Neural correlates of the experience of ugliness.

Previous studies have shown that the experience of beauty is dependent upon the co-activity of field A1 of the medial frontal cortex and sensory areas. This leaves us with the question of ugliness; are the same neural mechanisms involved in this experience, including neural activity patterns, or are different mechanisms at play? This question arises because ugliness, although often regarded as the opposite of beauty, could possibly be a distinct aesthetic category. Subjects were asked to rate faces according to how ugly they found them to be while their brain activity was measured with functional magnetic resonance imaging. There was moderate agreement in the experience of ugliness of faces among subjects. Univariate parametric analyses did not reveal any brain regions with increasing activity as the declared intensity of the experience of ugliness increased. In contrast, increasing activity appeared in the striatum and posterior medial orbitofrontal cortex with decreasing levels of ugliness. As with studies on facial beauty, representational similarity analysis revealed distinct neural activity patterns with the experience of facial ugliness in sensory areas relevant for face processing and in the medial orbitofrontal cortex. Thus, similar neural mechanisms appear to be involved in the experience of facial beauty and ugliness, the difference being the level and distribution of activity within the neural network. This suggests that ugliness and beauty are on the same aesthetic continuum.