The body is capable of working around a spinal cord injury (SCI) without having to repair it. Changes in the brain are required to restore at least some function to the lower limbs, suggests a recent study from UC Davis researchers.

“After injury, the spinal cord cannot go back to its original state before the injury. If an animal receives rehabilitation therapy, we now know that the spinal cord will go to a new state that supports functional recovery. Under these conditions, the brain must also change and re-learn to communicate with the new state of the spinal cord,” says Karen Moxon, professor of biomedical engineering at UC Davis and senior author of the study, published recently in eLife.

The study included rats with a severed spinal cord that could not voluntarily move their hind legs.

In the study, the rats performed physical therapy (cycling and semi-load-bearing treadmill training) and received the drug serotonin, which stimulates nerve cells.

Moxon and her team found that the physical therapy and drug treatment enabled the rats to partially recover their ability to move their hind limbs while on the treadmill, and to take conservative, independent steps, according to a media release from UC Davis.

This recovery occurred without healing of the break in the spinal cord. Instead, the nerve cells above the break appear to have re-routed their outputs to control muscles running down the animal’s trunk that span the break, according to Moxon. Brain areas that previously controlled the legs instead stiffened these back muscles, the release explains.

Stiffening these muscles allowed the rats to lift their hindquarters such that the leg muscles and the spinal cord below the break could make simple, repetitive leg movements resulting in the animal supporting its own weight and taking independent steps.

The results show that the body can, to some extent, work around a break in the spinal cord without having to repair it, Moxon adds.

“The system can find ways to bridge that lesion, up to a point,” she states. However, the rats are still not capable of voluntary movement of their hind legs—only reflexive movements.

Moxon hopes with future research that she will be able to connect the reorganized brain circuits to leg muscles through a brain/machine interface to restore voluntary movements.

[Source(s): UC Davis, MedicalXPress]