• All subjects must be judged by the investigator able to understand the nature, design, and procedures of the study and must be able to provide a signed and dated informed consent in accordance with Good Clinical Practice (GCP), International Conference on Harmonization (ICH), and local regulations.

• All subjects must be willing and able to comply with scheduled visits, required study procedures and laboratory tests.

• All subjects must be able to travel to the research sites for the study procedures.

• For female subjects: They must be either of non-childbearing potential (either surgically sterile or post- menopausal - defined as 12 months of spontaneous amenorrhea), or, if of childbearing potential, subjects must demonstrate to be non-pregnant (as demonstrated by negative urine β-HCG test at screening), non-breastfeeding.

• All subjects must comply with highly effective contraceptive measures. A highly effective contraceptive measure is defined as a measure that can achieve a failure rate of less than 1% per year when used consistently and correctly. These methods are listed in more detail below:

⁃ Oral, intravaginal, or transdermal combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation;

⁃ Oral, injectable, or implantable progestogen-only hormonal contraception associated with inhibition of ovulation:

⁃ Intrauterine device (IUD)

⁃ Intrauterine hormone-releasing system (IUS)

⁃ Bilateral tubal occlusion

⁃ Vasectomised partner

⁃ Sexual abstinence

• For sexually active male subjects, they must agree to use condoms to protect their partners from becoming pregnant for the duration of the study and for 3 months after the last administration of PET or SPECT ligands. They must also agree to ensure that they and their partners are routinely using a medically approved contraceptive method. It is important that male subjects not impregnate others for the duration of the study and for 3 months after the last administration of PET or SPECT ligands.

• \*\*All subjects must have adequate visual and auditory acuity according to investigator's judgement to complete the psychological testing.

• All subjects must have no use of medications with known interaction with serotonergic transmission (e.g. selective serotonin reuptake inhibitors, tricyclic antidepressant, triptans, etc).

• For subjects taking any drugs that might interfere with dopamine transporter SPECT imaging (neuroleptics, metoclopramide, alpha methyldopa, methylphenidate, reserpine, or amphetamine derivative) must be willing and able from a medical standpoint to hold the medication for at least 5 half-lives prior to screening DaTSCANä imaging.