Plausible models of interaction between dopamine and glutamatergic systems are described in chapters 1 and 2, and the importance of other neurotransmitter systems and receptors, especially serotonin, is detailed in chapter 9. Abi-Dargham reviews the recent evidence from brain imaging studies pointing toward a dopamine imbalance at a limbic level and once more confirming the role of dopamine in schizophrenia. As one would expect, the current hypotheses about the neurobiological basis of atypicality are explored, especially the apparent paradox of amisulpride, which has a strong and almost exclusive affinity to dopamine receptors while behaving clinically like an atypical antipsychotic. The authors posit that amisulpride, which is widely used in Europe but unavailable in North America, could offer some advantage in the treatment of negative symptoms in maintenance therapy. Furthermore, an inspiring reflection about a probable genetic mechanism of risk for schizophrenia, involving variations in the COMT gene, is put forward by Weinberger in chapter 7.