Although the influence of emotional states on immune function has been generally recognized, researches on the effects of negative emotion on individual SIgA levels have reported mixed findings. Our study aimed to elucidate the relationship between changes in EEG activity and cognitive and psychological mechanisms to the immune changes induced by negative emotion.
In experiment one, we investigated how the negative emotional arousal that was induced by watching a number of unpleasant pictures altered the concentration of secretory immunoglobulin A (SIgA). Although our results found discrepancies in the changing tendency of SIgA concentration among participants (some participants’ SIgA decreased after watching unpleasant pictures, whereas others increased), further analysis revealed a coherency among the changing of SIgA concentration, participants’ general coping styles and their actual emotion regulation strategies in perceiving unpleasant pictures, and the event-related potentials (ERPs) associated with the watching of unpleasant pictures. The participants whose SIgA increased after watching unpleasant pictures (the increasers) had higher positive coping scores in the Trait Coping Styles Questionnaire (TCSQ) than those whose SIgA decreased (the decreasers). Also, relative to the decreasers, the increasers tended to use more emotion regulation strategies especially when the presented pictures were extremely negative and exhibited a reverse dissociation pattern between the extremely negative pictures and the moderately negative ones in the amplitude of late positive potential (LPP) that was related to the cognitive evaluation of stimuli’s meaning.
On this basis, Event-related potentials were recorded first while participants passively viewed unpleasant pictures, and then during an emotion regulation block in which participants were instructed to reappraise unpleasant pictures in the experiment two. We also collected the immune index before and after the passive viewing block and the emotion regulation block. Our study proved that participants felt a less intense emotional response to unpleasant pictures that followed a reappraisal instruction. The decreasing emotional responding to unpleasant pictures decreased the amplitude of the LPP. But larger N2 was induced in the emotion regulation block, because the participants needed to obtained more attentional resources to detect and integrate more stimulus features to use the cognitive reappraisal strategy effectively.
The present study has important theoretic and practical significance. For the theoretic significance, our study elucidated the relationship between changes in EEG activity and cognitive and psychological mechanisms to the immune changes induced by negative emotion by using the technologies of ERP, experimental interview and psychological measurement. Meanwhile, our study also provided an explanation for the different changing tendencies of SIgA induced by negative emotions, and it plays an important role in further studying the cognitive neural mechanisms of immune level in response to emotion. As to the practical significance, our study suggests that individuals who use active emotion regulation in the face of negative emotion stimuli may experience significantly increases in immune system function, subsequently lowering the possibility of infection.