A Positron-Emission-Tomography (PET) Study to Measure the Blockade of Dopamine Receptors (D2) in Specific Areas of the Brain in Relation to the Plasma Concentrations of Paliperidone Extended Release (ER) and Oral Risperidone in Schizophrenia Patients and Healthy Controls

The primary objective of this study is to compare the effect of two different antipsychotic compounds which are used in the treatment of schizophrenia (paliperidone ER and risperidone) at their target sites in two specific areas of the brain in patients with schizophrenia. A specialized X-ray known as Positron Emission Tomography (PET) Imaging is used to assess the areas of the brain targeted by both compounds.