Many people think about what happens after death, so they wonder what the last moments look like, whether life really “flies by” before our eyes and what awaits us after the last breath. Scientists have been dealing with this topic for years, and now they have solved the dilemma – does dying look like a process of falling asleep or are we aware that we are disappearing.
Dying is a unique experience for the individual and their loved ones. There is much more than physiological changes that contribute to the experience of dying. For example, a person’s personality, the burden of the disease, the support of family and friends, the duration of the terminal illness and their spirituality – explains Dr. Patrick Steele, a specialist in palliative care.
However, there are certain physiological changes that occur universally.
Regular breathing patterns may change. Sometimes it can be faster than normal and sometimes slower. In the final days, there may be periods where there are long gaps between breaths. Breathing can become noisy at the end of life. It is the accumulation of waste products, secretions of the body. It’s often more upsetting for those listening than for the individual dying, Steele describes.
Study organizer Dr. Ajmal Zemar, a neurosurgeon at the University of Louisville, says this could mean that the idea that life “flies before our eyes as we die” is grounded in science. As a neurosurgeon, I sometimes deal with loss. It is indescribably difficult to convey the news of death to anxious family members – said the neurosurgeon, adding…
Something we can learn from this research is the following: even though our loved ones have their eyes closed and are ready to leave us, their brains may be replaying some of the most beautiful moments they experienced in their lives – Dr. Zemar added.
A twinkle in the eye
In addition to Zemar, another team of scientists momentarily restored a faint flash of life to the dying cells in the human eye. In order to better understand the way in which nerve cells are subject to lack of oxygen, a team of American researchers measured the activity in retinal cells of mice and humans immediately after death. They managed to revive the cells’ ability to communicate hours after death. When the cells were stimulated by light, postmortem retinas were shown to emit specific electrical signals, known as beta waves, writes Science Alert. These waves are also seen in living retinas and indicate communication between all layers of macular cells that allow us to see.
This is the first time a deceased donor’s eyes have reacted to light in this way, and some experts question the irreversible nature of death in the central nervous system.
“We were able to wake up the photoreceptor cells in the human macula, which is the part of the retina responsible for our central vision and our ability to see fine details and color,” explains biomedical scientist Fatima Abbas of the University of Utah.
In eyes obtained up to five hours after the death of the organ donor, these cells responded to bright light, colored lights, and even very dim flashes of light. After death, it is possible to save some organs in the human body for transplantation. But after the circulation stops, the central nervous system as a whole stops responding too quickly for any form of long-term recovery.
Different regions and different types of cells have different survival mechanisms, which makes the whole issue of brain death much more complicated. Learning how selected tissues in the nervous system cope with the loss of oxygen could teach us about the recovery of lost brain functions.
In 2018, scientists from Yale University made headlines when they kept a pig’s brain alive for as long as 36 hours after the animal’s death. The feat was achieved by halting the rapid degradation of mammalian neurons, using artificial blood, heaters and pumps to restore the circulation of oxygen and nutrients. A similar technique is now possible in mice and human eyes, which are the only extruded parts of the nervous system. By restoring oxygenation and some nutrients to the eyes of organ donors, researchers from the University of Utah and Scripps Research were able to trigger synchronous activity among neurons after death.
“We were able to get retinal cells to communicate with each other, the way they do in the living eye to mediate human vision,”
says visual scientist Frans Winberg of the University of Utah.
Initially, experiments showed that retinal cells continued to respond to light for up to five hours after death. However, the crucial intercellular beta-wave signals quickly disappeared, apparently due to the loss of oxygen.
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