The brains of decapitated pigs can be partially revived several hours after the animal has died, researchers have revealed, with some of the functions of cells booted back up when an oxygen-rich fluid is circulated through the organ. Importantly, although the researchers saw some preservation of flow through blood vessels and energy use, there was no higher level functional activity in the brain circuits.
Researchers spent six years developing a way to study brain cells while leaving them intact, which requires supplying the brain will oxygen and nutrients.
The researchers stress this study doesn't yet show it's possible to restore cell function throughout the entire brain, and the cells that were reanimated into metabolic activity were not communicating.
Brain cells begin to die when oxygen to the brain is cut off for a long period of time and this process has always been considered irreversible.
However, here was no sign of the brain-wide electrical activity in an electroencephalogram (EEG brain scan) that would signal awareness or perception, meaning that the brains remained biologically alive while being fundamentally dead. Molecular impairments then activate widespread degeneration of the brain.
Intrigued by their observations, the researchers retrieved processed pigs for food production to see the extent of postmortem brain viability.
In the new study, Sestan's team wanted to find out what happens in the brain after blood flow stops and test whether they could restore function to a dead brain in a way similar to the brain cells in petri dish.
How was function restored to the brain?
Researchers at Yale University have published their findings in the journal Nature. The technique may also broaden the study of brain injury and cellular fix, as well as how drugs affect the brain.
"An important fact, since restoration of blood flow to the rest of the body (following a cardiac arrest, for instance), may activate injury processes in non-brain tissues which produce substances that damage the brain (for example, through activation of inflammation)".
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, researchers said.
A specially designed blood-like chemical solution tailor-made to preserve endangered brain cells.
The study is a tremendous breakthrough that upends a lot of pre-existing assumptions in neuroscience, said bioethicist Nita Farahany, a professor and founding director of Duke Science & Society at Duke University. The blood substitute contained chemicals that would block neuronal activity, and sedatives were on hand to halt the proceedings if researchers detected any organized electrical activity. "Everyone agreed in advance that experiments involving revived global activity couldn't go forward without clear ethical standards and institutional oversight mechanisms".
But the experiment has also raised some ethical concerns. Firstly, was this somehow a chance finding, or can it be reliably replicated?
In the meantime, the research could spark new quandaries surrounding the determination of death itself, widely defined by one measure as the irreversible loss of all brain function.
While this discovery is sure to open a Pandora's Box of ethical questions - from "how do we measure consciousness" and "how do we ensure that these heads don't regain consciousness" to "what rights do these heads have being in that undead grey zone" - the study itself strictly adhered to ethical guidelines regarding animal welfare.