Empathy for pain in doctors versus synesthetes

A common warning given to students interested in a career in medicine is “you better have a tough stomach.” Luckily for physician-wannabes who tense up at the sight of blood, a new study published in NeuroImage suggests that it may be possible to change your brain’s response to watching pain being inflicted on others. The findings are nicely summarized at the BPS Research Digest blog:

Decety's team used electroencephalography (EEG) to monitor the electrical activity arising from the brains of 15 doctors and 15 controls while they looked at dozens of static pictures of people being pricked in various body parts by a needle or prodded by a cotton bud.

When a person looks at someone else in pain, their EEG response typically shows two distinct characteristics: a frontal component after 110ms, which is thought to reflect an automatic burst of empathy, and a more central, parietal component after about 350ms, which reflects a conscious evaluation of what's been seen.

As expected, the control participants showed an enhanced early and later phase EEG response to the needle pictures compared with the cotton bud pictures. The doctors, by contrast, showed no difference in brain response to the two categories of picture.

This means that doctors are essentially the opposite of people who experience synesthesia for pain, a condition I previously wrote about. Synesthesia for pain, the physical experience of pain induced by simply viewing pain in another, has mainly been identified in rare ‘phantom limb’ patients who have had an amputation but still experience sensations in the absent limb. If you can recall, certain areas of the brain are active when pain is felt: some areas involving emotion/affective processing, some areas involving cognition/evaluation, and other areas involving the actual sensation of pain. It is hypothesized that pain synesthetes have overly-sensitive responses to viewing pain in brain regions that are responsible for conscious pain perception.

In contrast, Decety’s new study suggests that doctors have under-active responses in the whole pain matrix. If this under-active response can be acquired by training (e.g. assisting surgeries in medical school), perhaps pain synesthetes could make their empathetic pain experiences go away by repeatedly viewing needles being pressed into others. However, this might not be the best treatment approach as it would probably be exceptionally painful for the synesthete.

Pain synesthesia is acquired (usually after injury/amputation), unlike most other identified forms of synesthesia in which people are supposedly born experiencing numbers as colours or sounds as tastes. Perhaps this means pain synesthesia can be cured as well.

Decety J, Yang CY, & Cheng Y (2010). Physicians down-regulate their pain empathy response: an event-related brain potential study. NeuroImage, 50 (4), 1676-82 PMID: 20080194

Fitzgibbon BM, Giummarra MJ, Georgiou-Karistianis N, Enticott PG, & Bradshaw JL (2010). Shared pain: from empathy to synaesthesia. Neuroscience and biobehavioral reviews, 34 (4), 500-12 PMID: 19857517