August 17th, 2021

> I've previously quoted Stephan Guyenet on the motivational system of lampreys (a simple fish used as a model organism). Guyenet describes various brain regions making "bids" to the basal ganglia, using dopamine as the "currency" - whichever brain region makes the highest bid gets to determine the lamprey's next action. "If there's a predator nearby", he writes "the flee-predator region will put in a very strong bid to the striatum".

> Stimulants increase dopamine in the frontal cortex. This makes you more confident in your beliefs (eg cocaine users who are sure they outrun that cop car) and sometimes perceptions (eg how some stimulant abusers will hallucinate voices). But it also improves willpower (eg Adderall helping people study). I think all of these are functions of increasing the (apparent) level of evidence attached to "beliefs". Since the frontal cortex disproportionately contains the high-level conscious processes telling you to (eg) do your homework, the drug artificially makes these processes sound "more convincing" relative to the low-level reinforcement-learning processes in the limbic system. This makes them better able to overcome the desire to do reinforcing things like video games, and also better able to overcome the prior on motionlessness (which makes you want to lie in bed doing nothing). So you do your homework.