The question becomes, “Do all brains register physical pain when they observe physical or social pain in others?” The outcome of a study printed in the journal Social Cognitive and Affective Neuroscience (“Familiarity Promotes the Blurring of Self and Other in the Neural Representation of Threat") suggests that the answer is no. Using functional magnetic resonance imaging (fMRI), James Coan PhD, a psychology professor in University of Virginia's College of Arts & Sciences, found that the human brain tends to compartmentalize others, placing people who are in your social network and who you love and feel close to in one bucket and strangers in another. Dr. Coan says that those in the first bucket actually become linked with your sense of self at a neurobiological level. Whether your brain responds to the threat of pain to yourself or an empathic response to the threat of pain to someone you love, the posterior insular cortex tends to be activated. This region has been liked with the sensory processing of physical pain as well as emotion, self-awareness, and some aspects of cognitive function. (This response was less strong when study participants were observing the threat of pain to a stranger.) This may help to explain pathological behaviors observed in terrorism or in some types of mental illness. More tomorrow.