Semir Zeki, a neuroscientist who is fascinated by the cognitive basis of beauty, pleasure and love, has measured the different ways our brains respond when we're making an aesthetic judgement compared to a perceptual judgement. So, in this case, he looked at how people's brains responded when they looked at two paintings and decided which was more beautiful compared to looking at two paintings and deciding which was more brightly coloured.
His main conclusion was that the two types of judgement are different- that making a judgement about aesthetics activated brain areas and neural pathways that were effectively silent when people decided how bright a painting was.
Two particularly important areas of our cortex (which is made up of the layers and layers of neurons that allow us to make memories and have higher thinking functions like attention and planning) that are activated when we're making a judgement about beauty is the orbitofrontal cortex, which doesn't seem to be activated at all when we're judging brightness.
Watching, measuring and understanding how these function will help to develop an idea of what exactly is going wrong in our brains when we have an affective disorder, such as depression, something that can rob people of their ability to appreciate beauty and take pleasure in things like music and art.