It's also because some of those transmission contain instructions to the nerve cells themselves, the human body doesn't work in Binary, a signals strength varies massively depending on the situation, and strong signals can actually take a different, more direct route than weak signals can, the nerve fibres adjust themselves, a strong signal can suggest an emergency so may be given priority, it also doesn't communicate with nerves serially or in parallel, but some strange mixture of the two, and the signals may also be followed up by a batch of instructions to the endorphines to release anti-toxins etc, so the whole signal is incredibly hard to decode properly.