• INCLUSION CRITERIA:
• Subjects will be recruited among individuals volunteering for NIH protocol 95-M-0150 A Neurobiological Investigation of Patients with Schizophrenia Spectrum Disorders and Their Siblings (PI: Daniel Weinberger, M.D.), NIH protocol 00-M-0085 Structural and Functional Imaging of Neuropsychiatric Patients and Normal Volunteers with 3.0 Tesla MRI and Magnetoencephalography. (P.I.: Venkata Mattay, MD) or NIH protocol 89-M-0160 Inpatient Evaluation of Neuropsychiatric Patients (PI: Jose Apud, M.D. Ph.D).
• Only adult subjects who are able to provide informed consent will be studied.
• Patients will be between 18 and 55 years of age. Healthy controls will be matched by age and sex to the patients.
• Control subjects must be healthy based on history, laboratory and physical exam obtained through the above mentioned protocols and will be included up to the age of 90 years.

EXCLUSION CRITERIA: (for patients and controls except where indicated)

• Subjects will be excluded if they don't fit the study requirements regarding age, ability to provide informed consent, absence of significant general medical, neurological or psychiatric disorders (except the disorder object of study), or intake of substances that interfere with central dopaminergic signaling.
• Current psychiatric illness except for patients with schizophrenia, schizoaffective disorder or other psychotic disorder
• Controls with current or prior use (or abuse) of substances that interfere with central dopaminergic signaling (e.g. antipsychotics, dopamine receptor agonists, catechol-o-methyltransferase inhibitors, anticholinergics, MAO-B inhibitors) except for patients on antipsychotics and other psychotropic agents which will be discontinued for at least 4 weeks under protocol 89-M-0160.
• Controls with current psychiatric illness other than schizophrenia, schizoaffective disorder, or other psychotic disorder
• Secondary causes of schizophrenia-like syndromes, e.g. amphetamine abuse, brain infarction, tumor, or trauma
• Neurological disorders except those of exclusively peripheral location
• Significant prior or current substance abuse, severe systemic disease, hypothyroidism not compensated by medication
• Laboratory tests with clinically significant abnormalities
• History of a significantly abnormal EEG, cranial CT or MRI
• Conditions that increase risk for MRI (pacemaker devices, ferromagnetic metal implants, etc.)
• Prior participation in other research protocols such that radiation exposure would exceed the annual NIH RSC limits
• Any medical condition that, in the opinion of the investigators, would interfere with the safe conduct of the study.