August 30, 2013 6:43 pm

Mini-brains raise big hopes and fears

Synthetic neuroscience will soon face serious ethical issues

The science-fiction prospect of a living, thinking “brain in a dish” took a small but significant step toward reality this week. Researchers have grown a mini-brain from human stem cells in a Vienna biotechnology lab.

This pea-sized “cerebral organoid” has the characteristics of a nine-week-old embryo’s brain, with active neurons. While it is far from demonstrating anything like conscious thought or sentience, and its creators are interested in understanding neurological disease rather than artificial intelligence, the mini-brain is an unexpected achievement that could soon be taken further – raising profound ethical issues.

The Austrian experiment shows that embryonic stem cells have an astonishing ability to grow in a bioreactor, assembling themselves into the most complex structure known to biology. The scientists provided a nourishing culture medium and flexible 3D support for the growing organoid but, once the cells were set on a path of neural development, special biochemical concoctions were not needed. The stem cells provided all the signals needed to guide their own development.

The scientific steps to make a larger and more powerful mini-brain seem feasible. A blood supply will be needed to deliver oxygen and nutrients for growth beyond the 4mm diameter achieved so far. And sensory connections are required to interact with the outside world.

With $1bn brain research programmes launched this year by the US and EU, scientists will not lack funding to build on the mini-brain experiment. Indeed, similar projects are already under way in other labs. Some are taking a biological approach, like the Vienna team, based on living cells. At the opposite end of the technological spectrum are initiatives such as Blue Brain in Switzerland that seek to simulate the brain in silicon through supercomputer modelling. In between are groups working with hybrid systems that combine electronics and living neurons.

Such research has several scientific justifications. Most immediate is the need for better ways to design and test potential treatments for brain disorders, for which lab animals are notoriously poor models. Computer scientists hope to learn from the human brain how to make machines more intelligent. Then there is the broader intellectual quest to understand mysteries such as memory, emotion and consciousness by studying synthetic brains.

Although few of today’s researchers would seriously expect within their own working lives to create a brain that matches the fully developed human original, the ethical questions will arise more quickly. At what point, for example, should we regard an artificial brain as alive? Should it receive the sort of protection from pain and abuse that we give to lab animals? Funding agencies will need ethics policies robust enough to safeguard scientific progress, while preventing irresponsible research into synthetic brains.

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