The most biologically-accurate robotic legs yet has been developed by US experts.
Writing in the Journal of Neural Engineering, US experts said the work could help understanding of how babies learn to walk – and spinal-injury treatment.
They created a version of the message system that generates the rhythmic muscle signals that control walking.
The team, from the University of Arizona, were able to replicate the central pattern generator (CPG) – a nerve cell (neuronal) network in the lumbar region of the spinal cord that generates rhythmic muscle signals.
The most biologically-accurate robotic legs yet has been developed by US experts
The CPG produces, and then controls, these signals by gathering information from different parts of the body involved in walking, responding to the environment.
This is what allows people to walk without thinking about it.
The simplest form of a CPG is called a half-centre, which consists of just two neurons that fire signals alternatively, producing a rhythm, as well as sensors that deliver information, such as when a leg meets a surface, back to the half-centre.
The University of Arizona team suggests babies start off with this simplistic set-up – and then over time develop a more complex walking pattern.
They say this could explain why babies put onto a treadmill have been seen to take steps – even before they have learnt to walk.
Writing in the journal, the team says: “This robot represents a complete physical, or <<neurorobotic>> model of the system, demonstrating the usefulness of this type of robotics research for investigating the neuropsychological processes underlying walking in humans and animals.”
Dr. Theresa Klein, who worked on the study, said: “Interestingly, we were able to produce a walking gait, without balance, which mimicked human walking with only a simple half-centre controlling the hips and a set of reflex responses controlling the lower limb.
“This underlying network may also form the core of the CPG and may explain how people with spinal cord injuries can regain walking ability if properly stimulated in the months after the injury.”
Scientists have shown that paralyzed rats have been able to walk again after their spinal cords were bathed in chemicals and zapped with electricity.
An injury to the spinal cord stops the brain controlling the body.
The study, published in the journal Science, showed injured rats could even learn to sprint with spinal stimulation.
Experts said it was an “exceptional study” and that restoring function after paralysis “can no longer be dismissed as a pipedream”.
In 2011, a man from Oregon in the US was able to stand up again while his spinal cord was stimulated with electricity. Rob Summers had been paralyzed from the chest down after being hit by a car.
Now researchers at the Swiss Federal Institute of Technology say they have restored far more movement in rats which became able to run and climb stairs.
Scientists have shown that paralyzed rats have been able to walk again after their spinal cords were bathed in chemicals and zapped with electricity
The spinal cord of the rats was cut in two places. It meant messages could not travel from the brain to the legs, but the spinal cord was still in one piece.
The researchers then tried to repair the damage. The spinal cord was injected with chemicals which stimulated the nerves in the spine and the base of the spinal cord was electrically stimulated as well. The scientists say they were reawakening the “spinal brain”.
However, this was not sufficient to restore movement. The rats were supported in a robotic harness and were shown a treat which they needed to “learn” to walk towards.
The lead researcher, Prof. Gregoire Courtine, said: “Over time the animal regains the capacity to perform one, two steps, then a long run and eventually we gain the capacity to sprint over ground, climb stairs and even pass obstacles.”
He said: “It is completely unexpected to see this recovery, they walk and climb stairs voluntarily.”
The scientists showed that new nerves were forming across the injury and there were also changes in the brain.
This is not, however, a cure for spinal cord injuries in people.
Prof. Reggie Edgerton, from the University of California Los Angeles, was part of the team which helped Rob Summers stand again.
He said the study was “important” and that it was becoming clear that engaging the brain was the key.
“You’ve got to make the rat want to step, it demonstrates the importance of training and rehabilitation,” he said.
How this works is still unknown. Prof. Reggie Edgerton speculated that “we are activating the spinal cord to a critical level” close to the level which would trigger movement, and a small signal from “the brain pushes it over” leading to movement.
An international group of researchers say a “miniature honeycomb” – or scaffold – could one day be used to encourage damaged nerves to grow and recover.
The scaffold can channel clusters of nerves through its honeycomb of holes, eventually healing a severed nerve.
The findings of their study on mouse nerves are published in the journal Biofabrication.
Academics hope to one day treat spinal cord injuries with the scaffold.
When nerves are severed, such as in car accidents, it can result in a loss of feeling and movement.
Repairing this damage can be a challenge – but nerves outside of the brain and spinal cord can repair themselves, if only over short distances.
The scaffold can channel clusters of nerves through its honeycomb of holes, eventually healing a severed nerve
One technique to improve this repair is to use tubes. Either end of the severed nerve is placed in a tube and the two ends of the nerve should grow and join in the middle.
Researchers at the University of Sheffield and Laser Zentrum Hannover, Germany, investigated using a honeycomb structure.
Dr. Frederik Claeyssens, from the department of materials science and engineering at Sheffield, said: “That is much more like the structure of the nerve itself.
“The nerve has small regions of ‘cable’ that go through from one end to the other end, you have a whole bunch of little cables inside a larger cable, that’s what we tried to reproduce with this type of scaffold.”
The honeycomb is made from photopolymerizable polylactic acid, which biodegrades once the nerve has repaired.
The researchers showed nerve cells could grow on the scaffold and are now testing it in mice to see if it can fully repair the damage.
Dr. Frederik Claeyssens said: “This technology could make a huge difference to patients suffering severe nerve damage.”
Scaffold technology is used in a range of “regenerative medicines”. Building a scaffold and then coating it with human cells has, for example, been used to give patients new windpipes and bladders.
