Which pathway is associated with positive symptoms of schizophrenia due to increased dopamine?

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

Answer: (A)

Positive symptoms in schizophrenia, such as delusions and hallucinations, arise from increased dopamine activity in the mesolimbic pathway. This pathway travels from the ventral tegmental area to limbic regions like the nucleus accumbens. When dopamine signaling here is heightened, it amplifies psychotic experiences, which is why blocking D2 receptors in this circuit with antipsychotics tends to reduce positive symptoms.

In contrast, the mesocortical pathway (to the prefrontal cortex) is more associated with negative and cognitive symptoms when its dopamine activity is reduced. The nigrostriatal pathway is mainly involved in motor control, and its disruption is linked to extrapyramidal symptoms from antipsychotic treatment. The tuberoinfundibular pathway regulates prolactin release, so its involvement shows up in endocrine side effects rather than core psychotic symptoms.