With the aid of a brain sensor, Matthew Nagle, who is paralysed from the neck down, was able to open an e-mail, pinch the finger of a prosthetic hand and play his way through a computer game – just by using his thoughts. Scientists, from Massachusetts General Hospital, USA, hope this research may lay the foundations for future restoration of limb movements for paralysed people.
Nagle, 25, has been paralysed since 2001 when he was the victim of a knife attack. Scientists inserted a NMP (Neuromotor Prosthesis) into the motor cortex of his brain. This is the area which controls voluntary movement. Even though Nagle has had no control at all over his body movements for five years (neck down) because his spinal cord was severed, the researchers found his motor cortex still working OK.
The NMP has an internal sensor that can identify brain cell activity. External processors convert the brain activity into signals that can be processed by a computer. The firing patterns of the neurons in his motor cortex were translated in a computer, which then gave movement commands to a computerised device that moved, a sort of artificial limb.
Just by using his thoughts, Nagle managed to move a cursor on the screen and open up an email message, play a computer game and open and close an artificial hand. He also managed to get the hand to open and close so that it held and moved objects. He can now turn the lights on and off – something his nurses had to do before.
Head researcher Dr Leigh Hochberg, said “One of the exciting results from the trial is that this part of the brain, the motor cortex, could still be activated voluntarily by this gentleman with spinal cord injury. The fact that this activity was still there, despite the injury that had occurred several years ago, is very encouraging for our potential ability to harness those signals to control an external device.”
The researchers say that one day people who have become paralysed for some reason will be able to reactivate their muscles, restoring brain-to-muscle control via a physical nervous system.
Experts say we are probably many years away from providing effective and safe technology for people who have lost movement in parts or the whole of their bodies. There are several obstacles to overcome, such as, making sure the device lasts long enough, preventing infection and rejection, finding a secure and efficient way of guaranteeing data transfer.
For people who are completely paralysed anything that can provide some small measure of independence is a giant leap forward.
Nature 442, 164-171(13 July 2006) doi:10.1038/nature04970
Neuronal ensemble control of prosthetic devices by a human with tetraplegia
Leigh R. Hochberg, Mijail D. Serruya, Gerhard M. Friehs, Jon A. Mukand, Maryam Saleh, Abraham H. Caplan, Almut Branner, David Chen, Richard D. Penn and John P. Donoghue
Written by: Christian Nordqvist
Editor: Medical News Today