Neural systems for recognising emotion from facial expressions

Humans are probably unique in the extent of their reliance on socially transmitted information in coping with physical and social environments. The face is a visible signal both of others� intentions and internal states, and facial expression continues to be a critical variable in social interaction. The exploration of the neural basis that underlies the perception of such facial signals was the main subject of this thesis. Our findings provide some new insights concerning neural substrates involved in the perception of specific emotional expressions as well as neural mechanisms that mediate the extraction of meaning during facial expression processing. The first experiment addressed the question of whether the perception of surprise in others is associated with a specific neural substrate. The results reveal that the perception of surprised facial expressions consistently recruits structures within the medial temporal lobes that have previously been associated with novelty detection. Our findings therefore suggest a close relation between perceiving surprise in others and the response to novel events. The first evidence that perception of disgusted facial expressions might be associated with a particular neural substrate came from investigations of people with Huntington�s disease who show a disproportionately severe impairment in recognising facial expressions of disgust. To explore which brain regions are associated with this deficit was the goal of the second study. Our finding of dysfunctionally decreased insula activation in pre-symptomatic Huntington�s disease provides an explanation for the clinical deficit in recognising facial expression of disgust and underscores the role of the insula in the emotion of disgust. With the detection of mirror mechanisms in monkeys and humans, simulation theories of emotion recognition have become increasingly popular. Do we understand what others feel by putting ourselves into the shoes of the other via a neural mechanism that simulates the observed expression? This question was addressed in the third experiment. The results show that we map the observed expressions onto neural circuitries associated with the production of these expressions and its somatosensory consequences, thereby providing a description of what the expression would feel like if produced in the observer. Such a mechanism is suggested to be important for empathic understanding of others� feelings