Laser-evoked potentials to noxious stimulation during hypnotic analgesia and distraction of attention suggest different brain mechanisms of pain control

Psychological accounts of hypnosis have hypothesized that hypnosis and atte ntion might share similar mechanisms and that hypnosis simply represents an extensive state of reduced attention. This assumption implies that reports of pain and electrocortical brain responses to painful stimulation should be similarly reduced when subjects are exposed to suggestions of hypnotic a nalgesia (HA) or requested to distract their attention from painful Stimuli (distraction or attention: DA) as compared to a control condition (CC). To test this hypothesis, we recorded event-related electrical brain potential s to noxious laser-heat stimuli and pain reports during HA, DA, and CC from subjects highly susceptible to hypnotic suggestions. Pain reports were sig nificantly reduced during HA and DA as compared to CC. The amplitudes of th e late laser-evoked brain potential (LEP) components N200 and P320 were als o significantly smaller during DA than during CC. However, no significant d ifference of these late LEP amplitudes was obtained for HA as compared to C C. Results indicate that hypnotic analgesia and distraction of attention re present different mechanisms of pain control and involve different brain me chanisms.