Researchers at the University of Iowa Roy J. and Lucille A. Carver College of Medicine and the Technical University of Aachen, Germany, used functional magnetic resonance imaging (fMRI) to find out if hypnosis alters brain activity in a way that might explain pain reduction. The results are reported in the November-December 2004 issue of Regional Anesthesia and Pain Medicine.
The researchers found that volunteers under hypnosis experienced significant pain reduction in response to painful heat. They also had a distinctly different pattern of brain activity compared to when they were not hypnotized and experienced the painful heat. The changes in brain activity suggest that hypnosis somehow blocks the pain signal from getting to the parts of the brain that perceive pain.
Initially, 12 volunteers at the Technical University of Aachen had a heating device placed on their skin to determine the temperature that each volunteer considered painful (8 out of 10 on a 0 to 10 pain scale). The volunteers were then split into two groups. One group was hypnotized, placed in the fMRI machine and their brain activity scanned while the painful thermal stimuli was applied. Then the hypnotic state was broken and a second fMRI scan was performed without hypnosis while the same painful heat was again applied to the volunteer’s skin. The second group underwent their first fMRI scan without hypnosis followed by a second scan under hypnosis.
Hypnosis was successful in reducing pain perception for all 12 participants. Hypnotized volunteers reported either no pain or significantly reduced pain (less than 3 on the 0-10 pain scale) in response to the painful heat.
Under hypnosis, fMRI showed that brain activity was reduced in areas of the pain network, including the primary sensory cortex, which is responsible for pain perception.
Clinical Hypnosis Modulates Functional Magnetic Resonance Imaging Signal Intensities and Pain Perception in a Thermal Stimulation Paradigm
Schulz‐Stübner & Al
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