28th February, 2022
We’ve all seen that scene in a movie when one of the characters is dying and flashbacks of their life start rolling on the screen. It’s emotional… and happens in real life too, neuroscientists at the University of Louisville, US find.
A case study on an 87-year-old patient facing his final moments of his life shows a spike in a neural activity pattern that is similar to memory recall. After developing seizures following a surgery, doctors used electroencephalography (EEG) to monitor the patient’s condition. Unfortunately, while still under EEG monitoring, the patient’s condition deteriorated and he passed away.
The patient had a do-not-resuscitate status (or DNR), and with the family’s consent, the doctors were allowed to monitor the EEG readings while the patient was experiencing the last moments of his life before his 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,” says neuroscientist Ajmal Zemmar, from the University of Louisville in the US.
Neural oscillations, or brain waves, are the collective electrical activities of neurons firing in the brain. Different frequencies of these waves have been labeled with Greek alphabets for differentiation. Additionally, each frequency is associated with different conscious states of the brain. For example, while we are sleeping, most of the brain waves are delta and theta, whereas when we recall a memory, they are gamma and alpha.
This pairing of gamma and alpha brain waves were observed during the last 30 seconds before the patient was announced dead after a cardiac arrest. “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,” explained the neuroscientists monitoring the EEG monitoring the patient.
While the neuroscientists acknowledge the limitations of the case-study, due to the traumatic state the patient was in before death, this finding resonates people’s feelings and stories after near-death-experiences (or NDEs). Such anecdotes describe the last few moments before death a “movie of one’s life” rolling before the eyes, which might be the result of the neural activity observed in the case study.
“Something we may learn from this research is: 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.”Neuroscientist Ajmal Zemma
Goosebumps and tears!
John Bader is the News Editor for I,Science and is studying an MSc in Science Media Production at Imperial College London