Jason Rhoades' work, The Creation Myth, for example fills a room with a bizarre, Heath Robinson-like machine representing the creative process - there's a trail of cables taking you through a series of sub-processes. It's a disturbing exhibit; sound, movement and smoke effects keep you uneasy, and Rhoades uses a lot of pornographic imagery - this has led to some discussion in the press but is completely appropriate in the context of portraying the range of thoughts that pass through a human mind, or the creative process; to my mind it also makes the work honest and personal.
Yoshitomo Nara also takes a literal approach, building a one-room house storing memories and personal, meaningful possessions, while you can explore Thomas Hirschhorn's mind in the form of a network of caves made from cardboard and tape. Yayoi Kusama creates a more surreal, beautiful experience - walking into a red and white polka dot universe which extends onto this balcony:
There are also exhibits by Charles Avery who continues to expand his fictional Island, including this artefact of it's culture - a mysterious, dimensionally transcendent cabinet.
Science fiction also grapples with this theme from time to time - say, Stephen King's novel Dreamcatcher where an alien presence banishes a character into his own mental space, or The Cell, where a psychiatrist literally enters her patient's thoughts to diagnose and heal them. It's a difficult concept to make convincing, just as it's difficult to invent realistic dreams or simulate insanity, and both these examples are flawed. This exhibition succeeds because each installation seems to communicate something real, and surprisingly frank, about the mind of its' creator.