Fig. 1.

Timeline depiction of the study assessing the potency and kinetics of tcVNS treatment in the context of traumatic and mental stress. Day 1 happened inside a HR-PET scanner where subjects underwent 14 scans, each lasting approximately 8 ​min. Six scans included the neutral scenery recordings, six scans included traumatic stress recordings followed by stimulation, and two scans included stimulation without acute stress. On days 2 and 3, subjects underwent public speech and mental arithmetic tasks, each followed by stimulation. Each day included 90-min breaks. Blood was drawn at the baseline and the numbered timepoints (0-22) over the course of three days. PACAP data was analyzed for timepoints baseline (timepoint #0), end of day 1 (timepoint #14), end of day 2 (timepoint #18), and end of day 3 (timepoint #22).