ARTICLE UPDATE - Individual differences in disgust sensitivity modulate neural responses to aversive/disgusting stimuli.

Mataix-Cols D, An SK, Lawrence NS, Caseras X, Speckens A, Giampietro V, Brammer MJ, Phillips ML.

European Journal of Neuroscience, 27, 3050-3058.

Little is known about how individual differences in trait disgust sensitivity modulate the neural responses to disgusting stimuli in the brain. Thirty-seven adult healthy volunteers completed the Disgust Scale (DS) and viewed alternating blocks of disgusting and neutral pictures from the International Affective Picture System while undergoing fMRI scanning. DS scores correlated positively with activations in brain regions previously associated with disgust (anterior insula, ventrolateral prefrontal cortex-temporal pole, putamen-globus pallidus, dorsal anterior cingulate, and visual cortex) and negatively with brain regions involved in the regulation of emotions (dorsolateral and rostral prefrontal cortices). The results were not confounded by biological sex, anxiety or depression scores, which were statistically controlled for. Disgust sensitivity, a behavioral trait that is normally distributed in the general population, predicts the magnitude of the individual's neural responses to a broad range of disgusting stimuli. The results have implications for disgust-related psychiatric disorders.

ARTICLE UPDATE - Differential effects of object-based attention on evoked potentials to fearful and disgusted faces.

Isabel M. Santos, Jaime Iglesias, Ela I. Olivares and Andrew W. Young

Neuropsychologia, in press

Event-related potentials (ERPs) were used to investigate the role of attention on the processing of facial expressions of fear and disgust. Stimuli consisted of overlapping pictures of a face and a house. Participants had to monitor repetitions of faces or houses, in separate blocks of trials, so that object-based attention was manipulated while spatial attention was kept constant. Faces varied in expression and could be either fearful or neutral (in the fear condition) or disgusted or neutral (in the disgust condition). When attending to faces, participants were required to signal repetitions of the same person, with the facial expressions being completely irrelevant to the task. Different effects of selective attention and different patterns of brain activity were observed for faces with fear and disgust expressions. Results indicated that the perception of fear from faces is gated by selective attention at early latencies, whereas a sustained positivity for fearful faces compared to neutral faces emerged around 160ms at central-parietal sites, independent of selective attention. In the case of disgust, ERP differences began only around 160ms after stimulus onset, and only after 480ms was the perception of disgust modulated by attention allocation. Results are interpreted in terms of different neural mechanisms for the perception of fear and disgust and related to the functional significance of these two emotions for the survival of the organism.

ARTICLE UPDATE - Does it look painful or disgusting? Ask your parietal and cingulate cortex.

Benuzzi F, Lui F, Duzzi D, Nichelli PF, Porro CA.

The Journal of Neuroscience, 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.