Cognitive and neural consequences of memory suppression in major depressive disorder

Negative biases in cognition have been documented consistently in major depressive disorder (MDD), including difficulties in the ability to control the processing of negative material. Although negative information-processing biases have been studied using both behavioral and neuroimaging paradigms, relatively little research has been conducted examining the difficulties of depressed persons with inhibiting the retrieval of negative information from long-term memory. In this study, we used the think/no-think paradigm and functional magnetic resonance imaging to assess the cognitive and neural consequences of memory suppression in individuals diagnosed with depression and in healthy controls. The participants showed typical behavioral forgetting effects, but contrary to our hypotheses, there were no differences between the depressed and nondepressed participants or between neutral and negative memories. Relative to controls, depressed individuals exhibited greater activity in right middle frontal gyrus during memory suppression, regardless of the valence of the suppressed stimuli, and differential activity in the amygdala and hippocampus during memory suppression involving negatively valenced stimuli. These findings indicate that depressed individuals are characterized by neural anomalies during the suppression of long-term memories, increasing our understanding of the brain bases of negative cognitive biases in MDD.     

ERP evidence for the control of emotional memories during strategic retrieval

Neural evidence for the strategic retrieval of task-relevant ‘target’ memories at the expense of less relevant ‘nontarget’ memories has been demonstrated across a wide variety of studies. In ERP studies, this evidence consists of the ERP correlate of recollection (i.e. the ‘left parietal old/new effect’) being evident for targets and attenuated for nontargets. It is not yet known, however, whether this degree of strategic control can be extended to emotionally valenced words, or whether these items instead reactivate associated memories. The present study used a paradigm previously employed to demonstrate the strategic retrieval of neutral words (Herron & Rugg, Psychonomic Bulletin and & Review, 10(3), 703-–710, 2003b) to assess the effects of stimulus valence on behavioural and event-related potential (ERP) measures of strategic retrieval. While response accuracy and reaction times associated with targets were unaffected by valence, negative nontargets and new items were both associated with an elevated false alarm rate and longer RTs than their neutral equivalents. Both neutral and negative targets and nontargets elicited early old/new effects between 300 and 500 ms. Critically, whereas neutral and negative targets elicited robust and statistically equivalent left parietal old/new effects between 500 and 800 ms, these were absent for neutral and negative nontargets. A right frontal positivity associated with postretrieval monitoring was evident for neutral targets versus nontargets, for negative versus neutral nontargets, and for targets versus new items. It can therefore be concluded that the recollection of negatively valenced words is subject to strategic control during retrieval, and that postretrieval monitoring processes are influenced by emotional valence.     

压抑遗忘的影响因素

人在生活中的一些负性经历或无效信息可以通过压抑提取而遗忘,这种遗忘称为压抑遗忘。压抑遗忘不仅受压抑时长、压抑次数、实验材料的情绪效价和唤醒度、期待效应等的影响,还受个体的年龄和精神障碍等的影响。今后应着重考察精神疾病个体记忆控制网络内的连接强度与压抑遗忘的关系,澄清压抑遗忘是否存在补偿机制。     

压抑遗忘的影响因素

人在生活中的一些负性经历或无效信息可以通过压抑提取而遗忘,这种遗忘称为压抑遗忘。压抑遗忘不仅受压抑时长、压抑次数、实验材料的情绪效价和唤醒度、期待效应等的影响,还受个体的年龄和精神障碍等的影响。今后应着重考察精神疾病个体记忆控制网络内的连接强度与压抑遗忘的关系,澄清压抑遗忘是否存在补偿机制。     

Rumination and overgeneral autobiographical memory

Two studies investigated the effects of rumination on the retrieval of autobiographical memories in high-depressed and low-depressed individuals. Experiment 1 administered either a rumination or distraction task prior to a cued autobiographical memory task. High-depressed participants recalled more overgeneral memories following rumination relative to distraction, whereas experimental inductions did not influence low-depressed participants. Experiment 2 administered either a positive or negative rumination task prior to a cued autobiographical memory task. Negatively valenced rumination led high-depressed participants to recall more overgeneral memories than positively valenced rumination; this effect was not observed in low-depressed participants. These findings accord with the proposal that rumination is a mediating mechanism in the retrieval of overgeneral memories, and extends this proposal by indicating that negatively valenced ruminative content is particularly instrumental in inducing overgeneral retrieval.     

