Gate control theory of pain

Wall, P. D. The gate control theory of pain mechanisms. A re-examination and restatement, Brain 1978, 191, 1-18. 

The gate control theory describes pain transmission. The gate mechanism that alters the transmission of painful sensations from peripheral nerve fiber to the thalamus and cortex of the brain is located in the dorsal horn of the spinal cord. The thalamus and cortex of the brain are where the body recognizes painful sensations as pain. 

The gate control theory (Melzack Casey, 1968 Melzack 8c Wall, 1965) was the first model to include psychological factors as an integral aspect of the pain experience. Turk and Flor (1999) describe the significance of the model ... 

There remains the question of how nature can inflict pain on an organism that can control its own reinforcement. Modern operant theory has corrected many of the awkward features of older, two-factor theories of punishment (Hermstein 1969) it portrays pain as simple non-reward, to which an organism attends because it contains adaptive information. However, pain cannot be just the absence of reward or. in terms of the model just presented, the absence of effective rationing devices for self-reward. The person in pain is not just bored, as he would be in a stimulus deprivation situation, but feels attacked by a process that prevents him from enjoying food, entertainment or whatever other sources of reward may be available. And yet the person must perform a motivated act, the direction of his attention to the pain, in order for it to have its effect. As we have seen, pain can be and sometimes is deliberately shut out of consciousness. How does nature get people to open their gates to pain ... 

The widely accepted theory of gate control was put forward by Melzack and Wall (1965). Wall (1978) later restricted the term to describe the immediate reception and control of sensory inputs that lead to effector triggering and sensation. Descending impulses from the raphe nuclei, reticular formation and other regions of the brain affect - and, in particular, inhibit - the activity of neurons in the dorsal horn, where gating functions are thought to be localized. Only when the gate is open does pain information pass to the brain. 

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