Patients of depression often have lower performance in perception, planning, and execution in cognition, compared to healthy controls. Depression has been reported to be associated with functional alterations in the resting state connectivity in the brain. This study investigates whether there are differences in neural dynamics measured by mental arithmetic tasks (MAT) between depressed and healthy subjects. To this end, this study employed an ROI-based functional connectivity analysis, within-condition interregional covariance analysis (WICA), to explore the correlates of the brain deactivation regions. Results of this study showed that the corresponding emotional loop is inhibited in healthy subjects and show the control loops of attention and emotion is inhibited in depressed subjects during MAT, and the patients with depression may produce a stronger stress response than the healthy subjects during the MAT. This may be the key reason for that the mathematical abilities of the depression subjects were inferior to that of the healthy subjects.