A theory of pain developed by Ronald Melzack and Patrick Wall in the 1960s that provides a physiologic basis for the role of an individual’s mental state in his or her perception of pain. The perception of pain depends on interaction between the central nervous system (the brain and spinal cord) and the peripheral nervous system (all the nerves outside the brain and spinal cord). When there is an injury, pain signals originate in the nerves associated with the damaged tissues and move through the peripheral nerves to the spine and then to the brain. According to the Gate Control Theory of Pain, before the pain signals reach the brain, they encounter “nerve gates” in the spinal cord that either open to let pain messages reach the brain or close to prevent them from reaching the brain. Two types of nerve fibers, A-delta and C fibers, are thought to transmit most of the pain messages to the spinal cord, but other types of sensory nerve fibers may send messages to the spinal cord that override these pain messages.
Scientists offer this example: If someone hits his elbow or head, rubbing the area may offer some relief. The theory may also help to explain why massage, heat, cold, transcutaneous electrical nerve stimulation (TENS) and acupuncture seem to alleviate pain.