Subsec fluctuations in extracellular dopamine encode prediction errors in humans

It always fascinated me how a lot of "state" in our neural networks is probably encoded in the extracellular fluids rather than in the neurons themselves. Biological neural networks really do not like it if you swap out their fluids (you can do this experimentally in vitro). For me it has always been one of those "nature really doesn't care about complexity" things ... it will just use whatever tools are available with little to no regard for our understanding of "boundaries". I'm not saying this complexity is strictly needed for intelligence (however that is defined) ... but I do always find it a little bit dishonest when scientists (and especially those working with pharmaceuticals) "zoom in" to the cells and then usually promptly forget that those cells are part of the much wider stage of tissues and eventually even everything outside the confines of our skin. Anyway, just my two cents.

Can someone please explain this in plain language?