What is Pain?

The International Association for the Study of Pain (IASP), which is the world’s largest pain-related professional organization, revised their official definition of pain last year. It reads: “Pain is a sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.” It was a revision of their earlier version from 1979, which also contained the phrase defining pain as a “sensory and emotional experience.” 

This definition of pain is arguably accepted worldwide by clinicians, researchers, and policy-makers. 

It is also commonly surprising to patients. For who thinks of pain as even in part emotional?

After all, pain is a sensation, not an emotion. Pain is like itches, tickles, numbness and tingling. All these experiences are sensations. They are associated with our tactile sense of perception. We do not see, hear or taste pain and itches and the like, but rather we tactilely feel them. Emotions are experiences such as being happy or mad or sad or joyful. These experiences are rightly not considered sensations. 

There is, however, cross over between the experiences of sensations and emotions. It is readily apparent with emotions, which commonly involves also having sensations. Excitement and fear, for instance, are palpable. We can sometimes almost burst with tingling energy when excited. Grade school children have tummy aches the night before the first day of school. Less readily acknowledged is that sensations also have emotional aspects to them.

Itches are aggravating, especially when they don’t easily go away, and scratching them is relieving. Tickles make us giggle, and we squirm in their playfulness. 

Pain is alarming. We wince, guard and protect. We cry tears and we cry out verbally. We look to others for help, and others react accordingly. Pain is a sensation that alerts us to something that is going wrong. It puts us on notice.

In this way, pain is like a fire alarm in a building. Fire alarms alert us to something that is going wrong in the building and we reflexively react with avoidance behaviors — we get out of the building. In a word, fire alarms are alarming. They are an auditory perception that is inherently alarming.

Pain is a similarly alarming perception. Of course, we do not hear pain, but feel it. We perceive it through our tactile sense, but it involves a similarly alerting and cautionary experience to which we reflexively react with avoidant behaviors (e.g., reflexively pulling away our hand from flame). 

We thus might capture the definition of pain as “a sensory and emotional experience” with a quasi-equation: pain = sensation + alarm. 

Mapping Pain onto the Brain

Pain as a sensory and emotional experience maps onto the brain. Suppose you broke your ankle, or stepped on a nail, or some other typically painful injury, and further suppose you were put into an MRI for a brain scan. Different parts of the brain that roughly correspond to both the felt sensation and alarm would light up in the scan (Da Silva & Seminowicz, 2019; Sperry et al., 2017). 

First, the somatosensory cortex of the brain would show up as active. This area of the brain corresponds to the sensation that would be felt. It is largely responsible for the type of sensation (whether it would be a dull ache, a sharp piercing sensation, an electrical sensation, or what have you) and where in the body it will be felt (the left ankle that has the fracture or the right foot with the nail sticking in it). Second, in addition to the somatosensory cortex, the scan would reveal activity in the limbic system and prefrontal cortex. These areas are responsible for a great many things, but one of which is our danger response, commonly known as “fight-or-flight” or “fight, flight, or freeze.” It is our innate alarm system — something that gets activated in response to threat.

It makes sense that we’d be built this way — that our danger response would go off when having a certain sensation that we call pain. It is signaling danger in the sense of harm. We accidentally touch flame with our hand or we break our ankle or step on a nail. Something is going wrong and as a result we experience pain.

Pain is the only sensation that puts us on notice in this way. It alerts us and we reflexively guard, protect, pull away and seek help. No other sensation, such as tickles or itches or numbness, typically puts us into a state of alarm. In this way, pain is an inherently alarming sensation. 

In our effort to clarify the IASP definition of pain as a ‘sensory and emotional experience… associated with… tissue damage,” we can thus be even more specific: pain is a sensation with an innate sense of alarm, or a sensory and alarming experience.

More information

For more information, please see these related topics: the neuromatrix of pain, central sensitization, cognitive-behavioral therapy, and the mission of the Institute for Chronic Pain to educate the public about empirical-based conceptualizations of pain and its treatments. 

References

Da Silva, J. T. & Seminowicz, D. A. (2019). Neuroimaging of pain in animal models: A review of recent literature. Pain, 4(4), e732. doi: 10.1097/PR9.0000000000000732 

Sperry, M. M., Kandel, B. M., Wehrli, S., Bass, K. N., Das, S. R., Dhillion, P. S., Gee, J. C., & Bar, G. A. (2017). Mapping of pain circuitry in early post-natal development using manganese-enhanced MRI in rats. Neuroscience, 352, 180-189. doi: 10.1016/j.neuroscience.2017.03.052

Date of initital publication: October 11, 2021

Date of last modification: October 11, 2021