The missing link in primate paralysis

For the first time ever, a primate has regained the use of a leg paralysed after a spinal injury, thanks to a new neuroprosthetic system that restores communication between the brain and the spine. The interface, which decodes cerebral activity related to walking and transmits it wirelessly to a spinal cord stimulator that activates leg muscles, has potential for human use. Technologist spoke to Marco Capogrosso, a senior researcher at the École Polytechnique Fédérale de Lausanne and key member of the project.

Technologist: What made this so challenging?

Marco Capogrosso: We designed this technology based on the knowledge we had accumulated with rats, so the big question was, “Would this translate to primates?” We were testing our understanding of how the spinal cord controls movement in primates and humans.

T. Could this work for humans?

MC. If it works in primates, it can work in humans. A clinical trial is now testing the stimulator in patients who have partial spinal lesions that allow only residual leg movement. We send recorded electrical signals directly to the spine to stimulate walking, without the brain-control component. We hope to reproduce not only the immediate effect seen in primates, but also a therapeutic effect observed in rats treated with physical training during stimulation, which created new spinal connections bridging the lesions and progressively improved control of their limbs.

T. How long might it take?

MC. In a few months, we might enable a person with a partial spinal cord lesion to walk in a lab. But translating this to daily life could take about 10 years. You have to build a system that will last 20, 30 years – or for life. Until a big company sees a market and chooses to invest, progress will be slow.