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The Nuance
The Fascinating Brain-Pain Connection
How expectation, emotion, and other neurocognitive factors affect our perception of pain
Imagine that you’re about to have a tooth pulled. Your dentist tells you that, unfortunately, the tooth’s roots are infected, and so the procedure is going to hurt. A lot. It can’t be helped.
Now imagine an alternate scenario. You still need that tooth pulled, but this time your dentist says nothing — one way or the other — about the pain you may feel.
In both of these scenarios, the painful stimulus is the same. The same tooth is going to be pulled, and it will probably hurt either way. But would you experience the same amount of pain? Almost certainly not. Your dentist’s comments — not to mention your mood, stress levels, and other factors — are capable of shifting your perception of pain in one direction or the other.
“What we experience — second to second, moment to moment — is an interaction of what’s coming in from the outside but also top-down processes from the cortex of the brain,” says Irving Kirsch, PhD, director of the Program in Placebo Studies at Harvard Medical School and Beth Israel Deaconess Medical Center.
Kirsch has spent much of his career examining the variables that affect these top-down processes. He explains that the amount of pain you feel will always be influenced by expectation — for example, if a dentist tells you something is about to hurt — as well as by emotion, attention, motivation, and other factors. This influence can be subtle or significant, but it’s never absent.
“We used to have this view of pain or other sensory processes as being some sort of veridical picture of objective reality, but we’ve learned that that’s not how perception works,” says Tor Wager, PhD, a distinguished professor in neuroscience at Dartmouth College. “We get signals from our body, but they’re not the only source of information that our brain uses to construct what we perceive.”
These and other new insights into the brain’s role in pain could transform the way doctors approach its management. These findings also have broader implications for the brain and its relationship to consciousness, reality, and all…
