Roadmap shows how ‘wetware’ can power AI computers

Technology News | February 28, 2023

By Peter Clarke

Scientists are developing biocomputers where three-dimensional cultures of brain cells, called brain organoids, provide the biological hardware. A roadmap for realizing this vision is described in a paper in the journal Frontiers in Science (see link below)

Many of the authors of this roadmao are drawn from different departments within Johns Hopkins University (Baltimore, Maryland) but some are from other universities in the US and Europe.

“We call this new interdisciplinary field ‘organoid intelligence’ (OI),” said Professor Thomas Hartung of Johns Hopkins University. “A community of top scientists has gathered to develop this technology, which we believe will launch a new era of fast, powerful, and efficient biocomputing.”

Silicon-based AI accelerator chips have developed rapidly in recent years with multichip systems coming close to human-like complexity. However, such systems still underperform in terms of energy efficiency by an order of 10^6.

Energy efficiency

Hence the interest in lab-grown brain organoids. These cells are not a mini-brain but have the structures of brain cells such as neurons and synapses. Also, whereas most cell cultures are flat, organoids have a three-dimensional structure. This increases the culture’s cell density 1,000-fold, meaning that neurons can form many more connections.

Also brain organoids have a superior ability to store data. “We’re reaching the physical limits of silicon computers because we cannot pack more transistors into a tiny chip. But the brain is wired completely differently. It has about 100 billion neurons linked through over 10^15 connection points. It’s an enormous power difference compared to our current technology.”

One of the first steps is to scale up the cell cultures: “They are too small, each containing about 50,000 cells. For OI, we would need to increase this number to 10 million,” he said.

I/O bandwidth is critical to computational performance.

“We developed a brain-computer interface device that is a kind of an EEG cap for organoids, which we presented in an article published last August. It is a flexible shell that is densely covered with tiny electrodes that can both pick up signals from the organoid, and transmit signals to it,” said Hartung.

Patient-based computing

For some medical applications of OI an additional level of sophistication is possible because it is now possible to produce brain organoids from adult tissue. This means that scientists can develop personalized brain organoids from skin samples of patients suffering from neural disorders, such as Alzheimer’s disease. They can then run multiple tests to investigate how genetic factors, medicines, and toxins influence these conditions.

“With OI, we could study the cognitive aspects of neurological conditions as well,” Hartung said. “For example, we could compare memory formation in organoids derived from healthy people and from Alzheimer’s patients, and try to repair relative deficits. We could also use OI to test whether certain substances, such as pesticides, cause memory or learning problems.”

Ethics

The roadmap document acknowledges that creating a human brain model with input and output as well as learning capabilities raises complex ethical questions.

One example is whether OI assemblies could develop consciousness. Could they experience pain or suffering? And what rights would people have concerning brain organoids made from their cells?

“A key part of our vision is to develop OI in an ethical and socially responsible manner,” Hartung said. “For this reason, we have partnered with ethicists from the very beginning to establish an ’embedded ethics’ approach. All ethical issues will be continuously assessed by teams made up of scientists, ethicists, and the public, as the research evolves.”