As we learn more about the human brain, we can begin to wonder if the rest of the body is necessary. Improved brain-machine interfaces are showing us how much can be accomplished by tapping directly into our thoughts.
While brainwaves can be read and interpreted through electrodes placed on the scalp, this method lacks the spatial detail of implanted electrodes. The recent action in practical thought-to-action science has taken place with direct physical connections.
For example, last summer brain researchers in Australia and the U.S. showed promising results by mounting electrodes on an expandable stent and threading it through blood vessels that lead to the brain. The sensors in the stent could sense when people’s brains signaled an intention to move, the sensors wirelessly sent this information to a computer which interpreted the signals. The interface allowed ALS patients to combine use of an eye tracker to move a cursor plus a thought-controlled click, making their communication faster and easier without surgery to implant electrodes.
Electrode-based therapy is still the gold standard, and Elon Musk’s company Neuralink has announced testing of a wireless implant that could provide a broadly useful direct interface between human brains and computers. Neuralink’s small implants include more than 1000 electrodes designed to send wireless signals to anything digital, like prosthetic hands or automotive controls. According to a story in Wired last year, “The reason that excites neuroscientists is that right now their tools are relatively crude. The standard is the “Utah array,” a single chip with 64 electrodes on it. Just putting it in or taking it out can damage the tissue around it, and it’s not good at isolating single neurons or covering a large area ... At the Neuralink presentation, Musk said that his prototype included sensors for motion, temperature, and pressure and 1,024 thin, flexible wires to pick up the electrical signals neurons put out while they’re neuron-ing.” Currently, this array can be wirelessly connected to a computer to learn to associate outbound signals with specific intentions.
Computer-aided brain-driven prosthetics have been improving by adding an element of touch feedback to the process. Until recently, a person using a brain-computer interface would use visual cues to pick up objects with prosthetic arms. However, according to this week's Ars Technica, researchers working with people paralyzed from the neck down added tactile feedback to the systems, allowing the test participants to drastically improve performance. The biggest improvements involved tasks requiring grasping an object. “While we may not always be consciously aware of them, touch and pressure play a major role in everything we do with our hands. By targeting the right area of the brain, the implant takes advantage of the systems the brain already has for managing this kind of sensory input.” As we understand more about these regions of the brain, the Brain/computer/ prosthetic interaction becomes easier and more efficient.
One of the most impressive recent achievements arrives this month out of Stanford and Brown Universities allowing a paralyzed person to type out about 90 characters per minute by imagining that he was writing the characters out by hand. This drastically beats the efficiency of earlier efforts that involve virtual keyboards and cursors. As noted by Wired, “there are other possible routes to getting characters out of the brain and onto the page. Somewhere in our writing thought process, we form the intention of using a specific character, and using an implant to track this intention could potentially work. . . Downstream of that intention, a decision is transmitted to the motor cortex, where it's translated into actions. Again, there's an intent stage, where the motor cortex determines it will form the letter (by typing or writing, for example), which is then translated into the specific muscle motions required to perform the action. These processes are much better understood, and they're what the research team targeted for their new work.”
By placing implants in the premotor cortex, researchers were able to capture the base intentions of the thinker at an earlier, clearer stage than simply the intentions of movement to effectuate the underlying ideas. Conceptually, this is an interesting advance. We had been focused on tapping into the same neurons that allow a person to type a message, but we are finding that, if we can catch the thought before the brain has converted it into a specific physical action, then we can skip a step in the brain’s process and make the brain-computer interface much more efficient. It makes one wonder whether stripping the process back even further, capturing thoughts of entire words, rather than letters, would create further efficiencies. Right now we can turn intentions toward physical action into the actions themselves. But this is an advance toward capturing the initial desire before it can be processed further by the action portions of the brain.
As the Wired article stated, “the system shows a very significant speed boost compared to previous implant-driven systems, and the accuracy is quite good. The system also has the potential to be similar to touch-typing, in that a user doesn't have to actually visually focus on letter production, allowing more normal interactions with the user's surroundings.” So we proceed closer to the holy grail of brain-computer interface: allowing a person’s brain to drive direct actions without involving the rest of the body at all.
This would be a clear victory for those with bodily impairments, but it also would be an excellent step toward systems that allowed us to manage all parts of our world without needed a body to manipulate our environment. We could speak to our home temperature control system or direct our automobile without touching anything. Arriving in the midst of a pandemic, the possibility of touchless control of our environments has a special allure. Maybe someday in the not-so-distant future, all we will need is an operational brain to be a fully functioning human.