GoKawiilThe development of the human brain, with its extraordinary range of cognitive abilities, is an awe-inspiring feat of evolution. Each of its tens of billions of cells must be born at precisely the right time, migrate to the correct locations, differentiate into as many as 3,000 distinct cell types, and form exquisitely specific synaptic connections with one another. Most of this happens before birth, but development continues for nearly three more decades.
None of this is easy to study. Conventionally, scientists have relied on animal models and scarce human brain tissue. But the advent of tiny laboratory-grown models of human brains called organoids has transformed their options.
Brain organoids are a transformative technology — but they need regulation
First created more than a decade ago, these organoids started off as very simple models. But in the past few years, scientists have refined the technology to grow more-intricate systems that represent more brain regions. Research has snowballed as scientists have used organoids to probe brain development, model neurodevelopmental conditions such as autism and schizophrenia and test new treatments for brain diseases. These tiny spheres are helping researchers to get at difficult-to-answer questions such as why the human brain develops so much more slowly than other mammalian brains do.
And this year, researchers are hoping to run the first clinical trial of a brain-disorder treatment developed entirely in organoids.
“The field is at an inflection point,” says developmental biologist Jürgen Knoblich at the Institute for Molecular Biotechnology in Vienna.
But organoids are not without their limitations. It’s hard to sustain them in the lab for more than a few months, for instance. And they lack complexity.
Looking ahead, there are also questions about whether properties such as sentience or even consciousness could emerge as technologies improve. “This is not remotely feasible at the moment,” says molecular neuroscientist Giuseppe Testa at the University of Milan in Italy, “but at some point, we may need to start scrutinizing for the emergence of more complex behaviour in a dish.”
The neuron’s journey
The first structure that will become the human brain starts to develop just three weeks after conception. It’s a hollow tube made up of the earliest neural progenitor cells.
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