I don’t think that any of {dopamine, NE, serotonin, acetylcholine} are scalar signals that are “widely broadcast through the brain”. Well, definitely not dopamine or acetylcholine, almost definitely not serotonin, maybe NE. (I recently briefly looked into whether the locus coeruleus sends different NE signals to different places at the same time, and ended up at “maybe”, see §5.3.1 here for a reference.)
I don’t know anything about histamine or orexin, but neuropeptides are a better bet in general for reasons in §2.1 here.
As far as I can tell, parasympathetic tone is basically Not A Thing
Yeah, I recall reading somewhere that the term “sympathetic” in “sympathetic nervous system” is related to the fact that lots of different systems are acting simultaneously. “Parasympathetic” isn’t supposed to be like that, I think.
I don’t think that any of {dopamine, NE, serotonin, acetylcholine} are scalar signals that are “widely broadcast through the brain”. Well, definitely not dopamine or acetylcholine, almost definitely not serotonin, maybe NE. (I recently briefly looked into whether the locus coeruleus sends different NE signals to different places at the same time, and ended up at “maybe”, see §5.3.1 here for a reference.)
I don’t know anything about histamine or orexin, but neuropeptides are a better bet in general for reasons in §2.1 here.
Yeah, I recall reading somewhere that the term “sympathetic” in “sympathetic nervous system” is related to the fact that lots of different systems are acting simultaneously. “Parasympathetic” isn’t supposed to be like that, I think.