Paris It looks like the beginning of a science fiction film, or even the horror of Frankenstein: researchers have been able to reconstruct some neural functions in the brains of dead pigs for several hours, an experiment that raises many ethical questions. The review natureHowever, this study is far from proving that it can be revived in the cerebral brain.
Indeed, the researchers insist on the fact that they did not find in the brain of the interrogee "any electrical activity that would be a sign of phenomena of conscience or perception."
"They do not live in the brain but in a brain whose cells are active," says study co-author Nannad Sistan.
According to this researcher at Yale University (USA), this work shows that "we have underestimated the ability of the cell to restore the brain."
In addition, these results indicate that the deterioration of neurons "after stopping blood flow can be a long-term process rather than a rapid one," according to a news release. nature.
The mammalian brain is very sensitive to the reduction in oxygen provided to them by the blood. When the blood flow is disturbed, the brain stops being oxidized, which damages it irreparably.
The researchers used 32 brains taken from dead pigs for four hours. Thanks to the pump system called Braynax, they were irrigated for six hours with a special solution, at a temperature equal to that of the body (37 degrees).
This solution, a blood substitute, is designed to oxygenate tissues and protect them from degradation associated with stopping the blood flow.
The results were prominent: decreased brain cell destruction, preservation of blood function, or restoration of synaptic activity (electrical or chemical signals in the contact zone between neurons).
According to the researchers, it can help to better understand the brain and to study it after death before it deteriorates.
It can also pave the way for future techniques to preserve it after a heart attack for example.
Even further, it can, theoretically, revive a dead brain, which remains for a moment science fiction.
"The immediate challenges of these results are above all moral," says a scientist who did not participate in the study, Prof. David Manon of the University of Cambridge. (UK).
"It challenges our understanding of what makes an animal or a person live," say other scientists in an interpretation published by nature Accompany your research.
"This study used a pig's brain that did not receive oxygen, glucose, or other nutrients for four hours, which opens up possibilities that were previously thought to be unthinkable," added Nita Farhani, Henry Greeley and Charles Yatino, respectively, Philosophy and neuroscience experts.
According to them, the study could undermine two principles.
"First, the fact that neural activity and consciousness is completely stopped after a few seconds or a few minutes of interruption in the blood flow in the mammalian brain," they say.
"Second, the fact that if you do not quickly restore the bloodstream, an irreversible process will begin, leading to the death of the cells and the organ," they continue.
They call for the establishment of "guidelines on the scientific and ethical issues that have emerged in this work."
In another interpretation published by me natureBioethics experts say that the development of the BrainEx technique may eventually harm organ donation.
For organ transplantation, organs are taken mainly from dead donors in the brain. If you begin to think that this condition can be reversible, how can you solve the removal of the organs?
Perhaps a fan of pop culture of the 80s, the trio Farahani, Griely and Atheno cite a copy of the American film the princess In order to summarize the subject of these works on minds, they must be dead, but their activity was partially restored.
In this fantasy comedy of 1987, a healer named Max Hans explains maliciously: "There is a small difference between death almost dead and hard (…) Almost dead, it's still a little alive."