In the realm of brain-computer interfaces, Neuralink seems to have captured everyone's attention.

Not long ago, the company posted a video on the X (formerly Twitter) platform, showcasing its first human subject to receive a brain implant, which was named Telepathy.

The subject is a 29-year-old man paralyzed from the shoulders down. After the implantation of the chip, he can play chess and move the cursor with his mind. He said in the video that learning to control it is "like using the Force."

This human trial has caused a great sensation, not because the subject has completed any special task.

In fact, scientists successfully achieved cursor movement with a brain implant as early as 2006, and the sensation it caused is simply because its technology is very advanced.The device it uses is very small and is wireless. The electrodes inside the device are very thin and fragile, and must be implanted into the brain by a robot.

At the same time, Elon Musk, the founder of Neuralink, is also a character with his own traffic. He has made bold claims about the company's technology, and many people are paying attention to his every word and deed.

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As we all know, Musk is very interested in using chips to enhance the brain, not just to restore functions lost due to injury or illness.

However, among all the companies trying to help people who have lost the ability to move or speak with brain-computer interfaces, Neuralink is not the only one.

With funding from Bill Gates and Jeff Bezos, Synchron, a company based in New York, USA, has already implanted brain-computer interface devices in 10 people.Last week, it launched a patient registration project aimed at preparing for a larger-scale clinical trial.

Now, let's take a look at the other companies developing brain chips, how their progress is going, and what different technologies and methods they are using.

Most companies working in this field have the same goal: to extract enough information from the brain to interpret the user's intentions.

This is to help those who cannot move or speak easily to communicate, either by helping them control the computer cursor or by converting their brain activity into speech or text.

There are many ways to classify these devices, but Jacob Robinson, a bioengineer at Rice University in the United States, prefers to classify them based on their invasiveness.This is a technical trade-off. The deeper the electrodes, the more invasive the surgery required for implantation, and the greater the risks.

However, deeper electrodes will also be closer to the brain activity that these companies hope to record, as they can capture higher resolution information.

For example, allowing the device to decode speech. This is the goal of companies like Neuralink and Paradromics.

Jacob Robinson is the CEO and co-founder of Motif Neurotech, which is developing a brain-computer interface that only penetrates the skull (more details to be introduced later).

In contrast, Neuralink's device is equipped with electrodes that enter the cerebral cortex. Robinson described it as "within the first few millimeters of the surface layer."Additionally, two other companies, the Austin, USA-based startup Paradromics and Blackrock Neurotech, have also developed chips capable of penetrating the cortex.

Robinson said, "This allows you to get closer to the neurons and obtain information on what each brain cell is doing."

Being closer to neurons and having more electrodes that can "listen" to their activity can increase the speed of data transmission or "bandwidth." The greater the bandwidth, the more likely the device is to convert brain activity into speech or text.

In terms of the number of participants, Blackrock Neurotech is far ahead. Since 2004, its Utah array has been implanted in dozens of people. Many academic laboratories in the United States are using this array.

It is this array that forms the basis of Blackrock's MoveAgain device, which received breakthrough device designation from the U.S. Food and Drug Administration in 2021. However, Robinson said that its bandwidth may be lower than that of Neuralink's device.Robinson said: "Paradromics has the interface with the highest bandwidth, but they have not yet demonstrated this on humans."

Its electrodes are mounted on a chip the size of a watch battery, but the device requires a separate wireless transmitter that needs to be implanted in the chest and connected to the brain implant via wires.

However, all these high-bandwidth devices have a downside. Synchron founder Tom Oxley said in a TED talk in 2022 that they all require craniotomy, but "the brain really doesn't like having needles inserted."

Synchron has developed an electrode array mounted on a stent, which is exactly the same device that doctors use to support blocked arteries.

This device, called Stentrode, can be delivered to the blood vessels above the motor cortex through an incision in the neck.This unique method of delivery avoids craniotomy surgery. However, Robinson said that placing the device above the brain rather than inside the brain would limit the amount of data it can capture.

He doubts whether the device can capture enough data to move the cursor, but it is enough to generate a click. "They can click yes or no, up or down," he said.

Newcomer Precision Neuroscience, a company founded by former executives of Neuralink, has developed a flexible electrode array thinner than hair, similar to a piece of tape. It slides on top of the cortex through a small incision.

The company launched its first human trial in 2023. In these preliminary studies, the array was temporarily implanted in people who were undergoing brain surgery for other reasons.

Last week, Robinson and his colleagues reported the first human test of the Motif Neurotech device in Science Advances, which only penetrates the skull.They temporarily placed this small, battery-free device above the motor cortex of a patient who was already scheduled to undergo brain surgery.

The device is called Digitally Programmable Over-brain Therapeutic (DOT). When they activated the device, they observed the patient's hand moving.

The ultimate goal of the Motif device is not to produce movement, as they are looking towards a completely different application: alleviating emotional disorders.

Robinson said, "Among all those with spinal cord injuries, there are many, many people suffering from severe depression, and medications are ineffective for them. Their despair is no different from that of others, it's just not well-known."

However, research indicates that the device's intensity is sufficient to stimulate the brain, which is the first step towards the goal of practical application.According to the introduction, the device is located above the brain, hence it cannot capture high bandwidth data. However, since Motif is not attempting to decode speech or assist people in moving a cursor with their brain, it does not require that much data.

Robinson said, "Your emotional changes are far less rapid than the words you speak."

Among these companies, which one will stand out remains to be seen, but as the field has gradually yielded results, controlling things with the brain no longer seems to be a plot from science fiction.

Nevertheless, these devices will still primarily be used by people with severe physical injuries.

As for Neuralink's so-called "redefining the boundaries of human capabilities" and "expanding the ways we experience the world," do not expect brain implant technology to achieve these goals soon.