If the brain and body are not supposed to be able to remember enough to recreate actual pain sensations just by thinking about it, then how can I actually feel the pain when I dream about cutting my thumb? (It was an odd way to wake up - I was dozing after the alarm went off, and was dreaming about wiping something off a utility knife blade with my thumb; I pressed it too far over the edge, sliced it, and was awakened by the "pain".)