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Tiny Human Brains Are Being Implanted in Rats

Any headline containing the words “tiny human brains,” “implanted” and “rats” can’t be good news, even if the implanting is being done by some of the most famous and reputable labs in the world. Yet that’s what’s going to be discussed (and probably argued about in the break-outs, bathrooms and bars) when 21 papers on tiny human brains or organoids are presented at the upcoming annual meeting of the Society for Neuroscience taking place in Washington, D.C., November 11-15.

The news comes from the journal STAT, which gives a detailed introduction to the scientific and medical innovations and ethical dilemmas that preceded these studies. Human brain organoids are blobs of human brain tissue grown from stem cells. They’re tiny and allegedly non-thinking but they react like human brains and have been used for drug testing and studies on brain diseases. The ethics of implanting them in non-human vertebrates will certainly be discussed since there is currently no ban on it but plenty of controversy.

I don’t feel smarter. Whose brain did you give me?

STAT looked at two of the more interesting and controversial studies. One was conducted by Fred “Rusty” Gage, a top neurobiologist at the famous Salk Institute. Gage led a team that performed what is believed to be the first reported vascularization – connecting the human brain organoid to a rat’s circulatory system. If that weren’t enough, they were able to see neurons from the human brain organoid send signals that were received and processed by the host rat’s brain.

Paging Dr. Frankenstein. Stat quotes legal scholar and bioethicist Hank Greely of Stanford University:

“[These advances are raising the question] of whether you are creating something human-ish that you have to take seriously in terms of according it dignity and respect — and figuring out what that even means.”

Human-ish? Is that a medical or a legal term?

Another study, led by University of Pennsylvania neurosurgeon Dr. Isaac Chen, implanted human cerebral organoids into the secondary visual cortex of the brains of 11 adult rats. The organoids survived for two months and connected naturally to the rat brains. When a light was shined in the eye of a rat, neurons fired in the human brain organoid. That’s not just connection … that’s integration.

Be the human … be the human.

Before jumping to unethical conclusions, Chen points out that his ultimate goal is to integrate healthy human brain organoids into damaged or diseased human brains to treat physical problems caused by accidents or stroke and eventually schizophrenia and autism.

However (there’s always a ‘however’ and in this case there are plenty of them), animal testing is being done first and no one has any idea if even a small number of human neurons implanted in a rat brain will give it human consciousness or advanced intelligence.

Paging Algernon … your flowers are ready.

The cat … or in this case, the brain … is already out of the bag and on its way to being in many more rat skulls in the not-too-distant future. Should a moratorium be placed on this type of research until tests can be done using computer modeling or robots? Is it ethical to put human brain organoids in a robot?

Whatever the case, we need to put these ideas into new horror movies before the rats take over Hollywood. Or have they already?


Paul Seaburn Paul Seaburn is one of the most prolific writers at Mysterious Universe. He’s written for TV shows such as “The Tonight Show”, “Politically Incorrect” and an award-winning children’s program. He’s been published in “The New York Times” and “Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn’t always have to be serious.

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