The Cognitive Neuromechanism Of Error Processing Following Acute Stress And Its Intervention

Stress is a risk factor in the fast-paced modern society.People often have to work and study under stress.Error processing is an important capability for individuals to optimize behavioral performance continuously and adapt to environmental changes for successful goal-directed behavior.It is still unclear how individuals monitor their error responses and regulate post-error performance following acute stress.To address this issue,we designed a series of experiments to explore the pattern of error processing following acute stress,and preliminarily investigated the method to prevent or reduce stress-induced error processing deficits.We explored the effects of acute stress and stress-induced cortisol levels on error monitoring in study 1,and investigated the effects of error awareness on error processing following acute stress in study 2.Besides,we explored the effect of acute stress on different stages of post-error processing and its intervention methods in study 3 and 4.We used the EEG method to explore the neural mechanisms by which acute stress and stress-induced cortisol levels affect error monitoring in Study 1(Experiment 1).We recruited 39 healthy male participants and randomly assigned them into the stress group and the control group.The Maastricht Acute Stress Test(MAST)was used to induce the stress responses in participants.The stress group were exposed to the standard version of the MAST which included several hand immersion tasks [ice-cold water(2 °C)] and hard mental arithmetic tasks,while the control group performed a simple version of the MAST.Participants performed two sessions of color-word Stroop task before and after the stress test while their behavioral and electroencephalography(EEG)data were collected.To ensure the sample sizes of high and low cortisol responders,the number of participants in the stress group was as twice as that in the control group.Based on the median of the increment in stress-induced cortisol levels,we further classified the stress group into low(N = 13)and high(N = 13)cortisol responders subgroups.The results showed that salivary cortisol,heart rate,perceived stress level and negative affect were significantly higher in the stress groups than that in the control group,indicating that the acute stress induction was successful.For ERP results,the smaller ERN amplitudes and larger CRN amplitudes during the post-MAST session were observed as a function of the stress-induced cortisol increment.Additionally,the Pe amplitudes in two subgroups of the stress group increased during the post-MAST session and were larger than that in the control group.These results suggest that acute stress enhances individuals’ emotional and motivational reactions to error responses,but the high cortisol level results in impaired automatic error detection.To explore the neural mechanisms of how error awareness influences error processing following acute stress,we implemented both behavioral and EEG methods in Study 2.In experiment 2,52 healthy male participants were recruited and randomly assigned into the stress group(N = 26)or the control group(N =26).This experiment adopted the Trier Social Stress Test(TSST)and Error Awareness Task(EAT)to reveal the process of error monitoring and post-error adjustment following acute stress.The TSST task included a5-minutes public speech task and a 5-minutes hard mental arithmetic task.The stress group performed a standard version of the TSST task,and the control group performed an easier version.EAT was adapted from the go/no-go task.Participants were not only asked to complete the go/no-go task,but also to mark the error responses.The results showed that TSST induced acute stress responses in participants successfully.The behavioral results revealed that the accuracy of error awareness in the stress group was significantly lower than that in the control group,and the negative affect under acute stress negatively predicted the accuracy of error awareness in the stress group.In the post-error trials,accuracy of trials after aware errors in the stress group was lower than that after unaware errors,and it was also lower than that of the control group.The results indicate that acute stress impairs individuals’ ability to identify error responses and the post-error adjustment.In experiment 3,we employed the EEG method to explore the temporal dynamics of error awareness following acute stress.49 healthy male participants were randomly assigned into the stress group(N = 23)or the control group(N = 26).The stress induction and the experiment task were the same as those of experiment 2.The behavioral results of experiment 3 were consistent with the results of experiment 2,and the stress group showed significantly smaller Pe and ΔPe amplitudes during aware errors than those in the control group.In addition,the ΔPe amplitudes during unaware errors in the stress group was significantly larger than that in the control group.These results indicate that acute stress lead to incomplete and inaccurate error awareness.In general,Study 2 showed that the biases in negative affect induced by acute stress not only impairs the generation of error