Scientists Research Use Of Electrical Stimulation To Make Artificial Limbs 'Feel' Real

Main Category: Neurology / Neuroscience
Article Date: 30 Jun 2008 - 2:00 PDT

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Scientists are investigating whether by electrically stimulating the skin they can 'trick' the brain into making an artificial limb feel like a real part of the body, in the hope of improving the quality of amputees' lives.

Exhibiting at the Royal Society's Summer Science Exhibition(1) this week, scientists from the Centre for Pain Research at Leeds Metropolitan University(2) will be demonstrating the key role that the brain plays in the way we feel sensations. The team are trying to manipulate this process by using TENS (Transcutaneous electrical nerve stimulation) machines, commonly used for pain relief for women in labour.

People who have had a limb amputated sometimes report that they still experience 'phantom' sensations from the absent limb. Although many factors are involved, this happens in part because of ongoing activity in the nerve pathways that used to be connected to the amputated limb. The team at Leeds Met is trying to manipulate this nerve activity with TENS. By putting electrodes on the nerves associated with the missing limb, they can use mild electrical currents to stimulate nerve fibres to send signals to the brain and 'trick' it into identifying them as coming from the foot, despite the fact that the foot is no longer there.

The research is important because an amputee may be able to gain better control of their prosthetic limb if they sense that it 'belongs' to their body.

Professor Mark Johnson said: "The brain is so important to what we feel, it's really a case of 'no brain, no pain', or any other sensation for that matter. Our experiments are designed to see whether we can make the sensation of TENS feel like it comes from a prosthetic hand in people with intact limbs. This will help us decide on the best design for a clinical trial in amputees.

"We are also trying to find out how useful TENS could be for 'phantom limb pain'. By adjusting the amplitude of TENS currents we can activate the same nerves that we activate when we rub pain better. This stops messages about tissue damage getting to the brain and this reduces pain. This could help the 80 percent or so of amputees that experience pain in the limb that is now missing."

Visitors to the exhibit at the Royal Society's Summer Science Exhibition will get to experience how an artificial rubber hand can be made to feel like their own.

Professor Johnson said: "We can create a very strong illusion that a rubber hand belongs to you, to the extent that you might try to move it as if it's your own hand. It's even possible to make a table or a book feel like part of a body. It's just an illusion of course, but it shows us how the brain tries to make sense of the world from the information it receives, and how we might be able to use this to help people adjust more quickly to using an artificial limb."

The Royal Society is an independent academy promoting the natural and applied sciences. Founded in 1660, the Society has three roles, as the UK academy of science, as a learned Society, and as a funding agency. It responds to individual demand with selection by merit, not by field. As we prepare for our 350th anniversary in 2010, we are working to achieve five strategic priorities, to:

- Invest in future scientific leaders and in innovation
- Influence policymaking with the best scientific advice
- Invigorate science and mathematics education
- Increase access to the best science internationally
- Inspire an interest in the joy, wonder and excitement of scientific discovery

The Royal Society Summer Science exhibition is a free exhibition open to the public:

Monday 30 June: 6pm-9pm
Tuesday 1 July: 10am-9pm
Wednesday 2 July: 10am-4.30pm
Thursday 3 July: 10am-4.30pm
Last entry 30 minutes before close

Venue
The Royal Society 6-9 Carlton House Terrace London SW1Y 5AG
Nearest underground stations - Piccadilly Circus and Charing Cross.

The Royal Society