Originally branded as a way to merge humans and computers, the company Neuralink isn't there yet. But its recent accomplishments in developing a new brain-machine interface could have medical benefits. In July of 2019, Neuralink announced successful tests of its technology in rats.
Using its newly developed device, Neuralink researchers could record neural activity via thousands of electrodes implanted in the brain. They hope that this system could eventually restore movement and sensation to people living with paralysis. According to one study from the Reeve Foundation, in the U.S. alone, there are 5.4 million people living with paralysis.
Founded by Elon Musk in 2016, Neuralink's original goal was to merge human brains with computers. Musk has shared that he fears Artificial Intelligence could become superior to human intelligence, but he also thinks that merging the two could keep humanity ahead.
So far, Neuralink is nowhere close to that lofty goal. It would require a highly detailed, comprehensive understanding of the human brain, and no one in neuroscience is there yet. But, the company has developed a brain-machine interface, a device that can record and stimulate neurons.
Once ready for human participants, the surgery will require just a small hole in the skull, a few millimeters in diameter. Image via Neuralink/YouTube
Brain-machine interfaces have been around for years now, primarily for therapeutic purposes. These devices have allowed people with neurological injuries to type by using their thoughts to control a cursor and an on-screen keyboard. It has helped others control robotic arms to grasp coffee mugs.
A brain-machine interface works by translating brain activity into commands capable of controlling software or hardware. In the brain, neurons communicate by firing action potentials, cascades of electrochemical signals. These signals pass down the arm of one neuron and are received by another neighboring neuron.
A brain-machine interface includes a small brain implant device that records this electric activity. Then, through a wired connection to a computer, it translates neural information into commands. For a paralyzed person with a brain-machine interface, those commands might control a computer program or robotic arm, for example. As scientists and engineers further advance the technology, in the future, this technology may be able to stimulate neurons too, to provide sensory feedback.
Mouse spinal neurons stained with a fluorescent chemical. Image via NICHD, CC BY 2.0
What Makes Neuralink Different?
Neuralink technology, though only tested in rats so far (Musk has claimed that they've also performed tests in one monkey), works in a similar way. But it does differ from traditional brain-machine interfaces. Traditional implanted electrode arrays are usually made of stiff metals than can damage brain tissue. They also have only up to 100 or so electrodes and require invasive brain surgery to implant.
The Neuralink array supports between 1,500 and 3,070 electrodes contained by thin and flexible "threads," about as wide as a quarter of the diameter of a human hair. The flexibility makes the threads far less damaging to brain tissue. But it's difficult for human neurosurgeons to successfully implant such delicate materials. That's why Neuralink also developed a robotic neurosurgery apparatus that can precisely and reliably implant these threads.
Neuralink developed a surgical robot to implant their device. Image via Neuralink/YouTube
According to the company's July announcement, their system has so far been successful. Neuralink's white paper, which has not been peer-reviewed, states that to implant the electrode array, the sewing machine-like surgical robot drills a small hole into the skull and then implants each thread into the brain's surface one at a time.
The surgical device also has a feature that counteracts the jiggling-motion of the brain from heartbeat and breathing, facilitating further precision. It can complete the surgery in about 45 minutes. After surgery, the implant transmits activity from the surrounding cells via a USB C cable to a computer. Neuralink claims that, while they haven't tested this capability, the electrodes can also stimulate neurons.
Made for Humans
As soon as the end of 2020, Neuralink hopes to test its tech in human patients. While being able to record and stimulate neurons with thousands of electrodes represents a huge advancement, Neuralink's technology still needs much more testing and its work should be reviewed by other scientists.
The company claims that the threads are designed for the long haul, but it's unclear how long they last in the brain. In one rat, the electrodes only stayed in place for two months, and some fell off in three other rats as well. The technology will need to prove much more durable before it's ready for human use. Current brain-machine interface implants can last six to nine years in primate brains.
During its July presentation, Neuralink outlined its vision for human applications. By the time it's ready for human use, Neuralink envisions its system, the N1 implant, as wireless and unobtrusive. The implant itself is smaller than a pinky fingernail.
Three of these implants would go in the motor cortex, the area of the brain responsible for creating movement. One implant would go in the somatosensory cortex, the area responsible for registering touch sensations. A small computer, about an inch long, tucked behind the ear would be the only visible component, connected to the wires implanted in the brain. The whole thing could be controlled by the patient's smartphone. The hope is that this could restore motion and some touch sensation to patients who need it. But Neuralink still needs to prove its technology is safe, develop the capabilities for wireless control, and show that their electrodes can stimulate the brain as well as record from it.
A small computer would fit just behind the ear and wirelessly transmit information to a smartphone app. Image via Neuralink/YouTube.
Neuralink also plans to improve the surgery. Eventually they hope lasers will be able to create the hole in the skull so that drilling isn't necessary. Musk's vision is for the surgery to be "as simple and automated as LASIK."
If Neuralink is successful, it could be significant for the millions of people living with paralysis in the U.S. Before any of this becomes a reality, Neuralink needs to prove it's safe. While the company could develop a therapeutic brain-machine interface, their long term goals likely won't be realized for many years, if ever. Creating a "symbiosis with artificial intelligence," as Musk has said, will likely require decades more of neuroscience, computational and medical research.