Mesolimbic pathway

• Controls the motivation and reward systems of the brain (e.g., pleasure, positive reinforcement)
• Stimulation causes positive symptoms (e.g., hallucinations)
• Primary target for antipsychotic drugs used in the treatment of schizophrenia (e.g., haloperidol)

Tuberoinfundibular pathway

• Dopamine release inhibits prolactin secretion from the anterior pituitary.
• Inhibition causes ↓ dopamine → ↑ prolactin → galactorrhea, sexual dysfunction, ↓ libido
• Antipsychotic drugs significantly affect this pathway.

Nigrostriatal pathway

• Controls motor function
• Altered activity causes extrapyramidal symptoms and movement disorders (parkinsonism in the case of inhibition, chorea in the case of stimulation). See Neuroleptic malignant syndrome.

Mesocortical pathway

• Controls executive functions, motivation, and reward systems of the brain
• Inhibition causes negative symptoms (e.g., apathy, lack of energy).
• Antipsychotic drugs have limited efficacy.