NDEs cannot be explained as brain activity

“Anyone who dies,” Dr. Parnia explains, “loses consciousness with the immediacy of a hammer blow, and electrical activity in the brain ceases in about ten seconds. Scientifically speaking, people who lose consciousness under these circumstances, by definition, should not be able to report highly lucid, details, and chronologically accurate memories and accounts of the experience. And in fact, the vast majority of patients who undergo any brain injury don’t remember anything immediately preceding or following the incident. Yet somehow people who claim these conscious mental processes during the period of clinical death enjoy an inexplicable ability to recall details of which they should be wholly unaware.”

“Because brain function is so complex, scientists investigating NDEs looked for further chemicals that could be involved in the dying brain theory—that is, the theory that a chemical change in some part or parts of the brain involved with human experiences, sensations, and feelings could be causing the experience to occur as a type of hallucination. Drugs administered at the time of death seemed like an obvious explanation, but an examination of the medical literature doesn’t support this possibility. Studies show that many NDEs took place without any medications even being administered or that people with and without the experiences had had the same medications.

“The bottom line is that no brain-based chemical change can define whether a sensation or feeling is real or not. The brain regions involved with any feeling or emotion may not distinguish how they have become active, just that something has activated them.

“Dr. Karl Jansen, a New Zealand brain researcher with expertise in the effects of drugs on the brain, studied the effects of ketamine and suggested that NDEs might be occurring as a hallucination through activation of the same areas of the brain when people are critically ill and deprived of oxygen. Testing this theory was another matter. Its major limitation is the same as the oxygen theory.

“Not only would identifying a specific receptor or chemical not determine the reality or otherwise of the experience, the receptor being discussed (the NMDA) receptor) is very widely found in the brain and is involved in many other experiences and activities, such as memory recall, without causing hallucinations. Therefore, it would not be sufficient to assume that simply by virtue of it being active, an experience is a hallucination or real.

“Another impediment to testing this theory, as with all chemical-based theories, is that after death has taken place, the brain has shut down and these cells are not in their usual state but are in fact undergoing their own process of death. They are severely abnormal and not in a state to mediate thought processes, whereas when someone has taken drugs and hallucinates, the brain is functioning and the cells are not dying, which is why he or she can experience these visions.

“The other problem with the theory was that the hallucinations described by people who used drugs were not like the visions described by those who had NDEs."

Sam Parnia, Erasing Death: The Science That is Rewriting the Boundaries Between Life and Death (HarperOne, 2013), 225-227.