Suppression-induced forgetting diminishes following a delay of either sleep or wake

ABSTRACT

We investigated the duration of suppression-induced forgetting (SIF), and the extent to which retrieval suppression differs between negative and neutral memories. We further examined if SIF was differently affected by sleep versus wake during the delay interval between retrieval suppression and re-test. Fifty participants first learned to associate neutral words with either neutral or negative images. Then, a subset of the words was shown again, and participants were asked to either recall (Think), or to suppress retrieval of (No-Think) the associated images. Finally, a memory test for all items was performed either immediately after the Think/No-Think (T/NT) phase (No Delay), or after a 3.5?h delay interval containing either sleep or wake. Results revealed a SIF effect only in the No Delay group, indicating that this forgetting effect dissipates already after a 3.5?h delay interval. Negative items were experienced as more intrusive than neutral ones during the T/NT phase.     

负性情绪材料的定向遗忘及心理机制

采用项目法定向遗忘的研究范式,在两个实验中分别采用文字和图片材料考察了情绪性记忆定向遗忘的效果及其心理机制。实验中采用了中性和负性两种实验材料,设置了两种记忆指令出现时间（2秒后提示和5秒后提示）,相对于中性材料,被试更不容易忘记负性材料。记忆指令出现的时间只影响图片材料的定向遗忘。研究表明负性情绪会干扰定向遗忘,选择性编码理论可以解释情绪性文字材料的定向遗忘,而抑制理论更能解释情绪性图片材料的定向遗忘效应。     

Directed forgetting of recently recalled autobiographical memories

In 6 experiments, the authors investigated list-method directed forgetting of recently recalled autobiographical memories. Reliable directed forgetting effects were observed across all experiments. In 4 experiments, the authors examined the impact of memory valence on directed forgetting. The forget instruction impaired recall of negative, positive, and neutral memories equally, although overall, participants recalled fewer unemotional memories than emotional memories. The preexisting organization of memories enhanced the directed forgetting effect, and a release from forgetting occurred only when the forgotten memories were directly cued. The authors discuss the roles of emotion, retrieval dynamics, and organization in these effects and suggest that the directed forgetting of recently recalled autobiographical memories may reflect the inhibition of recently formed memories of remembering, that is, episodic inhibition. The authors consider the implications of these findings for the control of autobiographical remembering in everyday life.     

Effects of sleep on positive,negative and neutral valenced story and image memory

During sleep, emotional memories are preferentially strengthened. However, most studies on sleep and emotional memory focus on comparing negative valence with neutral valence stimuli. This study compared the sleep-dependent memory effects for stories and images, each comprising negative, neutral, and positive stimuli. It was hypothesized that a sleep effect would be seen for negatively and positively valenced stimuli. A novel story memory task (comprising three stories), and photographs from the Nencki Affective Picture database were presented for learning to 61 healthy adults (ages 18–25). They were tested for memory on the two tasks immediately, and then again after either a 2-hr nap (n = 31; 17 women, 14 men) or 2-hr wake period (n = 30; 13 women, 17 men). At second testing, the sleep condition had significantly better recall compared to the wake condition on both tasks. There was a relationship with valence only for the story task, with better performance for the sleep condition on the negatively and positively valenced texts, but not on the neutral text. There were no significant relationships between memory measures and sleep-stage duration and EEG power variables. The story memory findings support the hypothesis that memory consolidation prioritizes emotional memory, whether positively or negatively valenced.     

基于Think/No-think范式的动机性遗忘研究:行为与脑机制

想/不想范式(Think/No-think,TNT)是基于go/no-go范式提出来的用于研究动机性遗忘过程的实验范式,主要过程是指个体对于记忆的提取抑制可以导致随后该记忆的遗忘。近年来TNT范式的大量行为学研究都一致性地发现记忆提取抑制可以产生负性控制效应,验证了在实验室情境下对动机性遗忘进行研究的可行性。其中,负性控制效应指的是压抑条件的项目相对于基线条件的项目的回忆量有显著降低。关于动机性遗忘发生的神经机制的探讨已积累了大量的研究证据,总结脑电(EEG)和功能核磁共振(f MRI)两个模态的研究,我们提出了动机性遗忘发生的多模态功能网络模型。最后,在该模型的基础上,我们展望了TNT范式未来的研究方向,其中特别注意到同步EEG-f MRI技术的应用有望为我们揭示出记忆提取抑制导致的动机性遗忘发生的动态过程。     

