Saturday, September 17, 2022

Near-death experiences: Why the physiological explanations are not sufficient

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Near death, many people have the most intense experience of their lives: a near-death experience. They leave their body - as they later report -, observe resuscitation efforts from above, enter another world, encounter deceased relatives there and a being of light who loves them unconditionally, relive their lives from the perspective of the people they have dealt with well or badly, and finally return to their bodies because their task in this life has not yet been fulfilled. After that, they are unshakably convinced that their lives have meaning and that there is life after death. Their values change: they are no longer competition- and success-oriented, but find it important to be fully present in the here and now and to lovingly encounter the people they are about to deal with.


Is this experience a sensory illusion of the dying brain? If so, it should actually be fully explainable physiologically, whether now or in the future. Or does it really happen at the transition to the world beyond, which awaits us after our death and from which our life on this side gets its meaning? Then every physiological explanation would have to come up against a limit which remains insurmountable.

If there is an expert on these questions, it is Bruce Greyson. The psychiatrist and neuroscientist is a natural scientist through and through. For a long time, he was convinced, like probably most of his colleagues: Everything that is, consists of physics; God does not exist; spirit exists only as an earth-historically late by-product of complex matter; when the brain dies, consciousness dies too. He abandoned this physicalist worldview only when he had a personal experience incompatible with it. Since then, he has been researching the phenomenon of near-death experience with the care and expertise of a natural scientist.

What has he found out? He reports about it among other things in his latest book "After". In the following, I rely mainly on his chapter about near-death experiences from the anthology "Consciousness Unbound" by Edward Kelly et al. (2021).

The physiological explanations and their limitations
How Greyson deals with all current physiological attempts of explanation: Of these, I can only offer a succinct summary here. If you want to know it more exactly, please read Bruce Greyson himself. With him you will also find the corresponding literature evidence and references to further literature.

Are near-death experiences caused by ...

  • ... lack of oxygen?
    Against this speaks:
    Near-death experiences also occur with increased or normal oxygen content in the blood.

  • ... an increased CO2 content in the blood?
    Against this speaks:
    Near-death experiences also occur with low and normal CO2 levels.

  • ... malfunctions of the brain?
    Against this speaks:
    Malfunctions of the brain impair the ability to think and lead to confused hallucinations. In contrast, near-death experiencers report clarity of thought. Their perceptions are not confused, but have a meaningful inner context.

  • ... medication?
    Against this speaks:
    Near-death experiences also occur without medication. Patients who receive medication report near-death experiences even less frequently than those who do not.

  • ... drugs?
    Against this speaks:
    True, some drugs produce experiences that can be described as spiritual. But these are very different from near-death experiences. This is also true of ketamine intoxication, which is actually said to bear the greatest resemblance to near-death experiences. While near-death experiences are usually exhilarating, with ketamine the terrifying experiences predominate.
    Most importantly, most near-death experiences do not occur under the influence of drugs.

  • ... REM activity in the brain, which is typical for dream states?
    REM is the sleep phase in which most dreams occur.
    Psychiatrists speculate that such REM activity could be induced by the dying brain to relieve the fear of death. In particular, they think of perceptions from the so-called "REM intrusion" such as an unusual light or the feeling of being dead.
    Against this speaks:
    After an REM experience, we realize that we have been dreaming. In contrast, near-death experiencers are unshakably convinced that their experience was real.
    Most importantly, near-death experiences often occur under conditions that make REM activity impossible, such as under general anesthesia.

  • ... hidden brain activity that is there without being detected by the electroencephalogram (EEG)?
    Against this speaks:
    It may be that there is
    some brain activity during a near-death experience that is not measurable. But the crucial question is a different one: Do those brain activities occur during the near-death experience that neuroscientists consider a necessary prerequisite for conscious experiences? These brain activities are measurable. And there are near-death experiences that have occurred at a time when it has been measured that these brain activities were not present.

  • ... an increase in electrical activity in the brain at the time of death?
    Against this speaks:
    This increase is not measurable with standard EEG. Therefore, it has only been detected with the bispectral index method. However, this method is very susceptible to interference. Various signals in the body, but also from the environment, can easily be misinterpreted as brain activity.
    In addition: Whereever this increase has been measured, a connection with near-death experiences has never been established.

Does enough electrical activity remain in the dying brain to produce a vivid and complex experience? Electrical activity was measured in the brains of dying rats 30 seconds after cardiac arrest. However, this was extremely low. It was only a fraction of the electrical activity before. To attribute this weak activity to the production of near-death experiences would contradict decades of clinical experience and research.

Most importantly, the increase in electrical activity after cardiac arrest in the brains of rats can be completely eliminated by anesthesia. However, near-death experiences also occur under anesthesia.

