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 trying to unravel the inner workings of the human brain. This hyper-complex organ contains around 86 billion specialized messenger cells – called neurons – that control everything from how we mediate our vital bodily functions to how we conjure up and express complex thought.
Revealing the secrets of its function would enable scientists to cure countless ailments and advance a range of related technologies.
To this end, some of the brightest boffins on the planet have created countless computer models of the brain with varying scales and levels of complexity. However, an international team of scientists tries a different approach, taking embryonic mouse brain cells and human brain cells created from stem cells and growing them on an array of microelectrodes.
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This network is able to track the behavior of 800,000 cells and apply electrical stimulation to boost their activity. Indeed, 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 based on how computer scientists think the brain might work,” comments Dr. Brett Kagan, lead author of the new study and chief scientific officer of Cortical Labs. “It’s generally 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 Neuron review, scientists took DishBrain and tried to get cells to act in a smart, coordinated way to complete a task. Specifically, they wanted to see if they could make the myriad cells act as one and successfully play tennis, 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 field the ball was on using electrical signals, and the frequency of these signals was used to indicate its direction and how far the ball was to cross an invisible wall to score .
According to a press release from the Australian site science in public, electrode feedback was also used to teach the model brain how to return the ball. Specifically, cell activity in two defined regions of the dish was collected and used to move a virtual paddle up and down.
However, training the model’s brain to move the paddle correctly was a challenge. Ordinarily, dopamine is released by the brain to reward correct action, which in turn encourages a subject to act in a specific way. With DishBrain, that 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 of their environment.
The team implemented the theory by hitting the flat with an unpredictable electrical stimulus when the racket failed to intercept the ball, after which the virtual ball would hit a random vector. Conversely, if the neurons were able to move the racket to successfully deflect the ball, then a predictable electrical stimulus was applied to all cells at once, after which play continued in a predictable fashion.
As the cells were inclined to make their surroundings predictable, they worked to understand the game and prolong the pong rally.
“The magnificent and pioneering aspect of this work lies in endowing neurons with sensations – feedback – and above all the ability to act on their world”, says Professor Karl Friston, co-author of the new study. from University College London. “Remarkably, cultures have learned to make their world more predictable by acting on it. »
The team found that DishBrain’s ability to extend a rally improved dramatically in just five minutes. In other words, the cells were able to self-organize to achieve a goal, using what the researchers defined as synthetic biological intelligence.
“The translational potential of this work is really 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 made up of exactly the same (neuronal) computational elements found in your brain and mine.”
In the future, the researchers plan to give DishBrain alcohol to see how it affects his pong performance. One day, the study authors hope the model could provide a useful alternative to animal testing and give doctors new insights into degenerative diseases like dementia.
Anthony Wood is a freelance science writer for IGN
Image credit: Cortical Laboratories