It's very cool, and uses the same principles as lots of other neurorehab electrical devices out there. I used an FES ('Functional Electrical Stimulation') device for a while that has a little accelerometer in it to figure out when I intended to take a step, and then stimulate (via conductive pads placed atop the skin) the correct muscles in the lower leg to lift the ankle up (dorsiflexion). Over time, when the brain correlates X input with Y result, even if Y is very very weak, bruised nerves can recover (in the case of recent brain/spinal injuries) and new nerves can grow. I was advised to have the device on its 'training' setting (where it would periodically activate a 'step') even when lounging on the sofa. Hebb said: "What fires together, wires together"...
My suspicion (tho I'd love to be educated on this) is that the reference patient did not have a truly 'complete' spinal cord injury, but rather one where there were at least some nervecells remaining/bruised. If there was a complete section of nerve wiring missing, I don't see how re-growth could occur (but perhaps there's some stem-cell wizardry that can help with that???). Anyway, it wouldn't matter much; if these devices become small and convenient enough, it's not much burden to wear them forever.
Yeah, if you watch the supplemental videos they mention that the patient had a partial injury and after 7 years of physical therapy was still unable to walk independently. After getting this implant and doing 6 months of PT, the patient was able to walk unassisted even with the brain interface not powered on.
> ..the most notable achievement is the fact that these three patients had complete spinal cord injury, instead of a partial one as with the 2018 patients.
Patients with “complete” spinal cord injury have been successfully treated as well:
> My suspicion (tho I'd love to be educated on this) is that the reference patient did not have a truly 'complete' spinal cord injury, but rather one where there were at least some nervecells remaining/bruised.
This is mentioned in the article at the start of the Discussion section:
> The validation of this digital bridge was restricted to a single individual with severe but partial damage of the spinal cord, and it therefore remains unclear whether the BSI will be applicable to other injury locations and severities. However, several observations suggest that this approach will be applicable to a broad population of individuals with paralysis.
The authors likewise anticipate that there won't be any technical hurdles in miniaturizing the technology and making it self-calibrating.
My suspicion (tho I'd love to be educated on this) is that the reference patient did not have a truly 'complete' spinal cord injury, but rather one where there were at least some nervecells remaining/bruised. If there was a complete section of nerve wiring missing, I don't see how re-growth could occur (but perhaps there's some stem-cell wizardry that can help with that???). Anyway, it wouldn't matter much; if these devices become small and convenient enough, it's not much burden to wear them forever.