Up to 12 healthy male volunteers, 20 to 65 years of age will participate in the study. The study population chosen is sufficient to examine variability in pharmacokinetic and imaging measurements. All male volunteer subjects will have a baseline brain magnetic resonance imaging (MRI) for eligibility and anatomical delineation of brain regions to be applied in positron emission tomography (PET) image analysis. An arterial line will be inserted on day the healthy volunteer arrives for the administration of study drug and PET imaging (Day 1). The arterial line will be placed in the opposite arm than the one being used to administer the single intravenous microdose of [11C]AZD1390. Blood samples will be collected after the administration of microdose [11C]AZD1390 bolus injection and during the PET imaging procedure. The arterial line will be removed at the conclusion of the PET imaging study after the last blood sample has been collected. Standard institutional procedures will be followed for arterial line removal. The study will conclude with a telephone follow-up call within 7 business days after the PET measurement.