On Thanksgiving, I had one of those dinner-with-family headaches that makes your face throb. I wanted to end everyone within a five-mile radius. Now, a new study in Nature Neuroscience may help explain why headaches make us so irritable. While studying mice, researchers discovered that sensory neurons in the face are directly connected to the amygdala, one of the brain’s chief emotional centers — implying that face pain is primed to provoke our emotions. The findings (while limited to rodents) may explain why headaches and toothaches are so emotionally trying.
“There has been this observation in human studies that pain in the head and face seems to activate the emotional system more extensively,” said co-author on the study Fan Wang of Duke University, in a statement. “But the underlying mechanisms remained unclear.”
Indeed, the literature on head and face pain is rife with clues that headaches have a unique hold over our emotions. Patients often rank head and face pain as more severe than pain throughout the body (an observation confirmed by fMRI brain scans) and studies suggest that, ironically, migraine patients occasionally bring on more migraines by stressing out due to fear of another painful episode. There’s even a condition known as Cephalgiaphobia — fear of headaches.
To find out why headaches hold such sway over our emotions, Wang and colleagues tracked brain activity in mice after irritating either their paws or faces. They found that face irritation caused an immediate, direct spike in the brain’s parabrachial nucleus (PBL), a region that coordinates emotions, whereas the brain signal in response to paw irritation meandered toward the PBL, attenuated-on-arrival. “This could explain why you have stronger activation in the amygdala and the brain’s emotional centers from head and face pain,” Wang said.
Wang and her team also confirmed that activating the PBL caused face pain in mice, while silencing this pathway reduced pain. And although this was only observed in mice, it represents a promising step toward helping people who suffer from chronic head and face pain. “We have the first biological explanation for why this type of pain can be so much more emotionally taxing than others,” said co-author Wolfgang Liedtke, also of Duke, in a statement.
“This will open the door toward not only a more profound understanding of chronic head and face pain but also toward translating this insight into treatments that will benefit people.”