Acupunture. Artwork illustrating a neurological theory to explain the effects of acupuncture, the traditional Chinese therapy that places needles in the skin (lower left). The traditional explanation is that needles inserted at acupuncture points can restore the balance and flow of an energy or life force called Qi. Neurological science explains the effects in terms of nerve signals. Here, the pain signal (red) and acupuncture signal (blue) travel from the knee to the spinal cord, and up the cord to the brain. At certain transfer points (spinal cord, box at lower right; and thalamus, box at top right) the acupuncture signal suppresses the pain signal. Also, in the brainstem's nucleus raphe magnus (box at centre right), the acupuncture signal triggers the release of endorphins, the body's natural painkillers.