National Geographic : 2016 Dec
Dorsal horn Pain signal from body Placebo- modulated pain response Response relayed to other parts of the brain Rostral ventromedial medulla Periaqueductal gray matter Spinal cord Hypothalamus Amygdala Anterior cingulate cortex Prefrontal cortex Thalamus Expectation of treatment P AIN TREATMENT The placebo effect The expectation of pain relief with treatment can create a placebo effect, activating a neurochemical response that intercepts and inhibits pain. The nocebo effect The part of the brain associated with memory and anxiety can cause more intense pain. The physiological processes of a nocebo effect are less understood because they are ethically difficult to test. JASON TREAT, NGM STAFF; KELSEY NOWAKOWSKI ART: STUDIO MUTI. SOURCES: IRENE TRACEY, UNIVERSITY OF OXFORD; FABRIZIO BENEDETTI, UNIVERSITY OF TURIN Dopamine Placebos can cause the release of dopamine in the brain; it regulates desire, pleasure, and reward. When a nocebo effect kicks in, dopamine is deactivated. CCK Released by anxiety, cholecystokinin can work against the ameliorating effect of opioids—a nocebo effect that increases pain. Prostaglandins In highaltitude headaches, prostaglandins dilate blood vessels in the brain to induce pain. This response falls during a placebo effect and rises with nocebo. mind over matter 43 3. Regulation Released neurochemicals meet the pain signal at the dorsal horn in the spinal cord, reducing its intensity. The thalamus relays this response to other parts of the brain. 2. Response The expectation of relief sends signals from the cortices to the brain stem to release neurochemicals, such as opioids, to counter the pain signals traveling to the brain. 1. Recognition An expectation of pain relief from treatment is processed by the prefrontal cortex and other cortical regions.