Scientists are proposing to develop a biological computer powered by millions of human brain cells that they say could outperform silicon-based machines while using far less energy.
The international team, led by Johns Hopkins University in Baltimore, published on Tuesday in the journal Frontiers in Science a detailed roadmap to what they call “organoid intelligence”. The hardware will include arrays of brain organoids – tiny three-dimensional neural structures grown from human stem cells – connected to sensors and output devices and trained by machine learning, big data and other techniques.
The goal is to develop an ultra-efficient system that can solve problems beyond the reach of conventional digital computers, while helping advances in neuroscience and other areas of medical research. The project’s ambition mirrors the work on the more advanced quantum computing, but raises ethical questions about the “consciousness” of brain organoid assemblies.
“I expect an intelligent dynamic system based on synthetic biology, but not limited by the many functions the brain has to serve in an organism,” said Professor Thomas Hartung of Johns Hopkins, who has assembled a community of 40 researchers to develop the technology.
They have signed a “Baltimore Declaration” calling for more research “to explore the potential of organoid cell cultures to advance our understanding of the brain and unleash new forms of bioinformatics while recognizing and addressing the associated ethical implications”.
Developing organoid intelligence into a commercial technology could take several decades, Hartung admitted. On top of the scientific challenges are ethical concerns about creating “intelligence in a dish” that can learn, remember and interact with its environment – and can develop consciousness even in rudimentary form.
An “embedded ethics” approach had been in place from the project’s launch, Hartung said, adding: “All ethical issues will be continually assessed by teams of researchers, ethicists and the public.”
Madeline Lancaster, a brain organoid researcher at the Laboratory of Molecular Biology in Cambridge, who is not associated with the project, was skeptical of the ambitions. “This is really very much science fiction, and while it’s exciting, the science just isn’t there yet,” she said. “There are major hurdles to overcome to do what the authors suggest.”
Karl Friston, professor of neuroscience at University College London, who is not involved in organoid intelligence, was more positive. “It’s definitely an idea worth pursuing,” he said. “There will be many small steps forward, but the direction of travel could be revolutionary.”
A necessary step, Hartung said, was to enable individual organoids to grow larger by finding a better way to fill them with nutrients in laboratory dishes. These tiny neural constructs need to be scaled up from about 50,000 cells today to around 10 minutes to help achieve what scientists will recognize as organoid intelligence.
Scientists are also developing technologies to connect organoids and communicate with them, sending them information and decoding their “thoughts”. Hartung’s laboratory has tested an interface, “a flexible shell densely covered with tiny electrodes that can both pick up signals from the organoid and transmit signals to it”.
One reason to turn to biological computing is that the brain processes and stores information so efficiently. The world’s most powerful supercomputer, the Frontier machine at Oak Ridge National Laboratory in the US, which became operational last year, matches a single human brain for processing power – an exaflop, or a billion billion operations per second – but uses a million times more energy.
The first applications of organoid intelligence will be in neuroscience and medicine. Researchers are already creating brain organoids from stem cells from patients with neurological conditions, to compare with healthy individuals and assess their response to drugs. Organoid intelligence will increase research into cognitive impairment caused by brain diseases – and its prevention.
Although the technology may take decades to deliver biocomputers powerful enough to compete with conventional silicon or quantum systems in terms of functionality such as artificial intelligence, proponents of organoid intelligence point to its enormous and unpredictable potential.
“I hope that we see things that are not just a copy of normal brain development,” Hartung said.