THE EFFECT OF HYPNOTICALLY INDUCED EMOTIONAL STATES ON BRAIN POTENTIALS-EVOKED BY PAINFUL ARGON-LASER STIMULATION

The relationship between pain perception and emotional states is well known. However, the nature of this relationship and how different emotional states affect sensory and cognitive dimensions of pain remains uncertain. Results from experimental investigations are often contradictory, which may be due to methodological difficulties in inducing pain and monitoring physiological responses. In addition, most studies have focused on a single emotion, and data on the relative effects of different emotional states are lacking. In the present study we attempted to eliminate some of these methodological problems. Laser evoke potentials were used as a quantitative correlate to pain perception and were measured in 12 highly hypnotically susceptible subjects during seven conditions: (a) a prehypnotic baseline condition; (b) a neutral hypnotic control condition; (c-e) hypnotically recalled anger, fear, and depression in randomized order; (f) a hypnotically recalled happy condition, and (g) a posthypnotic awake control condition. The pain evoked potentials were significantly decreased in the angry condition and significantly increased in the depressed condition compared with baseline. No differences could be detected for either the happy or the fear-related condition compared with the baseline or neutral hypnotic condition. A significant positive correlation between the subjective intensity of depression and the increase in evoked potentials was found, but none for the other three emotions. The results support earlier findings that clinical depression is related to increased pain perception, and findings that the expression of anger can inhibit the experience of pain. The lack of changes in pain-related potentials during the neutral and happy condition may indicate that effects of psychological interventions such as hypnotic analgesia may be due to specific cognitive processes rather than a relaxed or pleasant state in itself.