And Sharma says that further research will have to take into account other elements of walking. Rhythmic coordination of gait, for example — which the monkeys didn’t demonstrate — is controlled by a different group of neurons. Devices to enable human locomotion in paralysed patients would ideally include brain–computer interfaces, electrical stimulation for activating muscles, an exoskeleton-like device to help bear weight, and smarter electrical processing to enable gait control, he says.

Courtine has started a clinical trial at the CHUV University Hospital of Lausanne, geared towards rehabilitation by helping to stimulate coordinated walking in people who are paralysed. Two people have had the electric-pulse generators implanted in their lower spines. (The trial will not implant microelectrode arrays in the people’s brains, however, so they will not be able to control the movement themselves.)

As clinical trials proceed in Switzerland, Courtine is still regularly travelling back to China. Although the positive results have allowed him to negotiate the use of five monkeys at a Swiss primate laboratory, some of his experimental work still takes place in Beijing. China’s welcoming attitude to primate research will reap benefits for the country, Courtine says. “This is going to provide China with a tremendous leverage for translational medicine.”

David Cyranoski
Nature doi:10.1038/nature.2016.20967