Monkeys have successfully navigated various virtual environments using only their thoughts, thanks to a brain-computer interface (BCI). Researchers anticipate that these experimental findings could eventually enable individuals with paralysis to explore digital realms or gain more intuitive control over electric wheelchairs.
The study involved implanting three rhesus macaque monkeys with BCIs, as detailed by Peter Janssen at KU Leuven and his colleagues. Each animal received three implants, each equipped with 96 electrodes. These were strategically placed in the primary motor cortex, as well as the dorsal and ventral premotor cortices. While the primary motor cortex is frequently utilized in BCI research and associated with physical movement, the latter two areas are believed to process movement planning at a more advanced, abstract level.
Electrical signals captured by these implants were interpreted by an artificial intelligence (AI) model. This processed information then guided the movement of virtual reality avatars displayed on a 3D monitor, allowing the monkeys to control them.
Virtual Navigation Experiments
In their trials, the monkeys demonstrated the ability to control a sphere moving across a virtual landscape from a fixed perspective. Furthermore, they could command animated monkey avatars from a third-person viewpoint, akin to controlling characters in a video game.
Subsequent tests showed the monkeys navigating through virtual buildings. This involved tasks such as opening doors and moving between different rooms, showcasing a sophisticated level of control within the simulated environment.
A Higher-Level Connection to Movement
Many prior BCI experiments with humans have required participants to think of specific physical actions, like moving a finger, to operate a cursor. Janssen, however, suggests that the specific placement of sensors in the monkeys tapped into a more intuitive, higher-level connection to movement planning.
“We cannot ask these monkeys, of course, but we just think that it’s a more intuitive way of controlling a computer, basically,” Janssen commented. He noted that people often describe using current BCIs as an experience similar to “trying to move your ears”—a foreign and sometimes frustrating process that can demand weeks or months of practice to master.
Potential for Human Application
Janssen expressed confidence that this approach could be applicable to humans, potentially allowing individuals with paralysis to navigate virtual worlds or operate electric wheelchairs with greater ease. However, he cautioned that human trials are still some time away.
“There’s a bit of work necessary to know exactly where to implant a human because a lot of these areas are not very well known in humans, where they are exactly,” Janssen stated. “But once we figure that out, it should be possible. It should actually be easier because you can explain to the human what they are supposed to do.”
Flexibility and Abstract Brain Function
Andrew Jackson at Newcastle University highlighted the remarkable aspect of the monkeys’ ability to control movement from different perspectives and within varied contexts. He posited that the BCI might be accessing brain regions that process movement in abstract terms, granting it the flexibility to adapt across different scenarios. This adaptability is compared to how human players master different computer games using the same familiar controller.
“I’ve got a bunch of different buttons I can press, and in different games I have to work out the specific mapping between those different buttons and the particular game. But it’s a pretty easy thing to do because there’s only so many combinations I need to try,” Jackson explained. “If the new game actually involved me putting down the controller going over and opening my fridge or something, then it would be much harder.”
Previous Human BCI Trials
Several less complex BCI trials have already been conducted with human participants. In one instance, a man with paralysis successfully piloted a virtual drone through an intricate obstacle course by merely thinking about moving his fingers, with an AI model interpreting these brain signals.
In another study, an individual could mentally simulate writing with a pen, and a computer system translated these brain signals into text. These examples demonstrate the growing capabilities of BCI technology.
Neuralink’s Recent Human Trial and Challenges
In 2024, Neuralink, a company co-founded by Elon Musk, announced the first implantation of its BCI in a human subject. This allowed the individual to control a computer cursor. However, it was subsequently reported that after approximately one month, about 85% of the electrode threads had shifted. This displacement significantly reduced the user’s ability to control the computer.
Neuralink has faced past criticism regarding alleged animal cruelty in its experiments, allegations that Musk has denied. The company had also been subject to US Government investigations, which reportedly stalled during the Trump administration.
Journal Reference: Science Advances DOI: 10.1126/sciadv.adw3876