Monday, October 11, 2010

Embodyment of our emotions in our brains.

A long standing issue in the neuroscience of emotions has been whether signals from our body (i.e. afferent visceral signals via interoceptive afferent fibers that monitor the physiological state of our internal organs) are essential for the unique experiences of distinct emotions, or whether these signals are too crude and undifferentiated to enable the wide variety of emotional feeling we can have. This issue has been difficult to resolve in the absence of methods to measure and integrate central neural responses, peripheral physiological responses, and subjective experience. Harrison et al have now used a combination of functional magnetic resonance imaging (fMRI) and simultaneous recording of autonomic influences on two independent organ systems (heart and stomach) during the experience of two different forms of disgust: core and body boundary violation disgust, induced, respectively by participants watching videos of people eating disgusting food, or of a surgical operation. Although both scenes produced strong disgust, these feelings were associated with distinct gastric and cardiac effects as well as differential activation in the insula and other brain regions. Thus, interoception could contribute to the perception of emotion. The magnitude of subjectively experienced disgust, regardless of disgust form, correlated with anterior insula activity. I pass on one figure from the paper that shows areas of the insula selectively activated by core versus body boundary violation disgust:

Figure - Insula activations to core and BBV disgust. A, Core greater than BBV disgust. B, BBV greater than core disgust. Contrast estimates show activations in circled right ventral and dorsal insula, respectively, in order (left to right): high core, low core, high BBV, and low BBV disgust.

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