The Cognitive And Neural Mechanisms Of Motivated Suppression For The Self-related Negative Memory

In life,we are always willing to experience wonderful things.However,we are also likely to experience some negative events which were caused by natural and human beings.Negative events always accompany with negative memories.The intrusion of negative memories is the key incentive of many psychological diseases,including general anxiety,post-traumatic stress disorder,and depression.It is noteworthy that why some individuals can successfully suppress the intrusion of negative memories and recover from negative events by themselves.However,others can not suppress the intrusion of negative memories successfully and even cause serious mental illness.How can people successfully suppress the intrusion of negative memories and reduce negative impact of negative life events? Previous studies suggested that motivating suppression early traumatic memories can induced forgetting,that is to say,there exist motivated forgetting after suppressing negative memories.It is also found in the laboratory that the motivated suppression of the neutral or emotional memories can induce forgetting.However,can people motivated suppress their own experience negative memories? If can,how to suppress? Whether it has a positive impact after suppressing self-related negative memories? At present,these problems have yet to be solved.Answering these questions will help to understand that how individuals respond to negative events which were experienced by themselves.It is helpful to reveal spontaneous mechanism of motivated suppression of negative memories,and find out adaptive mechanismthat successfully suppressing negative memories.It is also helpful to reduce the adverse effect of negative life events,prevent the emergence of psychological problems,and treat clinical psychological diseases.There is no agreement on the previous studies on memories suppression.Some studies have found that motivated suppress memories can induce forgetting.However,others have found that motivated suppress memories can not induce forgetting.In addition,most of the previous studies were based on non-self-related memories.However,for non-self-related and self-related memories,their cognitive and neural mechanisms of memories suppression may be significantly different.In life,people tend to forget negative memories.Therefore,this study focuses on the motivated suppression of self-related negative memories.There is still controversial about the outcome of motivated forgetting of negative memories.Predecessors considered that the lost negative memories would be manifested in the form of hysteria.However,the current research argued that suppressing negative memories has a positive adaptability.The outcome of motivated forgetting for negative memories is the root of research.Therefore,the first question that this study will explore is that whether motivated forgetting of self-related memories has a positive adaptability.Moreover,previous studies have found that directly suppressed autobiographical negative memories led to forgetting,but its neural mechanism is unclear.And whether the autobiographical negative memories can be interpreted as a positive memories to induce forgetting? Its cognitive and neural mechanisms are unknown.Therefore,the second question this study will explore is how do the cognitive and neural processes operate when individuals motivated suppress autobiographical negative memories.Based on these two questions,the topic of this study is the cognitive and neural mechanisms of motivated suppression for the self-related negative memories.This topic will be discussed from four studies and seven experiments.Study 1,the purpose of Study 1 is to test whether motivated suppress self-experience negative memories has a positive adaptability.This study explore that whether the ability of motivated suppression of negative memories in every daily life can alleviate the risk factors(such as traumatic experience and neuroticism)on the impact of depression by questionnaires among health and depression subjects.The results of Experiment 1 show that the ability ofmotivated suppression can mediated and moderated the relationship between traumatic experience and depression.The mediating effect result remains valid while taking account of the effect of self-esteem between the traumatic experience and depression.The results of the Experiment 1 revealed that the higher ability of motivated suppression for negative memories in daily life,the less negative impact of traumatic experience on depression.The results of Experiment 2 show that the ability of motivated suppression can mediated and moderated the relationship between neuroticism and depression.The mediating effect result remains valid while taking account of the effect of rumination between neuroticism and depression.The results revealed that the higher ability of motivated suppression of negative memories in daily life,the less negative impact of neurotic traits on depression.In short,motivated suppression of negative memories in daily life can alleviate the negative impact of traumatic experience and neuroticism on depression,the results of the normal subjects and the main depression disorders(MDD)population are consistent.The results of Study 1 show that motivated suppression negative memories can partially alleviate the negative effect of traumatic experience and neuroticism on the depression among normal and MDD population.These results,in some extent,clarified the controversy that whether motivated suppressing induced forgetting is positive or not.These results confirmed that the ability of motivated suppression helped to maintain mental health,and it also supported the point of view that motivated forgetting has positive adaptability.Study 2,the purpose of Study 2 is to reveal the brain structure and functional connectivity underlying the ability of motivated suppression.This study explore the brain structure and functional connectivity bases of the motivated suppression capacity of negative memories in daily life in the perspective of individual differences.This study used thought control ability questionnaire to investigate the brain structure and functional connectivity of the ability of motivated suppression with VBM(Voxel-based morphometry)and resting state functional connectivity analyses.Experiment 3,the results of structure analysis show that the higher ability of motivated suppression,the larger the volume of gray matter of the right superior frontal gyrus(SFG).The results revealed that suppressing negative memories for a long-term can enlarge the