FRIDAY, July 3 (HealthDay News) -- Patients' emotional state may affect the way they process painful stimuli, even when it appears to have no impact on subjective responses to pain, according to a study published in the July issue of Gastroenterology.

Steven J. Coen, M.D., of Queen Mary University of London, and colleagues conducted a study of 12 healthy male volunteers aged 21 to 32 years who underwent functional MRI while being exposed to emotionally valent music used to induce negative emotion. The subjects received randomized painful and painless distentions to the esophagus when negative emotion was being induced and not induced.

The participants' sadness ratings showed a significant increase when they were induced to be in a negative mood, but this did not affect their perception of painful or painless stimulation, the investigators discovered. However, during negative emotion induction with painful stimulation, brain activity increased in the anterior cingulated cortex, anterior insula, and inferior frontal gyrus, and during painless stimulation there was more brain activity in the right anterior insula and anterior cingulated cortex, the researchers found.

"This study provides new information about the influence of negative affect on central processing of visceral pain," the authors write. "Evidence of right hemispheric dominance during negative emotion indicates this hemisphere is predominantly associated with sympathetic activity and that the right insula and right anterior cingulated cortex are integral to subjective awareness of emotion through interoception."

Abstract
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