Even after we die, some of our brain cells may experience one last and great momentary explosion of life, new research suggests on Tuesday. The study found evidence that certain “zombie genes” in our brain cells are active more frequently shortly after death, causing some cells to expand immensely for hours. The findings will not radically change our concepts of life and death, but they may have some important implications for the study of brain tissue taken post-mortem.
It’s no secret that our cells can stay alive and function for a while even after we die clinically, before flickering permanently. But, although almost every cell carries the same genetic information as the next, different cell types express this genetic information differently, with different genes being activated or deactivated. And when the researchers analyzed the gene expression of various cells inside a “dying brain,” they found several distinct patterns.
For their study, published In Scientific Reports on Tuesday, the team looked at brain tissue samples donated by patients who had recently had brain surgery for epilepsy (surgical treatments can safely remove parts of the brain involved in the seizure disorder). They then mimicked the process of brain death by leaving samples freshly removed at room temperature for various periods of time, for up to 24 hours. All the while, the team was collecting information about the cellular and genetic activity of these cells.
In most of the genes they studied, characterized as “household genes” that maintain basic cellular function, they found that the genes remained at the same level of activity for the entire 24-hour period. In the “neural” genes, the genes that are started in the cells of neurons responsible for brain functions such as thinking and memory, their activity began to decline after 12 hours.
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But in a third group of genes, linked to the function of glial cells – the immune system and brain support – gene expression actually increased after “death” and continued to grow until 24 hours later. The glial cells themselves have also expanded massively in size and even new “arms” grew, at the same time as the neurons in these samples degenerated.
Tthe results do not show that zombies are theoretically possible, aIt is not even a huge surprise that glial cells are active especially after death. Cells probably respond to the injury and inflammation that occurs in the brain when it is deprived of oxygen after one’s last moments. But the findings show a potential wrinkle for the way a lot of human brain research is conducted, according to the authors, because many studies are based on post-mortem brain examinations.
“Most studies assume that everything in the brain stops when the heart stops beating, but it’s not,” said study author Jeffrey Loeb, chief of neurology and rehabilitation at the University of Illinois at Chicago College of Medicine, in a statement. statement released by the university. Our findings will be needed to interpret research on human brain tissue. I just haven’t quantified these changes so far. ”
One problem is research into disorders such as Alzheimer’s disease and other forms of dementia are often dependent on the post-mortem brain samples that are collected 12 or more hours after death. If the findings here are valid, then many of these studies may lack important clues left in dying cells that could disappear later. Loeb and his team hope that future studies can better explain the changes that take place in a dying brain. A potential solution, for example, could be to collect brain samples for research even earlier post-mortem or to rely more on samples from patients who want to receive brain surgery.
The good news from our findings is that we now know which genes and cell types are stable, which degrade, and which grow over time, so that the results of postmortem brain studies can be better understood, Loeb said.