Brain-imaging technique can be used to assess empathy
Can we put ourselves in other people's shoes without ever having experienced their emotional suffering? Dr Nicolas Danziger from the French Institute of Health and Medical Research (INSERM) and his colleagues used an advanced brain-imaging technique to shed light on this important question. The results of the study are published in the journal Neuron. Some people have the capacity to empathise because they are able to identify with others' feelings through a 'mirror matching' mechanism that relies on previous experience. Others, who may never have experienced that particular feeling, are unable to directly empathise. People who fall into this second category depend on an inferential process called 'perspective taking'. 'Patients with congenital insensitivity to pain (CIP) offer a unique opportunity to test this model of empathy by exploring how the lack of self-pain representation might influence the perception of others' pain,' writes Dr Danziger. Past studies in brain imaging have shown similar patterns of brain activity when people feel their own emotions and identify the same emotions in others. In a 2006 study, Dr Danziger and colleagues demonstrated that CIP patients underestimate the pain of others in the absence of emotional cues, and that their assessments for pain were strongly related to 'inter-individual differences' in the empathy trait. For the present study, the researchers used event-related functional magnetic resonance imaging (fMRI) to evaluate the brain activity relating to empathy for pain in a sample of 13 CIP patients and a control group of 13 healthy participants. The team scanned the participants while they looked at pictures of people showing either body parts in painful situations (experiment 1) or facial expressions of pain (experiment 2). Each participant was instructed to imagine how the person in the picture felt. The researchers predicted that the CIP patients would demonstrate less activity in the brain regions that are purportedly involved in 'automatic resonance' to others' pain, including the anterior insula and anterior mid-cingulate cortex. They also anticipated that the regions of the brain involved in emotional perspective taking would jump into action when the patients tried to build a representation of the pain experienced by others. These areas included the midline brain structures of medial prefrontal and posterior cingulated cortices. They found that the CIP patients showed normal fMRI responses to observed pain in the anterior insula and the anterior mid-cingulate cortex, which are part of the so-called 'share circuits' for self and other pain. For the CIP patients, the researchers explained, the empathy trait predicted responses in the ventromedial prefrontal area to sensory representations of others' pain, as well as responses in the posterior cingulated area to emotional representations of others' pain. The findings suggest that CIP patients depend heavily on their empathic abilities to imagine the pain of others when functional resonance mechanisms shaped by personal pain experiences are missing. According to the researchers, the midline brain structures that become active are the 'neural signature of the cognitive-emotional process'. The study concluded: 'Our findings underline the major role of midline structures in emotional perspective taking and in the ability to understand someone else's feelings despite the lack of any previous personal experience of it - an empathetic challenge frequently raised during human social interactions.'
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