The positive symptoms of schizophrenia such as disorganized speech, delusions, and hallucinations seem to unique to humans. Current research on schizophrenia in general has remained very challenging, thanks to growing numbers in theories about the cause and progression of the disease. A lack of behavioral methods to selectively study positive symptom-like behaviors or alternative behaviors has made it even more challenging to develop animal models with rational pathology of schizophrenia. However, emerging neuroimaging findings and rich information obtained from several decades of hallucinogen studies are encouraging to establish animal models to explore various causative theories for positive symptoms in schizophrenia. In this chapter, we review neuroimaging and pharmacological findings related to delusions and hallucinations and briefly introduce behavioral methods to investigate positive symptom-related behaviors in animal models of schizophrenia.
