The reward circuit: reinforcement and dopamine
Explains the biomedical model's core idea: addiction hijacks the brain's reinforcement system — dopamine from the VTA to the nucleus accumbens — and how different drugs raise that dopamine directly or indirectly.
Where this fitsConnects to 3 · Unlocks 1
- Connects to
- Dopamine: receptor families, clearance and pathways — The mesolimbic pathway is one of the three dopamine pathways.
- Where drugs act: the brain's regions — VTA, nucleus accumbens, hippocampus and amygdala all appear here.
- Indirect agonists: reuptake inhibitors, enzyme inhibitors and releasers — Cocaine and amphetamine raise dopamine by reuptake block and release.
- Unlocks
- Why drugs keep reinforcing: prediction, tonic vs phasic, and speed — Why drugs keep reinforcing when natural rewards stop doing so.
Orient
The biomedical model of addiction (“brain-disease model of addiction”) treats it as pathological learning. Reinforcement learning: animal does an action, animal receives reward, action is reinforced. The reward circuit is the mesolimbic dopamine pathway, VTA to nucleus accumbens, whose purpose is to provide reinforcement upon fulfilling unmet biological need.
Course terms
Your professor's wording, word for word from the slides. Learn the term and this definition — the explanation underneath is only there to help it make sense.
- Biomedical model of addiction
“Brain-disease model of addiction”Slides 06, p. 2
Also framed as “pathological learning – behaviorism”.
- Reinforcement learning
“Animal does an action Animal receives reward Action is reinforced”Slides 06, p. 3
After learning, reinforcement can terminate — to keep behavior flexible.
- Mesolimbic dopamine pathway
“VTA to nucleus accumbens”Slides 06, p. 3
The reward circuit in the limbic system (Olds and Milner, 1954).
- Reward circuit
“Provide reinforcement upon fulfilling unmet biological need, encouraging behavior in the future”Slides 06, p. 4
Its purpose.
- Reinforcers
“Food, sex, comfort/safety, belongingness”Slides 06, p. 4
Can be more abstract: money, high fives, Instagram followers.
From your course: Course slides 06, pp. 6–11
Tip: the ← and → keys move through the lesson.
Full lesson: Dopamine families and pathways