After researchers were able to restore some activity to brains of pigs that been dead for hours, scientists are reexamining previously held beliefs about the brain and what it means to be “dead.”
The Yale University research team noted in the study, published Wednesday in the journal Nature, that the brains didn’t regain consciousness.
But the cells still showed a surprising amount of function. The scientists said they were able to detect “spontaneous synaptic activity,” meaning the neurons responded to external electrical stimulation. Cells that scientists removed from the brain and studied under a microscope had regained the shape of living cells, lead author Zvonimir Vrselja wrote.
The research doesn’t have immediate implications when it comes to the treatment of brain injuries for humans. However, it is challenging scientists’ current understanding of what separates the living from the dead.
“We had clear lines between ‘this is alive’ and ‘this is dead,’” Nita A. Farahany, a bioethicist and law professor at Duke University, told The New York Times. “How do we now think about this middle category of ‘partly alive’? We didn’t think it could exist.”
The 23 brains came from pigs that had been killed at a local slaughterhouse four hours earlier, The Washington Post reported. Scientists put the brains in an apparatus in their lab. Then, over the course of six hours, they infused the brains with a blood substitute.
Scientists found that, while the brains didn’t regain consciousness or awareness, they continued to consume oxygen and glucose. At a cellular level, scientists detected the “spontaneous synaptic activity” and noticed cells stopped decaying.
“It is not a living brain, but it is a cellularly active brain,” Dr. Nenad Sestan, a neuroscientist at Yale University, said in a briefing, according to The Times. “We wanted to test whether cells in the intact dead brain can have some functions restored.”
If they saw brain activity associated with consciousness, the scientists planned to use anesthesia and low temperatures to stop the experiment, Yale scientist and study co-author Stephen Latham said. There is no good ethical consensus about doing such research if the brain is conscious, he said.
Stuart Youngner, a professor of bioethics and psychiatry at Case Western Reserve University, told The Post that the findings of the research are “a breakthrough in understanding preservation of the brain."
"What’s unnerving about it is, it has really challenged assumptions that I was raised with as a physician about the fragility of the brain. It appears from this study that it's not as fragile as we thought it was,” Youngner said.