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In amazing leap, scientists map the feeling of touch into the brains of subjects with paralysis

In 2004, Nathan Copeland was in a devastating car accident that left him with C5 quadriplegia with no sensation below his chest. In the aftermath he felt hopeless, unsure if he would be able to do anything or contribute to society. This kind of depression is common among the 5.4 million Americans who have lost use of their limbs after strokes, accidents or catastrophic diseases such as multiple sclerosis.

Researchers at the University of Pittsburgh saw Copeland’s condition as an opportunity. For the past seven years, they have been working with him to explore the possibilities of controlling devices, such as robotic arms and computers, with his brain. The cutting-edge process uses a device called a brain-computer interface (BCI) to record brain activity, which is decoded and turned into control signals for the devices. 

New research from the group, published this May in the journal Science, shows that by adding a sense of touch to the robotic hand, Copeland was able to complete tasks nearly two times faster, completing a grabbing task in 10 seconds with the sensory feedback, instead of the 20 seconds it took before. This represents a huge advance in the pursuit of more natural movement through BCIs and prosthetics.

To achieve this, Copeland has four Utah arrays implanted in his brain. The arrays are 10×10 grids of electrodes, inserted 1.5 mm into the brain, to allow the BCI system to record signals from single neurons. Copeland has two implants in his somatosensory cortex, and two in the motor cortex. 

Here’s the amazing part: When Copeland imagines moving his hand, the sensors in his motor cortex pick up those signals and translate them into movement of the robotic arm. Then, as Copeland uses the robotic hand to move and grasp things, signals from sensors in the robotic hand are sent to the arrays in the somatosensory cortex, which Copeland’s brain then decodes as if they are actually coming from his hand. 

The end result is a system where Copeland is able to manipulate the robotic arm more naturally, without having to focus on the actual mechanics of it. Typically, users of robotic arms have to rely solely on visual feedback for control, meaning they move and control the arm based on where they see it in space. But humans rely heavily on proprioception, the sense that allows us to know where our bodies and limbs are, in order to grasp things and move through space. By adding this sense of touch via the BCI, Copeland is able to experience a form of proprioception. 

“The sensations that I feel during stimulation are not entirely natural,” says Copeland, “they’re not the same as if you actually grabbed something. But they’re not different enough that I’ve ever said they’re unnatural. They’re usually like a pressure or a tingle.”  

The researchers have also repurposed the system to enable Copeland to control a computer cursor. By mapping the imagined movements of his hand to a virtual computer mouse, Copeland can browse the internet, play games and even paint. He is able to perform more complicated operations, such as clicking and dragging, by imagining different positions, such as a closed or opened hand. 

The researchers have also developed a portable home system, which uses a medical-grade tablet to reproduce the results and experiments of the lab, but without the need for multiple computers.

While some people with paralysis are able to use eye-tracking devices or switches to control computers, others are “locked in,” meaning they are unable to move or communicate due to complete paralysis (save for vertical eye movements and blinking). With BCI technology, it’s possible that these people may be able to gain more rapid computer control. 

There is a long road ahead for BCI research consider the limitations on how long the implants are allowed to be kept inside the body (five years, in Copeland’s case), as well as questions of ensuring equal access for everyone who needs the technology, regardless of socioeconomic status. 

It’s an exciting future, though. The field of research is vast, with scientists exploring problems such as how to restore vision and speech with BCIs. People with paralysis may even be able to walk again some day, undoubtedly thanks in part to the work being done in Pittsburgh around sensory feedback of prosthetic limbs. 

It’s also easy to imagine a future where people seek elective BCIs to augment their body’s functions. Recent research at the University College London explored adding an extra thumb to participant’s hands, with mixed results, and there are a number of companies exploring non-invasive BCI systems that read electrical signals from the brain through the skin. The possibilities even go beyond extra limbs to exoskeletons, industrial use and perhaps even different modalities of computer control, gaming, and virtual reality. 

In the meantime, the focus is on the medical research, and Copeland is understandably excited about the possibilities. “It really wasn’t for me that I joined,” he says. “It’s to push the science forward so the next generation of people who go through these catastrophic injuries can maybe bypass the phase right after where they feel like their life will never be the same, or they’ll never be able to do the things they loved before, or still contribute to society.”