High resolution EEG indicators of pain responses in relation to hypnotic susceptibility and suggestion.

In this report we use a dense array (129 electrodes) EEG procedure to examine the effects of hypnotic susceptibility and hypnotic suggestions on electrocortical and self-report measures of painful stimuli. Self-report and event-related potential measures of six high and six low hypnotic susceptible individuals in response to pain were examined during an initial baseline condition and following a standard hypnotic induction under suggestions to either increase (hyperalgesia) or decrease (hypoalgesia) the painful stimulation. Our results show that high and low hypnotically susceptible individuals: (1) show few self-report or psychophysiological differences in response to baseline pain stimuli; (2) report differential pain experiences depending on hypnotic suggestions and (3) display differential psychophysiological indicators following an hypnotic induction with a suggestion of hypoalgesia. Overall, the findings suggest that hypnotic suggestions with high susceptible individuals modulate the later components of the evoked potential in a global manner and point up the importance of using both high and low hypnotically susceptible individuals preceding and following an hypnotic induction.