she tells us a story of a patient she once had in the ICU who was resuscitated after cardiac arrest.

NANCY: He couldn't describe it, but he was a completely different person with a sort of an aura, a whole sort of spiritual quality about him for 48 hours. And then after that, he reverted to his usual self. But I cannot forget the transcendent feeling that he emanated for those 48 hours afterwards.

CHAKRABARTI: I'd like to introduce Jimo Borjigin into the conversation now.

Jimo's a professor of neuroscience at the Shenzhen University of Advanced Technology in China, and also an adjunct associate professor of molecular and integrative physiology at the University of Michigan. And she joins us today from Shenzhen in China. Professor Borjigin, welcome to On Point.

JIMO BORJIGIN: Very good to be here.

Thank you, Meghna. Okay I want to try to weave your research and Charlotte Martial's research here together and beginning with a basic question. In terms of understanding what's happening in the brain in these near-death experiences, as Charlotte defined for us, our area of focus are people who went through cardiac or breathing arrests, right?

So their heart and their breathing stops. Obviously, the outcome of that is a denial of oxygen to the brain. So what are some of the first things that happen in the brain and how quickly does the brain respond to that drop or zeroing out of oxygen?

BORJIGIN: Yeah, it's all very good questions. So we've published a study in 2023 of four patients who died in the ICU.

After suffering at home crisis, three of them were cardiac arrest. The other one was a brain hemorrhage. So they're brought to the hospital comatose and was treated in the intensive care unit EEG and so forth. So in those limited examples, the patients were all comatose. And then an EEG or monitor, we are fortunate enough to be able to analyze EEG signals.

CHAKRABARTI: And what did you see? (LAUGHS)

BORJIGIN: Lots of interesting stories. Depends on how much time we have. So first of all, we saw the part of the brain responsible for vision. It's highly activated. That is occipital lobe or visual cortex and part of the brain responsible for memory, the temporal lobe, and many other functions that are highly activated.

In addition, the parietal lobe, which is extremely important for associating the sensory information and bring them to the frontal lobes, also very much activated, basically posterior hot zone is let up in two of the four patients, and in particular, the patient one was detailed in our publication.

In her case she was healthy, 24-year-old woman was pregnant and suffered cardiac arrest at home because she had Long QT syndrome, which is cardiac condition that is very risky for these kind of crisis. And she brought to the hospital emergency room and is comatose. And eventually her family and the physician got together, decided there was no hope for further really improvement, her condition.

So they remove the ventilator. So at this point, removing ventilators is like allowing patients die of asphyxiation, because they cannot breathe. They don't have oxygen coming into the system and their body have to take over of breathing functions and so forth.

So that patient one had breathing, maybe lasted for about 1.8 minutes. The heart was actually pumping faster and faster for 1.8 minutes, and after that, the heart activity suddenly stopped, meaning that heart rate is no longer increasing and it go, went opposite direction. That is a heart rate suddenly dropped tremendously and then died within seven minutes.

So suggesting that at one and eight minutes into the ventilator removal her heart was pumping or was functionally okay, but then one and eight minutes into the ventilator removal, she suffered clinical death because her heart is no longer pumping the blood. But the heart still, heart and brain electrical activity lasted for another seven minutes for patient one.

In the case of patient two lasted for 25 minutes. That is a clinical death occurred, and then the heart and brain still continued for another 25 minutes.

CHAKRABARTI: Wait. Can you hang on here for a second? I just want to be sure I understand this. In the second patient that you're talking about, ventilation was removed, but there was still cardiac activity and brain activity for 25 minutes.

BORJIGIN: Yeah. Yes. So there's a cardiac activity. So heart of course functions to pump the blood out of our body to bring the oxygen, but just because they cannot pump doesn't mean it does not have electrical activity. So this electrical activity in this case is called a pulseless electrical activity of the heart.

