Paralysed rats have been made to walk again by scientists who used electronic signals to simulate movement – and clinical trials on humans are due to start next year.
Scientists from Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland surgically implanted flexible electrodes into paralysed rats and used electrical currents to stimulate the spinal cord and to move their legs.
European Research project Neuwalk focuses on ways to restore motor functions to help those suffering with spinal cord injuries and Parkinson's disease.
Its experiment involved rats who had a severed spinal cord in the mid-back, so brain signals were unable to reach the lower body.
"We have complete control of the rat's hind legs," said EPFL neuroscientist Grégoire Courtine. "The rat has no voluntary control of its limbs, but the severed spinal cord can be reactivated and stimulated to perform natural walking. We can control in real-time how the rat moves forward and how high it lifts its legs."
The brain sends out electrical signals to the rest of the body via the nervous system. If the nervous system is damaged, the signals may be unable to get to a certain area, resulting in conditions such as paralysis.
It is known that an electrical stimulation of the nervous system can help relieve some symptoms of neurological disorders, such as restoring a sense of touch in the limb of an amputee or controlling the tremors in Parkinson's.
Source: Ecole Polytechnique Féderale de Lausanne
The researchers realised there was a direct correlation between how high the rat lifted its legs and the frequency of the electrical stimulation. Based on this, they were able to specifically design the electrical currents so the rat could overcome obstacles such as stairs and barriers.
"Simple scientific discoveries about how the nervous system works can be exploited to develop more effective neuroprosthetic technologies," said co-author and neuroengineer Silvestro Micera. "We believe that this technology could one day significantly improve the quality of life of people confronted with neurological disorders."
Researchers hope this new breakthrough could one day be implemented into rehabilitation therapy for those with spinal cord injuries and that clinical trials could start as early as next summer. They are also looking into ways of decoding signals directly from the brain, as opposed to an outside source, and using them to control leg movement.