| Depression is a common mental disorder that causes a persistent feeling of sadness and loss of interest.To advance both theory and treatment of depression,it is crucial to uncover the mechanisms underlying the hallmark features of depression.Depression individuals include depression patients and individuals with depression tendency,and the latter refers to having partial depressive symptoms but not meeting the diagnostic criteria for depression.The emotional memory bias of depressed individuals plays an important role in the occurrence and development of depression.Indeed,recent evidence suggests that working memory,which involves the ability to store and manipulate information relevant to current tasks and goals.In doing so,it acts as a buffer store,linking working memory to sensory memory and long-term memory,but like most buffer stores it has a limited capacity.Furthermore,recent evidence suggests that depression is associated with difficulties manipulating information in working memory.Results of these investigations converge on the formulation that depression is associated with increased elaboration of negative information,difficulties in cognitive control when processing this information,and difficulties disengaging from this information.Thus,the mechanisms underlying emotional information processing in working memory for individuals with depression tendency remains unclear.The present study using behavioural experiments and ERP techniques,designed three sub-studies with eight experiments to explore the characteristic of working memory processing bias of emotional information for individuals with depression tendency,and the effective mechanisms of reducing depression levels by improving negative emotional information processing bias.This line of experiments allows us to further reveal the characteristics of the working memory processing of emotional information for individuals with depression tendency,and to further reveal the mechanism on the training of the processing for negative emotional information processing bias to reduce the depression mood for individuals with depression tendency.Study 1 includes three experiments.In experiment 1,the working memory processing characteristics for individuals with depression tendency subject was examined,using a change perception paradigm,with the neutral,positive and negative emotional faces as the experimental material.The results showed when the participants were presented with negative and neutral emotions at encoding and negative emotions at detection stages,the memory accuracy for the participants with a depression tendency was higher than those without a depression tendency(control group);however,they showed no differences in other experimental conditions.To further reveal whether the spatial and temporal influence on attention allocation took part in the present results,the memory items were sequentially presented in Experiment 2 and simultaneously presented in Experiment 3.The results of both experiments were consistent with the findings of Experiment 1.Three experiments were designed to explore the influence of emotion priming on working memory processing for individuals with depression tendency in study 2.In Experiment 4,we adopted a change detection task,using neutral,positive and negative emotional faces as materials,to investigate the influence of emotion priming on the working memory processing of emotional information for individuals with depression tendency.The result showed that when the memory items were primed by negative and neutral emotion,individuals with depression tendency showed significantly higher accuracy of negative emotion than the control group;however,they showed no difference when the memory items were primed by a positive emotion.In Experiment 5,we investigated the influence of emotion priming on working memory guidance for individuals with depression tendency by using point detection task and paired-presented emotional faces.The result showed that,following negative and neutral emotion priming,individuals with depression tendency showed significantly faster responses for negative emotional information than the control group;following positive emotion priming,the two groups were no difference.In Experiment 6,positive,neutral,and negative emotional faces were used as experimental materials to investigate the influence of emotion priming on the working memory processing of emotional information for individuals with depression tendency.The result showed that,at the coding stage,following negative emotion priming,individuals with depression tendency,in comparison to the control group,induced higher p1 amplitude for negative emotional information;following neutral emotion priming,individuals with depression tendency,in comparison to the control group,induced higher p1 amplitude for negative and positive emotional information;following positive emotion priming,there was no significant difference between the two groups;however,during the retrieval stage,following neutral and negative emotion priming,individuals with depression tendency induced higher LPC amplitudes for negative emotional information than the control group;following positive emotion priming,the two groups were no difference.In study 3,we adopted the event-related potential technology to investigate the neural mechanism underlying the effects on the positive emotional information processing training for individuals with depression tendency.In Experiment 7,we adopted a cue-target task to investigate the neural mechanism underlying the effects on the working memory processing training of positive emotional information for individuals with depression tendency.The depression training group completed a working memory cue-target task,the task was performed5 times a week for 20 times.The depression control group and healthy control group completed a same times direction judgement training task.The results showed that after training,the training group induced lower N2 amplitudes at the coding stage and lower LPC amplitudes at the maintain stage on negative emotional information,and also received lower depression scores,in comparison to the control group.In Experiment 8,we adopted a cue-target task to investigate the neural mechanism underlying the effects on the perceptual processing training of positive emotional information for individuals with depression tendency.The depression training group completed a perceptual cue-target task,the task was performed 5 times a week for 20 times.The depression control group and healthy control group completed a same times direction judgement training task.The results showed that after training,the training group induced lower P1 amplitudes on negative and positive emotional information,and also received lower depression scores,in comparison to the control group.The main conclusions are as follows,(1)Compared to the control group,when negative and neutral emotions were presented at encoding,and negative emotions were detected at retrieval,the individuals with depression tendency performed better on negative emotional information;and the two groups were no difference when positive and neutral emotions were detected at the retrieval stage.(2)When the memory items were primed with negative and neutral emotions,individuals with depression tendency showed significantly higher accuracy and faster responses on negative emotional information than the control group,and showed no difference when the memory items were primed by a positive emotion.(3)This finding indicates that the positive emotional information working memory training can reduce the conflict between negative and neutral information during the working memory processing for individuals with depression tendency,and thus improves their resource allocation on the negative emotional information and reduces their depression level.Moreover,this training effect can be extended to perceptual processing. |
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