Mind power moves paralysed limbs

By Michelle Roberts Health reporter, BBC News

Scientists have shown it is possible to harness brain signals and redirect them to make paralysed limbs move.
The technology bypasses injuries that stop nerve signals travelling from the brain to the muscles, offering hope for people with spinal damage.
So far the US team from the University of Washington have only tested their "brain-machine interfaces" in monkeys.
The hope is to develop implantable circuits for humans without the need for robotic limbs, Nature reports.
Wired up
Spinal cord injuries impair the nerve pathways between the brain and the limbs but spare both the limb muscles and the part of the brain that controls movement - the motor cortex.

"Similar techniques could be applied to stimulate the lower limb muscles during walking "
Lead researcher Dr Chet Moritz

Recent studies have shown that quadriplegic patients - people who have paralysis in all four limbs - can consciously control the activity of nerve cells or neurons in the motor cortex that command hand movements, even after several years of paralysis.
Using a gadget called a brain-machine interface, Dr Chet Moritz and colleagues re-routed motor cortex control signals from the brains of temporarily paralysed monkeys directly to their arm muscles.
The gadget, which is the size of a mobile phone, interprets the brain signals and converts them into electrical impulses that can then stimulate muscle to contract.
By wiring up artificial pathways for the signals to pass down, muscles that lacked natural stimulation after paralysis with a local anaesthetic regained a flow of electrical signals from the brain.
Life-changing
The monkeys were then able to tense the muscles in the paralysed arm, a first step towards producing more complicated goal-directed movements, such as grasping a cup or pushing buttons, say the researchers.
Lead researcher Dr Chet Moritz said: "This could be scaled to include more muscles or stimulate sites in the spinal cord that could activate muscles in a coordinated action.
"Similar techniques could be applied to stimulate the lower limb muscles during walking."
The scientists found the monkeys could learn to use virtually any motor cortex nerve cell to control muscle stimulation - it did not have to be one that would normally controlled arm movement. And their control over the muscles improved with practice.
The researchers say they need to do trials in humans, meaning a treatment could be decades away.
Dr Mark Bacon, head of research at the UK charity Spinal Research, said: "This is clearly a step in the right direction and proves the principle that artificially transducing the will to move generated in the brain with relevant motor activity can be achieved.
"However, these results have been produced in experimental models where there is no injury per se."
He said injury-induced changes to the nerve circuits might hinder the technology's application in real life.
Also, brain-machine interfaces communicate in only one direction - in this case from the brain to the muscle.
"Sensory feedback, so important for fine control of movements and dexterity, is still some way away," he said.

腦部植入電子裝置有望可醫癱瘓
(星島)10月16日 星期四 14:39
美國 研究人員在實驗室內替一批四肢癱瘓的猴子進行試驗，在牠們的腦部植入一種電子裝置後，成功令猴子的四肢再度活動，而且可以發出訊號，重新控制肌肉。科學家形容這是一項重大的醫療突破和進展，有助研究新方法為脊椎受傷或中風 而導致四肢癱瘓的病人，進行治療。估計有關實驗可於5年內在人體內展開。 這批來自華盛頓 大學的科學家在《自然》周刊內發表研究報告，詳細解釋實驗的過程和結果。他們在癱瘓的猴子體內，植入一種極之幼細、用來監察腦細胞活動的電殛裝置，然後訓練猴子玩遊戲，把手腕左右轉動。 在過程中，電殛裝置不停記錄來自腦部的電子訊號，這些訊號會選擇迂迴的路綫，避開受了損害的區域，控制肌肉。　　接着，科學家把一種化學劑注入猴子體內，令牠們的手臂暫時癱瘓。今次，腦部發出的神經訊號會轉入電腦，進行過濾和分析，然後透過電綫傳到猴子的手腕。猴子再次玩遊戲，初時無法控制肌肉，但其後適應了，可以控制手腕活動。　　科學家莫里茨說，理論上，頸部以下癱瘓的病人，也可利用這種技術重新活動，但要普及化及進行臨床應用，恐怕會要等數十年。