Brain imaging pioneer Nancy Kanwisher, who uses fMRI scans to see activity in brain regions (often her own), shares what she and her colleagues have learned: The brain is made up of both highly specialized components and general-purpose "machinery." Another surprise: There's so much left to learn.

Our consciousness is a fundamental aspect of our existence, says philosopher David Chalmers: “There’s nothing we know about more directly…. but at the same time it’s the most mysterious phenomenon in the universe.” He shares some ways to think about the movie playing in our heads.