Broken hearts and broken bones: What’s the connection?

A mere reminder of one's partner through a simple photograph is capable of reducing physical pain

Happy couple

'Hurt feelings' or 'broken hearts' reflect painful experiences. Isn't it striking, however, that the language we use to describe emotional pain is, in fact, the language we use to describe physical pain as well? Broken heart and broken bones, for instance.

In 15 different languages, the words used to describe emotional pain are almost exclusively borrowed from the physical pain domain. But is feeling hurt or unloved truly comparable to feeling physical pain or is this merely poetic license or coincidence? Mounting evidence suggests that the connection is much deeper.

Defining pain

Before continuing to explore this connection, it is important to clearly define the different pains we will be referring to here to avoid any misinterpretation. What we refer to as emotional pain here, is referred to as social pain by cognitive social psychologists.

Social pain is defined as the distressing experience arising from the perception of actual or potential psychological distance from close ones or a social group. Put simply, it is the pain experienced when you feel rejected, treated unfairly or when any relationship in your life is threatened, damaged or lost.

Medically, physical pain is 'unpleasant sensory and emotional experience associated with actual or potential tissue damage', meaning the pain experienced upon bodily injury. Studies by the University of California, Los Angeles prove that both these type of pains share neural and computational mechanisms.

Anatomy of pain

The brain's physical pain system consists of three regions in the cortex: the somatosensory cortex, the insula and the dorsal anterior cingulated cortex [or dACC].

The somatosensory cortex helps us pinpoint the location of pain in the body, particularly pain on the outer surface of the body. For instance, it helps differentiate the pain applied to the left or the right hand.

The insula responds to painful stimulation, particularly internal or visceral forms of pain, and seems to provide the brain with a representation of the body's overall state.

The dACC is associated with the distress of physical pain—it determines how much a particular pain stimulation bothers an individual.

Pain researchers have subdivided pain experience into two psychological components: sensory processing and felt unpleasantness. According to neuroimaging studies, the dACC plays a role in the 'felt unpleasantness' of physical pain; whereas the somatosensory cortex and posterior insula are associated with the sensory-discriminative aspects of pain.

Specifically, increasing levels of dACC activity correspond with increasing levels of self-reported pain unpleasantness. Thus, individuals who are pain-sensitive by nature show more dACC activity and report greater levels of perceived unpleasantness to painful stimulation.

For decades, neurosurgeons have performed cingulotomies [a form of psychosurgery], a circumscribed lesioning of the dACC, to treat intractable [Ed: difficult to treat or manage] chronic pain. People who have undergone cingulotomies for chronic pain report that they are still able to feel the pain but that it no longer bothers them. This underlines the dACC's role in the distressing, rather than the sensory, component of physical pain.

The dACC-social pain connection

In addition to the part it plays in processing of physical pain, animal research shows that dACC is also relevant in our experience of social pain. One primate study found that when the dACC was electrically stimulated in monkeys, they produced the same distress vocalisations that they produced when they felt estranged from a caregiver. In another study, when the dACC in monkeys was surgically altered, their distress vocalisation significantly reduced even when they were separated from their mothers.

Several lines of evidence suggest that dACC [specifically areas 240 and 320] is involved in our experience [distress] of both physical and social pain.

Connection established

In order to examine whether social pain in humans uses the same neural circuitry as physical pain, University of California conducted the first functional magnetic resonance imaging [fMRI] study of social exclusion [Eisenberger, Lieberman, & Williams, 2003].

Participants were scanned while playing a computerised ball-tossing game, supposedly with two others, and were ultimately excluded from the game. Most of the subjects reported that being left out of the game in the later stages really bothered them. Scans found that subjects showed greater activity in dACC when they were excluded compared to when they were included.

Further, to quantify this social pain, subjects had to choose between having felt ‘rejected‘ and having felt ‘meaningless‘. Subjects who reported feeling more social pain also showed greater activity in the dACC during the exclusion phase of the game.

It was also found in the study that the right ventrolateral prefrontal cortex [RVLPFC], a brain region involved in pain regulation, was also more active during exclusion than it was during inclusion. The RVLPFC appeared to be helping to regulate or cope with the social pain—to the extent that it was active, subjects felt less distressed.

