Some of our brain cells receive more active hours after they die

Even after we die, some of our brain cells may experience one last, large momentary explosion of life, new research published Tuesday suggests. The study found evidence that certain “zombie genes” in brain cells are most often active 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 studying brain tissue taken post-mortem.

It’s no secret that our cells can stay alive and function for a while even after they’ve died clinically, before finally blinking. But even though almost all cells have the same genetic information as the next, different cell types express this genetic information differently, with several genes turned on or off. And when the researchers examined 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 given by patients who had recently undergone brain surgery for epilepsy (surgical treatments can safely remove parts of the brain involved in the seizure disorder). They then mimicked the brain death process leaving aside the freshly removed samples at room temperature for several periods of time, up to 24 hours. Throughout the time, the team collected information on the cellular and genetic activity of these cells.

In most of the genes they studied, characterized as “maintenance genes” that maintain basic cellular function, they found that the genes remained at the same level of activity throughout the 24-hour period. To the “neural” genes, nothing activated in the neuronal cells responsible for brain functions such as thinking and memory, its activity began to decline after 12 hours.

But in a third group of genes, linked to the function of glial cells – the immune and brain support system – gene expression actually increased after “death” and continued to increase until 24 hours later. Glial cells 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, aAnd it’s not even a big surprise that glial cells are especially active after death. Cells are likely to respond to injuries and inflammation that occur in the brain when they are deprived of oxygen after someone’s last moments. But the findings present a possible wrinkle of how much research is being done on the human brain, according to the authors, as many studies are based on post-mortem brain exams.

“Most studies assume that the whole brain stops when the heart stops beating, but that’s not the case,” said study author Jeffrey Loeb, head of neurology and rehabilitation at the University of Illinois at the Chicago College of Medicine, a statement released by the university. “Our findings will be needed to interpret research on human brain tissue. We just haven’t quantified these changes yet. “

One problem is research into disorders such as Alzheimer’s disease and other forms of dementia often depend on the post-mortem brain samples collected 12 or more hours later death. If the results here are valid, it is possible that many of these studies are missing important clues that remain within the dying cells and could disappear later. Loeb and his team hope that future studies can better explain the changes that occur in a dying brain. One potential solution, for example, could be to collect brain samples for even sooner post-mortem research or to rely more on samples from willing patients who receive brain surgery anyway.

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