How does China's non-invasive brain-computer interface technology achieve "mind typing"?

In May 2023, there was a piece of news that many friends may have paid attention to. Researchers from Tianjin University in our country developed a high-performance brain-computer interface called the "ultra-large instruction set and high-speed" non-invasive brain-computer interface system, which also created the world record for the largest instruction set of non-invasive brain-computer interface.

After reading the news above, some friends may ask, what is the use of "super large instruction set" and "non-invasive"? In fact, when it comes to brain-computer interface, many friends know that it is to establish a direct or indirect connection between the human brain and external devices, so that the brain and the machine can communicate. To put it bluntly, it is to analyze what your brain thinks and turn it into instructions to directly transmit to the machine. Of course, there is another type of input-type brain-computer interface, which is to input external information into the brain.

Whether it is input or output, it can be divided into invasive and non-invasive forms. The invasive method is easy to understand. Simply put, an electrode is implanted in the brain. We have seen similar things in many science fiction movies. After the electrodes are implanted, these electrodes can collect the brain's neural electrical signals, and then analyze these signals to roughly know what you are thinking, and then encode and transmit what you are thinking, and turn it into instructions to the machine.

The other is non-invasive, which does not require implantation. It collects signals outside the brain, such as scalp EEG, and then analyzes these to find out what you are thinking. We also sell EEG-controlled toy cars online, which use thoughts to control whether it moves forward or backward. However, you may find that the car does not move forward when you think about it, or moves backward when you think about it. It may be that the car moves forward when you think about a specific thing, such as the car moves forward when you think about "eggplant" and moves backward when you think about potatoes. Then, will thinking about three fresh vegetables make you go around in circles? You have to try it to know.

Of course, this is a toy, and it is relatively crude. But the principle is the same, collecting information about your brain activity from outside the head. However, this non-invasive brain-computer interface has its relative shortcomings, that is, it is more difficult to obtain a large amount of information and more accurate information, and the transmission of information is subject to certain constraints. After all, compared with the invasive method, people collect nerve electrical signals directly from the brain, which is more direct. The non-invasive method is outside, not so direct, and a little far away. Therefore, people are constantly trying to identify EEG signals more accurately and increase the amount of information that can be extracted and transmitted per unit time. Because if the amount of information per unit time is too little, it will be difficult for me to analyze what you are thinking at any time. You think of a potato and I thought you were going to move forward.

This scientific research achievement of Tianjin University is to use an ultra-large instruction set to transmit more complex and precise instructions, and transmit more information per unit time. Of course, behind this is also the precise recognition and distinction of EEG signals. To put it bluntly, it makes non-invasive brain-computer interfaces easier to use.

Image from Tuchong.com

This is actually very meaningful, because we say that invasive devices must be placed in the brain. After all, there are certain risks, unless it is absolutely necessary. You say that I want to implant an electrode in my brain to play a remote control car? No one does this. But non-invasive ones are different. I just wear something and use wearable devices. This greatly expands the application scope of brain-computer interfaces. Just like we say virtual reality technology VR, it makes us feel that the gaming experience is very good, very real, and immersive. But the reason why everyone is willing to play and use it is because you only need to wear a helmet and glasses. If you have to drill a hole in your head to play VR games, then no matter how good the experience is or how immersive it is, no one will play it. Therefore, non-invasive brain-computer interfaces are more easily integrated into our lives.

The team also demonstrated "mind typing" using this technology. The so-called "mind typing" has actually been studied by many people. It means that you don't type with your hands, but think with your head, and the words will come out. Some imagine the typing process, and some use a flashing virtual keyboard, such as the newlink created by Musk, but his is invasive. There is also mind typing that recognizes what letters you are thinking of by imagining the writing process. In 2021, someone published an article in Nature. By imagining the process of writing letters in the mind, the recognition is displayed, and the accuracy rate is said to be 99%. This can allow some paralyzed patients to write by thinking, and the input speed is also very fast. But his is also invasive, requiring the implantation of electrodes. If it is non-invasive mind typing, it will be very powerful. Many of us now use voice input, and in the future we may use thought input, and input it as soon as we think. But to achieve these, there are still many technical breakthroughs to be made.

In fact, the Tianjin University team has now built a domestic full-chain non-implantable brain-computer information interaction technology system from chips, electrodes, algorithms to systems. The three core indicators of EEG recognition accuracy, number of control instructions and information transmission rate have reached the highest international level. The record created by Chinese scientists also shows that our current scientific research strength is getting stronger and stronger. I believe that in the future, with the development of technology, non-invasive brain-computer interfaces will gradually enter our lives, and Chinese scientists will make more contributions in this regard.

This article is a work supported by Science Popularization China Starry Sky Project

Author: Zhang Yuzhi

Reviewer: Ye Sheng (Professor at Beijing University of Aeronautics and Astronautics)

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.