Visual cortex

The Eleventh Doctor provided Clara Oswald with a swallowable hologram projector which created a hologram shell for her to wear while projecting hologram clothes onto her visual cortex, which made her perceive the naked Doctor as still being dressed. (TV: The Time of the Doctor)

Foamasi language directly stimulated the visual cortex of the brain, meaning Foamasi effectively saw their language. (PROSE: Sleepy)