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New research suggests that the brain does not die immediately after the heart stops, but rather explodes in conscious activity.

Wen| Sara Reardon

edit| Liu Jiayu

Many people who have been resurrected from the dead have described having out-of-body feelings. Their experiences are very similar, such as life experiences flashing before their eyes, memorable moments reappearing in their minds, out-of-body experiences, feeling like they are looking at themselves outside their bodies, and so on.

Recently, a small study mapped the brain activity of four volunteers at the end of their lives. The results showed that when their hearts stopped beating, brain activity exploded.

A study published in May 2023 in the Proceedings of the National Academy of Sciences may explain why images of this life suddenly flash back in the mind after a heartbeat stops. "This suggests that the brain is recognizing the markers of conscious awareness," said Sam Parnia, a pulmonologist at New York University Langone Medical Center. "

Although death has long been medically defined as the irreversible cessation of the heart, recent research has shown that brain activity in many animals and humans can persist for seconds or even hours after the heart stops beating. For example, in 2013, neuroscientist Jimo Borjigin's team at the University of Michigan found that 30 seconds after the heart stopped beating in mice, the brain still showed signs of consciousness. Parnia said: "The binary concept of life and death is outdated. "

"Despite hundreds of years of research on clinical death or near-death, we know very little about brain activity in the dying process," Bolzikin said. "In her study, she and her team reviewed the medical records of four volunteers who were comatose and dependent on life support for vital signs, and doctors put EEG caps on the volunteers.

The EEG cap continuously monitored the electrical signals in each volunteer's brain. During the monitoring, the brains of two volunteers were suddenly lit up by a high-frequency pattern of neuronal activity in gamma waves, and two seconds later their hearts stopped beating. The high-frequency pattern persisted after the heart stopped beating. At the same time, related research has found that when a healthy person actively recalls the past, studies or dreams, the same brain electrical patterns appear, neuroscientists believe that this brain electrical activity is closely related to consciousness.

Ajmal Zemmar, a neurosurgeon at the University of Louisville in the United States, said gamma waves may indicate that different brain regions are working together to combine different sensations into awareness of objects. For example, combining vision, smell and hearing. By working in concert with these senses, we quickly perceive everything around us in our brains and build up a picture. "How the brain does this is one of the biggest mysteries in neuroscience," Zemora said. "But monitoring the same gamma waves in dying people suggests that there is a biological mechanism for the brain to recall memorable memories at the end of life. Zemora's lab had previously detected similar gamma waves in a patient who had died of a heart attack while his brain was being monitored for seizures.

A brain burst at death or a protective mechanism? Charlotte Martial, a biomedical scientist at the University of Liège in Belgium who studied near-death experiences, said: "This study is very important for the field of near-death experiences and for the field of consciousness more generally. But not all near-death survivors had flashbacks or out-of-body experiences, and only two of the four volunteers in Bolzikin's study showed gamma activity. Bolzikin pointed out that the two volunteers had a history of epilepsy, which she believes may have caused abnormal brain rhythms.

Bolzikin's team also found a significant increase in electrical activity in the brain's temporal-parietal-occipital junction, an area associated with consciousness that is activated during dreams, seizures and near-death experiences. She thinks the burst of brain activity is a survival protection mechanism that goes into this mode when the brain is deprived of oxygen. Studies of animals that experience brain death have found that when dying, the brain shuts down external signs of consciousness, releasing large amounts of signaling molecules and producing unusual brain wave patterns in an attempt to revive.

Bolzikin hopes to test her findings by collaborating with other medical centers to study brain activity in terminally ill patients. Zemora said it was crucial to find answers to how the death process occurred. Through this research, we can unravel the mysteries of death and learn more about the brain. It's a step closer to unraveling the mysteries of the human body and birth, aging, and death.

References:

https://www.science.org/content/article/burst-brain-activity-during-dying-could-explain-life-passing-your-eyes

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