Science & Technology



In creating so-called mini-brains, how close to a real human brain is too close?

Bradley J. Fikes, The San Diego Union-Tribune on

Published in Science & Technology News

Do I exist? Do you exist? How do I know you exist?

These ancient questions have been given new urgency by 21st century science. Some of San Diego's top researchers met recently in La Jolla to discuss them.

The topic was so-called mini-brains, pea-sized structures of human neurons grown from stem cells. Called human brain organoids by scientists, they are yielding important discoveries about autism, brain damage from Zika and other neurological conditions.

These mini-brains enable scientists to probe brain functioning in a way that's not ethical in healthy humans. said Dr. Alysson Muotri, a UC San Diego brain organoid researcher and a meeting leader.

But the mini-brains are becoming more complicated, giving rise to the theoretical possibility they might eventually acquire minds of their own, he said.

These mini-brains show no signs of consciousness at present, he said. And existing technological limitations make that very unlikely.


Muotri said mini-brain are limited in size because they don't develop blood vessels. That means that as the organoids grow in their cultures, the inner ones begin to die. They also don't develop all the types of cells found in a human brain.

But Muotri and colleagues recently demonstrated that these organoids can make brain waves similar to those of premature babies -- something never done before. And as for the future, it's impossible to say.

So while a self-aware human brain in a vat of nutrients is science fiction today, the scientists said it's important to be thinking seriously about these issues, and how to discuss them with the public.

Patricia Churchland is a Salk Institute professor emerita who studies the linkage between philosophy and neuroscience. She said the possibility that human brain organoids could eventually become self-aware should be considered.


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