There are provided isolated polynucleotide fragments for use in diagnosing and/or developing treatments for schizophrenia. Further provided is a method for diagnosing schizophrenia using one or more polynucleotides disclosed herein. Also provided is a method for screening a compound which regulates expression of a schizophrenia-related gene. Also provided is a chronic animal model of schizophrenia that mimics the functional deficits observed in patients and methods for producing the animal model comprising the administration of PCP to the animal.