US scientists partially revived the pig brain four hours after the animals were slaughtered.
Findings could foster the debate about the barrier between life and death and provide a new way of investigating diseases like Alzheimer's.
The study found that death of brain cells could be interrupted and even some links in the brain recovered.
However, there were no signals from the brain indicating consciousness or awareness.
Surprising findings challenge the idea that the brain goes on irretrievably declining within a few minutes of interrupting blood supply.
How was it done?
Thirty-two brains were collected from a slaughterhouse.
Four hours later, the bodies were linked to a system made by the Yale University team.
A rhythmic pump (to mimic the pulse) a specially designed liquid around the brain, which contains synthetic oxygen and medicine blood to slow down or restore the death of the brain cells.
The pork wrap was given to the cocktail party for six hours.
What did the study show?
The study, published in the journal Nature, showed a reduction in brain deaths, the restoration of blood vessels, and the effect of the brain.
The researchers found work synapses – the links between brain cells that allow them to communicate.
The brain also showed a normal response to the drugs and used the same amount of oxygen as the normal brain.
This was all 10 hours after the pigs were beheaded.
Of particular importance there were no signs of electrical activity across the brain in the electroencephalogram (scanning of the EEG brain), which would signal an awareness or perception.
Basically, they were still dead brains.
What have we learned?
The research transforms ideas about how the brain dies, which many think has happened quickly and irreversibly without the supply of oxygen.
Professor Nenad Sestan, professor of neuroscience at Yale University, says: "Death of cells in the brain occurs over a long period of time that we previously thought.
"What we show is the process of cell death is a gradual, gradual process.
"And that some of those processes can be delayed, preserved or even vice versa".
- Five ways to notice if anyone has Alzheimer's disease
- A breakthrough that can save our lives
Are these experiments ethical?
The pork cereal comes from the pork industry; animals were not collected in a laboratory for this experiment.
But Yale scientists were so concerned that pigs may become aware that they give medication to the separated brains to reduce brain activity.
And the team constantly followed the brain to see if there were signs of higher brain functions.
In that case, they would use anesthesia and complete the experiment.
Ethics, writing in nature, say new directions are needed in this field, since animals used for research could end up in a "gray area – not alive but not completely dead."
What's the point?
Scientists who study the brain in diseases such as Alzheimer's disease will benefit directly from this work.
The organ is the most complex structure in the known universe, but techniques such as freezing chunks of brain or growing colonies of brain cells in eating do not allow researchers to explore the full 3D brain wires.
In the long run, scientists hope to find better ways to protect the brain after trauma, such as a stroke or when oxygen is born at birth.
Dr. Andrea Bekel-Mitchener, from the Brain Initiative at the US National Institute for Mental Health, said: "This research line can lead to a new way of studying the post-mortem brain.
"Research can also be stimulated to develop interventions that promote brain regeneration after a loss of brain blood flow."
However, researchers say it is still too early for the field to make a difference for patients after the injury.
Professor Sestan said: "We do not yet know if we can restore the normal function of the brain."
Does this change the meaning of death?
Not at present, but some ethicists say we need to have the debate now, because people who are "dead in the brain" are the main source of transplant organs.
Dr. Dominique Wilkinson, professor of medical ethics and consultant neonatologist at Oxford, said: "Once someone is diagnosed as" brain-dead, "there is currently no way for that person to recover.
"The human person who has been, has left forever.
"If, in the future, it is possible to restore the function of the brain after death, to restore one's mind and personality, which, of course, will have important implications for our definitions of death."
But this is not the case at the moment.
Professor Tara Spiers-Jones, deputy director of the Center for Detection of Brain Sciences at the University of Edinburgh, said: "This study is a long way from preserving the function of the human brain after death as shown in the futurama Futurama, where which heads were stored in a jar.
"Instead, it is temporary preservation of some of the more basic cellular functions in the pig's brain, not the preservation of thought and personality."
Can the pig brain be aware?
In this experiment, the answer is clear. The brain is silent.
But the research asks as many questions as it suits:
- How long can researchers keep the brain?
- Will the results be even better if the researchers did not wait four hours before they started?
- Also, the team used drugs to suppress brain activity – would the headless brain be aware if they did not have it?
Follow James on Twitter.