To think or not to think,that is the question: Individual differences in suppression and rebound effects in autobiographical memory

Two studies explored the effects of forget instructions on autobiographical memory at immediate test and following delays of either 12–13 months, or 3–4 months. Using the Autobiographical Think/No-Think procedure (cf., Noreen & MacLeod, 2013), 24 never-depressed participants (Study 1) first generated 12 positive and 12 negative autobiographical memories and associated cues. Participants were then asked to recall the memory associated with some of the cues (i.e., ‘think’ condition), or to avoid saying or thinking about the memory associated with other cues (i.e., ‘no-think’ condition). Participants were then asked to recall the memories associated with all the cues at immediate test and following a delay of 12–13 months. Participants were found to be successful at forgetting both positive and negative autobiographical memories following ‘no-think’ instructions at immediate test but this forgetting effect did not persist following a 12–13 month delay. This pattern of remembering and forgetting was replicated in a second study (using 27 never-depressed participants) following a 3–4 month delay. Participants who had been less successful at forgetting ‘no-think’ memories at immediate test, were more likely to show rebound effects for those memories following a delay compared to memories which received neither ‘think’ nor ‘no-think’ instructions. Individual differences in inhibitory control and the efficacy of potential therapeutic interventions of ‘no-think’ instructions are considered.     

情绪对提取诱发遗忘的影响

从学习材料的情绪性和提取过程的情绪状态两方面考察了情绪对提取诱发遗忘的影响。结果发现提取练习对情绪性与非情绪性材料引发了同等程度的遗忘;提取练习阶段,当被试处于正性或中性情绪状态下也会发生明显的提取诱发遗忘现象,而当被试处于负性情绪状态时,提取练习不会导致对未提取项目的遗忘。研究结果表明,学习材料的情绪性不影响提取诱发遗忘,而提取过程的情绪状态会对提取诱发遗忘产生影响,负性情绪状态可以消除提取诱发遗忘。     

情绪一致性对有意遗忘的影响

有意遗忘是强调遗忘的有意性和指向性。对负性情绪的有意遗忘有利于个体的身心健康。本研究采用单字范式,实验一以正性、负性和中性情绪词为材料,探讨了情绪材料对有意遗忘的影响。结果发现,三类词语均表现出了显著的有意遗忘效应;实验二在实验一的基础上加入了情绪状态,探讨了情绪状态和情绪材料对有意遗忘的影响,结果发现,在积极情绪状态下,被试更多地遗忘负性情绪词;在消极情绪状态下,被试更多地遗忘中性词。表明个体对情绪信息的有意遗忘既受信息的情绪性影响,又受个体情绪状态的影响。     

Retrieval‐induced forgetting of emotional and unemotional autobiographical memories

This experiment extended the retrieval‐induced forgetting (RIF) procedure from simple, episodic information to emotional and unemotional autobiographical memories. In the elicitation phase, participants generated specific memories from their past in response to negative, neutral, or positive category cues. In the retrieval‐practice phase, they practised retrieving (and elaborated further on) some of the memories for some of the categories. In the final test phase, they tried to recall all memories. Memories that received retrieval practice were recalled more often on final test than baseline memories, whereas memories that were not practised, yet competed with practised memories via a shared category cue, were recalled less often than baseline memories. We discuss the roles of inhibition, competition, emotion, and self‐relevance, and consider what laboratory manipulations of memory might reveal about everyday and pathological personal memory.     

Retrieval inhibition of trauma-related words in women reporting repressed or recovered memories of childhood sexual abuse

Several authors have argued that survivors of childhood sexual abuse (CSA) who report to have repressed their traumatic memories are more skilled in forgetting emotional stimuli than survivors who have always remembered the abuse. The current experiment employed a list-wise directed forgetting task to investigate whether women reporting repressed (n = 16) or recovered (n = 23) memories of CSA are better at forgetting disturbing material, relative to women reporting having always remembered their abuse (n = 55) or reporting no history of abuse (n = 20). We found no support for the hypothesis that women reporting repressed or recovered memories of CSA are especially versed in inhibiting retrieval of trauma-related words. Additional analyses revealed that participants characterized by a repressive coping style did not display a superior retrieval inhibition mechanism for negative material.     

