Scientifically speaking, those last fleeting moments are precious, and it’s very rare that we get insight into what’s going on in the brain, in those moments, as it fades into silence.
What have scientists noticed in a dying brain?
Last year, scientists recorded for the first time, in great detail, the brain waves of a dying person.
Under tragic circumstances, they recorded a sudden spike in a specific type of brain activity, called “gamma waves”, with this spike accompanied by changes in other frequencies.
The new study reports a similar surge of short-lived “gamma activity” in two of four patients who were taken off life support.
Since 2013, neurologist Jimo Borjegen and his colleagues have been looking for similarities in the dying human brain to what they find in mice after induced cardiac arrest. He concluded that the brief flashes of brain activity they saw intensified, well above animal wakefulness levels that could be a biological flash.
“These findings prompted us to investigate brain neural activity in dying patients before and after ventilator removal,” Borjegen and colleagues write in their new paper.
A moment of awareness before death?
The team reviewed cases from the University of Michigan Academic Medical Center of patients who died in the neurological intensive care unit since 2014.
In two of four identified comatose patients, who died while doctors were still monitoring their condition after cardiac arrest or brain hemorrhage, EEG recordings revealed a strong surge of “gamma waves” in part of the brain.
The seizure specialist confirmed that it was not the after-effects of an epileptic seizure, leading the research team to believe that they may have encountered a possible sign of consciousness, a sense of awareness of our surroundings that arises from the chaos of tangled brain cells.
The initial burst of gamma waves has been identified in a region of the brain that is believed to be a “hot spot” for the so-called neural correlates of consciousness. A similar pattern of activity is seen in people who dream and in patients with epileptic seizures, who report having visual hallucinations and “spiritual” experiences.
A recent review describes how this “hot zone” of potential consciousness involves sensory regions of the brain, which may explain why people accurately remember times when they are close to death.
“We cannot exclude the possibility that the increased strength of gamma activity we recorded is indicative of a disease process unique to the death phase and unrelated to conscious processing,” Borjegen and colleagues conclude.
However, they hope that with each recorded case, we can understand a little more about the last moments of life and consciousness.
The researchers concluded, “This study lays the groundwork for further investigation of covert consciousness during cardiac arrest, which could serve as a model system for exploring the mechanisms of human consciousness.”
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