Explore the system
Trace dopamine pathways
Switch projections on and off without losing the anatomical relationships between source and target.
Sources and model limits
Original schematic. Positions show relationships; structures and concentrations are not to scale.
- Julien's Primer of Drug Action · 15 · 2 · Trace dopamine pathways · PDF 28, 29 · 2.14
Course notes and existing practice
Learning objective
Connect dopamine handling, D1/D2 receptor families, and the three named pathways without reducing dopamine to one behavioral label.
Transport, enzymes, and receptors
The course associates dopamine (DA) with DAT uptake and metabolism by MAO and COMT. Its receptors are metabotropic GPCRs. The D1 family contains D1 and D5; the D2 family contains D2, D3, and D4. The deck’s excitatory/inhibitory family shorthand is introductory course framing rather than a universal prediction of a whole neuron’s response.
Pathways are different connections
The mesolimbic example links VTA to nucleus accumbens and reward-related function. The mesocortical pathway is discussed through focus, attention, and working memory. The nigrostriatal, also called mesostriatal here, links substantia nigra to striatum and movement. Dopamine also appears in the course’s discussion of motivation and other functions, so pleasure alone is not an adequate definition.
Clinical associations are not diagnoses
Page 24 associates mesolimbic and mesocortical pathways with different symptom groupings in schizophrenia and the movement pathway with Parkinson’s disease. These are attributed study associations. They do not establish that one pathway explains an entire disorder or direct a treatment choice. Detailed drug modules remain planned.
- Dopamine
- DA, a catecholamine discussed across multiple pathways and functions.
- DAT
- Dopamine transporter, the course’s canonical dopamine membrane-uptake association.
- COMT
- Catechol-O-methyltransferase, an enzyme discussed in catecholamine metabolism.
- D1 receptor family
- The dopamine receptor family containing D1 and D5 in the deck.
- D2 receptor family
- The dopamine receptor family containing D2, D3, and D4 in the deck.
- Mesolimbic pathway
- The course’s VTA-to-nucleus-accumbens reward-related dopamine pathway.
- Mesocortical pathway
- The dopamine pathway discussed through cortical attention and working memory.
- Nigrostriatal pathway
- The substantia-nigra-to-striatum dopamine pathway discussed through movement.
Professor deck 3, PDF pages 23, 24. Explanation and terminology are paraphrased course material. Examples and study prompts are original, unscored teaching aids. Source conformance is separate from scientific or clinical review.
Worked examples are original instructional illustrations; they are not professor quotations or exam requirements.
Julien connection: a distinction to explain on your own
The book connects VTA projections with nucleus accumbens and wider cortical/limbic learning circuits. A group difference in receptor availability is not by itself proof of prior vulnerability, a diagnosis or evidence that dopamine alone explains addiction. Include memory, cues, stress and context.
Book connection: see the Julien Chapters 1–4 · Midterm study section in the Library for worked examples and recall practice. The cited source uses consolidated PDF page numbers.