Saturday, January 26, 2008

Does It Look Painful or Disgusting? Ask Your Parietal and Cingulate Cortex


Figure 1 (Benuzzi et al., 2008). Sample frames extracted from some video clips representing painful (left), disgusting (middle), and neutral (right) stimuli. All video clips began with 200–400 ms of a static hand or foot picture, followed by a stimulus rapidly approaching and contacting the skin. Needles and knifes apparently punctured the hand or foot, but actually they did not: the images were digitally corrected to simulate bleeding. [NOTE: blood not shown here. Perhaps the authors made use of this classic site, Jarrett's Blood Splatter Photoshop Tutorial.]

Think I made up the title of this post? No, it's the real title of a journal article published in the latest issue of the Journal of Neuroscience:
Francesca Benuzzi, Fausta Lui, Davide Duzzi, Paolo F. Nichelli, and Carlo A. Porro. (2008). Does It Look Painful or Disgusting? Ask Your Parietal and Cingulate Cortex. J. Neurosci. 28:923-931.

Looking at still images of body parts in situations that are likely to cause pain has been shown to be associated with activation in some brain areas involved in pain processing. Because pain involves both sensory components and negative affect, it is of interest to explore whether the visually evoked representations of pain and of other negative emotions overlap. By means of event-related functional magnetic resonance imaging, here we compare the brain areas recruited, in female volunteers, by the observation of painful, disgusting, or neutral stimuli delivered to one hand or foot. Several cortical foci were activated by the observation of both painful and disgusting video clips, including portions of the medial prefrontal cortex, anterior, mid-, and posterior cingulate cortex, left posterior insula, and right parietal operculum. Signal changes in perigenual cingulate and left anterior insula were linearly related to the perceived unpleasantness, when the individual differences in susceptibility to aversive stimuli were taken into account. Painful scenes selectively induced activation of left parietal foci, including the parietal operculum, the postcentral gyrus, and adjacent portions of the posterior parietal cortex. In contrast, brain foci specific for disgusting scenes were found in the posterior cingulate cortex. These data show both similarities and differences between the brain patterns of activity related to the observation of noxious or disgusting stimuli. Namely, the parietal cortex appears to be particularly involved in the recognition of noxious environmental stimuli, suggesting that areas involved in sensory aspects of pain are specifically triggered by observing noxious events.
Image credit: Jarrett Heather

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