So electrically is still going on, but no longer physically pumping the blood through the body, so the brain and all the other tissues are no longer getting the oxygen, the needs to function properly.

CHAKRABARTI: For 25 minutes. Okay. Let me go back to something else you said. And then Charlotte, I'd love to hear your thoughts on this.

So what you're saying is that after that moment of cardiac death, essentially where the heart does stop pumping, there's still electrical activity in the heart muscle. But going back to the brain, you said you actually see a spike in activity in certain parts of the brain. You talked about the visual cortex. The temporal lobe. The parietal lobe, it goes into, it's like almost electrical overdrive in the brain.

BORJIGIN: Exactly. That's true for the two of the four patients. Patient one and patient three. Not all four of them. But two selected. But the most obvious one is a patient one, who had amazing activation of visual cortex.

All the other areas that I mentioned, but more important is functionally connected. Those regions are so connected and they're well known to play functions such as in vision. Such as speech perception, such as out of body experiences. So I think those are areas that are demonstrated to be responsible for out of body sensation, for motion sensing, for light sensing, for sound sensing or speech perception.

So therefore, I think it matches quite well. Potentially for some of these near-death experiences that people report.

CHAKRABARTI: Actually, that was, Charlotte, that was the question I was going to turn to you. Because if you map your research on top of Jimo's, it does seem that there's significant overlap in terms of the narrative reports that you've collected and the actual like physical activity in the brain that Jimo is talking about.

MARTIAL: Exactly. So for me working on near death experience, this kind of study is very important. So I remember the day I read Jimo's specification, and of course the question I directly had in mind was is this activity, this peak of activity sufficient to trigger a near-death

Of course, this is a non-answer question so far, but I think Jimo's research are very important for the field of near-death experience.

CHAKRABARTI: Okay. So what's causing this electrical activity in these particular parts of the brain. Jimo, is there also, let's say a neurochemical surge as well, that's facilitating the overdrive of these neurons?

BORJIGIN: That was a very good question. So we didn't do this neurochemical analysis in human patients. Those are quite invasive.

CHAKRABARTI: Oh, the ethical, ethically problematic.

BORJIGIN: But in animal models, we have demonstrated in 2015. It's almost 10 years ago now, actually in the dying animals who are dying from asphyxiation, there's a massive release for neurochemicals of certain types.

For instance, dopamine levels go up like 20-fold. Before the heart stopped pumping, complete stopped the activity completely and norepinephrine level, which is responsible for alertness and so forth, increase the 40-fold and the serotonin level goes up a hundred-fold. So it's a massive neurochemical secretion, which may be responsible for some of these near-death experiences.

Of course, there's a long way to go until we actually understand more details of these pathways.

CHAKRABARTI: It seems to me, and this is a non-scientific observation, I'll be honest, but you're talking about dopamine, serotonin, et cetera, and these are all neurotransmitters that are very important, as you said, for heightened awareness, right?

In very acute states of being, it sounds like the brain is in a panic and trying to do everything it can to survive.

BORJIGIN: In a sense, yes. I think that's what a brain is doing. It is like defense mechanism in a way, maybe. But how fruitful that mechanism that is kicked in at this moment is up for the debate.

And we don't understand. And this is a truly actually beginning of our research in this area. To think that when the brain is seemingly dead, when somebody's unresponsive, unaware, comatose, and all we could think of is the brain is not functioning. But maybe it's the opposite, even though seemingly the person's not responsive, not talking, not moving as if a brain is hypoactive, that is not active.

But internally, brain seems to be extremely active, in animal's case 100%. So brain has paradoxically activated. So we're trying to understand why would the brain be activated, beyond just a defense mechanism, perhaps if maybe from there we could understand mechanism of consciousness or how the brain, how do we all die, what happens to our brain when we do.

So I think there's really lots of interesting questions to ask.

CHAKRABARTI: Yeah. Charlotte, do you dare to put forth a hypothesis of why the brain might be extremely activated when in these moments?

