[thedoc (OP)]

Patients who have heart attacks often report having strange experiences including seeing bright lights. But what causes them?
Read a transcript of the interview by clicking here

or [chapter podcast=1000466 track=13.08.15/Naked_Scientists_Show_13.08.15_1001208.mp3] Listen to it now[/chapter] or [download as MP3]

[grizelda]

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.

[dlorde]

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

... 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.

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.

[Europan Ocean]

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...

[dlorde]

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...

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.

[distimpson]

May be relevant to this discussion: New Brain Activity State Exists In 'Flat Line' Coma Patients, Scans Suggest http://www.huffingtonpost.com/2013/09/19/brain-activity-coma_n_3953473.html

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.

[dlorde]

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.

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

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?

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 all chemical processes are stopped I can not see how there would be any perception/consciousness, would this be considered a near death experience?

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?

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.

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.

[distimpson]

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?

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.

[Europan Ocean]

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.

[distimpson]

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.

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.