Participants receive 20 min sessions of 1.5 mA alternating current delivered over the dorsolateral prefrontal cortex, for 7 consecutive days.

Participants receive 20 min sessions of 1.5 mA direct current delivered over the dorsolateral prefrontal cortex, for 7 consecutive days.

Participants receive sham stimulation that administered similarly, but with current continued less than 30s.

Transcranial alternating current stimulation (tACS) is a non-invasive neuromodulation technique of the brain with an AC micro-electrical stimulator, two rubber electrodes in saline-soaked sponges, and a control software to set the output of the stimulation type. Participants receive 20 min sessions of 1.5 mA alternating current delivered over the dorsolateral prefrontal cortex, for 7 consecutive days.

The aim is to explore whether tES have a regulation effect on emotion processing of dynamic course. In the task, participants need to concentrate on the emotional picture with positive, negative and neutral faces. Then, different ERP components elicited by positive, negative and neutral faces using the signals recorded during facial emotion identification task. The investigators will analyze the ERP components change before and after stimulation to access tES effect on emotion processing.

The aim is to explore whether tES have a regulation effect at-risk of frequency domain. In the resting task, 8 mins resting EEG will be recorded. During recording, participants need to remain still and relaxed with their eyes open (O) and closed (C) in two alternating orders. In order to access tES effect on resting EEG, spectral analysis will be executed after the experiment. Analysis in frequency domain also contributed to expound the brain mechanism related cerebral cortex in emotion processing. In specific, EEG power of delta, theta, alpha, beta and gamma band would be calculated after recording. Besides, the EEG lateralization index also be analyzed between left and right brain.

The main objective is to explore whether tES has an effect on subjective scale after stimulation. The scales include State-Trait Anxiety Inventory (STAI) and Difficulties in Emotion Regulation Scale (DERS). The STAI is a brief self-report assessment for trait anxiety and state measurement. The scales contain two 20-item pools of emotional state and personality trait, each item rated on a 4-point intensity scale ranging from not at all to very much so or from never to almost always respectively. DERS, on the other hand, is also a self-report measure function to assess the emotion regulation.