Scientists have traced how an "itch" in the body turns into a neural impulse to "scratch" it in the brain.

How they did it: Researchers at the Chinese Academy of Sciences suppressed parts of the spinal cords in mice in order to stop scratching behavior that had been triggered by an itch sensation. Then, using a light-based system able to trace the mice's neural circuitry, they followed the itch-to-scratch mechanism from the spinal cord to a part of the brainstem called the parabrachial nucleus that is involved in registering pain and other sensations.

Why it matters: Scientists would like to understand how to turn off the command to scratch an itch because it could lead to a treatment for chronic scratching that damages the skin.