Individuals with chronic pain disorders have heightened fears of social evaluation and rejection

The connection is critical to our survival

Why would our brain be organised this way? To ensure our survival and safety.

For survival

UCLA researchers believe that the social pain system in the brain may have piggybacked onto the physical pain system during mammalian evolution, borrowing the pain signal to indicate broken social bonds. Mammals are born immature, incapable of providing for their own physical needs. Hence, they must stay connected to their caregivers.

The need for this social connection in young mammals actually supersedes their need for food, water, and shelter, because without a caregiver to provide for these needs, young mammals would not survive.

Just as evolution has wired us to feel pain when we lack food [hunger], water [thirst], or shelter [freezing, sunburn], perhaps evolution has wired us to feel pain when we lack or anticipate a lack of social connection to ensure our survival.

For safety

In addition to being responsible for the distress experience in physical and social pain, the dACC also takes on the task of being the conflict or discrepancy detector.

Think of the dACC as a neural alarm system. For an alarm system to function properly, it requires two components: a discrepancy monitoring system, which detects deviations from desired standards [e.g. detecting an excessive amount of smoke], and a sounding mechanism, which signals that there is a problem that needs to be addressed [e.g. an alarm bell ringing]. The discrepancy-detection function of the dACC can be likened to the detection of excessive smoke, whereas pain distress can be likened to the sound of an alarm bell ringing. And researchers feel that both theses functions of the dACC may actually be complementary ensuring our safety.

Sensitivity issues

Due to the overlap of areas of physical-social pain in the brain, enhanced sensitivity to one type of pain accompanies an enhanced sensitivity to the other. When young children experience physical pain, they experience social pain more easily and more frequently in response to separation from their caregiver. Similarly, individuals with chronic pain disorders are more likely than their healthy counterparts to be anxious about their partner’s commitment to the relationship and have heightened fears of social evaluation and rejection.

Conversely, rejection-sensitive individuals report more distress when watching video clips of people experiencing physical pain compared with non-rejection-sensitive individuals.

The reverse is also true. It is proven that increased social support, which reduces social pain also reduces experience of physical pain from chronic ailments, during cancer, following heart surgery, and during childbirth.

Pain is subjective

It is logical to infer that the intensity of pain we experience directly corresponds to the intensity of the painful stimulation. Meaning the more painful the stimulus, the more pain we feel is what we normally believe. However, this is not necessarily true.

The amount of distress we experience is a subjective matter and may have little or nothing to do with the intensity of stimulation. Studies have proven that, with hypnotic suggestion, the same physical stimulus can be experienced as more distressing or less distressing. It is this experience of distress that is correlated with activity in the dACC.

One experiment conducted by UCLA psychologists shows that a mere reminder of one’s partner through a simple photograph is capable of reducing physical pain.

The physical-social pain connection has an impact of medication as well. Opiate-based drugs, known for their effectiveness in alleviating physical pain, also lessen social pain.

Antidepressants, often prescribed for anxiety or depression resulting from social stressors, have recently been found to alleviate physical pain as well and are now prescribed regularly to treat chronic pain.

A gift of evolution

The common neural alarm system for social and physical pain is adaptive for our survival. Nevertheless, evolution’s solution to ensure nurturance might have unintentionally produced a lifelong need for social connection and a corresponding sense of distress when social connections are broken. On the brighter side, it has unwittingly given us a way to treating physical pain that goes beyond medication; and the way is love and support of our closed ones.

Excerpted from The pains and pleasures of social life: A social cognitive neuroscience approach and Why rejection hurts: a common neural alarm system for physical and social pain by Matthew D. Lieberman and Naomi I. Eisenberger, Department of Psychology, University of California, Los Angeles [UCLA], California. Matthew D. Lieberman is Professor of Psychology, Psychiatry and Biobehavioral Sciences, Franz Hall, UCLA, California. Naomi Eisenberger is assistant professor in the Department of Psychology at UCLA.

A version of this article first appeared in the July 2010 issue of Complete Wellbeing.

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