For most people, the sound of a knife dragging across a plate is unpleasant but forgettable. For someone with chronic back pain, that same noise can feel almost physically unbearable, and brain imaging now shows why.

For most people, the sound of a knife dragging across a plate is unpleasant but forgettable. For someone with chronic back pain, that same noise can feel almost physically unbearable, and brain imaging now shows why.