The primary outcome measures are: (a) To assess absolute quantitation of TSPO with [(11)C]ER176, we will determine the identifiability and time stability of distribution volume in the brain calculated with compartmental modeling. The difference in mean distribution volumes among subjects with different genotypes would be used to evaluate the genotype sensitivity of [(11)C]ER176. (b) To assess whole-body biodistribution and dosimetry of [(11)C]ER176 we will use the organ time-activity curves.