Does life really flash before our eyes when we die?

Guillaume Thierry, a professor of cognitive neuroscience at Bangor University, wanted to know how long people stay awake after death.

The first time I overcame the extreme horror of the concept of death and wondered what it might be like to experience death, I was about 15 years old. a guillotine.

The words I remember to this day are the last of Georges Danton on April 5, 1794, who is said to have told his executioner, “Show me my head, it’s worth seeing.” Years later, having become a cognitive neuroscientist, I began to wonder to what extent a brain suddenly detached from the body could still perceive the environment and be able to think.

Danton wants his head shown, but can he see or hear people? Was he awake, even for a brief moment? How did his brain stop working?

On June 14, 2021, I was intensely reminded of these questions. I was on my way to Marseille, France, summoned by my mother to Avignon because my brother was in critical condition, a few days after being suddenly diagnosed with terminal lung cancer. But when I landed, I was told my brother had passed away 4 hours ago. An hour later, I found him still perfectly still and beautiful, his head tilted slightly to the side as if he were fast asleep. Only he wasn’t breathing anymore and he was cold to the touch.

No matter how much I refused to believe it that day, and during the months that followed, my brother’s extraordinary inventive and creative mind vanished, vanished into thin air, only is palpable. works of art he left behind. However, during the last moment I was allowed to spend with his lifeless body in the ward, I felt the urge to talk to him.

And I did, despite 25 years of studying the human brain and fully knowing that about six minutes after the heart stops, and the blood supply to the brain is interrupted, the brain essentially dies. Then the decline reaches the point of no return and core consciousness – our ability to sense that we are here and now, and to realize that the thoughts we have are ours. own – lost. Is there anything left in my beloved brother’s mind to hear my voice and think, five hours after his death?

Some science experiments

The tests were done in an attempt to better understand the reports from people who have had near-death experience. Such an event is associated with out-of-body experiences, deep feelings of happiness, calling, seeing lights above, but also profound outbursts of anxiety or anxiety. Empty and completely silent. A major limitation of studies looking at such experiences is that they focus too much on the nature of the experiences themselves and often ignore the context that precedes them.

Some people who have undergone anesthesia while in good condition or had a sudden accident that resulted in an immediate loss of consciousness will have no basis to experience profound anxiety when their brain begins to shut down. work. In contrast, those with a long history of serious illness may have more difficulty.

It’s not easy getting the right to study what’s really going on in our brains during the last moments of our lives. But a recent newspaper examined the electrical brain activity in an 87-year-old man, who had sustained a head injury in a fall, when he died from a series of seizures and cardiac arrest. Although this is the first publication of such data collected during the life-to-death transition, the paper is highly speculative when it comes to “experiences of the mind”. ” comes with the transition to death.

The researchers found that certain brain waves, called alpha and gamma, changed patterns even when blood had stopped flowing to the brain. “Given the cross association between alpha and gamma activity involved in cognitive processes and memory recall in healthy subjects, it is tempting to speculate that such activity might aid in a single ‘remembering’ back to life’ can eventually take place in a near-death state. ,” they wrote.

However, such associations are not uncommon in healthy brains – and do not necessarily mean that life is flashing before our eyes. Furthermore, the study failed to answer my basic question: how long does it take after oxygen is stopped to the brain for essential neural activity to disappear? The study only reported on recorded brain activity over a period of about 15 minutes, including minutes after death.

In mice, experiment determined that after a few seconds, consciousness is lost. And after 40 seconds, most of the neural activity was gone. Some studies also show that this brain shutdown is accompanied by by releasing serotonina chemical associated with arousal and feelings of well-being.

But what about us? If people can be resuscitated after six, seven, eight or even ten minutes in severe cases, it could theoretically take several hours before their brains stop working completely.

I’ve come across a number of theories that try to explain why life is snuffed out in front of someone’s eyes when the brain is about to die. Maybe it’s a completely man-made effect related to the sudden increase in neural activity when the brain begins to shut down. Maybe it was a last resort, the body’s defense mechanism trying to overcome impending death. Or maybe it’s a deep-rooted, genetically programmed reflex that keeps our minds “busy” as the most traumatic event of our lives is about to happen.

My theory is a bit different. Possibly our most essential driver of existence is to make sense of our own existence. If that’s the case, then seeing one’s life flash before one’s eyes could be our last attempt – no matter how desperate – to find answers, necessarily fast-tracking. because we’re running out of time.

And whether or not we are as successful or as delusional as we are, this must bring about absolute mental happiness. I hope that future research in this area, with longer measurements of neural activity after death, possibly even brain imaging, will support this idea – whether it takes minutes or hours, for my brother’s sake and for all of us. .

Guillaume ThierryProfessor of Cognitive Neuroscience, Bangor University

This article was republished from Conversation under a Creative Commons license. Read original article. Does life really flash before our eyes when we die?

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