Some neuroscientists pointed out in the early 1980s that the “sudden death experience” has the characteristic characteristics of a typical marginal leaf (a part of the brain) that can be explained by the release of endorphins and enkephalins in the brain. Some neuroscientists suggested in 1983 that the release of endorphins can cause a “death experience” full of joy or emotion, while allyoxymorphone produces a “hell-like” near-death experience. The first formal “death experience” neurological model was proposed in 1987 and includes brain endorphins, neurotransmitters in the limbic system, and other brain parts.
In 1989, neuroscientists proposed a neurophysiological model of the “death experience”, arguing that serotonin plays an important role in producing a “death experience”. The study found that an anesthetic, ketamine, induces a “death experience.” By intravenous injection of a dose of ketamine, all the common contents of the “death experience” can be produced. In the 1990s, neuroscientists studied the hallucinogen dimethyltryptamine and proposed a hypothesis: a large amount of dimethyltryptamine released from the pineal gland in humans before or during sudden death. The cause of the phenomenon of sudden death.
In 2006, scientists passed through cardiovascular interventions, causing 42 healthy volunteers to experience fainting. Afterwards, these volunteers reported on the “death experience” of seeing light, tunneling, meeting relatives and visiting other worlds. In 2008, neuroscientists suggested that the “death experience” of clinical deaths is a mental dysfunction syndrome caused by a severe brain failure (caused by the cessation of blood circulation in the brain). Studies have also shown that hypercapnia (hypercapnia) in the blood can induce symptoms of “death experience” such as light, vision and mystical experience. There are also neuroscientists who suggest that the “death experience” is an illusion caused by cerebral hypoxia, drugs or brain damage.
The anesthesiologist Zola and his team at George Washington University in the United States believe that the “death experience” is caused by a surge in electrical activity caused by oxygen depletion in the brain before death. The degree of soaring is similar to that of a fully conscious person, but the former’s blood pressure is too low to detect, but it still produces vivid images and feelings. The gradual loss of brain activity occurs within approximately one hour before death and is interrupted by bursts of brain activity that last from 30 seconds to 3 minutes. The Zola team’s study of seven sudden death patients found that the increase in brain electrical activity occurred when blood pressure could not be detected. Their “sudden death experience” may be a memory of the total memory of synaptic memory, and dying. However, it is related to potentially reversible hypoxemia. A study released in 2010 said that the root cause of the “death experience” is that the high concentration of carbon dioxide in the blood changes the chemical balance of the brain, allowing the brain to “see” things.
In the “death experience”, the left temporal lobe activity of the brain increases. Stimulation of temporal lobe is known to induce hallucinations, “soul out” and memory flashbacks. In an experiment with one patient, electrical stimulation of the left temporal apical junction resulted in the patient’s illusion that another person was close to her. In 2011, an article published in the famous magazine Scientific American concluded that “the scientific evidence shows that all the features of the “death experience” have the roots of normal brain function errors.”
Some scholars claim that part of the “death experience” case occurs when the EEG is flat (ie, the brain is no longer functioning). However, some scholars have noticed that EEG is not a reliable indicator of brain death, because it can only detect half of the activity of the cerebral cortex, but it is not visible to the deeper cerebral cortex structure.
Many people who have experienced the “death experience” regard it as evidence of the existence of “post-mortem life” (“afterlife”) or “post-death consciousness”. The idealist claims that the “death experience” is evidence that “dematerialized consciousness” or “soul” exists separately from the flesh. However, materialists have pointed out that although physiological factors such as brain damage, intracranial hypoxia or hypercapnia are not sufficient to explain the full nature of the “death experience”, this does not overturn the scientific conclusion that only the living human body can produce consciousness. The idealism is simply untenable.
Scientists who have a negative attitude toward idealism point out that there is so far no evidence to support the existence of life after death. However, some studies have found that even during the period of unconsciousness, the brain can still record the impression. For example, in an experiment conducted in 1983, scientists used a vocabulary tape to test the memory of an anesthetized patient. After physical rehabilitation, these patients were able to identify which words appeared in the vocabulary that was played to them at a time that was significantly higher than the proportion of sporadic cases. The explanation for this is that even under the condition of total anesthesia, the brain still retains some of the ability to store new information. The “auditory” content accompanying “visual” in the “death experience” is likely to be related to this.
Scientists who don’t believe in “post-death consciousness” and “afterlife” also point out that the inference of the brain’s complete cessation of activity in clinically dead patients and the inference of the sudden death experience after brain death are untenable. In fact, most of the brain activity will not occur during the patient’s cardiac resuscitation attempt, as it takes too much time to save lives. So there is a possibility that even if the EEG shows a flat line (ie the patient has brain death), the patient still has brain activity, which is performed by functional magnetic resonance imaging, positron emission tomography or computer aided A tomography scanner can be explored because, unless it is directly connected to the brain through surgery, the electroencephalograph mainly measures the surface activity of the cerebral cortex.
In short, the mainstream scientific community still does not support the so-called “post-death consciousness”, and even less agrees with the existence of “soul.” In fact, although the scientific community still has controversy about the concept of consciousness, the standard of death, and the “death experience”, the mainstream view is still the material decision consciousness, and there is no consciousness without life.