Over on my web site I’ve posted an article I’ve just written for the Sunday Telegraph Magazine in England about an eerie brain disorder called musical hallucinosis. You’ve probably had a tune stuck in your head for an hour at least once in your life. Now imagine that the tune played all day and night–and imagine that it sounded as real as if a marching band was standing by your window.

Here’s how it starts:

Go here to read the rest.

Brain disorders always grab our attention because they have the power to warp the fabric of reality, or at least our experience of it. But they can tell us even deeper things about ourselves–specifically, how the human mind was assembled