Meanwhile, soft X-ray imaging has captured immune cells drifting toward acupuncture needles, where they release pain mediators. Even ultrasounds are helping researchers observe the ripple effect of a needle’s tug in real time and how those effects may vary depending on where a needle is placed.Together, these tools are beginning to map how a localized stimulus can ripple across the body—linking peripheral tissue, immune responses, and the brain’s pain-processing networks. Psychologically, the mere anticipation of potential healing plays its own role too, Yang adds. “Treatment expectancy and belief, mediated partly through the brain’s reward circuitry, may also contribute to acupuncture-induced pain...