Neuroscience

Pain isn’t just a physical sensation—it also carries emotional weight. That distress, anguish, and anxiety can turn a fleeting injury into long-term suffering.

Salk neuroscientist Sung Han, PhD, senior research associate Sukjae Kang, PhD, and colleagues have now identified a brain circuit that gives physical pain its emotional tone, revealing a new potential target for treating chronic and affective pain conditions such as fibromyalgia, migraine, and post-traumatic stress disorder (PTSD). The study identifies a group of neurons in a central brain area called the thalamus that appears to mediate the emotional or affective side of pain in mice. This new pathway challenges the textbook understanding of how pain is processed in the brain and body.

After nine months in the womb, humans enter a world filled with new textures and shapes. We must then quickly learn to recognize the sensation of these objects and distinguish which are harmless from those that are painful to the touch. But 7 to 10 percent of the global population develops mechanical allodynia, a form of chronic pain in which innocuous light touch is perceived as painful.

Salk neuroscientist Martyn Goulding, PhD, postdoctoral researchers Tejapratap Bollu, PhD, and Amandine Virlogeux, PhD, and colleagues have discovered that uncoordinated neuronal activity in the dorsal column nuclei drives mechanical allodynia, not a simple increase in activity as was previously assumed. When a brain area called the thalamus receives these altered signals, it no longer recognizes light touch as innocuous and instead interprets it as painful. In an act of self-preservation, the brain then initiates a pain-like response—better to be safe than sorry. This new understanding of how the brain processes and encodes pain is a crucial first step toward designing better therapeutics for acute and chronic pain.