MARTIAL: I think that today, it's difficult to say, but I agree with these hypothesis that can be a moment where the brain is trying to do everything it can to survive.

And regarding to that, I think that at least one of my hypotheses is that we can see near death experience as a defense mechanism, which maybe has been phylogenetically anchor in humans. And so here we can maybe make the assumption that near-death experience as a biological function at the moment of death.

Part III

CHAKRABARTI: I'd like to share another listener story with both of you.

This is Peter Panagore. He lives in East Boothbay, Maine. Peter says he's had two near death experiences. The first was in 1980 when he was ice climbing in Canada and suffered from severe hypothermia. And here's just a little bit of what he told us.

PETER PANAGORE: I had a peripheral vision of darkness, like a big sphere around me, and that big sphere started to close.

It went black, and I woke up and in front of me was this huge dark expanse, and way far in the distance, like a galaxy away, the single star appeared, a white star and the single white star rushed across this great expanse, and it communicated with me telepathically, and it said to me, I'm taking you. It's all over for you.

You're coming home. And it was like a gigantic orb of plasma, and I was shaped like a human, but I could see that I wasn't made of molecules, I was made of light.

CHAKRABARTI: Charlotte, let me ask you, in hearing the reports from the people who you have documented and then also Jimo's sort of in-depth investigation into what's going on biochemically in the brain.

It makes me wonder if we need to once again redefine what death actually is, right? Because right now, we've been talking about basically cardiac death, when someone's heart stops beating and the breathing stops. But to hear that there are some cases in which people have been experiencing something in their mind for 25 additional minutes, they're not really dead after their heart stops.

Charlotte.

MARTIAL: Sorry, it's just not clear. The question. Can you repeat.

CHAKRABARTI: I guess, is cardiac death or clinical death a good, a satisfactory dividing line now between life and death?

MARTIAL: I think that medicine has now a proper definition for clinical versus brain death condition. However, I think that the question that the remain open are about all the subjective experience that humans can experience at that time.

And also there is this question that remains open. It is, for example, for a patient that suffer from a cardiac arrest when exactly they did experience the near-death experience?

Was it just before, during, or after? With the research such as the recent one in animal and humans. We do the hypothesis that it's maybe just after the cardiac arrest, but just to say, today I think there are some questions that remains clearly open to have proper pictures of what we experience when we die or when we are in a severe physiological crisis.

CHAKRABARTI: Charlotte Martial, at the University of Liège in Belgium, thank you so much for joining us today. Okay.

MARTIAL: Thank you very much.

Thank you.

CHAKRABARTI: Jibo, I'd like to go even deeper into what your current research is showing about this activity. This activity spike in the brain after the heart stops.

So first of all, let's talk a little bit more about your rat studies. Because I understand that you did some studies in which certain neurotransmitters, there was, you explain, there was one that you did where you gave the rats carbon monoxide instead of oxygen. Is that right?

BORJIGIN: It is carbon dioxide.

CHAKRABARTI: Carbon dioxide. Okay.

BORJIGIN: Not carbon monoxide. It's a routine method for euthanizing animals at the end of our experiments. So it's not anything particular abnormal.

It's almost all experimental biologists know this protocol. We leave animals in the cage and then provide carbon dioxide sometimes with anesthetics and sometimes without, but it happens so fast. Within five minutes, the animals die. And during the studies, we also monitored a long, actually more than 20 neurotransmitters.

We published those results in 2015 studies. We saw this massive increase of neurotransmitters that are very important in neuroscience and for both animals and humans. We know the dopamine increased tremendously. Norepinephrine increased, the serotonin increased, and GABA increased. So these are really to the level that you never see in normal human beings.

400-fold increase of GABA. You never see normal human beings have this level of GABA increase. You never see 200 fold increase of serotonin in normal human brain. So this is just extremely abnormal level.

