The experience of people passing by with death usually leaves a lasting mark in the human brain. At this time, some people will have mysterious near-death experiences of the brain, such as the disappearance of pain, seeing the light at the end of the tunnel, feeling that they are out of the body, floating in the air, etc.
Although it is difficult to directly study such special experiences, scientists can reveal how the brain works under extreme conditions through experiments that produce similar experiences.
Near-death experience will leave a deep memory
when the body when subjected to blunt trauma, heart disease, suffocation and shock and other life-threatening injuries, will trigger near-death experience. In the hospital, 1 in 10 patients with cardiac arrest have had a similar experience. Thousands of survivors, after experiencing this fleeting painful moment, described it like this: They broke away from their damaged bodies, entered an environment beyond their daily existence, and were no longer bound by the usual boundaries of time and space. These mysterious and highly impactful experiences can lead to permanent changes in their lives.
The near-death experience is not an illusion. Their experience also includes encountering living or dead relatives, friends, and spiritual bodies such as angels; generating memory backtracking, even recalling good or bad memories in a lifetime; or distorting the perception of time and space. Part of the perception phenomenon can be explained by physiology. For example, the gradually narrowing tunnel scene is due to the decrease of blood flow around the retina, which causes the area around the visual field to lose vision first.
The near-death experience may be positive. This shocking experience will separate the peace of mind from the huge trauma suffered by the body, and make people feel like being one with the universe. However, not all near-death experiences are joyful. Some experiences are terrifying, accompanied by intense fear, pain, loneliness, and despair.
Any close contact with death will remind us of the uncertainty and fragility of life, and can break through some of our psychological defenses-these defenses would have kept us away from the idea of life disappearing. In most cases, the impact of these events will gradually diminish over time and eventually return to normal (although they may leave PTSD). However, near-death experiences may be recalled with unusual intensity and clarity in the following decades.
In a 2017 study, researchers at the University of Virginia in the United States asked whether the contradiction between increased cognitive function and impaired brain function during a near-death experience can be interpreted as a leap in imagination . The researchers conducted a questionnaire survey of 122 people who had experienced near-death experiences and asked them to compare the near-death experiences in their memories with real and imagined events that occurred at about the same time. The results show that the memories of near-death experiences are more vivid and rich in details than real or imagined situations. In short, in their memory, the near-death experience is “more real than reality.”
Neural activity is difficult to accurately understand
it is difficult to know precisely nervous system activity NDE, because the brain may be damaged due to various complicated ways. In addition, when the patient lies in the MRI scanner or the scalp is covered by electrodes, it will not happen to have a near-death experience.
However, by studying cardiac arrest, we may be able to gain some insight into what happened when the near-death experience occurred. At this time, the patient has not died, and the heartbeat can be restored by cardiopulmonary resuscitation. Now, the criteria for determining death also include irreversible loss of brain function. When the brain lacks blood flow (ischemia) and oxygen (hypoxia), the patient will faint in less than a minute, and his EEG will become equipotential, that is, the EEG is flat.
This means that in the cerebral cortex (the outermost layer of the brain), large-scale, all over the brain electrical activity has stopped. It’s like a small town that gradually loses power. Block by block is powered off, and local areas of the brain stop working one by one. However, the mind will continue to operate with the support of neurons that have not stopped activity: according to personal experience, memory and cultural background, continue to tell stories in the brain.
In this kind of “power failure” situation, the brain’s experience also constitutes the strange and special main content of the near-death experience. But for those who have experienced it, the near-death experience is as real as any perception that the brain produces when it is normally awake. When the entire brain stops working because of a complete “power failure”, thinking and consciousness will disappear. When the blood supply and oxygen supply return to normal, the brain will restart and resume daily functions.
Scientists used instruments to record the process of loss of consciousness and subsequent regaining consciousness of some people who received high-intensity training, and carried out a careful study on this. The phenomena they describe include the appearance of tunnel vision and bright light; the feeling of waking up from a partially or completely paralyzed sleep; the feeling of floating peacefully or the soul out of the body; feeling happy or even ecstatic; appearing short but intense dreams, often involving family members Many years later, the dialogue is still vivid.
The special nature of near-death experience also determines that scientists cannot study this experience under strictly controlled experimental conditions, but this situation may change. For example, we may be able to study some aspects of this phenomenon through mouse experiments.
Physiological mechanisms more research is needed
in many neurologists noticed that near-death experience with the effects of a class is called complex partial seizures arising similarities. This type of epilepsy can cause partial loss of consciousness, usually confined to a certain area of the brain hemisphere. Their onset is with signs, and these signs are related to the patient’s own special experience. Seizures may be accompanied by changes in the perception of object size, unusual taste, smell, or proprioception, as well as memory hallucinations, depersonalization, or ecstasy.
Whether it is caused by a spontaneous disease or triggered by a surgeon’s electrode, the direct connection between abnormal neural activity patterns and subjective experience supports that it originated from biological mechanisms rather than supernatural factors such as the soul. The origin of the near-death experience may also be the same.
It is still a mystery why the brain considers the experience of struggling to maintain functioning as positive and happy rather than panic during ischemia and hypoxia. However, it is interesting that humans will also have extreme experiences in some other occasions. For example, in scenarios such as deep diving, high-altitude rock climbing, flying, etc., the reduction of oxygen can bring people a sense of joy, dizziness, and high excitement.
To really understand the physiological mechanisms of near-death experiences, we
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neural activity abnormalities
Clinically, epilepsy characterized by ecstasy is also called Dostoevsky epilepsy. The name comes from the Russian writer Fyodor Dostoevsky at the end of the 19th century. He suffered from severe temporal disorders. Ye epilepsy. In the novel “Idiot”, Dostoevsky described the protagonist Duke Myshkin’s epileptic seizures in this way: When the seizure is or is about to happen, he always feels the whole heart, mind and body for one or two moments. All awakened in vitality and light. At that moment, he was full of joy and hope, and all his anxiety seemed to be swept away forever; however, these moments were the last seconds before the epileptic seizure, which signaled that the epileptic seizure was about to come, and it did not last for a second. Will be late. Of course it was indescribable at that moment. When the epileptic seizures stopped and the Duke recalled his symptoms, he often said to himself: “Although it is a disease, caused by abnormal nerve spasms in the brain, what does it matter? When I think about and taste these moments , It seems to be the highest level of harmony and beauty: in the deepest feeling at that moment, it is filled with infinite joy and ecstasy, with ecstatic piety and even the most complete life. I wish for this Give my life all the time.”
More than 150 years later, neurosurgeons can stimulate a part of the cortical area in the brain of epilepsy patients-the insula, to induce this feeling of ecstasy by implanting electrodes. This process helps to locate the epilepsy focus and prepare for possible resection. Patients report that they experience bliss, increased happiness, increased self-awareness, or increased perception of the outside world, and stimulating gray matter elsewhere in their brains can also trigger soul out of the body or visual hallucinations.
