[Imaging of hypnosis with functional magnetic resonance].

AIM

The aim of the study was imaging of the central nervous system activity with the fMRI method during hypnosis as well as confirmation of the observations linking subjective effects of suggested analgesia with the functional changes on the neurophysiological level.

METHOD

At first volunteers (7 female, 7 male) were examined with fMRI in the resting state and then four times during application of painful stimuli such as pricking of the right hand. Four experimental conditions were associated with this stimulation: only nociceptive stimulation, after analgesic suggestion, after hypnotic induction and after consecutive analgesic suggestion in hypnosis. In the fifth condition, concentration of attention was an experimental condition, while the control condition was distraction of attention (e.g. free associations). The contrast differences between measurements in the consecutive phases of the experiment were analysed.

RESULTS

Decreases of activity of regions known for contributing to pain reception were found, probably as an effect of analgesic suggestion. This effect was seen especially in the area of L-thalamus. Suggestion (more precisely--the reception of its content) was related mainly to the R-ACG area activity growth. Hypnotic induction was correlated with increasing activity of the L-orbitofrontal gyrus. Concentration of attention was linked with activity increase within inferior parietal lobule, occipital middle/superior gyri; in the left hemisphere in the orbital frontal gyri and insula/frontal operculum.

CONCLUSION

Both hypnosis and reception of analgesic suggestion are linked with increasing activity in particular brain areas, whereas the effect of analgesic suggestion demonstrates itself in the fMRI mainly by diminishing the reaction on painful stimuli.