At the start of each recording session, subjects were asked to judge the subjective equality of the loudness from all directions and alter these if necessary.
During part of each session, subjects received water and fruit juice at random intervals; during another part, the water and juice were administered every 10 seconds.
In the EL session, subjects were exposed to ambient light.
At the conclusion of the session, subjects completed a short questionnaire.
In their first session subjects completed a training session to get acquainted with the task before starting the MR session.
At the end of each 5 days session, subjects were asked to indicate which substance they thought they had received.
During each session, subjects performed maximal clenching and standardized jaw tasks, i.e., protrusion, lateral excursion, open/close, chewing.
During the Exhausting Session, subjects performed the bimanual coordination after exhaustion of forearms muscles (i.e. endurance time test).
On one session subjects received dietary depletion of the serotonin precursor tryptophan while on the other session they received a balanced placebo control diet.
During one session a 1-h video with trauma-related footage (traumatic video) was shown and in the other session subjects viewed a 1-h neutral video.
