Linguists used to think there was a special region of the brain devoted to language. But beginning in the 1990s, researchers with access to advanced brain imaging equipment like MRIs found that in fact the brain did not have a single region or node dedicated to processing language. What they noticed was that when a subject was read a sentence, say, "The shortstop fields the ball and throws it to first base," several regions of the listener's brain lit up. Which regions? Visual, suggesting the listener recalls a related scene from experience; motor, suggesting the listener recalls making a throw or catch; tactile, suggesting the listener has worn a glove and held a baseball. The effect is particularly strong when metaphors are used to convey the message.
Two things that occurred to me:
1. How wonderful that we have cobbled together something so powerful as language from the bits and pieces of machinery we already had on hand;
2. How much more powerful the writing instructor's direction to "Show, don't tell" becomes when it is supported by MRIs and science.