As brain-computer interface (BCI) technology that connects the brain and computers advances, a new era is opening where paralyzed patients can move the cursor on a computer screen or robotic limbs merely by thinking. However, current BCI technology faces limitations in accurately implementing user intent due to difficulties in increasing the consolidation pathway for communication between the brain and machines. A U.S. BCI startup has proposed a new method to overcome these limitations.
Science Corporation, a U.S. BCI company, is developing a method that secures more communication channels using neurons instead of inserting metal electrodes into the brain, while minimizing brain damage. The company was co-founded by a co-founder of Neuralink, a BCI company established by Elon Musk. Research results were published on the preprint platform 'bioRxiv' in November last year.
Existing BCIs created a coin-sized hole in the skull and attached electrodes to the brain's surface or inserted them deep into the brain to connect neurons and computers. This posed a risk of damaging brain neurons and blood vessels. Neuralink aimed to reduce brain damage by using thin and flexible polymer electrodes, but the possibility of still exerting physical impacts on the brain remains.
The Science Corporation research team developed a waffle-shaped grid BCI device. Each hole, with a diameter of 10 µm (micrometers, where 1 is one-millionth of a meter), contains one neuron derived from embryonic stem cells. The device, which has an area of 5 cm², contains an average of 90,000 neurons.
When the grid BCI device is placed on the brain surface, neurons emerge from the micro-holes and take root in the brain. The company noted that, unlike existing electrodes, which require direct insertion into the brain, this device only needs to be placed on the surface, reducing the risk of brain damage. Notably, the neurons implanted in the micro-holes have been modified to activate in response to specific frequency light signals. This is known as 'optogenetics' technology.
The research team created a glass window in the skulls of mice and installed the waffle-shaped device, then activated neurons by shining light. When the light was on, the mice moved to the left, and when it was off, they moved to the right in order to receive rewards. As a result, five out of nine mice learned new behaviors. This confirmed that the behavior of the mice could be controlled by light through the BCI device.
The neurons from the BCI device were confirmed to penetrate through the membranes directly surrounding the brain and reach the cerebral cortex. The research team predicted that since the neurons in the BCI device connect naturally with the brain, it could safely connect more channels than existing methods.
However, there is criticism that the device developed this time does not strictly constitute BCI technology. Jack Judy, a professor at the University of Florida, stated, "The device developed this time is not yet a complete interface," and noted, "Unlike BCIs, where information emerges from the interface, this method involves controlling neurons spread throughout the brain with light."
Science Corporation stated that it is developing a complete BCI device with both input and output capabilities based on this research. Instead of micro-holes, they plan to place neurons in a long trench, with light-emitting diodes (LEDs) for activating neurons on one side and sensors for recording the action potentials of neurons on the other side. At the same time, they intend to develop a device made from human neurons and experiment with larger animals to verify commercial viability.
Allen Madinly, co-founder of Science Corporation, said, "Turning the idea into a functioning prototype is a significant challenge," and added, "Whether this will prove valuable is a task we must advance and demonstrate in the future."
Meanwhile, Elon Musk's Neuralink announced in January that it successfully implanted a BCI chip into the brain of a third patient, stating, "We plan to conduct 20 to 30 more implants this year." Neuralink is currently conducting two clinical trials approved by the U.S. Food and Drug Administration (FDA). The research aims to enable paralyzed patients to control computers or smartphones and operate robotic arms through thought.
References
bioRxiv(2024), DOI: https://doi.org/10.1101/2024.11.22.624907