Researchers have built a hybrid biocomputer — combining a laboratory-grown human brain tissue with conventional electronic circuits — that can complete tasks such as voice recognition.

The technology, described on 11 December in Nature Electronics1, could one day be integrated into artificial-intelligence (AI) systems, or form the basis of improved models of the brain in neuroscience research.

The researchers call the system Brainoware. It uses brain organoids — bundles of tissue-mimicking human cells that are used in research to model organs. Organoids are made from stem cells capable of specialising into different types of cells. In this case, they were morphed into neurons, akin to those found in our brains.

The research aims to build “a bridge between AI and organoids”, says study co-author Feng Guo, a bioengineer at the University of Indiana Bloomington. Some AI systems rely on a web of interconnected nodes, known as a neural network, in a way similar to how the brain functions. “We wanted to ask the question of whether we can leverage the biological neural network within the brain organoid for computing,” he says.
Harnessing brainpower

To make Brainoware, researchers placed a single organoid onto a plate containing thousands of electrodes, to connect the brain tissue to electric circuits. They then converted the input information into a pattern of electric pulses, and delivered it to the organoid. The tissue’s response was picked up by a sensor and decoded using a machine-learning algorithm.

To test Brainoware’s capabilities, the team used the technique to do voice recognition by training the system on 240 recordings of eight people speaking. The organoid generated a different pattern of neural activity in response to each voice. The AI learned to interpret these responses to identify the speaker, with an accuracy of 78%.

Although more research is needed, the study confirms some key theoretical ideas that could eventually make a biological computer possible, says Lena Smirnova, a developmental neuroscientist at John Hopkins University in Baltimore, Maryland. Previous experiments have shown only 2D cultures of neuron cells to be able to perform similar computational tasks, but this is the first time it has been shown in a 3D brain organoid.
Better brain model

Combining organoids and circuits could allow researchers to leverage the speed and energy efficiency of human brains for AI, says Guo.

The technology could also be used to study the brain, says Arti Ahluwalia, a biomedical engineer at the University of Pisa in Italy, because brain organoids can replicate the architecture and function of a working brain in ways that simple cell cultures cannot. There is potential to use Brainoware to model and study neurological disorders, such as Alzheimer’s disease. It could also be used to test the effects and toxicities of different treatments. “That’s where the promise is; using these to one day hopefully replace animal models of the brain,” says Ahluwalia.

But using living cells for computing is not without its problems. One big issue is how to keep the organoids alive. The cells must be grown and maintained in incubators, something that will be harder the bigger the organoids get. And more complex tasks will demand larger ‘brains’, says Smirnova.

To build upon Brainoware’s capabilities, Guo says that the next steps include investigating whether and how brain organoids can be adapted to complete more complex tasks, and engineering them to be more stable and reliable than they are now. This will be crucial if they are to be incorporated into the silicon microchips currently used in AI computing, he says.