Scientists at various institutions are working on technologies that allow people to see, hear, and move artificial limbs by tapping into the brain’s neurons.

We are now well on the way to being able to restore vision and hearing to people without those senses.

Like the development of the internet, this change is happening in stages.

Also, like the internet, the military’s Defense Advanced Research Projects Agency (DARPA) is playing a leading role in the effort.

“We’re building a broadband modem for the brain,” Matt Angle, chief executive officer of Paradromics Inc., told Healthline.

Along with five university research teams, his company was awarded a DARPA contract last month to develop a “high-resolution neural interface” that could eventually lead to new ways of restoring senses.

The ultimate goal of DARPA’s program is the development of neural interfaces that would allow the brain to directly communicate with computers, and vice versa.

Scientists working on this new program will try to make the interfaces capable of engaging in two-way communication with more than 1 million neurons.

The interaction with that many neurons is small, relative to the 86 billion neurons in the average human brain. However, it’s still considered large given current technological capabilities.

The program could give researchers a deep enough understanding of brain functioning to open the door to new sensory therapies.

“If you lose an eye today, you can’t regrow an eye or reconnect the optic nerve. That’s really far away, more than 20 years,” Angle said. “But you can functionally restore vision by connecting a brain to a computer with a camera. That’s credible.”

And that’s what they’re doing.

Animal trials for therapies developed by Paradromic — a company creating neural interfaces for advanced prosthetic therapies — are set to begin next year. The first human trials wouldn’t be before 2021.

Paradromics has been working on an implant that would connect the brain to microprocessors.

The implant would use a bundle of 10,000 wires, each smaller than a human hair at 20 microns in diameter, to tap directly into what someone is thinking or saying.

Ehud Isacoff, PhD, director of the UC Berkeley Helen Wills Neuroscience Institute, is tackling the challenge of making that technology possible.

The facility at UC Berkeley got one of the DARPA grants to back its development of a way to read and communicate with neurons in the visual part of the brain, which would help someone with an amputated limb control an artificial limb.

To “read” these neurons, the scientists would use a type of miniature microscope that could watch a million neurons at once.

To “write” to them, they would simulate normal brain activity through optogenetics, which involves projecting light patterns onto specific neurons to affect their behavior.

The microscope, Isacoff says, “is miniaturized from a room-size system to something the size of a sugar cube. Pretty exciting.”

Eventually, the technology could make possible the development of a system that sends sensory input directly into the brain from a camera or array of sensors, leading to what Isacoff calls “the prosthetics of the future.”

Before any prosthetics, though, the new technologies will continue a breakthrough in our understanding of how the brain works.

For decades, studying the brain meant recording the sensory input and behavior from single cells or a group of cells, Isacoff told Healthline.

Then optogenetics, developed in the early 2000s, made it possible to “play back” observed patterns to the brain to try to determine which patterns drive perception or behavior.

But those methods are still being developed to the point where they’d be able to affect enough neurons to modify perception or behavior.

Despite the DARPA goal of reaching 1 million neurons, exactly how many would need to be included still isn’t clear.

“How many neurons do you have to watch and control to capture a percept? We don’t know,” said Isacoff. “If we can scale up from hundreds to a million neurons will we be ‘there’? Is it enough to read or write in one part of the brain, or do you need to do it in [all the places known to participate in a given behavior]?”

The new technology being developed is as much about being able to ask and — hopefully — answer those questions about how to restore vision or touch.

Other research projects are proceeding in this field without DARPA grants.

Kernel in Los Angeles, Elon Musk’s Neuralink, Facebook, and other startups and tech giants are working on brain-computer interfaces.

And a number of university teams are making rapid progress.

But DARPA has a history of success with “tech that has reached a certain point but needs to be pushed out of the nest,” said Angle, citing self-driving cars as one example.

He said DARPA has a mandate to get new technology out there — in part, in this case, to help wounded veterans.

But he noted there will likely be other applications we can barely even imagine right now.