Fig. 1.

Experimental design. Timing of MRI test sessions on days 4–6. Sessions were 5.5 h in duration (340 min total). X-axis denotes time relative to administration of the blinded study capsule at time 0 (black arrow). Participants entered the scanner 90 min after administration of the study capsule (vertical dashed black line). MR spectroscopy was conducted 140–150 min post-capsule (gray shading). Physiological data were collected at half hour intervals for internal validity (open arrows). Mood data were collected at half hour intervals outside the scanner to assess subjective drug effects (see Materials and methods for details). Participant arrival and departure times are indicated (gray arrows)