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Input/output within the body vs. outside the body
Our latest class discussion was rather comforting to me in terms of dealing with the input/output question. It's confusing (and seems to be for lots of others, too, judging by this thread) to think that things can happen with absolutely no discernible cause or that clear-cut causes can have no effects. But I think it makes a lot more sense when considering what we talked about in class: the idea that what happens inside the nervous system interacts less than 1% of the time with what happens outside the nervous system.
If 99.999% of neurons are interneurons, then it's going to be insanely difficult, and possibly pointless, to match up behaviors, or arrangements of neurons, with inputs and outputs -- at least if we think of inputs and outputs as being things that come into or go out from the large-scale nervous system (and thus the body). In the case of sensory and motor neurons, we can see things happening as a result of things coming into the nervous system or things being sent out from the nervous system. But, when it comes to interneurons, we don't necessarily see any big interaction happening with the BIG box.
I wonder what that says about the little boxes, though. If each little motor neuron has its own input/output box, and other types of neurons send inputs to that box or receive outputs from it . . . does that not still mean that we can have inputs and outputs for every change in behavior? Or can each little box, or each little neuron, do things completely of its own accord, without really connecting itself to any other neuron? It's easy for me to accept that the nervous system as a whole needs no inputs or outputs to do something -- just because so much happens WITHIN the box, without interaction with other things -- but does that mean each little input/output box can also send or receive without interacting with other input/output boxes?