1990s SYMBOLIC HAND CAUGHT IN RAT TRAP (Photo by Camerique/Getty Images)gettyWe all know what a complainer is: its a person who finds the dark side of everything, who turns a casual conversation starterHow are you doing?into a somber soliloquy about all the (usually minor) problems making their life unbearable.Too often, people with chronic pain are viewed as complainers by friends, family, and even their clinicians. That view misunderstands the neuroscience of most chronic pain. Consider a now-classic study, involving brain scans and fingers crushed by hydraulic pistons.A volunteer sits in a research lab with a rubber probe resting on her thumbnail. The probe, with a point the thickness of a colored pencil, is attached to a hydraulic piston calibrated to increase pressure on her thumbnail in precise increments, ranging from 0.45 kg/cm2 (approximately equivalent to balancing a Harlequin romance on top of the rubber probe) to 9 kg (the weight of a well-fed dachshund). At small amounts of pressure, she reports being unbothered by the probe. But by the time the piston exerts 1.4kg of pressure on her thumbnail (think: a large bag of rice), she tells the researchers she is feeling pain.It was the early 2000s, and the study was led by Dan Clauw, a rheumatologist at the University of Michigan. Deriving its name from the Greek word Rheuma, which roughly translates as bodily discharges, the specialty typically focuses on disorders like gout and lupus that are characterized by painful joint swellings, sometimes accompanied by viscous discharge. Clauw is a renowned rheumatologist, but not for studying diseases like lupus, nor for concerning himself with bodily discharges. He studies chronic pain.And in that study, he was trying to understand the neuropsychology of fibromyalgia, a disorder in which people experience widespread bodily pain, typically in soft tissues rather than joints, with nothing palpably abnormal on physical examno redness, no swellingother than an exquisite sensitivity to pressure on those tissues.Clauw projects the demeanor of a Scrabble afficionado rather than the that of a mad scientist who crushes peoples thumbnails. Clauw was subjecting participants to pain in order to understand the cause of those pains. In the study, his team measured the pain thresholds of two groups of volunteers: people with fibromyalgia and people with no history of chronic pain. Think of a pain threshold as the amount of a noxious stimuli it takes before a person says that hurts. The stimulus could be hot temperature, cold temperature, electrical shocks, or, as youve probably figured out, hydraulic pressure. In the study, Clauws team confirmed what previous research had established: that it took about twice as much pressure for healthy people to report pain as it did for those with fibromyalgia.An uncharitable interpretation of these findings would conclude that people with fibromyalgia are complainers. They dont feel more pain than anyone else, they just report feeling more pain. The kind of discomfort most people would describe as being 2 out of 10 they describe as being 6 out of 10. By this interpretation, the problem for people with fibromyalgia is less about how much pain they feel and more about how much they complain about things that arent even painful.But there is another possibility. Rather than having lower thresholds for complaining that sensations are painful, people with fibromyalgia might actually experience pain at lower thresholds. This might sound like semantics. I call it pain, you call it a different threshold for reporting pain. But feeling pain and reporting pain arent the same phenomenon. Pain signifies suffering and distress, a feeling that noticeably disrupts people;s ability to function normallyto read a book, enjoy a movie, or spend a restful night in bed. Accompanying this feeling will be bodily changes signifying that they are experiencing an active injurystress hormones surge; pain centers of the brain race into action. That means we need to know not only when someone reports something as being painful but, also, whether the parts of their body that sense and experience pain are active when they make those reports.Clauws study was designed to disentangle these two competing interpretations. To do so, before subjecting peoples thumbnails to near-dachshund levels of pressure, his team placed participants in fMRI scanners. That abbreviation stands for functional magnetic resonance imaging, and its a technique that identifies shifts in oxygen use across the brain. When people lay in fMRI scanners, researchers can locate which parts of their brain are relatively active when they report feeling happy, or when they tell researchers they are experiencing pain.When Clauws team exerted 5kg of pressure on peoples thumbnails, both groups of volunteers people with and without fibromyalgia reported feeling pain. Simultaneously with these reports, pain centers in their brains lit up, amygdalas and anterior insulas firing in response to the stimuli.By contrast, when Clauws team exerted very small amounts of pressure on peoples thumbnails, the pain regions of peoples brains were quiet, showing no increases over baseline, both for people with fibromyalgia and those without. So far, no difference between the two groups.Now for the critical test: what happens when Clauws team exerts just enough pressure for people with fibromyalgia to report pain while those without fibromyalgia remain nonplussed? If people with fibromyalgia are simply complainers, their brains will look like the same as people who dont have the disorder. Neither group will exhibit neurological signs of pain, but people with fibromyalgia will still complain about the pressure on their fingers.But thats not what happened. Instead, in healthy people, the pain centers in their brains remain dim. However, in people with fibromyalgia, the pain centers light up, waves of electricity racing from left to right, from midbrain to the higher cortex, the same pattern of brain activity occurring when they are subjected to dachshund-levels of pressure. This brain activity leads to the provocative conclusion that people with fibromyalgia dont simply have lower thresholds for reporting a stimulus as painful. They have lower thresholds for experiencing pain.As I explored previously, clinicians do a disservice to people with chronic pain whey they look at the location of their pain (the lower back), find no pathology (normal xray), and tell them theres nothing wrong. As Clauws study shows, the problem could be hypersensitive pain pathways in the persons brain.