‘Biocomputing’: Scientists use human brain cells

Scientists propose to develop a biological computer powered by millions of human brain cells. According to them, the computer would perform much better than silicon-based machines and at the same time consume much less energy.

A team led by Johns Hopkins University in Baltimore (USA) published on Tuesday (28) in the specialized journal Frontiers in Science a detailed road map to arrive at what it calls “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 taught through machine learning, “big data” and other techniques.

The objective is to develop an ultra-efficient system that can solve problems that are beyond the reach of conventional digital computers and, at the same time, help the development of neuroscience and other areas of medical research. The project’s ambition reflects work done with more advanced quantum computing, but it raises ethical questions around the “consciousness” of brain organoid assemblies.

“I hope for an intelligent dynamic system based on synthetic biology, but that does not suffer the limitations imposed by the many functions that the brain needs to perform in an organism”, said Professor Thomas Hartung, from Johns Hopkins, who brought together a community of 40 scientists to develop The technology.

They signed a so-called “Baltimore statement” calling for further research “to explore the potential of organoid cell cultures to advance our understanding of the brain and put new forms of biocomputing into action, while acknowledging and addressing the associated ethical implications.”

Hartung admitted that developing organoid intelligence to convert it into commercial technology could take decades. In addition to the scientific difficulties, there are the ethical issues connected with creating an “intelligence on a board” that will be able to learn, remember and interact with the environment — and that can develop consciousness, even in a rudimentary way.

Since the project was launched, the focus has been on the ethical dimension, according to Hartung: “All ethical issues will be evaluated continuously by teams composed of scientists, ethicists and the public.”

Madeline Lancaster, a brain organoid researcher at the Laboratory of Molecular Biology in Cambridge, is not affiliated with the project and is skeptical of its ambitions. “This is still very much in the realm of science fiction. While it’s interesting, the science is just not there yet,” she said. “There are huge hurdles that will have to be overcome to do what the authors are proposing.”

Karl Friston, professor of neuroscience at University College London and not involved with organoid intelligence, was more positive. “It is an idea that deserves to be studied, without a doubt”, he commented. “There will be many initial steps ahead, but the path taken could be revolutionary.”

Hartung said a necessary step is to enable individual organoids to grow larger. That will require a better way to infuse them with nutrients in laboratory dishes. These tiny neural constructs will have to grow from about 50,000 cells today to about 10 million cells before they can help bring about something that scientists would recognize as organoid intelligence.

Researchers are also developing technologies to link organoids together and communicate with them, sending them information and decoding their “thoughts”. Hartung’s lab tested an interface, “a flexible shell that is so densely covered with tiny electrodes that it can pick up signals from the organoid and transmit signals to it.”

One reason to turn to biological computing is the efficiency with which the brain processes and stores information. The world’s most powerful supercomputer, the Frontier machine at Oak Ridge National Laboratory in the US, which became operational last year, matches the processing power of a single human brain — an exaflop, or a billion billion operations. per second—but consumes 1 million times more power.

The first applications of organoid intelligence will be in neuroscience and medicine. Scientists are already creating brain organoids from stem cells derived from patients with neurological problems, to compare them with healthy individuals and assess their response to drugs. Organoid intelligence would bolster research into cognitive impairment caused by brain disease and its prevention.

The technology may take decades to create biocomputers powerful enough to compete with conventional silicon or quantum systems in producing functionality like artificial intelligence, but proponents of organoid intelligence point to its immense and unpredictable potential.

“I hope we see things that are not just a copy of normal brain development,” Hartung said.

^{Translated by Clara Allain}