Sense of Touch Restored After Spinal Injury Using Brain-Interface Device

The research participant, who has been partially paralyzed for a decade, can hold a coffee mug, swipe a credit card and even play Guitar Hero.

(Ganzer et al. / Cell)

(CN) — An expert team of researchers reported Thursday that they have been able to restore sensation to the hand of a research participant with a severe spinal cord injury using a brain-computer interface system.

Our sense of touch is something we might take for granted, but it is an essential factor for researchers in developing technologies to restore limb function to people paralyzed due to spinal cord injury or disease.

In a study published in the journal Cell, the scientists from Battelle and the Ohio State University Wexner Medical Center discussed their new technology that takes neural signals that are so small they can’t be perceived, and enhances them via artificial sensory feedback sent back to the participant, resulting in greatly increased motor function.

“We’re taking subperceptual touch events and boosting them into conscious perception,” said first author Patrick Ganzer, a principal research scientist at Battelle. “When we did this, we saw several functional improvements. It was a big eureka moment when we first restored the participant’s sense of touch.”

The participant in this study is a 28-year-old man named Ian Burkhart, who suffered a severe spinal cord injury following a diving accident in 2010 that left him partially paralyzed. Since 2014, Burkhart has been working with a team of investigators on a project called NeuroLife with the ultimate goal of restoring function to his right arm.

The scientists successfully developed a device that works through a system of electrodes on his skin and a small computer chip implanted in his motor cortex and uses wires to route movement signals from the brain to the muscles.

This setup completely bypasses Burkhart’s spinal cord injury and gives him enough control over his arm and hand to lift a coffee mug, swipe a credit card and play Guitar Hero.

“Until now, at times Ian has felt like his hand was foreign due to lack of sensory feedback,” Ganzer said. “He also has trouble with controlling his hand unless he is watching his movements closely. This requires a lot of concentration and makes simple multitasking like drinking a soda while watching TV almost impossible.”

The investigators found that although Burkhart had little to no sensation in his hand, when they stimulated his skin, they saw a resulting neural signal, so small that his brain was unable to perceive it, still was able to get to his brain.

Ganzer explained that even in people like Burkhart who have what is considered a “clinically complete” spinal cord injury, there are almost always a few wisps of nerve fiber that remain intact.

The authors further explain in their report exactly how they were able to boost these extremely miniscule signals to the level where the brain would respond.

The subperceptual touch signals were artificially sent back to Burkhart’s brain using what is known as haptic feedback, which would include common examples such as the vibration from a mobile phone or game controller that lets the user feel that something is working.

This groundbreaking new system allows the subperceptual touch signals coming from Burkhart’s skin to then travel back to his brain through artificial haptic feedback that he can feel and act on.

A few advances took place in the BCI system that led to three significant improvements. The first is how they enable Burkhart to reliably detect something by touch alone, which could prove useful in the future as it may be used to find and pick up an object without being able to see it.

Secondly, this is also the first BCI system that allows for both restoration of movement and touch at once, and this enhanced touch during movement gives him a greater sense of control and allows him to do things more quickly.

Lastly, this is the first time a BCI system has been able to sense how much pressure to use when handling an object or picking something up. Take for example using a light touch when picking up a fragile object like a Styrofoam cup, but a firmer grip when picking up something heavy.

Moving forward, the investigators note that their long-term goal for this BCI technology is to develop a system that works just as well in the home as it does in the laboratory. Currently they are working on a groundbreaking sleeve containing the required electrodes and sensors that could be easily put on and taken off.

Additionally, they are working to develop a system that can be controlled with a tablet rather than a computer, to make it smaller and more portable.

“It has been amazing to see the possibilities of sensory information coming from a device that was originally created to only allow me to control my arm in a one-way direction,” Burkhart said.

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