Some of our brain cells become more active hours after death, according to a study


Image of a human brain taken by a positron emission tomography scanner.

Image of a human brain taken by a positron emission tomography scanner.
Picture: Fred TANNEAU / AFP (fake images)

Even after we die, some of our brain cells can experience one last, momentary burst of life, new research published Tuesday suggests. The study found evidence that certain “zombie genes” in our brain cells fire more frequently shortly after death, causing some cells to vastly expand for hours. The findings will not radically change our concepts of life and death, but they may have some important implications for studying brain tissue taken post-mortem.

It is no secret that our cells can remain alive and function for a time even after we are clinically dead, before they finally shut down. But although almost all cells carry the same genetic information as the following, different types of cells express this genetic information differently, with various genes turned on or off. And when the researchers looked at the gene expression of different cells within a “dying brain,” they found some different patterns.

For your study, published In Scientific Reports on Tuesday, the team examined brain tissue samples donated by patients who had recently undergone brain surgery for epilepsy (surgical treatments can safely remove parts of the brain involved in seizure disorder). They then mimicked the brain death process by leaving the freshly drawn samples at room temperature for various periods of time, up to 24 hours. Meanwhile, the team collected information on the cellular and genetic activity of these cells.

In most of the genes they studied, characterized as “house genes” that maintain basic cell function, they found that the genes remained at the same level of activity throughout the 24-hour period. In “neural” genes, genes that are activated in neuronal cells responsible for brain functions such as thinking and memory, its activity began to decline after 12 hours.

Glial Cell Images

Images of glial cells “after death” as they increased in size and developed new growths.
Picture: Jeffrey Loeb / UIC

But in a third group of genes, linked to the function of glial cells, the brain’s immune and support systems, gene expression actually skyrocketed after “death” and continued to rise for up to 24 hours later. Glial cells themselves also massively expanded in size. and new “arms” even grew, at the same time that the neurons in these samples were degenerating.

TThe results do not prove that zombies are theoretically possible, aAnd it’s not even a big surprise that glial cells are especially active after death. Cells are likely to respond to injury and inflammation that occurs in the brain when it is deprived of oxygen after someone’s final moments. But the findings present a potential problem with how a lot of research on the human brain is carried out, according to the authors, since many studies are based on post-mortem examinations of the brain.

“Most studies assume that everything in the brain stops when the heart stops beating, but this is not the case,” said study author Jeffrey Loeb, chief of neurology and rehabilitation at the University School of Medicine. from Illinois to Chicago, in a statement published by the university. “Our findings will be necessary to interpret research on human brain tissues. We just haven’t quantified these changes so far. “

One problem is that research into disorders like Alzheimer’s disease and other forms of dementia often depend on postmortem brain samples that are collected 12 or more hours later death. If the findings here are valid, then many of these studies could be missing important clues left within dying cells that could later disappear. Loeb and his team hope that future studies can better explain the changes that take place in a dying brain. A possible solution, for example, could be to collect brain samples for research even before the autopsy or to rely more on samples from willing patients who are going to have brain surgery anyway.

“The good news from our findings is that we now know which genes and cell types are stable, which are degraded, and which increase over time, so the results of postmortem brain studies can be better understood,” Loeb said.

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