Researchers at the University of Sydney have discovered a detailed “pain map” within the human brainstem that regulates pain sensations in specific areas of the body.
The study, published in Science, shows that different regions of the brainstem activate when relieving pain in the face, arms, or legs, suggesting the brain can target pain with high accuracy.
Using advanced 7-Tesla fMRI scanners, the team studied 93 volunteers exposed to heat stimuli on various body parts. A placebo cream was applied, and participants reported reduced pain even when the temperature was later returned to the original level.
This confirmed that the brain’s response was genuine, showing the placebo effect activates specific pain-relief circuits.
The researchers identified two key brainstem regions, the periaqueductal grey (PAG) and rostral ventromedial medulla (RVM), which coordinate pain control.
Upper sections of these areas respond to facial pain, while lower sections manage pain in the arms and legs. This discovery reveals the brainstem’s ability to provide localized pain relief rather than a generalized effect.
The study also highlights the potential for non-opioid therapies. Unlike opioid-based painkillers, which affect the whole body, the brainstem’s cannabinoid-linked pathways may allow targeted treatment with fewer side effects. Scientists say this could lead to safer options for people with chronic pain in specific areas.
“This map provides a blueprint for creating more targeted pain treatments,” said lead author Dr. Lewis Crawford. “By pinpointing the exact areas of the brain involved in pain reduction, we can develop therapies that act precisely where needed, reducing risks and enhancing effectiveness.”
