Scientists have taught a collection of brain cells living in a dish how to play a version of the arcade game pong. The research could one day give doctors a ‘sandbox’ with which to test treatments for brain diseases.
For hundreds of years, the scientific community has been attempting to unravel the inner workings of the human brain. This hyper-complex organ contains around 86 billion specialized messenger cells – known as neurons – that control everything from how we mediate our vital bodily functions, to how we conjure and express complex thought.
Unlocking the secrets to its function would allow scientists to remedy countless ailments, and advance a range of related technologies.
To this end, some of the brightest boffins on Earth have created countless computer models of the brain with varying scales and levels of complexity. However, an international team of scientists is trying a different approach, by taking embryonic mouse brain cells and human brain cells created from stem cells and growing them on top of a microelectrode array.
This array is capable of tracking the behavior of the 800,000 cells, and of applying electric stimulation to prompt activity in them. In effect, DishBrain, as the team calls it, is a relatively simplistic living model of part of a living brain.
“In the past, models of the brain have been developed according to how computer scientists think the brain might work,” comments Dr. Brett Kagan, lead author of the new study and Chief Scientific Officer at Cortical Labs. “That is usually based on our current understanding of information technology, such as silicon computing. But in truth, we don’t really understand how the brain works.”
In a new study published in the journal Neuron, scientists took DishBrain and attempted to make the cells act in an intelligent, coordinated way to complete a task. More specifically, they wanted to see if they could get the myriad cells to act as one, and successfully play the tennis game, Pong.
The team used a series of electrodes to create their virtual pong court. They were able to tell the cells which side of the court the ball was on using electrical signals, and the frequency of these signals was used to indicate its direction, and how far away the ball was from passing through an invisible wall to score.
According to a press release from the Australian site Science in Public, feedback from the electrodes was also used to teach the model brain how to return the ball. More specifically, the activity of cells in two defined regions of the dish was gathered and used to move a virtual paddle up and down.
However, training the model brain to correctly move the paddle was challenging. Ordinarily, dopamine is released by the brain to reward a correct action, and this in turn encourages a subject to act in a specific way. With DishBrain, this was not an option.
Instead, the team turned to a scientific theory known as the ‘free energy principle’ which asserts that cells like neurons will do what they can to reduce the unpredictability in their environment.
The team implemented the theory by hitting the dish with an unpredictable electrical stimulus when the paddle failed to intercept the ball, after which the virtual ball would set off again on a random vector. Conversely, if the neurons were able to move the paddle to successfully deflect the ball, then a predictable electrical stimulus was applied to all of the cells at once, after which the game continued in a predictable way.
Since the cells were inclined to make their environment predictable, they worked to understand the game and prolong the pong rally.
“The beautiful and pioneering aspect of this work rests on equipping the neurons with sensations — the feedback — and crucially the ability to act on their world,” says Professor Karl Friston, a co-author of the new study from University College London. “Remarkably, the cultures learned how to make their world more predictable by acting upon it.”
The team discovered that DishBrain’s ability to extend a rally improved significantly over the course of just five minutes. In other words, the cells were able to self-organize to complete a goal, using what the researchers defined as synthetic biological intelligence.
“The translational potential of this work is truly exciting: it means we don’t have to worry about creating ‘digital twins’ to test therapeutic interventions,” comments Professor Friston. “We now have, in principle, the ultimate biomimetic ‘sandbox’ in which to test the effects of drugs and genetic variants – a sandbox constituted by exactly the same computing (neuronal) elements found in your brain and mine.”
Moving forward, the researchers are planning to give DishBrain alcohol to see how it affects its performance at pong. One day, the authors of the study hope that the model could provide a useful alternative to animal testing, and allow physicians to gain new insights regarding degenerative diseases like dementia.
Anthony Wood is a freelance science writer for IGN
Image credit: Cortical Labs