A sudden burst of high-frequency brainwaves in dying patients may help shed more light on the mysterious “near-death experience” reported by survivors across the world, scientists have said.
For decades, people who had returned from death’s grasp told stories that share many common elements, such as moving towards a radiant white light, reliving past memories and seeing faces of departed loved ones. While skeptics dismiss those stories as mere hallucinations, some scientists question whether there is something fundamentally real that causes people of different cultural and religious backgrounds to have remarkably similar experiences.
Dr. Jimo Borjigin, a neurology professor at the University of Michigan, has been studying the nature of consciousness in both humans and animals using tools that can read brain signals. She hypothesized that the dying process itself may activate certain parts of the human brain and provide a glimpse of consciousness, even after the heart stops beating.
In a study published this month, Borjigin and her colleagues said they found early evidence supporting this hypothesis.
The study itself is a follow-up to animal studies conducted by Borjigin’s team almost ten years ago, which proved that rats have an increase in electrical activity in their brains as they die. The team now recorded a similar surge of activity in dying human brains.
For the study, the scientists examined data collected from four cardiac arrest patients who died in the hospital after doctors deemed their condition completely beyond hope and removed them from life support with their families’ permission. While they were under intensive care unit treatment, all four patients had electrodes placed on their heads to monitor their brainwaves using a technology called electroencephalography, or EEG.
According to the EEG data, two of the four patients showed an increase in heart rate along with a surge of gamma waves when their life support was switched off. In humans, the gamma wave pattern is a hallmark of consciousness, typically associated with heightened awareness and active thinking.
On top of that, the increased gamma wave activity was detected in the temporo-parieto-occipital (TPO) junctions in the back of the brain, a “hot zone” heavily involved in high-level brain functions such as visual-spatial processing, musical memory, and face and object recognition. This is also a part of the brain that becomes active during dreaming.
“Had they survived, those two patients might have had some story to tell,” Borjigin told online magazine New Scientist.
The team did note that their findings only point to the possibility that the patients might have visions as they were dying, since it’s impossible to ask them what they had seen when the gamma brainwave surge occurred.
“Although the marked activation of the posterior hot zone in the dying brain is suggestive of elevated conscious processing in these patients, it does not demonstrate it,” they wrote. “We cannot determine whether the activation of the posterior hot zone detected in our patients was correlated with having a subjective experience, as none survived the cardiac arrest.”
The team also noted that the two patients both had a suspected history of an epileptic seizure: one experienced seizures only during her pregnancies, while the other developed status epilepticus—seizures lasting longer than five minutes—a day before the cardiac arrest killed her. While it’s possible that those seizures had permanently changed their brains, there’s no evidence that people with a history of epilepsy are more likely to have a near-death experience.
For future investigation, the University of Michigan scientists said that larger, multi-center studies including EEG-monitored ICU patients who survive cardiac arrest could provide more data crucial in understanding whether or not the gamma wave bursts are evidence of hidden consciousness even near death.
The study was published on May 1 in the Proceedings of the National Academy of Science (PNAS), the official scientific journal of the U.S. National Academy of Sciences.