Virtual Hands Help Stroke Victims Recover

Using a brain-computer interface, biological engineers have created "virtual reality hands" that may help survivors of stroke and other kinds of injury to the brain and spinal cord regain use of their arms and hands.

Brain-computer interface technology can tell doctors and therapists whether rehabilitative exercises are activating parts of the brain associated with better recovery.

In a small scale clinical trial led by engineer Alexander Doud,  a medicals school student., presented at the American Heart Association’s Scientific Sessions 2013, survivors of stroke were able to use mental imagery to retrain their brains to move their arms and hands even while their arms and hands were too weak to move on their own.

Mental commands were conducted through a brain-computer interface that looks something like a hair net, an EEG (electroecephalograph) cap that detects changes in brain waves that it transmits to the simulation. When the user imagines a movement, specific neurons in the brain generate an electrical current. The electrodes in the EEG cap transmit signals to a computer that generates images that correspond to the desired movement.

Doud's technology is completely non-invasive. No one has to have a chip or an eletrode implanted in the brain to make use of the brain-computer interface. The device is only worn as needed, and no part of the EEG penetrates the brain, skull, or even scalp, although glue used to hold the electrodes in place can be messy and hard to wash out of the hair.

Doud told the press that the new virtual hands technology provides patients with a "practice space" that they can use without physically moving their hands at all. In traditional physical therapy for stroke victims, the physical therapist moves patients' hands or arms while asking them to imagine moving them on their own power. In the virtual hands program, patients control realistic-looking images of hands with the power of their own thoughts, without actually moving a muscle.

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Doud and colleagues trained six survivors of stroke who had lost use of arms and hands to use 3-D glasses to produce the illusion that they were moving their own arms. In the simulation, the patients became about 81% accurate in exercises requiring them to use their virtual hands to reach a glass or a jar. Doud says that the technology can be adapted to train patients to pick up a toothbrush or open a jar with only minimal changes in programming, and it only takes 3 or 4 hours of training to help users reacquire individual lost skills. The program can adapted to specific tasks that patients find especially motivating.

Because this initial study was conducted with just six patients, larger and more diverse groups of volunteers will be needed to validate the use of the technology. But because of the relatively low cost of the technology, Doud believes that the virtual hands system can be developed for commercial distribution in the relatively near future.

Other Surprising Uses For Virtual Hands Technology

In the US, virtual hands technology is being used for physical rehabilitation after stroke and other forms of brain injury, but in the UK, a version of this technology is being used treat anxiety and depression caused by body image.

The English researchers based their study on an earlier set of experiments that established the "rubber hand illusion." In the earlier experiments, French researchers asked volunteers to place their left hands behind a screen so they could not see them. The scientists then placed a rubber hand in front of the volunteers where they could see it.

The experimenter stroked the index finger of the real left hand that the volunteer could not see with a feather wand at the same time as the experimenter stroked the index finger of the fake left hand that the volunteer could see. If the experimenter did this for 2 minutes, then about 2/3 of test subjects began to experience the rubber hand as if it were real. When the researcher asked the volunteers to close their eyes and point to their  left hand, most people pointed to the fake hand, not the real hand.

The team at the University of Sussex took the experiment a step further by using the image of a virtual hand rather than a rubber hand, and timing the display of the image so it changed color from red to black in sync with the heartbeat. The experimenters also ran a session in which the colors of the hands changed out of sync with the heartbeat.

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Obviously, none of us has hands that change color from red to black with our heartbeats. However, when the virtual images these obviously fake, virtual hands were synchronized with another sensory input into the brain, in this case, heartbeat, the volunteers again pointed in the direction of the images of the virtual hand when asked to close their eyes and point to their left hands.

These experiments suggest that when people are depressed by body image the cycle can be interrupted by providing them with a virtual reality image of their bodies seen in synchrony with their heartbeats. People who suffer body dysphoric disorders can find some relief in these computer-generated images, which the brain may adopt as reality with enough practice. The use of this technology is frought with challenges, but it may provide a safe, inexpensive, drug-free method to treat intractable mental health problems that fuel potentially dangerous conditions such as anorexia.