OK, but clearly I feel pleasure sometimes. And everything that's happening in my brain is chemical, right? So if we zoom in on the instant that I'm feeling pleasure -- not the thing that caused the pleasure, but the pleasure itself -- what's going on? For example, is there a "pleasure neuron" that turns a "pleasure gear" when it gets activated?
Actually, this is making me rethink my earlier statement about carbon-based lifeforms -- perhaps whatever chemistry capable of causing pain or pleasure is a strict subset of organic chemistry.
You’re going to need a deeper expert to go much further than this, but it’s basically a mapping of the sensory inputs to pleasurable responses. Many of which are hard coded into the brain’s design. Like sugar.
Drugs are probably better suited to mess with these than surgeons.
I think you’re asking though if something is intrinsically pleasurable to an organism. The answer is no. But all life has generally evolved to sensibly reward useful things and discourage bad things. So most brains are designed to interpret specific inputs as pleasurable. It’s not inconceivable that with advanced technology we could design an organism that experienced pleasure from whatever sensory inputs.
Actually, this is making me rethink my earlier statement about carbon-based lifeforms -- perhaps whatever chemistry capable of causing pain or pleasure is a strict subset of organic chemistry.