SHARING OTHER PEOPLE’S PAIN

Our ability to feel what other people are feeling seems to be manifested through mechanisms that are largely involuntary and non-intentional. Thus, human empathic responses appear very early in the course of children’s development; children seem to be literally “pre-wired” to form relationships with their mothers.

This affective resonance is important not only for creating the critical bond between children and their mothers, but also for creating the emotional ties with other individuals that will foster mutual assistance and reproduction later in life, and hence the survival of the species in the long run. This automatic mental resonance with other people also helps us to make quick predictions about other people’s actions and needs, thereby improving communication, an important adaptive asset in a social species such as ours.

Human empathy would thus appear to be deeply rooted in the evolutionary history of our non-human primate ancestors and, many authors believe, would appear to provide a biological basis for our moral behaviours. Scientists have proposed many possible mechanisms to explain how human empathy may have developed. Among the most significant of these mechanisms are those involving mirror neurons.

The first part of the brain in which mirror neurons were identified was the premotor cortex, in the early 1990s. Some neurons in this area become activated when we make a particular motion, such as picking up a cup to drink from it. However, some of these same neurons also become activated when we are completely motionless ourselves but see someone else making exactly the same motion. The discovery that a visual stimulus can thus activate neurons in a motor area of the brain in a very specific way aroused great interest in the scientific community.

Subsequent studies identified mirror neurons in various other parts of the brain as well. Because mirror neurons let us simulate in our own brains what is going on in someone else’s, this combination of their neurons and our own has been described as a “shared neural network”. Studies have found such shared neural networks not only in the sensorimotor circuits of the brain, but also in the brain circuits responsible for emotional reactions. This may help to explain why, for example, we can be moved to tears by an actor in a film or on stage: the actor’s expressions of an emotion may activate the parts of our own brains that correspond to this emotion.

These findings made it necessary to define mirror neurons more broadly as a class of neurons that are activated not only when we experience an endogenous cognitive event ourselves, but also when we see signs that another individual is experiencing (or is about to experience) the same kind of cognitive event.

These studies thus reveal a partial overlap between someone’s neural activity when they are actually having a painful experience themselves and their neural activity when they are observing someone else having such an experience. The partial nature of this activation has suggested some possible explanations of how we distinguish these two situations so as not to confuse someone else’s distress with our own.

Philip L. Jackson and other authors have shown that experiencing empathy for other people’s pain does not generate the same activation patterns in our brains as imagining ourselves to be in pain when we are not actually in the midst of a painful experience. When we imagine ourselves in pain, the pain matrix is activated in far broader areas of the brain, including in particular the secondary somatosensory cortex and the dorsal portion of the anterior cingulate cortex.

However, some studies using transcranial magnetic stimulation have shown that we do have some ability to map the part of another person’s body that is in pain onto our own somatosensory cortex. Further experiments will be needed to determine the true extent of this isomorphism in the empathic response.

Be that as it may, the role of brain structures such as the anterior cingulate cortex in empathic responses to other people’s observed emotions has been confirmed in situations not involving pain. For example, this structure becomes activated not only when someone smells an unpleasant odour themselves, but also when they see an expression of disgust on the face of someone else who is smelling such an odour.

Some individuals lack empathy and the ability to perceive other people’s emotions. This is the case for psychopaths, who often have only very superficial affective states, feeling little or no remorse, for example, when they commit a crime. This difficulty in experiencing their own emotions makes it hard for them to recognize other people’s distress, as has been confirmed by the limited responses measured in the autonomic nervous systems of psychopaths while they are witnessing other people experiencing fear, sadness, or disgust. People with autism are another group who often show a limited ability to feel empathy for others. In one study, for example, Iacoboni asked autistic children and normal children to observe and imitate facial expressions for various emotions while he recorded the children’s brain activity with a functional magnetic resonance imaging device. Though both groups performed the task successfully, the autistic children showed less activity in their mirror-neuron circuits, especially in the inferior frontal area, while doing so. Moreover, the extent to which this activity was reduced corresponded to the severity of their autistic symptoms. Iacoboni therefore concluded that the integrity of our mirror-neuron systems seems to be essential for normal social development.