Few things are as tormenting as a migraine, a headache or a blow to the face. Pains located in the jaw area, forehead, ears or mouth are often classified by people as “particularly penetrating and long-lasting pain”, even more so than a sprain in another part of the body.
The reason, say researchers at Duke University, could be that blows or conditions in these regions send much sharper signals to the brain, which translates into a greater feeling of emotional exhaustion. In fact, it is this feeling of emotional fatigue that makes us experience headaches and face pain differently, at an intensity that we would classify as “higher.”
Fan Wang, a neurobiologist at Duke University and author of the study, explains that doctors usually focus on treating the sensation of pain that afflicts patients, however, they do not address the emotional aspects of pain, which are extremely important.
Sensory neurons in the head and face (green) connect directly to one of the brain’s primary emotional signaling centers, called the parabrachial nucleus (PBL). Pain in the head or face stimulates PBL neurons, highlighted in pink. Credit: Courtesy of Fan Wang, Duke University
The results of the study, published in the journal Nature Neuroscience, describe how pain signals from the head compared to other parts of the body are conducted to the brain through two different groups of sensory neurons. Scientists indicate that neurons in the head are most likely more sensitive to pain than neurons in the body, although this does not explain the heightened emotional suffering that patients experience in response to headaches.
This suffering is represented in functional magnetic resonance images (fMRI) where researchers were able to notice greater activity in the amygdala – a region of the brain involved in emotional experiences – in response to headache; activity that was lower in response to bodily pain.
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To determine to what degree the functioning of these neural circuits varied, Wang and his team tracked brain activity in mice after irritating a paw or face. They found that irritating the face led to increased activity in the brain’s parabrachial nucleus (PBL), a region that connects directly to the instinctive and emotional centers of the brain.
“This will open the door not only to a deeper understanding of chronic headache and facial pain, but also to treatments that will benefit people.”the researchers conclude, being that some cases such as trigeminal neuralgia can be so serious that many patients seek surgical solutions in vain, since even after cutting the neural pathways that carry signals from the head and face to the brain they continue to experience pain. .
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