TUESDAY, Feb. 7 (HealthDay News) -- Patients who are thirsty may feel increased sensitivity to pain, although pain does not enhance or reduce feelings of thirst, according to a report published online Feb. 3 in the Proceedings of the National Academy of Sciences Early Edition. The two sensations together trigger a pattern of brain activation on positron-emission tomography that is different from either alone.
Michael J. Farrell, Ph.D., from the University of Melbourne in Australia, and colleagues examined cerebral blood flow changes in 10 subjects in response to mild pain induced by thumbnail pressure and thirst induced by saline infusion.
The two stimuli activated both overlapping and unique regions of the anterior cingulate and insula when given separately. However, simultaneous signals triggered activity in the pregenual anterior cingulate and ventral orbitofrontal cortex, two regions not affected by either signal alone, and which may function as signal integration centers.
Further, the subjects reported an increase in pain sensation when both signals were present, but felt no change in sensation of thirst. "The acute onset of pain has more immediate implications for tissue integrity than the early experience of thirst," the authors write.
Abstract
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