Scientists have accidentally discovered what goes on inside a human brain just before a person dies after a man with epilepsy died of a heart attack while undergoing a brain scan to detect and treat his seizures.

The subsequent study of the man’s brain activity, which has been published in Frontiers in Aging Neuroscience, suggests an explanation for people reporting experiencing vivid life recall in near-death experiences.

During the 30 seconds before and after the man’s heart stopped, his brain waves were remarkably similar to those seen during dreaming, memory recall and meditation, suggesting that people may actually see their life “flash before their eyes” when they die.

The phenomenon of replaying past memories when you die has been reported by some people who have had near-death experiences. But this is the first scientific evidence that this “flash” might be real. However, as this is the only case study, it is impossible to make further assumptions about how common the phenomenon may be or what the experience may be like.

Dr Ajmal Zemmar, a neurosurgeon at the University of Louisville, US, who organized the study said: “We measured 900 seconds of brain activity around the time of death and set a specific focus to investigate what happened in the 30 seconds before and after the heart stopped beating.

“Just before and after the heart stopped working, we saw changes in a specific band of neural oscillations, so-called gamma oscillations, but also in others such as delta, theta, alpha, and beta oscillations.”

These brain oscillations, which are more commonly known as brain waves, are patterns of rhythmic activity present in living human brains.

The team also gathered data on other types of oscillations during death, including delta, theta, alpha and beta waves. But it was the gamma waves that pointed toward the man replaying memories from throughout his life in his brain — a phenomenon known as life recall.

A diagram showing the frequencies of different types of neural oscillations, or brain waves.

A diagram showing the frequencies of different types of neural oscillations, or brain waves. (Image credit: Shutterstock)
“Through generating oscillations involved in memory retrieval, the brain may be playing a last recall of important life events just before we die, similar to the ones reported in near-death experiences,”Zemmar said in the statement.

Experiments in rats have shown that the rodents also experience similar levels of gamma oscillations around the time of death, according to the statement. Therefore, the researchers speculate that life recall may be a universal experience shared by a majority of mammal dying brains, although there is minimal evidence to back this up.

But the researchers warned that it would be premature to conclusively state that life recall is a real phenomenon. The dying man was elderly and had epilepsy, which is known to alter gamma wave activity.

This could have meant his brain activity during death was different from that of someone without epilepsy. Moreover, there is no way to know if the man was actually seeing, or perceiving, his past memories or if he was just in a dream-like state brought on by his failing nervous system.

Therefore, much more research is needed to make concrete conclusions about life recall, the researchers cautioned. The report of the man’s case was not published until six years after his death because the researchers were hoping to uncover more case studies of dying brains to support their claims, but they came up empty-handed, according to the BBC.

However, the findings could provide a source of comfort to friends and family members during the “indescribably difficult” experience of losing loved ones, the researchers said. “Although our loved ones have their eyes closed and are ready to leave us to rest, their brains may be replaying some of the nicest moments they experienced in their lives,” Zemmar said in the statement