CHAKRABARTI: What does GABA do?

BORJIGIN: GABA is inhibitor neurotransmitters. Actually, it suppress the neuronal activity. Suppressed neuronal excitation.

So it makes me believe, because the GABA increase is tremendous. It last actually around 20 minutes after the carbon dioxide was infused into the cage, suggesting to me that the whole process of what the brain is doing is actually has this systematic, it's not random reaction.

This is almost like programmed in the animal's brain and human brain to deal with hypoxia. So when faced with hypoxia, this is life threatening for not just for the heart and for the rest of the body, but also extremely important for the brain. Without oxygen, the second you lose oxygen. In fact, our data published in 2023 shows this, within seconds of the ventilator withdraw.

That part of the brain immediately gets activated is the visual cortex. So literally within seconds. So I think the brain has extremely exclusively sensitive mechanism to detect oxygen level when it fluctuates.

CHAKRABARTI: Can I just jump in here?

BORJIGIN: Yeah, sure.

CHAKRABARTI: So about GABA, you said it inhibits neuronal activity.

BORJIGIN: Yes. Yes. Okay.

CHAKRABARTI: Is the GABA spike happening at the same time as say the serotonin or the dopamine or the norepinephrine spikes? Because it seems to be that doesn't really make sense to me.

BORJIGIN: Yeah. Here's the thing. Because the phenomenology is as soon as somebody is suffering cardiac arrest or even heart attack, not before the arrest.

So first thing happens, the person drops to the ground, okay? Lose their consciousness, no longer talking, moving. So all of these, my study would suggest is controlled behavior. It's not simply consequence of a passive loss of the brain function. It's actually, brain says, oh, there's a crisis coming.

Got to stop all discretionary functions my brain would use the energy for. Okay, what are the discretionary function of the brain? Anything you are not doing during the nighttime where you're asleep. Think about it. When you're walking and talking, moving. Active listening, very sensitive to sensory perceptions.

So while you're sleeping, all of these functions are tremendously reduced, if not stopped, for instance, voluntary movement and so forth. So these have to be actively stopped, says brain knows oxygen supplies is precious at this moment. So they need to stop everything that is consuming on oxygen.

Now you have to stop --

CHAKRABARTI: Can I just jump in here again. Do you forgive me? This is just so fascinating.

BORJIGIN: No, yeah, go ahead.

CHAKRABARTI: Because I can think of an analogy, another physiological analogy that, for example, when you're suffering from hypothermia, for example or you're just in a very deeply cold environment, the body tends to rebalance a little bit, at least the flow of blood.

To keep your core warm, right? Where your most vital organs are, and therefore your extremities actually get colder, something similar there.

BORJIGIN: Yeah. Similar. Also think about a hibernation. Animals hibernate during the wintertime when their food resources are scarce, so they have to reprioritize, so they lower their body temperature, they lower their metabolism, and to survive, survive the wintertime.

So in a similar manner, I believe their brain has its own mechanism to deal with the temporary lack of oxygen. Of course, if it's no longer temporary, it's a forever last lack of oxygen, then the animals go on die. But if it's temporary, then you could be have syncope and you fall to the ground and now rebalance, the body postures.

And then you may wake up from the short syncope. But if it's cardiac arrest, if heart doesn't come back in time, then it might be much longer. Protracted rescue effort is needed. So I think this, so therefore I believe that GABA, it's really the key there to suppress all discretionary function in the brain.

So make your brain to have room and time using the precious time or come up with some kind of high rescue effort and through communication with your heart.

CHAKRABARTI: And so this is where things like norepinephrine come in.

BORJIGIN: I believe norepinephrine, serotonin and dopamine.

Yeah. So adenosine, another transmitter is really interesting, increased tremendously. This is a chemical actually puts you to sleep. So somehow brain simultaneously on one hand suppress some set of neurons that contributes to voluntary function of your body, move your arms and so forth, and puts your brain to sleep so that your body would rely on respiration and cardiac so that your body still functions to some extent.

