“Imagination is the only weapon in the war against reality,” Lewis Carroll famously wrote in Alice in Wonderland. To the scientifically minded, in the pursuit of an ever-clearer picture of reality, such a weapon may seem of little use.

Imagination might feel like the trivial stuff of childhood fairy tales and senseless daydreams. Besides, few things appear more slippery and unquantifiable than the contents of someone else’s head. The faculty, though, is something neurologists and neuroscientists are now beginning to understand in more detail and, in doing so, proving that the power of imagination isn’t to be underestimated.…