3 New subjects recruited for fMRI 3 PET Subjects lost to follow-up Supplemental Figure 1 – Study Experimental Design PET: 5-HT1A [11C]CUMI 3 New subjects recruited for fMRI Healthy Subject N = 13 Citalopram Saline† fMRI: Emotional Faces Task M = 2.4 years (SD = 0.15) Healthy Subjects N = 13 (N = 10 with PET) Citalopram‡ Saline‡ N = 10 3 PET Subjects lost to follow-up > 1 week † A total of N = 13 healthy subjects completed the two fMRI scans (i.e., after citalopram and saline infusions). Of the N = 13, ten subjects previously completed a PET 5-HT1A[11C]CUMI scan in which they received citalopram and saline. Only the dorsal raphe 5-HT1A[11C]CUMI BPND from the saline (placebo) infusion was used as a continuous predictor in the fMRI analysis of those 10 subjects. ‡ Citalopram and saline infusions were single-blinded, counterbalanced, and minimum of one week between scans.