What happens to the brain as people transition from alive to dead has puzzled scientists for centuries – until now.
A team of neuroscientists have captured the first-ever brain activity of a dying human brain, which suggests people go experience ‘life review.’
Life reviews have been widely reported by those who have had near-death experiences who said they saw their entire life history play out in a rapid manifestation of autobiographical memory.
Many describe this as the experience of seeing their life ‘flash before their eyes.’
The recording was made when an 87-year-old patient underwent cardiac arrest while being treated for epilepsy.
Doctors had strapped a device on his head to monitor brain activity, but the man died during the process.
However, the neuroscientists captured 900 seconds of brain activity around the time of death, allowing them to see what happened in the 30 seconds before and after his heart stopped beating.
The measurements of brain waves before and after showed areas involved with memories and retrieval were still active.
Dr Ajmal Zemmar of the University of Louisville, Kentucky said: ‘Through generating brain oscillations [brain waves] 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.
Scientists have found new clues about what happens moments after death
‘These findings challenge our understanding of when exactly life ends and generate important subsequent questions, such as those related to the timing of organ donation.’
Dr Zemmar and his colleagues published their data in the journal Frontiers in Aging Neuroscience in 2022.
The Canadian patient was being treated for epilepsy, prompting doctors to place an electroencephalography (EEG) to study brain waves related to seizure activity.
This device attaches to the scalp via electrodes that detect and amplify brain waves, with the neurological activity showing up as wavy lines on what’s known as an EEG recording.
Later on, the patient went into cardiac arrest and died while the EEG was still monitoring his brain, providing the first evidence of what happens in the brain moments before death.
‘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,’ Dr Zemmar said in a statement.
Brain oscillations, or brain waves, are repetitive patterns of electrical impulses normally present in living human brains.
Different types of brain waves reflect different brain functions and states of consciousness.
Gamma waves are involved in high-cognitive functions such as memory retrieval, which is associated with memory flashbacks.
‘Through generating brain 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.
The neuroscientists captured 900 seconds of brain activity around the time of death, allowing them to see what happened in the 30 seconds before and after his heart stopped beating
Researchers suggested that the brain could be biologically programmed to manage the transition into death, potentially orchestrating a series of physiological and neurological events rather than simply shutting off instantly.
‘On the metaphysical side, if you have these things, it is intriguing to speculate to say that these mechanisms – these brain activity patterns that occur when we have memory recall and dreaming and meditative states – they recall just before we go to die,’ said Zemmar.
‘So maybe they’re letting us have a replay of life in the last seconds when we die.
‘On the spiritual side, I think it is somewhat calming. I face this at times when you have patients that pass away and you talk their families; you have to be the bearer of bad news.
‘Right now, we don’t know anything about what happens to their loved one’s brain when they’re dying.
Dr Ajmal Zemmar, a neurosurgeon at the University of Louisville, Kentucky, was one of the doctors who treated the 87-year-old patient. He organized the study of the patient’s brain wave recordings
‘I think if we know that there is something happening in their brain, that they are remembering nice moments, we can tell these families and it builds a feeling of warmth that in that moment when they are falling, this can help a little bit to catch them.’
Scientists still aren’t sure exactly how and why the life review phenomenon happens, but they do have some theories.
One suggests that oxygen deprivation during a life-threatening event can trigger the release of neurotransmitters, or chemical messengers that transmit signals between neurons.
This causes neurons to fire rapidly, and this heightened activity may lead to the perception of vivid memories and images.
Another possible explanation is based on where memories are stored in the brain.
Scientists believe some highly emotional memories are stored in the amygdala, which is the same part of the brain that is responsible for the fight or flight response.
The activation of this brain region during a life-threatening experience may therefore release these vivid memories, causing them to flash before your eyes.
While Zemmar’s finding does not directly point to one of these explanations or another, it does offer evidence to suggest that the life review phenomenon is real.
What’s more, ‘These findings challenge our understanding of when exactly life ends and generate important subsequent questions, such as those related to the timing of organ donation,’ Zemmar said.
‘When do you go ahead with organ donation? When are we dead? … Should we record EEG activity in addition to EKG to declare death?
‘This is a very, very interesting question for me. When is exactly the time when we die? We may have tapped the door open now to start a discussion about that exact time onset.’
But more case studies will be needed in order to begin answering these questions.
‘Scientifically, it’s very difficult to interpret the data because the brain had suffered bleeding, seizures, swelling – and then it’s just one case. So we can’t make very big assumptions and claims based on this case,’ Zemmar said.
