Mad scientist YouTuber is growing a rat brain and teaching it to play Doom

A rat looks at the viewer.
(Image credit: unoL via Getty images)

Getting Doom running on things is a favourite pastime of the tech-inclined, with id's classic title now available on anything from pregnancy tests to potatoes. One of my favourites veered slightly off-tangent from that, being not about how to get Doom running but instead training rats called Carmack and Romero to play it.

Now YouTuber The Thought Emporium has gone one step further in an experiment that is alternately amazing, terrifying, and leads to deep philosophical thoughts about Cacodemons. The guy's got a bunch of lab-grown rat neurons that are forming networks and being trained to play Doom. 

The experiment uses cortical rat neurons, because of their affordability and because they can learn well enough for these purposes (you too can order a million frozen rat neurons online, what a world). Yes, you could use human neurons to the same end, and no doubt someone watching this video will be off to order some imminently, but they're expensive and almost seem overkill because playing Doom can be stripped-down to relatively simple yes / no patterns.

So The Thought Emporium more-or-less breaks down Doom as a top-down 2D game rather than 3D, because the 3D effect is visual rather than having any impact on actions in the game. Thus the neurons have to perform actions like moving forwards or back, rotating the character, firing and changing weapons. The neurons themselves are associated with an electrode array with 46 electrodes that they can somehow trigger in a way I frankly don't understand. But based on audio stimulus, which somehow spatially communicates the above elements of the game, they can trigger these electrodes in patterns.

The video details the process of growing the neurons, how they gradually form clusters over time and in some cases form blob-like clumps that are actually too large for the purposes of the experiment. At one point The Thought Emporium refers to these patterns of neurons and dendrites as a "galaxy" which seems entirely right, though one can't help but feel a creeping sense of unease as some of the implications of this settle in (it doesn't help that their fridge for sample storage is called the Meatcubator).

Every time the neurons make a kill in the game, they receive a "pleasant tone", while when they get killed the stimulator electrodes play "an unpleasant tone." Yeah this is Pavlov's dogs but with a neural network rather than a bunch of dogs. If you're beginning to feel this all sounds a bit like the Matrix, yes, and also try not to think about how this is basically just our brains at scale. It's rat neurons playing Doom, I keep reminding myself, not an existential message about how your treasured Ultra Violence run wasn't all that impressive. 

The Thought Emporium goes on to detail some of the ways in which the neurons are being stored and encouraged to grow, and outlines some of the techniques they intend to pursue to create, among other things, organoids from their self-organisation. They further outline how the next step is growing the neurons from skin cells rather than buying them, for cost purposes, rather than "blending a pet shop rat" (which to be clear they did not do). At this point you may be thinking of Quake rather than Doom, a game all about some ungodly smooshing together of squishy organic life and razor-edged machines, but that's just the neurons talking.

The Thought Emporium shows off some clips throughout of Doom being manipulated by the neurons, but much of this video is focused on the process of getting there: future uploads are promised that will detail the Doom playing more thoroughly.

Much of this is extremely hard to comprehend, and I feel my slight ethical queasiness is probably an outlier when many will look at this and think about the wonder of achieving consciousness and realising you're Doom guy.

Id made the most magnificently gory titles about humanity fighting back against horrors that in some cases turn out to be all-too manmade. I've always thought of "can it run Doom" as a really funny question. But "can it play Doom" is one that, with this, begins to hurt me plenty. The Thought Emporium's twitter bio says they're "as close to a real mad scientist as you'll find", and that certainly seems to sum it up. 

Rich Stanton

Rich is a games journalist with 15 years' experience, beginning his career on Edge magazine before working for a wide range of outlets, including Ars Technica, Eurogamer, GamesRadar+, Gamespot, the Guardian, IGN, the New Statesman, Polygon, and Vice. He was the editor of Kotaku UK, the UK arm of Kotaku, for three years before joining PC Gamer. He is the author of a Brief History of Video Games, a full history of the medium, which the Midwest Book Review described as "[a] must-read for serious minded game historians and curious video game connoisseurs alike."