Neural structures associated with recognition of facial expressions of basic emotions

People with Huntington's disease and people suffering from obsessive-compulsive disorder show severe deficits in recognizing facial expressions of disgust, whereas people with lesions restricted to the amygdala are especially impaired in recognizing facial expressions of fear. This double dissociation implies that recognition of certain basic emotions may be associated with distinct and non-overlapping neural substrates. Some authors, however, emphasize the general importance of the ventral parts of the frontal cortex in emotion recognition, regardless of the emotion being recognized. In this study, we used functional magnetic resonance imaging to locate neural structures that are critical for recognition of facial expressions of basic emotions by investigating cerebral activation of six healthy adults performing a gender discrimination task on images of faces expressing disgust, fear and anger. Activation in response to these faces was compared with that for faces showing neutral expressions. Disgusted facial expressions activated the right putamen and the left insula cortex, whereas enhanced activity in the posterior part of the right gyrus cinguli and the medial temporal gyrus of the left hemisphere was observed during processing of angry faces. Fearful expressions activated the right fusiform gyrus and the left dorsolateral frontal cortex. For all three emotions investigated, we also found activation of the inferior part of the left frontal cortex (Brodmann area 47). These results support the hypotheses derived from neuropsychological findings, that (i) recognition of disgust, fear and anger is based on separate neural systems, and that (ii) the output of these systems converges on frontal regions for further information processing.