This study is to see how well MSP-2020 attaches to specific targets in the brain called serotonin type 2A receptors (5-HT2AR). This study will also look at how much of the study drug (and its metabolite) is in the blood and how long the study drug stays in the blood, as well as the safety of MSP 2020.

Inclusion Criteria

1. Able to stay in the CRU for up to 4 days.
2. Body mass index (BMI) between 18.0 to 32.0 kg/m2 (inclusive).
3. In good health as determined by: a. Medical history; b. Physical and neurological examination; c. Concomitant medications; d. ECG; e. Screening echocardiogram; f. Serum chemistry, urinalysis, haematology, coagulation, and serology (HIV screen, HBsAg, and anti-HCV) tests.

Exclusion Criteria

1. In first-degree relatives, a history of any schizophrenia-spectrum disorder, psychotic disorder, or bipolar and related disorders.
2. History of allergy to tracer [11C]CIMBI-36.
3. MRI incompatibility due to implants including but not limited to pacemaker, artificial joints, or non-removable body piercings, and/or other contraindications for MRI such as claustrophobia, metal objects/fragments, or fragments in the head or body that would present a risk during the MRI scanning procedure, or have worked with ferrous metals (eg, welding), or have motor problems that prevent the participant from lying still for the MRI.
4. Pathological MRI findings that would preclude from trial participation.
5. History of prior radiation exposure for research purposes such that participation in this trial would result in an ionising radiation exposure of > 10 mSv within a year (12 months) of the first PET scan that would cause the participant to exceed the yearly dose limit.
6. Have a negative modified Allen test at screening.
7. Contraindications to radial arterial cannula (including but not limited to cellulitis or other infections over the radial artery, absence of palpable radial artery pulse, or a clinically significant abnormal coagulation profile).
8. Clinically significant abnormality in past medical history, or at the screening physical examination, that in the investigator's or sponsor's opinion may place the participant at risk or interfere with outcome variables including absorption, distribution, metabolism, and excretion of drug. This includes, but is not limited to, history of or concurrent cardiac, hepatic, renal, neurologic, endocrine, gastrointestinal, respiratory, haematologic, dermatologic, and immunologic disease.
9. History of alcohol and/or substance use disorder within the last 24 months according to the Diagnostic Statistical Manual of Mental Disorders and in past medical history or in the investigator's opinion, or intake of > 21 units of alcohol weekly, and the inability to refrain from alcohol use from 48 hours before screening and within 72 hours prior to dosing until discharge from the CRU on Day 2. One unit is equivalent to 1 (25 mL) measure of 40% spirits. For reference, one 330 mL bottle of 5% beer contains 1.7 units and a standard (175 mL) glass of 12% wine contains 2.1 units.

Note: Other protocol-specified Inclusion/Exclusion criteria may apply.

Anonymized individual participant data (IPD) that underlie the results of this study will be shared with researchers to achieve aims pre-specified in a methodologically sound research proposal. Small studies with less than 25 participants are excluded from data sharing.