This question is about a complete rebuild of the nervous system. The question as proposed here: Improving human reaction time has only answers concerning upgrading current nervous system.
One of the common tropes of super-soldiers is a faster brain so you can see things in slow-motion and extremely fast reflexes, often dozens of times faster than what normal human nerves would be capable off. But how would you go about making a nervous system that is actually capable of such feats?
For this question, I'm assuming important secondary nerve functions can be performed by glands or "normal" nerve-ends that are attached to the super-nervous system at intervals.
I'm also asking for a biological nervous system that the body can maintain and repair when necessary. For clarity: These soldiers would supplement robotic and cyberneticly enhanced soldiers mostly as canonfodder. The goal would be to split the resource requirement between more rare materials+fuel sources and humanoids that use biological compounds and food instead of fuel.
For the nerves there's two things that can improve their ability. First is thinner nerves, as that would allow more muslce-fibers to be directly actuated by a nerve, second is a faster signal propogation.
I'm thinking about biological optical fibers, but don't know if that's possible. Alternatives could be extremely long myelin sheeths, but I'm not sure if those would be possible or what kind of speed you would gain from it. What's left would be biological electrical wires.
Does anyone have an idea what would be a feasible soft-science nerve? Preferably with the potential propogationspeed of a signal added.