cthia wrote:
And Jonathan, it is incorrect that the brain doesn't simply continue to send out the same signals exhaustively. If you digest the video, it tells you it does. Just because a limb is amputated does not mean the brain discontinues sending the same signals. Per the video, it does not. Which, according to the evidence reported by amputees of experiencing ghost sensations, is intuitive.
Apparently the brain does not alter the old signals. The subject simply has to learn to reconnect and harness the signals, telephone wires if you will, that have already been laid down. Which is intuitive as well, or muscle memory would be shot all to hell.
Again, muscle memory is simply a sub process controlled automatically by the thought. A truth the monkey proves with aplomb.
Please consume the video upstream in it's entirety.
The brain continues to send out signals. (And receive bogus sensor inputs; hence phantom pain). Without the ability to see how your missing limb moved the signals might even remain entirely unchanged.
But I don't see how someone's dexterity or skill as a result of training could improve if the brain wasn't altering the signals in response to that training; at least to some degree. After all the brain is a neural net that originally learned how to control limbs based on feedback, and continues to do over your life as the responses to signals alter (additions or reduced strength, reduced range of motions, etc. etc.) - it would seem almost impossible for it to avoid learning somewhat (but probably not grossly) different signals whenever the physical response to them alters noticeably. (Sure the changes might be 90% the new limb adjusting to the signals, but I find it hard to believe that the changes are 100% on the new limb's side)
Edit - or I guess it might depend on what we're calling the signal. The nerve impulse to activate a given muscle to 20% strength might remain unchanged - but which muscles to activate, at what strength, and for how long, would change over time as the capabilities of the muscles and joints alter. So the collective group of signals necessary to achieve the precise desired outcome (especially for tasks requiring very exacting tolerances of both strength and precision like Honor's martial arts), alters over time and with training. That collective group would be somewhat distinct from person to person, and even over time for the same person as the brain adjusts to their current condition. So I don't see how a large change in condition like replacing a limb could avoid the brain racing the limb's learning software, each trying to adjust its behavior, on the way to regaining the desired control over its motions.