Their “gate control theory of pain” proposed a series of controls, or “gates,” between the site of injury and the brain. When pain messages are sent from damaged tissue through the nervous system, they pass through several “gates,” starting in the spinal cord, before they get to the brain. But these messages travel only if the brain gives them “permission,” after determining they are important enough to be let through. If permission is granted, a gate will open and increase the feeling of pain by allowing certain neurons to turn on and transmit their signals. The brain can also close a gate
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