Hypnosis and analgesic suggestions in fMRI

Aim: To verify data concerning the influence of verbal analgesic suggestions on the signal of pain and the hypothesis of hypnotic state neurophysiological specificity. Material and method: Brain activity of 14 volunteers under various conditions was measured using fMRI: 1. (basic experiment) - pain stimulation only; 2. pain stimulation after analgesic suggestion; 3. pain stimulation during hypnosis; 4. pain stimulation during hypnosis after analgesic suggestion. Activity of the whole brain and in particular regions of interest (ROI) was analysed. Results: The verbal suggestion of analgesia, with or without hypnosis, decreased the pain signals in most ROI analyzed, especially the L-thalamus. Reception of analgesic suggestion seems to be connected with an increase of activity in the Anterior Cingulate Gyrus (ACG), especially in the right hemisphere. Hypnosis seems to be connected mainly with increasing activity of orbitofrontal regions, especially in the left hemisphere. Conclusions: The reaction to analgesic suggestion is independent of hypnosis. In neuroimaging procedures, hypnosis presents mainly an activity in orbitofrontal regions.