But then so there's like immediate reprioritization of your brain functions after the hypoxia hits you.

CHAKRABARTI: Okay, let's go back. This is so fascinating, but let's go back for a moment to another On Point listener. This is Karen. She's in Atlanta, Georgia, and she told us she had a near death experience just one week after her first child was born.

Karen tells us she developed an infection and started hemorrhaging at the hospital.

KAREN: I remember looking down on the room and seeing this horrible looking woman in the bed who is the color of the sheets. My husband holding her hand and I was thinking, oh gosh, I wonder who that person is. And I felt this warmth and there was a light and it felt like pure love.

I had a choice that I could stay and go toward that light, or I would have to go back and get into my body.

CHAKRABARTI: That sense of light and pure love that so many people report. I'm seeing how the dopamine and norepinephrine might be playing a role there. But Jimo, you've also done studies or your studies have also revealed some interesting things about like how the brain still has some kind of sensory perception hearing.

Is that right?

BORJIGIN: Yeah, so I think that, so our data shows the part of the brain that has the strongest activation, strongest activity is the left parietal temporal and occipital junction. So we call a TPO junction, Temporo-Parieto-Occipital junction. So within that area, there has visual information communicating between the visual cortex and the parietal lobe and with the temporal lobe.

And there's information between the temporal lobe and parietal lobe. These are the sensory areas of the brain, so that part of the brain responsible for speech perception, language perception, understanding languages on the left side of the brain. And emotion, empathy. Empathy, sympathy is actually thought to be located in the right side of the analogous regions.

And then clearly visual cortex is highly activated. So I think the survivors frequently described, they were able to hear somebody, let's say, emergency room doctors or nurses that say something, or the sound of equipment that is used for their surgery. And so that's probably true that it's actually, they maintain the sensory perception even though they cannot respond to that sensory perception, but they're able to hear conversations, particularly there may be their loved ones or somebody to the rescue.

So that's really interesting phenomenon that I think our data seems to support.

CHAKRABARTI: I was just thinking don't stop talking to your loved ones, right?

BORJIGIN:  Yes. Yes. Yes.

CHAKRABARTI: But especially in these moments, that seems to be what your research is showing. The empathy part is also very interesting. Because I think you've either done research or this correlates with other people's research where there are folks who've had these near-death experiences who maybe wouldn't self-report as being totally empathetic beforehand. But afterwards, when they regain consciousness, does that sense of empathy endure after the near-death experience?

BORJIGIN: Apparently, so the empathy really itself could not really be expressed during the comatose period for sure, but when they survive the ordeal and then maybe what's really enduring, what long lasting impact, that influence actually, their choice of a career afterwards, many people would decide to quit whatever they were doing.

They say they want to be more empathetic toward the others. They want to switch to different careers instead of working for money, maybe working for something else. So I think many people report increased empathy to others afterwards. And actually, that could be, effect could be long lasting.

And we know that empathy and the right side of the Temporoparietal junction has something to do with empathy. So I believe that because this area is strongly activated in patient one, I believe this may be the source of the empathy in these survivors.

Of course, even though we publish two out of four patients have the activation of the brain, so there's a distinction even between the patient one and patient three.

CHAKRABARTI: One last quick thing, you talked about how part of the brain that gets activated is very essential to memory, and I wonder if this helps explain people very frequently reporting, the phrase, I saw my life flesh before my eyes.

BORJIGIN: Yes. The life review.

Yeah, it's a rapid process. Because everything is in the gamma frequency, as fast as the brainwaves, yes, the memory because when your sensory system is all activated and then it's interactive with the temporal lobe, it can contrast in, try to pull, every time there's image.

You tell yourself, did I see this image before? Did I remember the sound before, image before? So you also pull that information from your temporal lobe. It's very important for auditory perceptions, for the memory.

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