What exactly is beauty?, is an old and unanswered question. It is one of those fringe qualia of consciousness not a perception but a feeling, like familiarity or certainty, which is attached to a perception. But the criteria for this feeling has never been settled. A recent paper by Ishizu and Zeti (citation below) looks for the traces of beauty in the brain. Here is the abstract:
We wanted to learn whether activity in the same area(s) of the brain correlate with the experience of beauty derived from different sources. 21 subjects took part in a brain-scanning experiment using functional magnetic resonance imaging. Prior to the experiment, they viewed pictures of paintings and listened to musical excerpts, both of which they rated on a scale of 19, with 9 being the most beautiful. This allowed us to select three sets of stimulibeautiful, indifferent and uglywhich subjects viewed and heard in the scanner, and rated at the end of each presentation. The results of a conjunction analysis of brain activity showed that, of the several areas that were active with each type of stimulus, only one cortical area, located in the medial orbito-frontal cortex (mOFC), was active during the experience of musical and visual beauty, with the activity produced by the experience of beauty derived from either source overlapping almost completely within it. The strength of activation in this part of the mOFC was proportional to the strength of the declared intensity of the experience of beauty. We conclude that, as far as activity in the brain is concerned, there is a faculty of beauty that is not dependent on the modality through which it is conveyed but which can be activated by at least two sourcesmusical and visualand probably by other sources as well. This has led us to formulate a brain-based theory of beauty.
Of course, there are many other areas of the brain involved in beauty but none with the overlap of vision and hearing found in the A1 part of the orbito-frontal cortex. They give a specific location to their area A1 as a reference for other researchers. This seems to be the seat of an abstract sense of beauty. Facial attractiveness activates A1 or very nearby. This is also in the general area associated with pleasure, reward, desire, value evaluation and judgments. The visual and auditory activity in A1 have a different onset after stimulus and so probably do not follow the same path from some other shared area but arrive independently, musical before visual beauty.
The caudate nucleus also is activated with an intensity matching experience of beauty but only for visual not auditory stimuli. This area has been associated with romantic love.
We might expect that if beauty has an abstract area of activation than ugliness would too. Not so, there seems no overlap of visual and auditory ugliness. Ugliness appears tied to particular sorts of ugliness, not a symmetrical opposite of abstract beauty. It is perhaps an emotional reaction involving fear, disgust or similar.
We did not find activity in A1 of mOFC that correlates positively with the experience of ugly stimuli, although ugliness, too, involves a judgment. Instead, the parametrically modulated activity with the experience of ugliness was confined to the amygdala and left somato-motor cortex. This implies that there may be a functional specialization within the brain for at least two different kinds of judgment, those related to positive, rewarding, experiences and those related to negative ones.
Beauty has a specific neural correlate. Its activation probably depends on the individual, the object and the situation. It is a value judgement in the broadest sense, a positive judgement based on pleasure, desire and reward.
Ishizu, T., & Zeki, S. (2011). Toward A Brain-Based Theory of Beauty PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0021852