People who see death before their eyes are often described with similar experiences, vivid memories of memories, feelings of floating above their bodies, or seeing bright lights. What is it really like when you face death's death?
While there is plenty of anecdotal evidence of people having near-death experiences, scientists have little or no data on what happens in the brain as people move toward death.
In a recent study, a group of scientists managed to collect ongoing data on the neurodynamics of the brain during the time of death.
Quoted from Science Alert, Friday (2/25/2022) when an 87-year-old patient had a seizure after undergoing surgery due to a fall, doctors used electroencephalography (EEG) to monitor his condition. Unfortunately, the patient's condition deteriorated and he died during this recording.
Due to the patient's non-resuscitation status, and with the consent of the family, the unexpected event allowed scientists to record the electrical activity of a dying human's brain.
"We measured 900 seconds of brain activity around the time of death and focused specifically on investigating what happens in the 30 seconds before and after the heart stops beating," said Ajmal Zemmar, a neurosurgeon at the University of Louisville, US.
"Just before and after the heart stops working, we see changes in certain bands of neural oscillations, called gamma oscillations, but also in others such as delta, theta, alpha, and beta oscillations."
Neural oscillations are the collective electrical activity of the neurons working in the brain, and are more commonly known as brain waves. These waves of electrical activity occur at different frequencies, and different frequency bands have been associated with different states of consciousness.
Thus, neuroscientists have succeeded in associating different brain wave frequencies with specific functions such as information processing, perception, awareness and memory during wakefulness, and dreaming and meditation states.
Right after the patient had a heart attack that led to his death, his brain activity revealed a relative spike in the strength of the gamma bands that interacted most with alpha waves. This pattern is the same as when the brain generates memories.
"Given that cross-coupling between alpha and gamma activities is involved in cognitive processes and memory in healthy subjects, it is interesting to speculate that such activity may support the last possible 'recall of life' in a near-death state," the research team wrote.
The author notes several things. First, the patient's brain is in a post-traumatic state with bleeding, swelling, and seizures. In addition, the patient has received large doses of anti-seizure drugs, which may also affect the oscillatory behavior of the nerves.
There was also no "normal" brain scan in this patient to compare his brain activity. However, the researchers were unable to have access to such data on healthy patients whose death was unlikely to be anticipated. Therefore, obtaining near-death phase records can only come from patients who are already sick.
Despite these limitations, the team's findings do point to a potential link between the brain waves observed during death and the phenomenological experience of NDE, in which participants describe their lives flashing before their eyes.
What we know about brain waves during memory retrieval provides evidence that the brain may pass through stereotypical patterns of activity during death. The authors also noted similar findings to changes in neural activity that have been observed in rodents during death.
Interestingly, the results are consistent with the idea that the brain regulates and carries out biological responses to death that can be conserved across species with bound evolutionary lineages and broadly similar neural structures.
While researching brain activity prior to death can be difficult, especially when patients leave bereaved family members, Zemmar is pleased to know that our brains can immerse us in the memories we love most when we leave this world.
"Something we can learn from this research is this: even if our loved ones close their eyes and are ready to leave us to rest, their brains may be replaying some of the best moments they experienced in their lives."