Some of our brain cells become more active hours after we die

A photograph of a human brain taken by a positron emission tomography scanner.

A photograph of a human brain taken by a positron emission tomography scanner.
Image: Fred TANNEAU / AFP (Getty Images)

Even after we die, some of our brain cells can experience one last and great moment of life experience, new research indicates on Tuesday. The study found evidence that certain “zombie genes” in our brain cells are more frequently active shortly after death, causing some cells to expand tremendously for hours. The findings will not radically change our concepts of life and death, but they may have important implications for the study of brain tissue taken post-mortem.

It is no secret that our cells can stay alive and function for a while, even after we are clinically dead, before they finally flicker. But although almost every cell contains the same genetic information as the next, different types of cells release this genetic information differently, with different genes being turned on or off. And when the researchers looked at the gene expression of different cells in a ‘dying brain’, they found some clear patterns.

For their study, published in Scientific Reports Tuesday, the team looked at samples of brain tissue donated by patients who recently underwent brain surgery for epilepsy (surgical treatments can safely remove parts of the brain involved in the seizure). They then mimicked the process of brain death by leaving the newly removed samples at room temperature for 24 minutes. All the while, the team was gathering information about the cellular and genetic activity of these cells.

In a majority of the genes they studied, which are characterized as ‘household genes’ that maintain basic cellular function, they found that the genes remained at the same activity level throughout the 24 hours. In the “neuronal” genes, genes are turned on in the neurons responsible for brain functions such as thinking and memory, their activity began to decline after 12 hours.

Images of the glial cells

Images of the glial cells “post-death” as they grow larger and develop new growths.
Image: Jeffrey Loeb / UIC

But in a third group of genes, linked to the function of glial cells – the immune and support system of the brain – the gene expression actually increased after ‘death’ and increased until 24 hours later. The glial cells themselves have also greatly expanded and even new “arms” grew, at the same time as the neurons in these monsters degenerated.

Tthe results do not prove that zombies are theoretically possible, aIt is not even a big surprise that glial cells are especially active after death. The cells probably respond to the injury and inflammation that goes on in the brain when it is deprived of oxygen after someone’s last moments. According to the authors, the findings are a possible ripple for how much human brain research is done, as many studies rely 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, head of neurology and rehabilitation at the University of Illinois at Chicago College of Medicine, in ‘ a statement released by the university. ‘Our findings are needed to interpret research on human brain tissues. We just have not quantified these changes so far. ”

One problem is that research on disorders such as Alzheimer’s disease occurs and other forms of dementia are often dependent on post-mortem brain samples collected 12 or more hours later death. If the findings are valid here, many of these studies may be missing important clues left behind in dying cells that may later disappear. Loeb and his team hope that future studies can better take into account the changes that take place in a dying brain. A potential solution could be, for example, to collect brain samples even earlier post-mortem examination or to rely more heavily on samples from willing patients who get a brain operation 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 results of post-mortem brain studies can be better understood,” Loeb said.

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