The Effects Of Childhood Trauma And Acute Stress On College Students' Reward Learning And Its Neural Mechanism

Research on the reward learning ability of individuals who have experienced childhood trauma is beneficial to the healthy growth of adolescents and the implementation of the“Healthy China 2030”plan.A review of existing studies shows that childhood trauma is an important family component that hinders individuals’growth and social adaptation,and acute stress is an important factor influencing individuals’reward learning.In view of this,this study will combine the questionnaire method with behavioral experiments and Event-related potentials（ERP）experiments to explore the characteristics of reward learning in individuals who have experienced childhood trauma and how childhood trauma and acute stress interact to influence reward learning.In this study,study 1 focuses on using questionnaires combined with behavioral experiments to initially explore the effects of childhood trauma on reward learning.There were27 subjects in the childhood trauma group(M_age=20.85 years,SD=2.46 years)and 32 subjects in the normal group(M_age=21.19 years,SD=2.15 years),and a total of 59 subjects participated in the behavioral experiment.The results were longer keystroke response times for the childhood trauma group than for the control group.This study further found that for the normal group,the correct rate of reward learning was higher than the correct rate of punishment learning;the response time of reward learning was shorter than the response time of punishment learning.For the trauma group,we only found that the response time for reward learning was shorter than that for punishment learning.Study 2 focuses on the behavioral and ERP techniques to explore how reward learning is affected by the co-occurrence of childhood trauma and acute stress,and the neural mechanisms behind it.The study used a mixed experimental design of 2（childhood trauma:childhood trauma group,control group）×2（acute stress:acute stress situation,control situation）,with 41subjects participating in the experiment.Among them,22 subjects were in the childhood trauma group(M_age=20 years,SD=1.31 years)and 19 subjects in the control group(M_age=19.26 years,SD=1.15 years).Participants in Study 2 completed the reward learning task successively in a control situation and an acute stress situation,while behavioral data and EEG activity data were collected from the subjects.The behavioral results showed that the main effect of stress was significant,as evidenced by a significantly longer keystroke response time in the control situation than in the acute stress situation.The ERP results showed that（1）the mean N100amplitude evoked by the childhood trauma group was greater than that of the control subjects during the stimulus presentation phase;（2）the mean N100 amplitude was greater in the acute stress situation than in the control situation during the stimulus presentation phase;（3）the interaction effect between childhood trauma and acute stress was significant during the feedback presentation phase,as shown by the following:in the control situation,the N100 wave amplitude evoked during the task feedback was significantly smaller than that of the control group;in the acute stress situation,the difference in N100 wave amplitude between the two groups was not significant;（4）in the feedback presentation stage,the main effect of acute stress was significant:the Rewp wave amplitude evoked by the subjects in the task was significantly lower under acute stress.In summary,both distal stress（e.g.,childhood trauma）and proximal acute stress can affect individual reward learning.On the one hand,childhood trauma hurts the stimulus presentation phase and the feedback learning phase of an individual’s reward learning task.On the other hand,acute stress can cause individuals to frequently modulate their own stress response system to adapt to the current environment in the short term,but overload the response stress system by repeatedly invoking it over time.In response to the ERP results,the present study found that childhood trauma interacted with acute stress,and individuals who had experienced childhood trauma performed worse than the normal group in normal situations,but when they were exposed to stress,they used fast life history strategies to prompt themselves to adapt to the current stressful environment.This study provides an empirical basis for sensitization model of life history strategies.