The Relationship Between Chronic Stress And Negative Emotional Processing In Healthy Adult Men

We encounter various stressful events in our life.Stressful events activate the hypothalamic-pituitary-adrenocortical axis(HPA axis)and lead to the secretion of glucocorticoids.The short-term or moderate stressful event will allow individuals to concentrate and be more alert,in order to better cope with threat and challenge.Chronic stress occurs when a stressful event or its effect persists.Chronic stress not only harms the individual’s physical health,but also has extensive effects on the brain,cognition and behavior.Existing animal and human studies have shown that chronic stress decreases the volume of the prefrontal cortex and its associated executive functions such as working memory,behavior monitoring and emotion regulation,while it increases the amygdala volume and amplifies the amygdala-dominated emotion(especially negative emotion)reaction.Emotional processing is a crucial function of the brain,and it plays an important role in survival,especially under the situation of environmental change and chronic stress.Therefore,it is of great practical significance to study the relationship between chronic stress and emotional processing.Considering the gender differences in stress reaction,this study takes healthy adult men as the research object.At present,most of the research on chronic stress and emotional processing use questionnaire to measure emotion processing,and a few uses functional magnetic resonance imaging(f MRI)technology to locate the brain regions for emotion processing.The event-related potentials(ERPs)technique has a high temporal resolution,which is helpful to understand the dynamic process of different processing stages of emotion processing.There are two experiments in this paper,aiming to explore the relationship between chronic stress and negative emotion processing about rejection by others and committing an error.By using true and false word judgment task(i.e.,implicit evoked emotion task),experiment 1 explored the relationship between chronic stress and emotion processing by rejection words.We first evaluated the level of chronic stress through the Perceived Stress Scale(PSS10),and then used the ERP to measure the neural activity induced by rejection word.The results showed that compared with the neutral condition,the rejection conditionsignificantly induced a larger P3 amplitude.Correlational analysis showed that chronic stress level was positively correlated with difference of P3 amplitude(rejection condition-neutral condition),and the result still existed after controlling the personality by The Big Five Personality scale.These results suggested that chronic stress is related to the late stage of rejection processing,i.e.,the higher the level of chronic stress,the more sensitive the individual is to rejection,and the more attention resources are involved to process rejection information.Rejection by others will induce negative emotion,and committing an error by oneself will also cause negative emotion.Experiment 2 used the auditory Go/No Go task to explore the relationship between chronic stress and negative emotion induced by error processing.We first evaluated the level of chronic stress through the PSS10,and then used the ERP to measure the neural activity induced by errors.The results showed that chronic stress score was positively correlated with the emotional component of error processing,i.e.,Pe amplitude after error commission,and chronic stress score still significantly predicted the Pe amplitude after controlling the trait anxiety and depressive symptoms.However,chronic stress has no significant relationship with the ERN amplitude,a component associated with automatic detection of errors.These results suggested that the higher the level of chronic stress,the greater the allocation of emotional/motivational attention to one’s own error.By using cognitive neuroscience method,this paper verifies the results from animal studies in healthy adult men: individuals with higher level of chronic stress are more sensitive to negative emotional events.Specifically,individuals with higher level of chronic stress deploy more attentional resources to the negative emotional information in the environment as well as their own erroneous behaviors.The findings from this paper,on the one hand could help us better understand the emotional reaction to chronic stress.On the other hand,understanding the emotion processing under chronic stress can provide scientific evidence for the early assessment and intervention of stress-related emotional disorders.