awareness,but also results in poor performance adjustment after error responses.We investigated the effect of acute stress on different stages of post-error processing in Study 3(Experiment 4).50 healthy male participants were randomly assigned into the stress group(N = 24)or the control group(N = 26).We employed the TSST task and an adapted color-word Stroop task in this experiment.Three response-stimulus intervals(RSIs)were employed in this color-word Stroop task(200ms / 700 ms / 1200 ms)to examine the processing patterns of different stages in post-error processing.The results showed that the post-error slowing in the control group and the stress group decreased gradually with the extension of RSI;the accuracy of post-error processing in the control group increased gradually with the extension of RSI,but this effect wasn’t shown in the stress group.Furthermore,the accuracy on1200 ms RSI was close to the accuracy on 700 ms RSI in the stress group,and the accuracy on 1200 ms RSI in the stress group was significantly lower than that in the control group.These results indicate that acute stress impairs post-error adaptive adjustment.We also investigated the possibility of reducing stress-induced error processing deficits through high-definition transcranial magnetic direct current stimulation(HD-tDCS)technology in Study 4(experiment 5).There were 71 healthy male participants in experiment 5.35 participants in the stress group(anodal group: 16,sham group: 19)and 36 participants in the control group(anodal group: 17,sham group:19).Participants were randomly assigned into stress-anodal group,stress-sham group,control-anodal group and the control-sham group.The stress test and the experiment task were the same as those of experiment 4.Based on previous studies,HD-tDCS was used to modulate the cortical excitability of the left dorsolateral prefrontal cortex(dl PFC)to reduce stress-induced error processing deficits.The ‘4 × 1’ HD-tDCS setup which included a center electrode and four return electrodes that were arranged in a circle around the center electrode was used to modulate cortical excitability.The positions of the electrodes were determined by referring to the 10-20 international EEG system,and the center electrode was placed at F3,while the surrounding four electrodes were placed at FP1,Fz,C3,and F7 respectively.Consistent with experiment 4,the accuracy of post-error processing on 1200 ms RSI in the stress-sham group was significantly lower than that in the control group,and anodal dl PFC stimulation significantly increased the accuracy in post-error processing with the lengthening of RSI in the stress group.These results excluded the moderating effects of stress response levels and chronic emotional states.In general,study 4 suggests that anodal stimulation on left dl PFC can upregulate the cortical excitability of this brain area,which can reduce the negative effect of acute stress on adaptive adjustment following error responses.In this study,we utilized behavioral,EEG,and HD-tDCS methods to investigate the cognitive neuromechanism of error processing following acute stress and its interventions.We first explored the effects of acute stress and stress-induced cortisol levels on error monitoring by EEG method.The results showed that acute stress increased individuals’ emotional and motivational responses to error signals,but high cortisol levels caused impaired error detection,indicating that the cortisol level plays an important role in the effects of stress on error processing.After including explicit error awareness judgment,we found that acute stress not only impaired the error awareness,but also had negative influence on the post-error adjustment.Consistent with the biphasic-reciprocal model,these results was related to hyperactivity of the amygdala caused by acute stress.The relocation of resources between the executive control network and the salience network caused by acute stress results in that individuals can’t monitor their error responses accurately and perform post-error corresponding adjustments.These results provide new evidence for understanding the performance regulation in the stressful situation further.We also explored the effect of acute stress on different stages of post-error processing,and the results revealed that participants couldn’t improve their performance in the adaptive processing stage during the post-error adjustment following acute stress.Besides,acute stress impaired participants’ ability to gradually improve their behavioral performance after error responses.These results proved that acute stress impairs post-error adaptive adjustment and provided new evidence for the multi-stage theory of post-error adjustment.Finally,we tried to explore the potential method to reduce the negative effects from acute stress on post-error adjustment,and the results showed that the facilitated cortical excitability of the left dl PFC by HD-tDCS reduced the deficits in post-error adaptive adjustment following acute stress.These results revealed the central role of dl PFC in post-error adaptive adjustment and provided evidence for the treatments or interventions of cognitive control impairment caused by stress-related mental diseases(eg.,PTSD,depression).