In the last minutes of life, some people’s brains produce surprisingly organized surges of electrical activity that may reflect consciousness, but scientists aren’t entirely sure. Is not.
This surge can occur after a person stops breathing but before the brain stops functioning, according to new research published Monday (May 1) in the journal PNAS. Somewhat similar to those seen when in a waking or dream-like state, presumably these electrical surges reflect otherworldly experiences reported by people nearing death. leads to From outside; tunnel and white light. Or the feeling of reliving an important memory.
However, all patients in the current study eventually died, so it is impossible to know if they had such an experience.
“When it comes to the dying process, we know very little about it,” said Jimo Borjigin, a neuroscientist at the University of Michigan School of Medicine who led the study. “This is probably the first study to really show how the brain dies in seconds,” Borjigin told Live Science.
Related: Is brain death reversible?
Near-death experience
Some who have returned to life from the brink of death report seeing or hearing unexplained things during reanimation or while appearing unconscious. The reason for these near-death experiences is unknown, and it’s not even clear if they are death-specific.
Daniel Conziera, a neurologist at the University of Copenhagen, said international research suggests that only about half of so-called “near-death experiences” are actually life-threatening situations. Stated. The other half happens during meditation or in frightening situations that don’t endanger your health or affect your brain’s metabolism, Kondiziella told his Live Science.
“The problem is that you can’t tell from the experience itself whether someone has had cardiac arrest or fainting. [a brief loss of consciousness] Or a near-miss car accident,” said Kondiziella.
Because people who survive to report near-death experiences are inherently different than those who have died, for example, because their brains are not permanently disabled, people who have actually died are also subjective to these subjective experiences. It’s hard to tell if you have experience or not.
In 2013, Borjigin and her colleagues measured brain electrical activity in rats euthanized by cardiac arrest. They found that the brain showed a surge of what are called gamma waves, the highest frequency electrical oscillations in the brain, for about 30 seconds after the heart stopped. Gamma waves are correlated with conscious experiences, but they don’t necessarily prove that someone is conscious. These are just one of many indicators someone might be aware of and be vigilant about.
In 2022, another group of doctors happened to be monitoring an 87-year-old man’s brain with an electroencephalogram (EEG) when he died suddenly. Similar to Borjigin’s rat, the man’s brain showed a surge of gamma-ray activity during his 30 seconds before and after his heart stopped.
“Reading” the Dying Brain
In their new paper, Borjigin and her team made a deliberate effort to use EEG to capture what the brain looks like during death.
The researchers were given permission to monitor a dying patient in an intensive care unit whose respiratory support was removed after treatment proved futile. The study included a total of four patients, all comatose after cardiac arrest.
Thirty seconds to two minutes after the ventilator was removed, gamma wave surges were seen in two of the four patient’s brains. Interestingly, this gamma activity appeared organized in that gamma waves in some parts of the brain were associated with predictable patterns of activity in other areas.
The temporoparietal junction, the brain region where the temporal and parietal lobes meet, was particularly active in gamma waves toward the back of the brain behind the ear. This area is known to be activated when people have out-of-body experiences or dreams, Borjigin said.
The new findings mirror what was seen in an 87-year-old patient who died unexpectedly, says Borjigin, a neuroscientist and data scientist at the University of Tartu who co-authored the 2022 study. “I’m very happy to have confirmation,” said Raul Vicente, who was not involved in the study.
“The more consistent results we get, the more evidence that this is likely the mechanism that’s going on at death, and the more we can pinpoint this to one place, the better,” said a neurosurgeon at the university. Ajmal Zemmar, who is also a co-author of the 2022 study, said Louisville Health.
Zemmar and Vicente are optimistic that these signals could be signs of a conscious experience of the moment of death. But Kondziella is more skeptical, reflecting the debate in this area.
“We know that heart death takes time, as opposed to brain death,” he said. Minutes pass between the heart stopping and the brain cells dying, he said. “It’s not a big surprise for those few minutes. You’ll see abnormal electrophysiological activity in your brain.”
According to Conziera, some people may experience some kind of near-death experience during these moments, but they may never know for sure. may not be from A more likely explanation for near-death experiences, which include both life-threatening and non-life-threatening experiences, could be “the intrusion of REM sleep into wakefulness,” he said. A state in which the brain is a mixture of waking and dreaming states. (REM sleep is characterized by patterns of dream and brain activity that are very similar to those of wakefulness, including gamma waves and other low-frequency waves.)
Borjigin’s team is still collecting end-of-life data in hopes of adding evidence that the dying brain can produce predictable gamma wave patterns. Other research groups are already trying to use artificial intelligence to identify objects seen in dreams based on brain activity. Similar mind-reading techniques may be possible with unconscious and dying patients, Vicente said.
“This opens up the opportunity to be able to decipher what different comatose people are thinking at some point, if we collect enough data,” said Vicente.
Copyright 2023 LiveScience, a company of the future. all rights reserved. This material may not be published, broadcast, rewritten or redistributed.
