Study examines brain’s complex activity in thirst, pain

Dr. Peter T. Fox is one of the co-authors of the article revealing the results of the study.

When we are thirsty, we are more sensitive to pain. Now a new study conducted in San Antonio and Australia shows why – the brain activates differently when we are both thirsty and in pain than when we are thirsty alone or in pain alone.

The positron-emission tomography (PET) study is by researchers at the Health Science Center’s Research Imaging Center, the Southwest Foundation for Biomedical Research in San Antonio, the Howard Florey Institute at the University of Melbourne, Australia, and the Baker Heart Research Institute, also in Australia.

The PET scans of 10 human subjects who experienced intermittent, harmless pain (pressure on their left thumbnail) and varying degrees of thirst confirmed the relationship between thirst and heightened perception of pain. But it was the first human study to map “a functional topography for pain and thirst” in the brain, showing activity in various structures including the insulae and the anterior cingulate cortex. The findings are in the Proceedings of the National Academy of Sciences.

The pattern of activations when thirst and pain were concurrent pointed toward an integrative role for two regions, the pregenual cingulated cortex and ventral orbitofrontal cortex, in the processes of context-dependent changes in sensation, the authors wrote.

From San Antonio, Peter T. Fox, M.D., professor and director of the Research Imaging Center (RIC), Frank Zamarippa of the RIC, and Dr. Robert Shade of the Southwest Foundation for Biomedical Research are co-authors. Australian collaborators are Dr. Michael J. Farrell of the Howard Florey Institute and the Center for Neuroscience at the University of Melbourne; Dr. Derrick Denton, Howard Florey Institute and the Baker Heart Research Institute at Alfred Hospital in Prahran, Victoria, Australia; Dr. Gary F. Egan, Howard Florey Institute and Center for Neuroscience; and Dr. John Blair-West, Department of Physiology, University of Melbourne.

The work was supported by the Robert J. Jr. and Helen C. Kleberg Foundation, the G. Harold and Leila Y. Mathers Charitable Foundation, the Brown Foundation, the Search Foundation, and the National Health and Medical Research Council of Australia.

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