Can near-death experiences be attributed to a brain region?
Greyson also discusses in detail the attempts to find out in which region near-death experiences are located by stimulating certain brain regions. The main candidate here is considered to be the right temporal lobe. In fact, however, out-of-body experiences have been reported after brain surgery involving a wide variety of brain regions.

Perceptions artificially induced by stimulation of brain regions are quite different from near-death experiences:

  • Near-death experiencers repeatedly share correct observations from their out-of-body experiences that have as a prerequisite that they actually left their bodies. This is not the case with artificially induced out-of-body experiences.

  • The life reviews in near-death experiences are consistent, accurate, memorable, meaningful, and life-changing. In contrast, artificially induced memories are fleeting and dreamlike, and do not produce a change in one's outlook on life.

Another argument against attributing near-death experiences to a specific brain region is that memories of near-death experiences lead to activity in multiple brain regions.

Recent developments
In March 2022, news broke in the press that Estonian neurosurgeons had found the scientific explanation for near-death experiences. I summarized what Greyson had to say about this in my post of August 22, 2022.

Unfortunately, I have not yet found a statement from Greyson on the attempts to explain near-death experiences by discharge waves of the nerve cells. These waves occur a few minutes after a cardiovascular arrest, says neurologist Jens Dreier in Spektrum der Wissenschaft online (5.8.2022) (in German). According to him, they gradually spread throughout the brain, whose activity has actually already ceased 30 to 40 seconds after the cardiovascular arrest. Could these discharge waves be the cause of the light phenomena in near-death experiences? Dreier does not rule this out, but brings another possibility into play: endogenous drugs that might be released in this context. However, he himself describes these possibilities as "pure speculation". And because the discharge waves begin minutes after cardiovascular arrest, they can hardly explain those near-death experiences that take place before that time.

Interim
All physiological explanations for near-death experiences presented so far have as a prerequisite that a part of the reality of near-death experiences is ignored: Either one ignores those near-death experiences for which the proposed physiological conditions do not apply. Or one ignores features of a near-death experience that cannot be explained in this way.

But perhaps there is no need for
one explanation for all near-death experiences? Couldn't "near-death experience" be understood as a collective term for different phenomena with different physiological causes?

Against this, there are some features that most near-death experiences have in common: They are experienced as real, usually even more real than the reality that otherwise surrounds us; they are extremely complex and consistent; and they convey the same values across cultures: What matters in life is not status and material wealth. Rather, we are on earth to love and to learn.


Do near-death experiences show that consciousness can detach from the body?
Some phenomena associated with near-death experiences are considered by many to be concrete evidence that consciousness can detach from the body:

  • Increased mental activity at a time when such activity is not possible according to current brain research.

  • Perceptions during one's own operation from a perspective outside one's own body that are subsequently verified and confirmed by a third party.

  • Subsequently confirmed perceptions with sensory organs at a time when these sensory organs are switched off (e.g. visual perceptions despite taped eyes during surgery).

  • Subsequently confirmed observations at distant locations where the perceiving person was not physically present at the time of his/her observation.

  • Visual perceptions of blind people, including people blind from birth.

The phenomenon of terminal mental clarity also points in the same direction: people with high degree of dementia sometimes show mental clarity shortly before their death, which should actually no longer be possible in view of their irreversible brain damage.

Are near-death experiences cause for hope in life after death?
If consciousness can detach from the body: Does this mean that we have reason to hope that life continues after death? The following points of view speak in favor of this:

  • The conviction of almost all near-death experiencers that they - or a part of them - will live on after death.

  • Near-death experiences of children: These never report encounters with their closest living caregivers, but always encounters with people who have already died. This speaks against the fact that they are fantasies.

  • Encounters with the recently deceased, of whose death the person knew nothing before his near-death experience. Near-death experiencers have never been mistaken about whether a person is deceased or still alive.

  • Encounters with close deceased persons of whom the near-death experiencer did not know before, for example with the disowned biological father or with a sibling who died early and whom the parents had kept silent.

  • Near-death experiencers are always convinced that they met real people during their experience.

Conclusion
Near-death experiences are extremely intense, complex, and consistent experiences that often occur under conditions in which they are impossible according to current neurophysiological models. Sometimes they are accompanied by phenomena that are incompatible with the current scientific worldview. The experiencers themselves consider their experiences to be real, and afterwards they are unshakably convinced that life continues after death.

This finding does not force you into anything. How you deal with it is up to you. Whatever conclusion you may come to: You will always find experts who agree with you and experts who don't. Because this is where we touch on the ultimate questions. And experts can at best provide clues to these questions. Something else is decisive: your personal power of judgment. Don't let yourself be too impressed by any experts, regardless of which direction they belong to, but trust your own judgment instead.


Sources

This translation is based on DeepL Translator.

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