The Basic Science of Pain

A wrong and misleading model of pain

Descartes made a great advance in the understanding of pain, from believing that pain was punishment from the gods to a physical problem. This famous figure describes the pathway for promptly moving one’s foot away from a hot flame. In the figure the heat of the flame near the foot activates a fiber within the nerve tubule that traverses up the leg to the spinal cord and, finally, to the brain. Descartes compared this fiber with a cord attached to a bell—by pulling on the other end of the cord, the bell will ring.

Learning that this model of pain is wrong and misleading can open your mind to the possibility of retraining the brain to reduce chronic pain.

Descartes’s theory has the advantages of being easy to understand and seemingly having a good correspondence with our experience. It has the disadvantages of being wrong and misleading—especially for people with chronic pain. It is misleading for people with chronic pain because it causes them to focus on tissue problems (remove the foot from near the flame), but ignore the bigger problem, the brain. If we update Descartes’s picture with more modern understanding we find that the bell can ring by itself! The brain can generate chronic pain with little or no input from tissues.