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Mirror-touch synesthesia is linked with empathy
http://www.nature.com/natureneuroscience
Nature Publishing Group
Michael J Banissy & Jamie Ward
Watching another person being touched activates a similar neural circuit to actual touch and, for some people with mirror-touch synesthesia, can produce a felt tactile sensation on their own body. In this study, we provide evidence for the existence of this type of synesthesia and show that it correlates with heightened empathic ability. This is consistent with the notion that we empathize with others through a process of simulation.
Recent research indicates that peoples ability to empathize with others relies on shared affective neural systems in which common brain areas are activated during both experience and passive observation. Moreover, building on the discovery of mirror neurons in the monkey brain1, functional imaging has suggested the existence of mirror systems in humans not only for actions, but also for sensations and emotions26. For example, watching another human being touched (relative to an object being touched) activates the primary and secondary somatosensory cortex along with premotor and superior temporal regions. These systems may be crucial for empathy because they enable the observer to simulate anothers experience by activating the same brain areas that are active when the observer experiences the same emotion or state7. Consistent with this, a recent study provides evidence that increased activations in the auditory mirror system are correlated with improved perspective-taking abilities8. Moreover, this correlation not only included premotor areas, but also extended to somatosensory cortices, indicating that individuals may start to mirror the tactile consequences of heard actions8. Furthermore, there is a growing body of evidence suggesting that individuals with autistic spectrum disorder (ASD) have impaired activity in the action mirror system9,10, which may lead to the decits in imitation and empathy observed in ASD11.
One recent study reported a single case of vision-touch or mirror-touch synesthesia in which the observation of touch on other humans results in tactile sensations on her own body. Functional magnetic resonance imaging showed that these conscious tactile experiences are associated with hyperactivity in the same mirror-touch network that is evoked by observed touch in nonsynesthete controls in which no overt tactile experience is elicited3. As such, mirror-touch synesthesia offers a unique opportunity to explore the role that the...