E Y E
Another organ, the eye basically translates light into chemistry, into signas to the visual cortex that enable it to see. Recently I came across a glaring inconsistence about the human eye and the brainin a movie called 'Transcendence' with Johhny Depp (aptly named "Will Caster"): a scene involved the awesome consciousness of Will uploaded to an AI, performing eye surgery on a man blind since birth: you can repair the eye, but the brain and mind behind it will not be used to processing the visual observations and relating them to what is seen.
Now mind you, the actual learning process might be quite speedy because the basic concepts are already in the human mind, based on other senses. So finally seeing the people you have already felt, heard and imagined will directly be coupled to visual inputs that correspond.