Near-death experiences and consciousness

The most remarkable thing, Van Lommel says, is that his patients have such consciousness-expanding experiences while their brains register no activity. But that’s impossible, according to the current level of medical knowledge. Because most scientists believe that consciousness occurs in the brain, this creates a mystery: How can people experience consciousness while they are unconscious during a cardiac arrest (a clinical death)?
After all those years of intensive study, Van Lommel still speaks with reverence about the miracle of the near-death experience. “At that moment these people are not only conscious; their consciousness is even more expansive than ever. They can think extremely clearly, have memories going back to their earliest childhood and experience an intense connection with everything and everyone around them. And yet the brain shows no activity at all!”
This has raised a number of large questions for Van Lommel: “What is consciousness and where is it located? What is my identity? Who is doing the observing when I see my body down there on the operating table? What is life? What is death?”
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In order to convince his colleagues of the validity of these new insights, Van Lommel first had to demonstrate that this expansion of the consciousness occurred, in fact, during the period of brain death. It was not difficult to prove. Patients were often able to describe precisely what had happened during their cardiac arrest. They knew, for example, exactly where the nurse put their dentures or what doctors and family members had said. How would someone whose brain wasn’t active know these things?
Nevertheless, some scientists continue to assert that these experiences must happen at a time when there is still some brain function going on. Van Lommel is crystal clear in his response: “When the heart stops beating, blood flow stops within a second. Then, 6.5 seconds later, EEG activity starts to change due to the shortage of oxygen. After 15 seconds there is a straight, flat line and the electrical activity in the cerebral cortex has disappeared completely. We cannot measure the brain stem, but testing on animals has demonstrated that activity has ceased there as well. Moreover, you can prove that the brain stem is no longer functioning because it regulates our basic reflexes, such as the pupil response and swallowing reflex, which no longer respond. So you can easily stick a tube down someone’s throat. The respiratory centre also shuts down. If the individual is not reanimated within five to 10 minutes, their brain cells are irreversibly damaged.” He is aware that his findings on consciousness fly in face of orthodox scientific thinking. It is remarkable that an authoritative science journal like The Lancet was willing to publish his article. But it wasn’t without a struggle. Van Lommel recalls with a smile, “It took months before I got the green light. And then they suddenly wanted it finished, within a day.”

After 15 seconds there is a straight, flat line and the electrical activity in the cerebral cortex has disappeared completely.

Our results show that medical factors cannot account for NDES...

Our results show medical factors cannot account for recurrence of NDEs...

With lack of evidence for any other theories for NDE, the thus far assumed, but never proven, concept that consciousness and memories are localised in the brain should be discussed. How could a clear consciousness outside of one's body be experienced at the moment the brain no longer functions during a period of clinical death with flat EEG?

We defined clinical death as a period of unconsciousness by an insufficient blood supply to the brain

Now where does it say that there is a flat EEG for the entire period of time?

assumption doesn't mean that all of those people were flatlining when they had their NDEs. Whether there was any electrical activity or not is only important if you can show that the NDE actually occurred during that period, not merely that they recall it as having done so but some actual objective measure to allow you to place the timing.

There is only one claim of flat EEGs... so it's really hard to accept as scientific evidence.

The important point is whether there's believable evidence of conscious activity happening without corresponding brain activity. The quality of the conscious experience doesn't matter at all.

Sorry, I didn't catch what this means.