SCIENTISTS IN AMERICA have partially revived pig brains four hours after they were slaughtered.
While it had been thought that brain activity ceased once the flow of oxygen did, the experiment shows that cell death occurs longer than previously thought.
Using the severed heads from 32 pigs that had been killed for meat at a slaughterhouse near his lab, Yale neuroscientist Nenad Sestan and his team removed each brain from its skull.
They then pumped a liquid containing chemicals that stop neurons from firing, to protect them from damage and to prevent electrical brain activity from restarting.
The scientists monitored the brains’ electrical activity throughout the experiment and, just in case, were prepared to administer anesthetics if they saw signs that the brains might be regaining consciousness.
For six hours, the scientists monitored the pig brains and discovered that certain brain cells’ normal functions had restarted – like consuming sugar and producing carbon dioxide – and that their immune systems appeared to be working.
They also found that blood vessels in treated brains responded to a drug that makes vessels widen.
The team, however, never saw co-ordinated electrical patterns across an entire pig brain, which would indicate advanced brain activity or even consciousness.
‘Ethical questions’
The experiment, which brings up ethical questions about the definition of death, raises hopes for medical advances, particularity in the field of Alzheimer disease research.
“Cell death in the brain occurs across a longer time window than we previously thought,” Prof Sestan has said.
Such research might lead to new therapies for stroke and other conditions, as well as provide a new way to study the brain and how drugs work in it, he said.
“For most of human history, death was very simple,” Christof Koch, president and chief scientist of the Allen Institute for Brain Science in Seattle, Washington, has said. “Now, we have to question what is irreversible.”
Scientists and governments are now left to confront the legal and ethical quandaries related to the possibility of creating a conscious brain without a body, Nature science journal notes.
“This really is a no-man’s land,” says Koch. “The law will probably have to evolve to keep up.”
Koch wants a broader ethical discussion to take place before any researcher tries to induce awareness in a disembodied brain. “It is a big, big step,” he says. “And once we do it, it’s impossible to reverse it.”
The pig brain experiment also enters an ethical minefield, he said. It questions the widely used definition of death as the irreversible loss of brain function because irreversibility “depends on the state of the technology; and as this study shows, this is constantly advancing,” he said.
The BrainEx system is far from ready for use in people, Prof Sestan has said, not least because it is difficult to use without first removing the brain from the skull.
With reporting from Associated Press
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