In energetic terms, localisable and quantifiable by biochemists, what is “desire”?
How might we measure it?
How might we measure it?
In mice they have a stain for the expression of a particular type of "early" expression gene which coincides (most of the time) with neural activity. But this kind of staining is only useful for animal models you can sacrifice. I suppose if you wanted to explore this in humans you'd have to use PET with some neuronal population specific ligand or some fMRI modality(s).
https://en.wikipedia.org/wiki/Motivational_salience - this wikipedia article is helpful, but they mistakenly (as was tradition) cite the neurological substrates of liking (the shell of the nucleus accumbens) as the source. And that isn't correct even if the ventral tegmental area (wanting) projects heavily to it.
That is a good question. A desire is a term of the mind, and it is not easily connected to the brain and physiology. The only one I can think of is the conscious desire to breathe - iirc, it is directly correlated to the amount of CO2 in the blood (not O2, the first suspect). We don't yet have strong correlates to hunger, for example, so it might take a while for other desires, but I would bet there would be some correlates. On the other hand, behavior can reveal a lot. Some economists would say we can find the strength of one desire by comparing it to another. How much of A are we willing to give in order to get some exact amount of B? It is not exactly measurement of desire, but we can end up with a list of priorities.
We usually appreciate 'desire' as desire for something positive but perhaps a better approximation would be separation from a state of peace.