Set a "spell" for your brain so that no one can eavesdrop on my secrets ever again.

On September 10th, Elon Musk's brain-computer interface company, Neuralink, posted on X that 12 people worldwide have undergone its brain-computer interface chip implantation surgery. All patients have used the device for a cumulative total of 2,000 days, with the total usage time exceeding 15,000 hours.

Neuralink posted on X, presenting relevant data on its brain-computer interface chip implantation surgery | Screenshot

The trend of brain-computer interfaces is growing stronger, which easily reminds people of the plot in "Ghost in the Shell": In Japan, where brain-computer interface technology is highly developed, hackers can invade electronic brains through system vulnerabilities, ultimately erasing a person's soul and turning them into the hackers' puppets.

Perhaps one day, we will be able to control our phones with our thoughts, "download" knowledge directly into our brains, and even have "telepathy" with others... But the question is, if hackers really invade our brains, steal our memories, and tamper with our thoughts, what should we do?

When Thoughts Are No Longer Safe

In 1945, the Soviet Union gave a wooden national emblem to the US ambassador to the Soviet Union, but secretly placed a non - electronic bug inside. It took a full seven years and four different ambassadors before the Americans discovered the bug.

With an unprotected brain-computer interface system, eavesdropping will be even easier. In 2022, Japanese scientists were able to monitor brain signals through functional magnetic resonance imaging and reproduce to some extent the images seen by the subjects.

Top: The image seen by the subject. Bottom: The reproduced image. | Reference [1]

Since it's possible to "eavesdrop" on the brain, "controlling" it is not far off. Many people born in the 1980s and 1990s have played the game "Command & Conquer: Red Alert". In the game, the Yuri unit can control units of other forces, turning them into puppets. This can be achieved through a brain-computer interface system with the function of stimulating the brain, such as the common research on restoring motor function disorders nowadays.

In the 1960s, Yale University professor José M. R. Delgado, who was born in the land of bullfighting, and his team were able to stop a raging bull by stimulating its brain with an implanted chip. This experiment was one of the prototypes of brain-computer interfaces and sparked a lot of controversy at that time.

As technology continues to develop, "deleting" and "implanting" memories will also become possible. In the movie "Men in Black", every time the protagonist solves a supernatural event, they brainwash ordinary people who are accidentally involved to erase their memories. In the future, through brain-computer interfaces, we may not only be able to delete memories but also write or rewrite them.

A 2019 study achieved "memory transplantation" in zebra finches: When a young finch was learning a courtship song, the neural signals in its hippocampus were recorded. Then, these signals were used to stimulate the hippocampus of another young finch. As a result, the finch learned a courtship song it had never learned before through neurobiological methods.

Set a "Password" for Your Brain

Although we can use external factors such as laws and regulations to prohibit these illegal behaviors, scientists are also making technology more user - friendly to avoid these problems. This year, a research team from Stanford University published a paper in "Cell", providing a new idea for solving this problem -

They invented a method to "set a password" for the brain's inner speech for the first time, making your thoughts truly your own.

A traditional brain-computer interface is like an "interpreter". Scientists create a list of words and record the characteristics of the brain's electrical signals when the user imagines "saying" these words. Then, when the user imagines "saying" a certain word again, the system can compare these characteristics and guess what the user wants to say.

Like an interpreter, a brain-computer interface converts the brain's electrical signals into corresponding words | Image generated by Gemini

However, this method has a major problem - imagining oneself speaking is tiring, and the speaking speed is slower than normal. So, the scientists at Stanford University came up with a smarter idea: Directly "eavesdrop" on your inner speech.

Inner speech, or "inner monologue", is the little voice that keeps "chattering" in your head and is common during thinking and other activities. Through traditional biological methods, scientists have learned that inner speech and actual speech have similar but not identical brain potential characteristics. In other words, a brain-computer interface system for decoding speech may also be able to decode inner speech.

But what if I'm secretly scolding my boss in my mind or thinking about a little secret, and the brain-computer interface accidentally "hears" it? It's simple, just set a "password". The research team calls it the "keyword strategy".

They set a long and unique "password" for the brain-computer interface using the title of a British children's literature work and its adapted movie - "Chitty-Chitty-Bang-Bang". They collected the brain signals of participants when they silently repeated this phrase in their minds multiple times and used this data to train a special neural network detection module to accurately identify the neural characteristics corresponding to this "password".

The promotional poster for "Chitty Chitty Bang Bang" in 1968. To this day, scientists have used its title as a unique "password" in brain-computer interface research. | IMDb

Only when the system detects this unique neural activity pattern will it "unlock" and start analyzing subsequent brain signals; without the password, the system will remain "silent" and will not decode any content. In real - time tests, the accuracy of this keyword detection was as high as 98.75%, which is very reliable.

Like every new technology, depending on the users' different purposes, it can be used to save lives or misused for evil. But when that day truly arrives, the fastest - computing "brain" designed by humans will perfectly integrate with the most energy - efficient "brain" born in nature, no longer restricted by the physical body - isn't this the romance of science?

References

[1]Takagi, Y., & Nishimoto, S. (2022). High-resolution image reconstruction with latent diffusion models from human brain activity. bioRxiv (Cold Spring Harbor Laboratory). https://doi.org/10.1101/2022.11.18.517004

[2]Zhao, W., Garcia-Oscos, F., Dinh, D., & Roberts, T. F. (2019). Inception of memories that guide vocal learning in the songbird. Science, 366(6461), 83–89. https://doi.org/10.1126/science.aaw4226

[3]Kunz, E. M., Krasa, B. A., Kamdar, F., Avansino, D. T., Hahn, N., Yoon, S., Singh, A., Nason-Tomaszewski, S. R., Card, N. S., Jude, J. J., Jacques, B. G., Bechefsky, P. H., Iacobacci, C., Hochberg, L. R., Rubin, D. B., Williams, Z. M., Brandman, D. M., Stavisky, S. D., AuYong, N.,... Willett, F. R. (2025). Inner speech in motor cortex and implications for speech neuroprostheses. Cell, 188(17), 4658 - 4673.e17. https://doi.org/10.1016/j.cell.2025.06.015

This article is from the WeChat official account "Guokr" (ID: Guokr42). Author: Jiujiu, Editors: Bayun, Li Xiaoqiu. Reposted by 36Kr with permission.