When people have their feelings hurt, what is actually happening inside the body to cause the physical pain in the chest?

—Josh Ceddia, Melbourne, Australia

Robert Emery and Jim Coan, professors of psychology at the University of Virginia, reply:

terms such as “heartache” and “gut wrenching” are more than mere metaphors: they describe the experience of both physical and emotional pain. When we feel heartache, for example, we are experiencing a blend of emotional stress and the stress-induced sensations in our chest—muscle tightness, increased heart rate, abnormal stomach activity and shortness of breath. In fact, emotional pain involves the same brain regions as physical pain, suggesting the two are inextricably connected.

But how do emotions trigger physical sensations? Scientists do not know, but recently pain researchers uncovered a possible pathway from mind to body. According to a 2009 study from the University of Arizona and the University of Maryland, activity in a brain region that regulates emotional reactions called the anterior cingulate cortex helps to explain how an emotional insult can trigger a biological cascade. During a particularly stressful experience, the anterior cingulate cortex may respond by increasing the activity of the vagus nerve—the nerve that starts in the brain stem and connects to the neck, chest and abdomen. When the vagus nerve is overstimulated, it can cause pain and nausea.

Heartache is not the only way emotional and physical pain intersect in our brain. Reent studies show that even experiencing emotional pain on behalf of another person—that is, empathy—can influence our pain perception. And this empathy effect is not restricted to humans. In 2006 a paper published in Science revealed that when a mouse observes its cage mate in agony, its sensitivity to physical pain increases. And when it comes into close contact with a friendly, unharmed mouse, its sensitivity to pain diminishes.

Soon after, one of us (Coan) published a functional MRI study in humans that supported the finding in mice, showing that simple acts of social kindness, such as holding hands, can blunt the brain’s response to threats of physical pain and thus lessen the experience of pain. Coan implicated several brain regions involved in both anticipating pain and regulating negative emotions, including the right anterior insula (which helps to regulate motor control and cognitive functioning), the superior frontal gyrus (which is involved in self-awareness and sensory processing) and the hypothalamus (which links the nervous system to the endocrine system).

Although the biological pathways underlying these connections between physical and mental pain are not well understood, studies such as these are revealing how intricate the connection is and how very real the pain of heartache can be.