UPDATE: I'm claiming victory. Neuralink disclosed it has been testing vision implants in monkeys, although it hasn’t made as much progress as I anticipated.

In a presentation lasting more than two hours, Elon Musk said he hoped to win US Food and Drug Administration approval to implant a Neuralink computer inside a human’s skull in six months. The expected application is to see how well a paralyzed person can control a computer mouse using their brain-waves. Previous timelines set by Musk for human tests have not been met. Nor is this idea new. A small group of patients have been brain-controlling computers since the early 2000s using other devices.

As we predicted in this article, Neuralink has also started experiments to produce vision in monkeys, saying it had placed its electrode device into the visual cortex of two monkeys. It is the first time that Neuralink claims to have written information into an animal brain. Engineers showed a video of a monkey moving its gaze in response to visual stimulation—the simplest possible demonstration of a vision-producing technique. Musk claimed an implant could “restore” vision to totally blind people. A more realistic outcome is that a brain implant might produce a field of single-color spots of light that could be used to create a low fidelity visual display.

Elon Musk’s brain-computer interface company Neuralink likes to give progress reports via theatrically staged events that it livestreams.

Its next event, scheduled for tonight at 6 pm Pacific time, was announced by the company via a brief video invitation in which the words “please join us for show and tell” appeared as if they were being typed in green letters on a screen.

The mysterious message immediately had Neuralink fans guessing what it could mean.

Here at MIT Technology Review, we consider such teases an invitation to make hard predictions about what Neuralink will show, relying on our understanding of brain-interface research, Neuralink’s capabilities, and in this case, a timely bit of information from a tipster.

With that in in mind, I predict Neuralink will announce it is not only reading brains with its electronic interface, but is now writing information into them, something it could demonstrate with a “vision prosthetic” that generates images inside an animal’s brain.

That’s possible because electrically stimulating the visual cortex, which lies at the back of the head, produces flashes of lights called “phosphenes” that an animal or person can perceive.

I think the demonstration could work like this: Researchers will send stimulation into a monkey’s visual cortex, creating spots of light arranged into, say, the shape of the letter “A.” Imagine, furthermore, that the monkey is trained to tell you what it sees, for instance by typing the letter A on a keyboard.

That could be the “show” and the “tell” hinted at by Neuralink in its announcement.

Such a vision prosthetic would not only be cool, but it’s totally feasible, even relatively easy to do—and certain to draw oohs and ahhs from Musk’s crowd of fans and followers.

Here's how it would work

The first demonstration that you could make people see spots of light by stimulating people’s brains dates way back to the 1970s. The idea now is to use more electrodes at once to create more phosphenes, then arrange these into a kind of very crude display, like an old-fashioned ballpark scoreboard.

Recently, a group in Spain, using an implant called the Utah array, which has 96 electrodes, found that that a blind woman could use such a system attached to her brain to make out letters.

In its prior events, Neuralink has followed somewhat cautiously in the footsteps of other neuroscientists. For instance, in 2021, it showed a video of a monkey playing the video game Pong with its brain. However, a human with a brain implant had already played the game 15 years before.

Instead of entirely new applications, what's actually important about Neuralink is that it has developed a sophisticated type of brain implant using thin wires studded with electrodes. It implants the wires into animal brains using a neural “sewing machine” robot that used optics to avoid blood vessels. The device is wireless, too, transmitting information out from under the skull, making it more practical.

When Musk launched Neuralink in 2017, he outlined plans for “a high-bandwidth, long-lasting, biocompatible, bidirectional” brain implant. This brain modem, or “wizard’s hat,” he believed, would somehow allow humans to keep pace with artificial intelligence.

Despite the grandiose vision, Neuralink has more recently been talking about practical aims, like helping paralyzed people control a computer.

That is why the company’s earlier demonstrations involved implanting its electrodes in the motor cortex of the brains of pigs or monkeys. That allows researchers to read movements and transmit these to a computer, like when that monkey used its brain signals to move the Pong paddle.

Guessing game

After Neuralink’s latest invitation came out, some company fans guessed that it was a signal that today’s demonstration would involve an animal typing with its brain.

That certainly is one possibility. Krishna Shenoy, a Stanford researcher and adviser to Neuralink, is working with human patients who’ve set world records at brain typing. Shenoy’s human subjects use an older type of implant, called the Utah Array.  

As far as we know, Neuralink’s implant is not yet being tested in humans, although monkeys can be taught to brain-type, too. In 2016, Shenoy showed that monkeys could use their motor cortex brain signals to move a cursor and transcribe text from the New York Times and Hamlet.

Despite that, we still think today’s demo will involve a vision implant. But how will the monkey “tell” what it sees? The monkey could type the answer with its fingers, or even use a second brain implant to type with its thoughts.

Another reason to believe it’s a vision system is that Musk has claimed brain implants can cure a huge range of diseases. And showing a possible technique for treating blindness is one that the multibillionaire has hinted at himself.

During an interview with podcaster Joe Rogan, Musk claimed that a Neuralink device “could fix almost anything that is wrong with the brain. So it could be something that … returns your eyesight, even if you have lost your optic nerve.”

“Really?” Rogan asked. “Yeah, yeah, absolutely,” Musk replied.

To treat a neuropsychiatric disorder, like depression, it’s probably necessary to put electrodes deep in the brain. But the visual cortex is conveniently located right at the back of the brain, near the skull, where it's easy to get at.

Neuralink’s implant could make a good vision prosthetic. Its electrodes go inside the brain, near neurons, so they don’t use much electricity, making it safer. Their system of thin wires could also reach more locations, which means more phosphenes, and possibly a higher-resolution “display.”

In studies carried out at the University of Utah years ago, researchers covered students’ eyes with a screen into which holes had been poked. They found with about 700 holes, they could still navigate obstacle courses and even read books.

That means about 700 phosphenes could make a useful form of vision, even though it’s nothing like natural sight, which is incredibly rich, in color, and travels along a million axons from the eye to the brain.

Exactly how the demo will be carried off is anyone’s guess. Although Musk is a drama-magnet, Neuralink has played it pretty conservative in the past, so we don’t expect anything too crazy. For example, while Neuralink once brought a pig onstage, we wouldn’t expect any kind of live demonstration involving a rhesus monkey. They’re a bit aggressive, and animal rights campaigners are already criticizing the company and its university partners for hurting animals. But there could still be a video demonstration involving a primate, as was the case with the monkey that played Pong.

Certainly, Neuralink could go wild if they wanted to. It's entirely possible for Musk to type letters live, right into a monkey’s brain, and have the animal transcribe his message.

After taking over Twitter, Musk has been acting like a court jester, making rash but, in his view, true comments about free speech and other matters.

I think it would be pretty funny if all Musk’s recent tweets had been transmitted by him and typed by a monkey.

But that is my stretch goal. Everything about Neuralink tells me they will be fairly cautious and stick to a basic demonstration of implant-driven vision. The company wants to show that its device is useful, could help people, and outline a cool future that will attract talented engineers to apply for jobs there.

I could be wrong about all this. So I am definitely tuning in to Neuralink’s event. And so should you. Even though Neuralink’s demonstrations of brain-interfaces aren’t really new, it’s always a great show.

We thank the following individuals for sharing insights and predictions used in the preparation of this item: Eduardo Fernandez, Universidad Miguel Hernandez; Konrad Kording, University of Pennsylvania; Richard A. Normann, University of Utah; Sumner Norman, AE studio; Ryan Tanaka, Neura Pod; and Anonymous.