How can the aversion response be explained neurologically?

Question

If Dopamine and Dopamine D2 receptor is involved in craving, wanting and clinging towards something or incentive salience

Dopamine is closely associated with reward-seeking behaviors, such as approach, consumption, and addiction.[38] Recent researches suggest that the firing of dopaminergic neurons is a motivational substance as a consequence of reward-anticipation. This hypothesis is based on the evidence that, when a reward is greater than expected, the firing of certain dopaminergic neurons increases, which consequently increases desire or motivation towards the reward (from dopamine on Wikipedia )

What is the opposite mechanism in humans - by which we are experiencing aversion from something?

For example, someone finds something rotten, stinky and covered in white fuzzy mold in a plastic bag. Eww! Gross! Get it away! don't touch it! Keep distance. What is neurologically responsible for the person's feeling of aversion towards an object like that?

Are there different pathways to aversion?

For example, would seeing a person who looks like a witch from fairy tales (old, ugly, rotten teeth, lots of warts, body odor) cause the same aversion response as moldy food?

Answer 1

I remembered that Disgust is one of the 6 major emotions and there is quite a lot written about it:

The neural basis of disgust

The scientific attempts to map specific emotions onto underlying neural substrates dates back to the first half of the 20th century. However, it was not until the mid-1990s when it was recognized that six basic emotions, including disgust, were each related to a specific neural structure and therefore considered to be a part of the clinical neurosciences.[23] Functional MRI experiments have revealed that the anterior insula in the brain is particularly active when experiencing disgust, when being exposed to offensive tastes, and when viewing facial expressions of disgust.[24] The research has supported that there are independent neural systems in the brain, each handling a specific basic emotion.[4] Specifically, f-MRI studies have provided evidence for the activation of the insula in disgust recognition, as well as visceral changes in disgust reactions such as the feeling of nausea.[4] The importance of disgust recognition and the visceral reaction of "feeling disgusted" is evident when considering the survival of organisms, and the evolutionary benefit of avoiding contamination.[4] [edit]