It’s the stuff of B-movies: a giant brain sitting in a fluid-filled vat in the center of a laboratory. Whether it's friendly or hostile depends on the story. But the "brain in a jar" concept fascinates us in modern times. Recent research findings suggest that our brains may stay conscious after our bodies die – and could revive even after death. If this is possible, would it change how we view death itself?
Pig Brain Experiments and Redefining Death
When is a person truly dead? We’re still struggling to answer this question. Modern medicine defines brain death as the complete cessation of brain function, including the brain stem itself. That's because the brain stem controls involuntary processes such as breathing and circulation. And it's why keeping bodies alive after brain death requires artificial life support.
Currently, brain death is irreversible. We haven’t found a way to revive brains that have stopped functioning altogether. But recent experiments involving pig brains could present new possibilities – and quandaries. Nature reported in April 2019 that Yale University researchers brought disembodied pig brains back to life. They did so four hours after the animals had died. The team used a system called BrainEx to pump in a blood substitute with oxygen and nutrients.
The research team saw some promising results. They restored some critical cellular functions – metabolizing sugars and manufacturing proteins. They were also able to preserve the brains’ internal structures. The brains’ cellular processes functioned for about a day and a half after revival.
Regaining Consciousness After Brain Death
Could revived brains regain consciousness? The pig-brain research team avoided that question during their experiments. The researchers used chemicals that blocked neurons from firing. The brains displayed no systematic neural activity and never gained consciousness.
But other experiments suggest that consciousness may be possible. Another research team in 2018 grew “mini-brains” by producing cerebral cortex tissue from human stem cells. This detail is key because the cortex handles learning and interpreting sensory information. The mini-brains spontaneously generated brain waves somewhat resembling those from premature babies’ brains.
The Problem With Brains in Jars
Science journalist Sara Reardon explains that the mini-brains aren’t even close to being real brains. They lack other parts of the cortex plus critical brain structures. But the mini-brain and pig-brain experiments point to paths into unchartered territory. And future research could call for serious practical and ethical considerations.
To understand how this could play out, let’s consider the “brain in a jar” trope. Science writer Philip Ball argues that any computer-brain comparison is too simplistic. Brains in jars and on computer chips lack a key ingredient: experience. It shapes our brains' cognition and function in many ways. PTSD is a relevant example: Brains shaped by extreme or multiple traumas have overactive amygdalas. The amygdala is like a "warning system" to keep us out of danger. But when it's hyperactive, it can trigger frequent and excessive panic.
Like Johnny Five from the “Short Circuit” films, our brains need input. And we gather that input from our senses. But what if brains in jars or computer chips receive sensory data simulating actual experiences? Whatever those brains conceive can’t be applied to objects outside its frame of reference, says philosopher Hilary Putnam. Even if we perfectly reproduce trees in those brains’ simulated realities, they still aren’t real trees. They’re pixels, bytes, or neurological impressions of trees.
The Ongoing Search for Answers
It’s too early to tell what could come out of all these brain experiments. We’re probably a long way off from sticking brains in jars, on computer chips, or inside flesh or mechanical bodies. But regardless of future scientific findings, defining death may not be any easier than it is now. And if life after brain death becomes a real possibility, qualify of life and preventing suffering will remain as important ethical issues.
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