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Abstract:
In neuroimaging studies the amygdala has been implicated in
the perception of fear (Morris et al, 1996) and the insula in
disgust (Phillips et al, 1998). The amygdala has been shown to
habituate during processing of facial expressions (Breiter et al,
1996). In this study we investigated whether a similar habituation
in response to repeated presentation of facial expressions of
disgust (Ekman & Friesen, 1976) takes place in the insula. 6
right-handed male volunteers participated in four consecutive
5-minute experiments, each consisting of 5 cycles of periodic
alternation between 30s epochs of disgust and neutral stimuli. Data
acquisition and analysis has been described previously (Phillips et
al, 1998). The activation pattern changed over the course of the 4
experiments. In the first there was activation of the insula,
medial frontal cortex and posterior visual areas. This pattern of
activation increased during the second experiment. In the third run
the pattern of activation remained similar but now occurred during
the OFF-phase in response to the neutral stimuli. In the fourth
experiment there was no insula activation and hardly any other
activation. These results suggest that there is indeed habituation
of the neural response to repeated presentations of facial
expressions of disgust.
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