This is a kidney glomerulus, but the brain has them too, they’re a cluster of nerve endings. source
Here we have a beautiful example of “quantum hedonics,” which is what I call the ability for odors to be considered both good and bad in a population, and even within the same individuals. (Hedonics means whether a thing is considered good or bad.)
At the end of Hidden Scents, there is an essay detailing this paradoxical nature of the smell of isovaleric acid, which is the smell of both vomit and Parmesan cheese. How can a thing be both good and bad at the same time? One cannot categorize a system where some of its components are, simultaneously, opposites of eachother. In this case, as suspected at the end of the article clipped below, the subjective status of the molecules may depend on the other molecules present. The identity or the status of one thing is dependent on the identity or status or presence of all the others. Therefore, in this type of situation, things do not exist in themselves but as an inseparable part of a whole.
Stinky or fragrant? Predicting changing odor preferences
Published in Neuron, the work shows how the activity of neurons in the olfactory processing center of the Drosophila brain can be decoded to predict behavioral responses to odors, and reveals that the relative preference of odors can flip depending on the situation.
Their model suggests that each glomerulus contributes to attraction or aversion with a specific weight. Summing the transformed and weighted activity of all glomeruli not only matched the real behavioral responses to the odors used to make the model, but also accurately predicted responses to new odorants. Kazama notes that contrary to the prevalent hypothesis in the field, the results imply that this computation does not rely on a small subset of glomeruli, but likely requires most, if not all, of them.
The model also predicted that the relative preference of odors would vary, and could even switch, depending on the nature of other odorants present in the environment.