Retrieval-induced forgetting of negative stimuli: The role of emotional intensity

Repeatedly retrieving a subset of previously studied items can cause forgetting of related non-retrieved material. We examined whether such retrieval-induced forgetting holds also for negative material. Participants studied neutral and negative stimuli and then repeatedly retrieved a subset of the neutral material. Later, a recall test was conducted in which participants were asked to recall all previously studied items. On average, retrieval practice on the neutral items caused the same amount of forgetting for neutral and negative items, indicating that the emotionality of material does not affect retrieval-induced forgetting. More detailed analysis, however, revealed that the forgetting of negative items decreased with both the emotional intensity of a negative item and the dispositional negative affectivity of a participant. The decreases in retrieval-induced forgetting may have been driven by item-specific processing of material, which is known to be enhanced for highly negative stimuli and participants high in dispositional negative affectivity and to reduce or even eliminate retrieval-induced forgetting.     

Subliminal backdoors to forgetting emotional memories

Weakening negative memories often requires first remembering those events. To bypass this distressing process, Zhu et al. elicited forgetting by subliminally reactivating negative memories near in time to retrieval suppression of unrelated memories. Casting an amnesic shadow over harmful, reactivated memories thereby brings new therapeutic possibilities, and questions, to light.     

Memories affect mood: evidence from covert experimental assignment to positive, neutral, and negative memory recall

Memory recall has been proposed as a common and effective mood regulation strategy. Although several studies have presented results suggesting that recalling valenced memories affects subsequent mood, their designs allow for alternative interpretations of the observed effects. Two such alternatives include the reverse effect (mood effects on memory due to non-experimental assignment to memory recall condition) and demand characteristics of the experiment. We used covert experimental assignment to memory condition, asking subjects (N=314; 56% female) to recall memories that were primarily positive, neutral, or negative. Results showed the expected effect on mood (p<.002), with reported mood worst in the negative memory condition, better in the neutral condition, and best in the positive condition. These results suggest that valenced memory recall does indeed exert an effect on mood, and may do so even without the individual's awareness.     

Examining the role of emotional valence of mind wandering: All mind wandering is not equal

To evaluate the role of emotional valence on the impact of mind wandering on working memory (WM) and sustained attention, we reanalyzed data from three independently conducted studies that examined the impact of stress on WM (Banks & Boals, 2016; Banks, Welhaf, & Srour, 2015) and sustained attention (Banks, Tartar, & Welhaf, 2014). Across all studies, participants reported the content of their thoughts at random intervals during the WM or sustained attention task. Thought probes in all studies included a core set of response options for task-unrelated thoughts (TUTs) that were negatively, positively, or neutrally emotionally valenced. In line with theories of emotional valenced stimuli on capture of attention, results suggest negatively valenced TUTs, but not positively valenced TUTs, were related to poorer WM and sustained attention in two studies. Neutral TUTs were related to poorer WM but not sustained attention performance. Implications for models of mind wandering are discussed.     

Forgetting the unforgotten affective autobiographical memories in nonclinical dissociators

Inefficient memory inhibition has been observed in nonclinical and clinical dissociators. Paradoxically, dissociators also report unusual forgetfulness. Investigating how forgetting emerges in dissociators may uncover the antecedents for their self-report memory problems. We postulated that set switch can link inefficient memory inhibition to forgetting. Recollection detour, which involves an affect switch, may elicit forgetting of previously uninhibited memories in nonclinical dissociators. This hypothesis was verified in participants with high- and low-dissociation proneness via a retrieval practice paradigm using positive and negative autobiographical memories. After the study and retrieval-practice phases, memories of the practiced affect category were tested without and with intervening recall of the unpracticed affect category in the control and detour condition, respectively. Nondissociators showed reduced recall in the control condition, replicating the retrieval-induced forgetting (RIF) effect and recollection detour did not alter the RIF effect. By contrast, nonclinical dissociators showed the RIF effect in the detour condition but not in the control condition. Detour to recollecting memories of another affect category rendered an aftereffect of forgetting of previously uninhibited memories in nonclinical dissociators. (PsycINFO Database Record (c) 2012 APA, all rights reserved).