This is fascinating stuff. After months sitting in petri dishes, groups of cells called organoids – minibrains for want of a better term – kick into action along a timeframe similar to developing fetal brains. As npr report:
And clusters of lab-grown human brain cells known as organoids seem to follow a similar schedule, researchers reported Thursday in the journal Cell Stem Cell.
“After these organoids are in that six-to-nine-months range, that’s when [the electrical patterns] start to look a lot like what you’d see with a preterm infant,” says Alysson Muotri, director of the stem cell program at the University of California, San Diego.
The finding suggests that organoids can help scientists study the earliest phase of human brain development and perhaps reveal the earliest biological beginnings of conditions such as schizophrenia and autism.
But the presence of humanlike brain waves in a dish is also likely to focus attention on the ethical questions surrounding this sort of research.
Brain organoids, popularly known as “minibrains,” start out as just a few stem cells in a dish.
But with the right sort of assistance from researchers, they can grow into spheres the size of a pea and begin to look and act like human brain tissue.
So Muotri had his lab begin monitoring the electrical signals coming from these organoids as they grew.
Early on, electrodes picked up just a few spikes of electrical activity. But after several months, “we realized that the number of spikes were too many,” Muotri says. “We’d never seen that before.”
As the organoids continued to grow, the electrical spikes measured became even more common and started to occur at different frequencies.
“And what we could tell is not only the neurons are connecting to each other, but they are forming these microcircuitries,” Muotri says. “That’s when we started seeing these brain waves.”
It appeared that the brain cells were communicating with one another and forming networks, he says.
“We thought, wow. I mean, it’s nice that we have this system,” Muotri says. “But how close is that to the human brain?”
To find out, the team trained a computer to recognize the brain waves produced by babies born up to three months prematurely. Then they had the computer look at the brain waves from organoids as they grew and matured in the lab.
“After 25 weeks, the machine gets really confused,” Muotri says. “It can no longer distinguish the brain waves coming from the human brain and the brain waves coming from the organoids.”
The result adds to the evidence that organoids offer a way to study a wide range of brain diseases and disorders “that have origins in these very early stages of brain development,” Muotri says. These include bipolar disorder, schizophrenia and autism, he says.
This now presents some interesting ethical questions, but it is certainly something that has philosophical ramifications outside of ethics, such as with mind-brain supervenience and the idea that the mental world of the mind depends on the physical world of the brain.