Paralysed limbs moved by brain power17th October 2008
Researchers in the United States say it may be possible to redirect the brain's signals in people with paralysed limbs, enabling them to move them.
Scientists at the University of Washington have recently tested "brain-machine interfaces", a kind of technology which bypasses injuries that stop nerve signals travelling from the brain to the muscles.
Tested on monkeys, the newly-developed technique may offer some hope to people with spinal damage.
Writing in the journal Nature, the scientists now hope to develop implantable circuits for humans without the need for robotic limbs.
The motor cortex - the part of the brain that sends signals to move the muscles - and the limb muscles are usually left intact in cases of spinal injury.
However, the nerve routes that the messages need to travel along in the central nervous system are impaired.
Even people who are paralysed in all four limbs - quadriplegic patients - have been shown to retain the ability to send out motor signals by 'willing' their hands to move, even when nerve pathways have been blocked by injury.
A research team led by Chet Moritz used a brain-machine interface to re-route motor contex control signals from the brains of monkeys in which a temporary state of paralysis had been induced.
They were able to transmit the signals to the arm muscles of the monkeys using the gadget, which is the size of a mobile phone and can interpret brain signals and convert them into electrical impulses which can then stimulate the limbs.
They found that muscles which had been paralysed with anaesthetic were reconnected with the brain's motor signals.
Monkeys wired up to the device could then tense the muscles in the paralysed arm. This points to the potential for more complicated movements to be produced as well, like holding a cup or pushing buttons.
Moritz said similar techniques could be applied to stimulate the lower limb muscles during walking, or indeed virtually any motor cortex nerve cell to control muscle stimulation.
However, new treatments could be decades away, as researchers still need to conduct trials in humans.
Spinal research experts called the move a step in the right direction and proved the principle that artificially transducing the will to move generated in the brain with relevant motor activity can be achieved.
But they added that the monkeys were not themselves injured.
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