A Study of Dopamine Type 2 (D2) Receptor Occupancy Following a Single Oral Dose of OROS Paliperidone

Inclusion Criteria: * Within 20% of ideal body weight * If a woman, must be surgically sterile, or practicing an effective method of birth control (e.g., prescription oral contraceptives, contraceptive injections, intrauterine device, double-barrier method, male partner sterilization) before entry and throughout the study * and must have a negative serum beta HCG test at screening * Healthy on the basis of a pre-study physical examination, medical history, anamnesis, electrocardiogram, magnetic resonance imaging of the brain, and the results of blood biochemistry and hematology tests and a urinalysis carried out less than 2 weeks before the first dose. If the results of the biochemistry or hematology tests or the urinalysis testing are not within the laboratory's reference ranges the volunteer can be included only on condition that the investigator judges that the deviations are not clinically significant. Exclusion Criteria: * History or suspicion of alcohol, barbiturate, amphetamine or narcotic abuse * History of cardiac arrhythmias, bronchospastic or respiratory disease, cardiovascular, neurologic, renal, hepatic, endocrine, or immunologic disease * Drug allergy to raclopride, paliperidone, or risperidone or any of its excipients * Use of concomitant medication, except for paracetamol and hormonal contraceptives. All other medication must have been stopped at least 14 days before the first PET examination * Received an experimental drug or used an experimental medical device within 30 days before the planned start of treatment * Previously used an antipsychotic medication * Previously participated in a PET study or measurement * Had a significant loss of blood \<1 month before the first PET examination * Pregnant as confirmed by a positive beta-HCG test at screening and before the first PET examination, or breastfeeding * Claustrophobia.