The purpose of this study is to understand the reliability of [18F]-FTC-146 brain uptake in healthy controls.

The purpose of this study is to understand the reliability of [18F]-FTC-146 brain uptake in healthy controls under test and retest conditions.

Inclusion Criteria:

1. ages 18-65
2. either gender and all ethno-racial categories
3. capacity to provide informed consent
4. Female participants are expected to use an effective method of birth control throughout the study

Exclusion Criteria:

1. Any current or lifetime psychiatric diagnosis
2. Current or past use of psychotropic medication
3. Pregnant or nursing females
4. Major medical or neurological problem
5. Presence of metal in the body that is contraindicated for MRI scans