Indeed, stimulation of the tipper brain stem in animals seems to block pain completely. At least, the animals act as though they are not experiencing pain when their tails are shocked or overheated. Stimulation of this same area of brain stem has been used to treat a few difficult pain problems in man. In some of these patients, a few minutes of stimulation will lead to many hours of relief from chronic pain. Many treatments that work well for human acute pain, however, are of little value in chronic pain problems.
Stimulation locally releases substances with opiatelike properties.
It has also been proposed that opiate drugs control pain through this same system. Since the internal morphine pain control system can be stimulated electrically and by drugs, it can presumably be stimulated naturally by appropriate experiences. There are, for example, many war stories of soldiers who seem to feel no pain from a wound until after they have been evacuated from the battlefield. One approach was to see if morphine-blocking drugs also blocked the placebo responses. These dental patients had just had an impacted wisdom tooth extracted, a procedure which predictably causes postoperative pain for some time.