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Brain Imaging in Neurosciences - An Interdisciplinary Approach

AUTHOR(S): Halsband, U.DATE: June 2006
DESIGN: Experiment
SUBJECTS: Seven right-handed volunteers with high-hypnotic susceptibility
OBJECTIVE: This study examined a fundamental question: Is verbal memory processing in hypnosis and in the waking state mediated by a common neural system or by distinct cortical areas?

INTERVENTIONS: Subjects were PET-scanned while encoding/retrieving word associations either in hypnosis or in the waking state. Word-pairs were visually presented and highly imaginable, but not semantically related (e.g. monkey-street). The presentation of pseudo-words served as a reference condition. An emission scan was recorded after each intravenous administration of O-15 water. (Result 1.) In order to further analyze the effect of hypnosis on imagery-mediated learning, sets of high-imagery word-pairs and sets of abstract words were administered. In the first experimental condition word-pair associations were presented visually. (Result 2.) RESULT - 1: Encoding under hypnosis was associated with more pronounced bilateral activations in the occipital cortex and the prefrontal areas as compared to learning in the waking state. During memory retrieval of word-pairs which had been previously learned under hypnosis, activations were found in the occipital lobe and the cerebellum. Under both experimental conditions precuneus and prefrontal cortex showed a consistent bilateral activation which was most distinct when the learning had taken place under hypnosis.

RESULT - 2: In the second condition it was found that highly hypnotisable persons recalled significantly more high-imagery words under hypnosis as compared to low-hypnotisables both in the visual and auditory modality. Furthermore, high-imagery words were also better recalled by the highly hypnotisable subjects during the non-hypnotic condition. The memory effect was consistently present under both, immediate and delayed recall conditions.

CONCLUSIONS: The findings advance the understanding of the neural representation that underlies hypnosis and the neuropsychological correlates of hypnotic susceptibility.
SOURCE: Journal of Physiology-Paris. 99 (4-6): 470-482