Schizophrenia: the fundamental questions.

Identifying the correct phentotype of schizophrenia is perhaps the most important goal of modern research in schizophrenia. This identification is the necessary antecedent of indentifying the pathophysiology and etiology. A working model is proposed, which suggests that the phenotype should be defined on the basis of abnormalities in neural circuits and a fundamental cognitive process. This type of unitary model may be more heuristic than early ones that were based on heterogeneous signs and symptoms.