This study will include 20 patients with MDD (observation group) and 20 healthy control participants without MDD (control group). fNIRS will be adopted to assess regional oxygen saturation of the blood in the MDD-related cerebral cortex: the prefrontal and bilateral temporal cortex. Based on the results of the fNIRS, to explore cerebral hemodynamic changes in the prefrontal and bilateral temporal cortex in patients with MDD. By observing the changes of hemodynamic characteristics of the prefrontal cortex and bilateral temporal cortex of the observation group and the control group during the course of intradermal acupuncture, explore the immediate response of the hemodynamic characteristics of the prefrontal cortex and bilateral temporal cortex of the observation group to the intervention of the GB acupoints.
Gallbladder meridian(GB) acupoints may play an important role in the treatment of major depressive disorder (MDD). Therefore, this study is designed to focus on the traditional Chinese medicine (TCM) theory of  gallbladder dominating decision , take the GB as the entry point, and use functional Near-Infrared Spectroscopy(fNIRS) technology to observe the effect of intradermal acupuncture on the cerebral hemodynamic indexes of the prefrontal cortex and bilateral temporal cortex of patients with MDD.