Amputees can be tricked into 'feeling' life-like sensations from robotic limbs using virtual reality, according to new research
- Scientists convinced patients a prosthetic hand belonged to their own body
- They did this by combining the senses of sight and touch, researchers found
- It could revolutionise treatment of maimed members of the Armed Forces
Amputees can be tricked into 'feeling' life-like sensations from robotic limbs using virtual reality headsets, according to new research.
By combining the senses of sight and touch using the VR headset, scientists were able to convince patients a prosthetic hand belonged to their own body.
Patients wore virtual reality goggles which showed the index finger of the prosthetic limb glowing at the same point researchers administered artificial touch sensations.
This unique combination of sight and sensation convinced people the prosthetic was a natural extension of their own body.
The latest findings could revolutionise treatment of maimed members of the Armed Forces and other people who have lost arms or legs, scientists say.
It is estimated that half of amputees with prosthetics do not actually use them because their missing limb simply does not fit their prosthesis.
Commercially sold prosthetic limbs are rarely able to provide sensory feedback to the wearer, other than what they are able to see themselves.
This means the patient has no sense of touch from the prosthetic limb and must constantly watch it for correct use.
Dr Giulio Rognini and colleagues from the Swiss Federal Institute of Technology in Lausanne have proven that using virtual reality amputees can be convinced the prosthetic hand belongs to their own body.
In preliminary experiments the groundbreaking technique worked on two patients who have lost hands, according to the paper published today in the Journal of Neurology, Neurosurgery & Psychiatry.
Instead of using the sense of sight alone, researchers managed to incorporate touch as well.
'The brain regularly uses its senses to evaluate what belongs to the body and what is external to the body', said Dr Rognini.
By combining the senses of sight and touch, scientists managed to convince patients a prosthetic hand belonged to their own body
'We showed exactly how vision and touch can be combined to trick the amputee's brain into feeling what it sees, inducing embodiment of the prosthetic hand with an additional effect that the phantom limb grows into the prosthetic one.
'The setup is portable and could one day be turned into a therapy to help patients embody their prosthetic limb permanently.'
In two hand amputees, scientists provided artificial tactile sensations at the tip of the index finger - of the phantom limb - by stimulating the patient's nerve in the stump.
At the same time, the patient wore virtual reality goggles which showed the index finger of the prosthetic limb glowing in synchrony with the administered touch sensations.
Both patients reported feeling as though the prosthetic hand belonged to their own body.
When asked to evaluate the position of their hands, both patients felt as though their phantom limb had extended into the prosthetic limb.
In two hand amputees, scientists provided artificial tactile sensations at the tip of the index finger - of the phantom limb - by stimulating the patient's nerve in the stump
Previous to the experiment, they both reported that the phantom hand was small and directly connected to the stump.
They said it felt as if the phantom limb had no forearm, a change in size referred to as 'telescoping' in scientific jargon.
In fact, their phantom limb extended during the experiment, and remained extended for up to ten minutes afterwards.
The experiment requires the patient to passively observe two sensations on the fingertip, the visual glow and the artificial touch happening in synchrony, in order for this to take place.
The study builds upon research that opened new avenues is prosthetics.
In 2014, in a European collaboration led by EPFL, scientists overcame a major hurdle by giving an amputee the ability to feel - in real-time - with the help of their prosthetic hand.
Information about touch coming from sensors at the prosthetic fingertips were directly processed and relayed into the nervous system via electrodes that were surgically wired to the stump's main nerves.
Two years later in 2016 scientists showed that the enhanced prosthetic technology could even help the same amputee detect differences in texture.
HOW DO MIND CONTROLLED PROSTHETICS WORK?
Prosthetics that attach to part of the human body are often objects that allow a person to perform a specific function - such as blades for running.
Scientists are working to develop prosthetics that are personalised and respond to the commands of the wearer.
To do this, small pads are placed on the skin of the patient.
They are located around the end of muscles and where the nerve endings begin.
The pads detect the electrical signals that are produced by the muscle nerves and translate this via a computer.
To trigger these sensors, the patient must actively think about performing an action.
For example, in order to signal a bicep contraction, the person wearing the prosthetic would have to think about bending their arm.
By understanding what muscles are being signalled by the brain to contract, scientists can predict how a limb would move.
This is then recreated by the prosthetic in real-time, allowing wearers to think an action and then the artificial limb will perform it.