volume of gray matter in brain region of SFG.The results offunctional connectivity analysis show that the higher ability motivated suppression,the stronger resting-state functional connectivity between the right SFG and the left middle temporal gyrus(MTG).The results revealed that suppressing negative memories for a long-term have a strong resting-state functional connectivity basis,this functional connectivity can mediated the relationship between neuroticism and the motivated suppression ability.The results of the Study 2 revealed that individuals with high ability of motivated suppression for negative memories in daily life are of the larger volume of gray matter in the right SFG,and exist the stronger spontaneous brain functional connectivity from control network project to default network.The weakness functional connectivity between SFG and MTG partly explained the negative relationship between neuroticism and motivated suppression ability.These results proved the conclusion of Study 1.In short,motivating suppression induced forgetting not only contributes to the protection of mental health in behavior level,but also with a larger brain structure and a stronger functional connectivity.Study 3,the purpose of Study 3 is to explore the cognitive and neural processing when people motivated directly suppressed negative life events.This study adopted ATNT(Autobiographical Think/No-think)paradigm with directly suppressed method and used autobiographical memory material and based on 2(experimental materials: neutral and negative)?3(experimental conditions: respond,suppress and baseline)Event-related design experimental design.Experiment 4 investigated the cognitive processing of directly suppressed autobiographical negative memories.The behavioral results show that the accuracy of memories under the suppression condition has decreased,and the reaction time has increased.These results indicated that suppressed self-related negative memories increased the difficulty to recall,and resulted in forgetting.But this forgotten effect can not last until a week or a month later.The motivated suppressed autobiographical negative memories led to forgetting.Its cognitive mechanism is that the memory extraction process was blocked and resulted in forgetting.Experiment 5 investigated the neuroimaging processing of directly suppressed the autobiographical negative memories by task fMRI(Functional magnetic resonance imaging).The neuroimaging results show that the suppressed process for autobiographical negative memories activated memoriescontrol-related brain areas,such as the SFG,middle frontal gyrus and inferior frontal gyrus in frontal cortex,and putamen,insula in subcortical regions.The regions which involved in self-related default network reduced activation,including the medial prefrontal cortex(mPFC)and the precuneus.Comparing the inhibitory and recall conditions,the functional connectivity analysis results further found that there exists interaction among the right dorsolateral prefrontal(DLPFC),the bilateral mPFC and precuneus.The results revealed that the neural mechanism of the suppressed process for the negative memories of self-related experienced event is different from the negative memories which is not self-related.From the previous studies and this study,we found that suppressing not self-related negative memories is that excluding memories out of mind,but suppressing self-related negative memories is that excluding self-related information out of mind.Study 4,the purpose of Study 4 is to explore the cognitive and neural processing when people motivated substitute suppressed negative life events.This study adopted ATNT paradigm with substitute suppressed method and used autobiographical memory material and based on 2(experimental materials: neutral and negative)?3(experimental conditions:respond,substitute and baseline)Event-related design experimental design.The purpose is to reveal the cognitive and neural mechanisms when people treat the autobiographical negative events in positive perspective.Experiment 6 investigated the cognitive processing of substituting suppressed autobiographical negative memories.The behavioral results show that the accuracy under the substitution condition is significantly lower than the baseline condition,and its reaction time is higher than the baseline condition.The results illustrated that the negative memories being interpreted into autobiographical positive memories increased the difficulty to recall,and resulted in forgotten.But this forgotten effect can not sustain until a week later.It is a valid way to forget autobiographical negative memories by interpreting it into positive memories,the cognitive mechanism of this conclusion is that the new positive memories disturbs the old negative memories to result in forgetting,this forgetting comes true by a indirect way.Experiment 7 investigated the neural processing of the substituted suppression of autobiographical negative memories by task fMRI.The neuroimaging results show that,in the processing of substituting suppression,two brainregions involved in memories competition was activated,including the left mid-ventrolateral prefrontal cortex(mVLPFC)and in the left caudal prefrontal cortex(cPFC).The hippocampus involved in formation of new memories also was activated.The activated left hippocampus can alleviate current negative emotion,and this processing was reinforced by a positive self-concept.To some extent,the results revealed that when people treat the autobiographical negative events in a positive perspective,the activated mVLPFC and cPFC are involved in the competition between old and new memories,the activated hippocampus is involved in the formation of the new memories,and the left hippocampus being activated during the substituting suppression may play an positive role in maintaining mental health.To sum up,this study is the first to reveal cognitive and neural mechanisms of motivated suppression for self-related negative memories in daily life.To some extent,the results of this study clarify the controversy of motivated forgetting of negative memories,and further verify the point that motivated forgetting has an adaptability mechanism.The results reveal the brain structure and functional connectivity bases of the motivated suppressed negative memories in daily life,and the characteristic of the cognitive and neural mechanisms when people deal with negative life events in directed suppression or in a positive attitude.This study provide necessary preventive strategies to reduce the adverse effects on healthy individuals,and provide necessary interventions for MDD.