Why don't we see upside down?
Major parts of the visual system. Note that the lens in the eye flips the image upside down and this orientation is carried through the system's pathway all the way to the visual cortex (back of the brain) Primary visual cortex is where we have our first conscious awareness of visual input and that input is further processed (decoded) in secondary and tertiary visual cortices (most senses are set up with these 'tiers' of processing in subsequent neighboring cortical zones).
Do we see the world upside down? Nope, we quickly adapt to this image flip - and this makes the point that the neural code is simply neural energy representing information and NOT the information itself (and certainly not the 'thing' itself).