It’s a question that worries many people: What is death like? Do we see a light at the end of a tunnel, our own dying body, or does life flash before our inner eyes once more? Some people report this after a near-death experience. An American study now suggests that at the moment of death, our brains actually trigger memories.
accidental discovery
At least that’s what brain waves recorded in a dying patient in a hospital suggest. The fact that this brain activity was recorded is due to a coincidence: the attending physicians performed several electroencephalograms (EEG) on an 87-year-old man who had undergone head surgery after a fall and was suffering from epileptic seizures.
An EEG records the electrical activity of the brain. During this recording, the patient suffered a heart attack and died.
In total, the scientists report in the journal Frontiers in Aging Neuroscience, 15 minutes of brain activity were recorded when the man died. “We focused on what happened in the 30 seconds before and after cardiac arrest,” said study leader Ajmal Zemmar, a neurosurgeon at the University of Louisville.
“Shortly before and after the heart stopped beating, we saw changes in a specific frequency range of neuronal oscillations, called gamma oscillations, but also in others like delta, theta, alpha, and beta oscillations.”
important life events
These brain waves map patterns of rhythmic neuronal activity. Different waves are associated with different functions, with the frequency patterns described in the study being similar to those observed when meditating or recalling memories. This suggests, speculates Zemmar, that shortly before death, the brain can play back the last memories of important life events, generating such oscillations, “similar to near-death experiences.”
Frank Erbguth, medical director of the Neurology Clinic at the University of Nuremberg, is not surprised by the observations: “It’s not news that the human brain creates its own world of images in certain situations.” This is known, for example, by migraine patients, but also by drug users. “So near-death experiences are one of several very different phenomena in which the brain produces images,” says the president of the German Brain Foundation.
What happens in the brain is easy to explain. With death, the carbon dioxide content in the cells increases: “This leads to a change in the brain’s electrical system and brain metabolism – near-death experiences are located on these two keyboards.” This can also be experienced by people who are particularly good at meditating.
gamma waves
In these, the EEGs showed increased gamma spectra – similar to those reported in the study, says Erbguth: “And we know that these gamma activities indicate that memories are retrieved.” At the same time, gamma waves are very fast, oscillating at a speed of 30 Hertz per minute. “The gamma band cannot be seen on a conventional EEG,” says the neurologist. Therefore, the differentiated evaluation of the wavebands performed in the study is a new aspect.
Another study in 2013 showed similar results, except that these changes in gamma waves occurred in rats. The authors of the current study suggested this as a possibility that when the brain dies, it carries out a biological response that may be the same across species.
However, their study is based on a single patient whose brain was injured and who also had epileptic seizures: “Such epileptic activities mean that the brain’s electricity is really shaken,” Erbguth noted. It’s hard to draw conclusions from this about the normal dying brain.
Overall, the study provides another facet of knowledge about the dying brain, which is already comprehensive: if blood circulation stops, the brain stops communicating between nerve cells, certain rhythms of the brain’s electrical system change, and the cells have a electrical again Output.
most beautiful moments
As early as 2018, German and American neurologists described in the Annals of Neurology that this happens in the form of a spreading wave of discharge. Erbguth explained the attention these studies regularly receive, promising to take a look behind the curtain of death: “But everything we look at happens in front of the curtain.” Even people with near-death experiences were close to death.
However, the current study for neurosurgeon Zemmar offers hope for loved ones: “What we can learn from this research is that even when our loved ones have their eyes closed and ready to settle down, their brains may be repeating some of the most beautiful moments they experienced.”
Neurologist Erbguth put it more soberly: “Our brain is at least capable of producing images again.” Near-death reports showed that it was legitimate to assume this ability for the really dying brain.
However, studies of resuscitation medicine found that while two-thirds of people who had a near-death experience saw pleasant images, one-third reported bad scenes. “I would be pleased if the transition to death was accompanied by beautiful experiences,” Erbguth said. “But I’m afraid that’s not in your hands.”