The Safety, Tolerability, Pharmacokinetics and Pharmacodynamics Study of RO6889450 in Healthy Volunteers

• A body mass index (BMI) between 18 to 30 kilogram per square meter (kg/m^2) inclusive
• Body weight in the range of 50 to 100 kilogram (kg) and right-handed - Part 2 only
• For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods
• For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures, and agreement to refrain from donating sperm
• Fluent in the language of the Investigator and study staff (including raters)
• Able to participate and comply with the study restrictions

Part 1 and Part 2:

• Disorders of the central nervous system (CNS), psychiatric disorders, behavioral disturbances
• Participants who, in the Investigator's judgment, pose a suicidal or homicidal risk
• Any personal or familial history (first degree) of seizures, epilepsy or other convulsive condition
• Positive family history of psychosis or mood disorders up to first degree relative
• Angle closure glaucoma, history or current significant ophthalmologic or neurologic condition that would adversely affect the pupillometry assessment
• Suspicion of regular consumption of drug of abuse and/or any history of alcohol addiction with positive urine drug screen and/or positive alcohol urine test, or regular smoker
• Positive result on hepatitis B (HBV), hepatitis C (HCV), or human immunodeficiency virus antibody (HIV 1 and 2)
• Any prescribed or OTC medications (including vitamins or herbal remedies) taken within 4 weeks prior to first dosing or within 5 times the elimination half-life of the medication prior to first dosing (whichever is longer)
• Taking any nutrients known to modulate CYP3A activity (e.g., grapefruit juice; Seville orange) within 2 weeks prior to administration of study drugs
• Clinically significant abnormalities in laboratory test results (including hepatic and renal panels, complete blood count, chemistry panel and urinalysis)
• Participation in an investigational drug or device study within 90 days prior to screening
• Dietary restrictions that would prohibit the consumption of standardized meals
• Concomitant disease or condition that could interfere with, or treatment of which might interfere with, the conduct of the study, or that would, in the opinion of the investigator, pose an unacceptable risk to the participant in this study

Part 2:

• Contraindications for magnetic resonance imaging (MRI) scans or any brain/head abnormalities restricting MRI eligibility. Any sensorial impairment such as deafness and reduced visual acuity which cannot be corrected in the fMRI scanner
• Use of any psychoactive medication, or medications known to have effects on CNS or blood flow taken within 4 weeks prior to first dosing or within 5 times the elimination half-life of the medication prior to first dosing (whichever is longer)
• Fulfilment of any of the MRI contraindications on the standard radiography screening questionnaire