Researchers Find Similarities of Pain, Pleasure Systems

New advances by Harvard Medical School (HMS) researchers have confirmed what philosopher Baruch Spinoza suspected in the 17th century—that pain and pleasure are just different degrees of the same sensation.

The study, published in the Dec. 6 issue of Neuron, is the first to correlate the pain and pleasure systems.

By analyzing brain images, researchers working at Mass. General Hospital isolated specific brain circuits involved with painful sensations.

Applying both warm and scalding hot heating pads to the palms of eight male subjects and mapping their neural activity, researchers found that painful and pleasurable stimuli activate the same brain structures.

The scanning technique used is also the first to objectively index the measurement of pain, according to Associate Professor of Radiology David Borsook, who led the team of researchers.

“The finding has a number of implications,” Borsook said.

The discovery could lead to breakthroughs in the treatment of both acute and chronic pain, said Assistant Professor of Radiology Lino R. Becerra, who also worked on the project.

“So far, most studies have concentrated on the discriminating aspect of pain,” Becerra said.

“Through this objective measurement we will better understand the perception of pain and we will better be able to correct it,” Becerra said.

Chronic pain has presented a particularly difficult problem for neurologists, because continuous painful stimulation actually alters the physical structure of brain circuits.

The technique employed by the HMS researchers is especially promising for the treatment of chronic pain because it allows for a better understanding of exactly which structures are being affected.

Borsook said he agrees that although there is no “magic potion” for the treatment of chronic pain, his study’s findings could lead to the creation of drugs that will target pain-related neural circuits more directly.

“There’s no question that we can do better in minimizing chronic pain with analgesics that don’t have such strong negative side effects,” he said.

Morphine, which is commonly used to treat chronic pain, has serious side effects such as dizziness and nausea.

About 30 to 40 million Americans suffer from chronic pain.

—Staff writer Sarah A. Dolgonos can be reached at dolgonos@fas.harvard.edu.