f you have ever wanted to watch around 200,000 living human neurons play the classic 3D shooter game DOOM without a human body to help them navigate a controller, today is apparently your lucky day.
In 2022, researchers took mouse and human neurons and placed them on an electrode array designed to stimulate the brain cells and record their responses. This setup was then paired with the classic 1972 video game Pong, in which players control a paddle and attempt to bat a ball past their opponent. To enable the neurons to play, the device provided electrical feedback about the position of the ball on screen at the time, and the neurons coordinated in order to bat it away again.
That was pretty cool, as long as you don’t think too deeply into the horror of the neurons’ existence. But now Cortical Labs has gone a step further, making around 200,000 living neurons play DOOM.
“Pong was much simpler. There was a direct relationship. The ball went up, the paddle went up. It was a direct input output relationship. DOOM was much more complex,” Alon Loeffler, scientist at Cortical Labs, explains in the video below.
DOOM is a far more complex three-dimensional environment (or, technically, 2.5D) with enemies, attacks, and plenty of ridiculous gunfire, Loeffler points out. Though more complex, the team used a similar method employed to play brain Pong.
“When a demon appears on the left of the screen, specific electrodes stimulate the sensory area of the neural culture on the left side,” Loeffler added. “The neurons react to that stimulation. We then listen to their response, the spikes, and interpret that activity as motor commands. If the neurons fire in a specific pattern, the DOOM guy shoots. If they fire in another pattern, he moves right, and so on.”
200,000 neurons sounds like an awful lot of neurons, but to put it in context, there are around 86 billion neurons in a human brain. Nevertheless, with the help of a little stimulation, these disembodied neurons were able to navigate DOOM (or rather, a copyright-free game Freedoom, which uses the DOOM engine).
“Is it an e-sports champion? Absolutely not. Right now, the cells play a lot like a beginner who’s never seen a computer. And in all fairness, they haven’t,” Loeffler said. “But they show evidence that they can seek out enemies, they can shoot, they can spin. And while they die a lot, they are learning.”
To be clear, these neurons are not aware that they are playing Freedom, nor freaking out at the demon-filled environment. Though sentience in more complex neurons and the question of consciousness may be raised further down the line, these neurons are responding to feedback from electrical signals, and are not aware of what their responses to this stimulation mean to fans of retro videogames.
As Gizmodo notes, whilst it is an impressive demonstration, further questions about ethics will be raised as this technology progresses. For instance, they suggest we could end up with a situation where somebody’s cells are now a professional Call of Duty player, like a shoot-em-up version of the situation with Henrietta Lacks’s immortal cell line.
If you’re wondering what the real-world applications for something like this are, teaching neurons to play a three-dimensional game is a step towards using biological or “living” computers that can manage complex tasks like controlling robot arms for precision experiments or allowing a robot to identify what it is touching. Using brain cells as a computer processing hub could also reduce the massive amounts of energy needed to power artificial intelligence (AI)
While the team is pleased with the results, they say that there is room for improvement, with the neurons needing to be trained in what the “right” and “wrong” actions are within their environment. Nevertheless, they are pleased with the infrastructure that allows them to do just this.
