![]() And after 40 seconds, the great majority of neural activity has disappeared. In rats, experiments have established that after a few seconds, consciousness is lost. What’s more, the study did not answer my basic question: how long does it take after the cessation of oxygen supply to the brain for the essential neural activity to disappear? The study only reported on brain activity recorded over a period of about 15 minutes, including a few minutes after death. However, such coupling is not uncommon in the healthy brain – and does not necessarily mean that life is flashing before our eyes. “Given that cross-coupling between alpha and gamma activity is involved in cognitive processes and memory recall in healthy subjects, it is intriguing to speculate that such activity could support a last ‘recall of life’ that may take place in the near-death state,” they write. ![]() The researchers discovered that some brain waves, called alpha and gamma, changed pattern even after blood had stopped flowing to the brain. While this was the first publication of such data collected during the transition from life to death, the paper is highly speculative when it comes to possible “experiences of the mind” that accompany the transition to death. But a recent paper examined electrical brain activity in an 87-year-old man who had suffered a head injury in a fall, as he passed away following a series of epileptic seizures and cardiac arrest. It isn’t easy to get permissions to study what actually goes on in the brain during our last moments of life. On the contrary, someone who has a protracted history of a serious illness might be more likely to get a rough ride. Some people, having undergone anaesthesia while in good shape or having been involved in a sudden accident leading to instant loss of consciousness have little ground to experience deep anxiety as their brain commences to shut down. One key limitation of studies looking into such experiences is that they focus too much of the nature of the experiences themselves and often overlook the context preceding them. Such an event has been associated with out-of-body experiences, a sense profound bliss, a calling, a seeing of a light shining above, but also profound bursts of anxiety or complete emptiness and silence. Could there be anything of my beloved brother’s mind left to hear my voice and generate thoughts, five hours after he had passed away? Some scientific experimentsĮxperiments have been conducted in an attempt to better understand reports from people who have had a near death experience. Then, deterioration reaches a point of no return and core consciousness – our ability to feel that we are here and now, and to recognise that thoughts we have are own own – is lost. What can brain waves really tell us? ShutterstockĪnd I did, despite 25 years of studying the human brain and knowing perfectly well that about six minutes after the heart stops, and the blood supply to the brain is interrupted, the brain essentially dies. Only he was not breathing anymore and he was cold to the touch. ![]() An hour later, I found him perfectly still and beautiful, his head slightly turned to the side as if he was in a deep state of sleep. But when I landed, I was told my brother had passed away four hours ago. I set off to Marseille, France, having been summoned to Avignon by my mother because my brother was in a critical state, a few days after being suddenly diagnosed with terminal lung cancer. On June 14, 2021, I was violently reminded of these questions. ![]() Words I remember to this day were the last of Georges Danton on April 5, 1794, who allegedly said to his executioner: “Show my head to the people, it is worth seeing.” Years later, having become a cognitive neuroscientist, I started wondering to what extent a brain suddenly separated from the body could still perceive its environment and perhaps think.ĭanton wanted his head to be shown, but could he see or hear the people? Was he conscious, even for a brief moment? How did his brain shut down? ![]() I had just discovered gruesome aspects of the French revolution and how heads were neatly cut off the body by a Guillotine. The first time I reached past the sheer horror of the concept of death and wondered what the experience of dying may be like, I was about 15. ![]()
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