What ACTUALLY Happens When Your Life Flashes Before Your Eyes
At the brink of death in the Pawtucket Patriot Ale Brewery, Peter Griffin takes quite the stumble in Season 19 of Family Guy, putting him in a montage of memories otherwise known as his “life flashing before his eyes.” In movies, literature, and countless forms of storytelling, these fantastical experiences of near-death have become almost colloquial to audiences. Though it may be assumed that this theory is a part of the many generational conspiracies of our time, the “life review phenomenon” has been well discussed by psychologists Raymond Moody, Kenneth Ring, and Barbara Rommer.
Primarily in Kenneth Ring’s research, the “life review phenomenon” was based on a collection of phenomenological evidence that describes an altered state of consciousness in which a person rapidly sees much or the totality of their life history. The great similarities between different reports of this experience were concluded not to be a result of chance or accident as demonstrated in societies across the world and time. However, in the early 90s, critics became skeptical when it was discovered that related research was being used to attempt to prove the afterlife. Thus, these studies were falsified and the “life review phenomenon” was categorized as what we know as the Mandela Effect.
But…new evidence may say otherwise.
The electroencephalogram, or EEG is one of our primary methods of measuring brain activity. EEGs work by attaching electrodes to the surface of the cranium and measuring the rhythmic patterns of electrical activity produced by the brain. Think of it as a stethoscope that listens to the brain rather than the heart. These cyclic patterns are categorized into several types of “brain waves” by their frequencies, each associated with different states of mind. These brain waves, in order of decreasing frequency, are called gamma, beta, alpha, theta, and delta. Surges in higher frequency brain waves such as gamma and beta are associated with alertness, while lower frequency waves are prevalent during relaxation, with delta waves dominant during sleep. Thus, EEG is capable of measuring levels of stimulation and can be used to determine whether or not a subject is asleep, and what phase of sleep they are in. Dreaming typically occurs during a phase of sleep known as rapid eye movement (REM) sleep, but this is not always the case: scientists in 2017 were able to use EEGs to predict if an individual experienced dreams no matter which phase of sleep they were in. This is because dreaming is associated with an increase in higher frequency waves compared to dreamless — or “unconscious” sleep.
One application of EEG is the monitoring of patients under anesthesia, where knowledge of the individual’s state of mind is highly valuable for guaranteeing effectiveness and comfort. For this purpose, the bispectral index (BIS) uses EEG data to produce a value ranging from 0 to 100, where 0 indicates complete and deep unconsciousness and 100 indicates total wakefulness. Due to this implementation, BIS monitors have been used for patients who are withdrawing from life support. In a 2009 case study of seven terminally ill patients, it was found that while BIS value declined with blood pressure, it surged briefly after blood pressure became undetectable — the onset of death. Upon retrieval of EEG data, this surge was seen to have accompanied a swell in higher frequency gamma brain waves. Shortly afterwards, the EEG measurement became “isoelectric,” indicating brain death.
Similar observations were made by researchers at the University of Michigan, who performed their experiment on rats. When the rats were put under anesthesia and experienced induced cardiac arrest, spikes of synchronous gamma wave activity immediately preceded brain death. One possible explanation for this phenomenon is that a lack of oxygen would then trigger neurons to fire spontaneously and rapidly in the brain.. In their resting phase, neurons are actually in a state of high potential energy with an interior that is more negatively charged than the exterior. When the neuron fires, the charge reaches an equilibrium, and energy then must be expended to return to the resting state. Therefore, it is possible that low oxygen conditions lead to an inability to maintain the resting state and a spontaneous firing of neurons — like a dam bursting — explaining the sudden spike in brain activity right before death. The researchers who conducted the 2009 study propose this as a mechanism for the vivid experiences described by those who have survived near death experiences.
Interestingly, a recently published (2022) human case study provided a similar connection–a spike in neural activity–to those with rats. After undergoing cardiac arrest, an 87-year-old man entered the emergency room with the symptoms of experiencing seizures. Shortly after his passing away, an accidental discovery was revealed. Since an EEG is set up when a patient is suspected of having (or recently had) seizures, the machine was able to record the first evidence of the dying human brain in a non-experimental setting. The post-cardiac arrest recording illustrated an increase of absolute power in gamma and a decrease in theta activity, which shows that the brain can generate coordinated activity during the near-death period. Compared to low delta, theta, and alpha modulate gamma activity in rodents, cross-coupling between alpha and gamma activity was observed in the human study. It is essential to note the role of alpha band oscillations because they dominate the visual cortex by processing information through verbal and spatial memory. A dream-like cognitive and memory recall is expected when cross-coupled with gamma activity. Given that this occurs in healthy patients, scientists have discussed that such activity could support a last “recall of life” in the near-death state.
Although the history of research into the “life review phenomenon” is tumultuous, its pervasiveness in our society warrants further investigation. Considering how these findings may be put into a general argument, there are many caveats for the last case described, such as the influence of post-injuring network activity, deprivation of oxygen, and anesthesia. Nevertheless, the discussion still points to the overall similarity in oscillatory changes between the highly controlled rodent studies and the present work: suggesting that the brain may pass through a stereotyped activity during death. For further investigation, an ethical dilemma arises regarding the circumstance of being at the brink of death for a human. Previous human reports were limited to their EEG set up, while current findings were done unexpectedly during an episode of cardiac arrest. Overall, this case has been a pleasant surprise to the field of neurology. Despite that there may not be a direct, societal impact once these findings are finalized, neurosurgeon Ajmal Zemmar best puts it, “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.”
Vicente, R., Rizzuto, M., & Sarica, C. (2022, February 28). Enhanced Interplay of Neuronal Coherence and Coupling in the Dying Human Brain. Froniers. Retrieved March 19, 2022.
Chawla, L., Akst, S., & Junker, C. (2008, November 8). Surges of Electroencephalogram Activity at the Time of Death: A Case Series. Journal of Palliative Medicine. Retrieved March 19, 2022, from https://www.liebertpub.com/doi/10.1089/jpm.2009.0159
Filippo, D. (2006, December). An overview of the near-death experience phenomenon. National Louis University. Retrieved March 19, 2022, from https://digitalcommons.nl.edu/cgi/viewcontent.cgi?article=1026&context=faculty_publications
Wetzel, C. (2022, February 28). Brain scans of dying man suggest life flashes before our eyes upon death. Smithsonian. Retrieved March 19, 2022, from https://www.smithsonianmag.com/smart-news/brain-scans-suggest-life-flashes-before-our-eyes-upon-death-180979647/
Borjigin, J., Lee, U. C., Liu, T., Pal, D., Huff, S., Klarr, D., Sloboda, J., Hernandez, J., Wang, M. M., & Mashour, G. A. (2013). Surge of neurophysiological coherence and connectivity in the dying brain. Proceedings of the National Academy of Sciences, 110(35), 14432–14437. https://doi.org/10.1073/pnas.1308285110
Siclari, F., Baird, B., Perogamvros, L., Bernardi, G., LaRocque, J. J., Riedner, B., Boly, M., Postle, B. R., & Tononi, G. (2017). The neural correlates of dreaming. Nature Neuroscience, 20(6), 872–878. https://doi.org/10.1038/nn.4545
This article was written by Michael Xiong, who is a junior undergraduate student at UC Berkeley studying Chemical Biology, and Aneal Singh, who is a freshman undergraduate student at UC Berkeley studying Molecular and Cell Biology.
This article was edited by Annabel Davis, a senior undergraduate student at UC Berkeley studying Cognitive Science, and Jacob Marks, a junior undergraduate pre-medical student at UC Berkeley studying Cognitive Science.