Which dopamine pathway is most associated with positive symptoms in schizophrenia?

• A. Nigrostriatal
• B. Tuberoinfundibular
• C. Mesolimbic
• D. Mesocortical

Answer: (C)

Positive symptoms in schizophrenia, such as delusions and hallucinations, are best explained by overactivity of dopamine in the mesolimbic pathway. This circuit runs from the ventral tegmental area to the nucleus accumbens, and heightened dopamine signaling here is linked to the salience misattribution that characterizes these experiences.

Other pathways have different roles: the nigrostriatal tract, from the substantia nigra to the striatum, is primarily about motor control, so its dysfunction relates more to movement disorders than core psychotic symptoms. The tuberoinfundibular pathway, from the hypothalamus to the pituitary, mostly affects prolactin regulation, so its involvement explains hormonal side effects rather than positive psychotic features. The mesocortical pathway, projecting to the prefrontal cortex, is more associated with negative and cognitive symptoms when underactive. Because positive symptoms align most directly with increased dopamine activity in the mesolimbic circuit, this pathway is the best fit.