Human Brain Transplants  — Are They Possible?

In the 1983 film “The Man with Two Brains,” Steve Martin’s character falls in love with the disembodied brain of a woman named Anne. The Conversation

But what once sat in the realm of movies and science fiction novels now seems slightly more plausible. Recent advances in neuroscience have lead to human cells being grown into “mini brains” in the lab, and brains of decapitated pigs being “kept alive” for a day and a half.

So are we closer to a time when brains may be able to function in isolation from a body — leading to head transplants or even brains frozen and brought back to life in the future?

I think such possibilities are a long way off.

brain transplant

A Brain Without A Body

Professor Nenad Sestan of Yale University reported in March that he and his team restored blood circulation to the brains of decapitated pigs, and kept brain cells alive and functioning for up to 36 hours.

This technology, called “BrainEx”, restores circulation by connecting the brain to a series of pumps and heaters that pump artificial blood and carry oxygen to key regions, including areas deep inside the brain. This allows even microcirculation — the flow of blood to the smallest blood vessels and cells — to be restored.

This work opens up a number of potential future research avenues, including the ability to test new treatments for Alzheimer’s disease and other neurological conditions.

A more developed area of neuroscience is the generation of brain organoids, “mini brains” grown from human stem cells and kept alive in the laboratory.

These organoids mimic features of the developing brain, allowing researchers to undertake research into conditions such as autism spectrum disorders and schizophrenia.

It doesn’t get much kookier than this 1983 trailer.

Are The Brains Really Alive?

Sestan believes his approach to keeping pig brains alive is likely to work in other species, including primates.

But what might keeping brains “alive” mean for the individual? Might it be possible for the disembodied brain to retain its consciousness and memory, devoid of any sensory input or ability to communicate?

Monitoring of the pig brains via a technique known as EEG showed no sign of complex electrical activity indicating thought or sensation. This could be due to lowered activity or damage of brain cells during the procedure.

But some research has indicated that, even when the EEG is a flat line, there may still be some activity in deep brain structures such as the hippocampus, a brain area critical for memory.

The question of measuring activity is also relevant to the brain organoids. With improvements in techniques, there is the potential that organoids may become more complex. Although it’s still very unlikely, it’s possible they may take on aspects of higher-order brain functioning, such as feeling pleasure and pain, storing memories, or even experiencing some degree of consciousness.

What is Consciousness?

Consciousness is one of the most difficult brain phenomena to explain, and a question that modern neuroscience is just beginning to make progress on. It’s even difficult to actually define what consciousness is.

Australian philosopher David Chalmers has referred to these challenges as the “hard problem” of consciousness — understanding why consciousness occurs.

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