Scientists Harness Virtual Reality to Teach Damaged Limbs New Tricks

Take a stroke victim who needs to retrain a hand: Tel Aviv team uses VR to trick the brain into thinking the hand practiced something it didn't.

A man uses a virtual reality headset decorated with female eyes, at the Mobile World Congress wireless show in Barcelona, Spain, Tuesday, Feb. 23, 2016.
Manu Fernandez, AP

Practice makes perfect, they say. But what if you have to learn a new skill but can't practice it, because of, say, paralysis?

Scientists at Tel Aviv University, led by Prof. Roy Mukamel, have demonstrated that the brain can be "tricked" into learning a physical skill without any corporeal practice at all, using virtual reality. If developed into a technology in the future, it could be useful for stroke victims, for instance, who need to recover motoric capabilities.

"Patients suffering from hemiparesis — the weakness or paralysis of one of two paired limbs — undergo physical therapy, but this therapy is challenging, exhausting, and usually has a fairly limited effect," Mukamel explains.

Virtual reality is more familiar to us laypeople from gaming, riding virtual roller coasters at technology fairs, falling out of a plane, and so on. With the VR headset on, your body may be on the couch but you feel, even physically, as though you're fighting a dragon, or riding an extreme roller coaster, and so on – no matter the quality of the graphics.

The experience can be so engrossing that many people suffer nausea and other side effects when taking the headset off and returning to real reality.

In other words, it is a visual manipulation that we feel all too palpably. The  team led by led by neuroscientist Mukamel wanted to see if an untrained hand could be tricked into making motions that the brain – fooled by virtual reality – thought the hand had learned, as reported in their paper "Neural Network Underlying Intermanual Skill Transfer in Humans" in Cell Reports, Volume 17.

Yes, one hand knows what the other is doing

The study involved 53 healthy volunteers, who first completed baseline tests to assess the motor skills of their hands, the paper explains. Then they strapped on virtual reality headsets that showed, rather than cyborg aliens, simulations of their two hands, but with a twist.

At first the virtual reality technology showed the “mirror image” of their hands: When a subject moved his real right hand, the virtual left hand would move. Participants went through a specific sequence of finger movements with their right hands. What they "saw" was the virtual left hand doing the movements.

Next, the participants donned gloves on their left hands, which were controlled by the movement of the right hand. So, if the right hand moved a finger, the same finger would be involuntarily moved on the left hand. Again, while the right hand was making the movement, the headsets showed the movement being made by the virtual left hands.

When the volunteers moved their right fingers and watched their left hands on the virtual reality headsets, afterward, they could use their left hands more efficiently.

But the biggest improvement was when the virtual reality screen showed the left hand moving, while in reality it was the right hand moving while the motorized glove moved the left hand.

Ergo: The left hand can learn even when it is not moving under voluntary control.

The brain did not make the left hand move. It made the right hand move, and that movement was tracked by the motorized glove on the left hand, which involuntarily moved. Yet it learned best that way.

“We effectively tricked the brain,” Mukamel says.

Very effectively. Engrossment in virtual reality can be so total that the technology is even being eyed for acute pain management, such as while giving birth. It isn't that the body doesn't know it's in pain. It does. But the mind is distracted and doesn't care as much.