Fig. 1.

Overview of experimental design and multilevel stress response. (A) The core fMRI experiment consisted of 10 blocks of mental arithmetics, sectioned into prestress, stress, and poststress periods. Within each period, six blocks of mental arithmetics (∼60 s) alternated with rest phases (∼40 s). ANS recording was continuous. Blood samples were collected at 0, 10, 20, 30, 45, and 60 min, and subjective ratings were made at times 0, 30, and 60 min. During the recovery period, subjects remained lying on the MRI table but outside the magnet. The stress intervention elicited a marked response at all levels of observation in the EXP group. Panels display estimated marginal means (±1 SEM) as gained from the repeated-measures ANOVA for both groups. The time window of the stress condition (specific to the EXP group) is indicated by a reddish bar. (B, Top) Note the delayed increase in stress-induced serum cortisol (corrected for circadian drift and baseline offset). (Middle) There is a steep immediate stress-induced increase in pulse rate as derived from pulse plethysmography (PPG). (Bottom) Stress-induced increased negative affect (see Results for statistical details). ECG, electrocardiography; EDA, electrodermal activity.