Neurotransmitter Pathways Quiz
Every major neurotransmitter system starts in a small cluster of cell bodies and projects widely from there. Learn the source nuclei and the projections, and both pharmacology and a large slice of psychiatry become much easier to reason about.
The four modulatory systems
Dopamine arises in the substantia nigra and ventral tegmental area, projecting along four pathways — nigrostriatal for movement, mesolimbic for reward, mesocortical for executive function, and tuberoinfundibular for prolactin control. The side effects of antipsychotics fall directly out of that list.
Serotonin arises in the raphe nuclei of the brainstem and projects almost everywhere. Noradrenaline arises in the locus coeruleus and drives arousal and vigilance. Acetylcholine arises in the basal forebrain, including the nucleus basalis of Meynert, and is central to attention and memory — its loss is a hallmark of Alzheimer's disease.
Why the source matters
Because these systems are anatomically narrow at the source and enormously broad at the target, small lesions produce diffuse symptoms, and drugs acting on one receptor subtype produce effects across many behaviours. Knowing the pathway explains why a Parkinson's drug can cause impulse control problems, and why an antipsychotic can cause both a movement disorder and a rise in prolactin.
Common questions
What are the four dopamine pathways?
The nigrostriatal pathway controlling movement, the mesolimbic pathway handling reward, the mesocortical pathway supporting executive function, and the tuberoinfundibular pathway regulating prolactin release.
Where is serotonin produced in the brain?
In the raphe nuclei, a set of clusters running along the midline of the brainstem, which project diffusely to almost the entire brain.