I was actually expecting more, since that is effectively IO for the whole body, and each individual nerve fiber tends not to fire more than tens of Hz.
Imagine attempting to wire up a datacenter that is actively trying to rewire itself (and not necessarily to your plans).
it's all connected to an organic deep neural network
which means that the specific arrangement of the physical wires doesn't matter. because there's a training period in which the neural network literally learns to control the body anyways
[1] https://www.ncbi.nlm.nih.gov/books/NBK326735/ [2] https://www.theguardian.com/education/2012/nov/12/improbable...
Motor and senory nerves reacted differently.
When motor nerves reconnected, I still couldn't contract the muscles and went through a series of steps to relearn how to use the limb. First I was trying to "move" the leg, but effectively the "IP address" for the leg was changed so my "move" signals were going to where my head thought the leg was instead of to the new connection. Instead, I would estim a specific muscle and "listen" in my head for where "noise" was coming from. That "noise" was the electric buzzing from the estim'd muscle contraction. Eventually, I learned how to concentrate to make a muscle contract, and many steps later (pun intended), I learned to walk again.
Sensory nerves didn't need a push signal, they're like a constant inbound feed when connected. When the sensory nerves reconnected, it is something you definitely notice. Going about your day, and suddenly you feel an jolt, like being shocked, and over the next few hours to days the area that is reconnecting is burning, stinging, feels like it is being crushed by pressure, and cold all at the same time. It was much more intense than when your arm falls asleep. The sensation can be maddening but it eventually passes as your body begins to sort and acclimate the signals.
All of these steps on calibrating the sensory nerves and learning how to contract and coordinate muscles is something we take for granted as people usually sort it out when they're infants.
You can't put into words how weird it is to fall over because your brain thinks your foot is somewhere it isn't. Or how suddenly you become incredibly aware of how the front of your calf feels. Or how overjoyed you are to be able to move your toes again for the first time in a year. It's not like what you see on the movies.
Wallerian degeneration -- yes, degeneration -- is part of the healing process of some grades of nerve injury. Things literally get worse before they get better, as the fragment left of the crushed axon degenerates to its root and then regrows. It's incredibly slow -- around 1mm/day at most -- and a matter of probabilities. What's also worth mentioning is that there are plenty of internal nerves too, where restoring function after a trauma would be life-changing -- like the Vegas nerve, which buggers up lots of things if damaged slightly, or, in my case, some of the nerves in the fundus and neck of the bladder, meaning that my toileting is really very different than it was before.
I'm glad you're doing better, and hope you continue to do so. I've no idea if the device the article is talking about will ever help, but nerve injuries cause so much disability worldwide I'm glad they're continuing to be worked on.
Your description also made me reflect on infants, and whether we effectively "feel more" in that stage, as our nervous systems are self-calibrating and adjusting gain.
Regenerative medicine of living tissues is extra hard.
As another commenter posted, there are 31 "bundles" of nerves carrying a total of a few hundred thousand individual fibres. The odds of re-connecting a human spine correctly are simply incredibly small.
Building something to interface with a biological system, though, is another matter entirely. It could as well be alien technology. It requires reverse engineering a lot of extremely complex stuff that was not designed by our civilization. So incomprehensibly complex that we only fairly recently made enough progress in other fields to be able to build tools to meaningfully poke at it.
To the best of our knowledge, it wasn't designed at all. It's more like giving a monkey a typewriter and millions of years, with a very crude feedback function (evolution/natural selection) that makes it very hard to backtrack out of a local maximum.
It's quite hard to interface with it because it's not designed to be interfaced with and the whole thing works pretty much by accident, and where changing any variable could throw it off.
Obviously. There is no functional separation between components (some proteins do multiple unrelated jobs), there's no distinct hierarchy (layers just kinda flow into each other), and there's way too much global state that works seemingly something like this: https://www.youtube.com/watch?v=I5mwVv5NjhA
We have always (OK, at least since Ancient Egypt) known more about mathematics than about physics.
We have always (...) known more about physics than about chemistry.
We have always (...) known more about chemistry than about our bodies.
The available technology mirrors that.
Repairing severed nerves is more like an entropy-reversal class problem. I don’t think we could even put a sufficiently broken tea cup back together exactly as it was.
How does the bus protocol work - it is not like it is 5V/-5V , it is insanely complex ???.
It's just interesting the way we've progressed.
I think we're just blind to how insane nature is compared to our mere half assed copies of organic processes
A typical human cell is on the order of 10 micrometers. If you need to bridge even 1 cm of that, you're bridging ~a thousand cell-widths. If you think of a cell as the somatic equivalent of a house in a city, that's the equivalent of an infrastructure project spanning (based on a quick count of the number of houses on each block in Oakland) the equivalent of around six miles, or roughly from downtown Oakland to El Cerrito on a map of the Bay (~4 BART stations). And you have to do that on a scale where precision manufacturing is incredibly hard, where you're dealing with extremely difficult problems of chemical synthesis, in a living body, without provoking the body's defense or repair mechanisms to stop you. And that's assuming you even know what you're trying to do, which requires an understanding of the machinery of those cells that we often don't have.
https://www.khanacademy.org/science/biology/human-biology/ne...