Directed forgetting of negative self-referential information is difficult: an FMRI study

Obliviate! Reviewing Neural Fundamentals of Intentional Forgetting from a Meta-Analytic Perspective

Intentional forgetting (IF) is an important adaptive mechanism necessary for correct memory functioning, optimal psychological wellbeing, and appropriate daily performance. Due to its complexity, the neuropsychological processes that give birth to successful intentional forgetting are not yet clearly known. In this study, we used two different meta-analytic algorithms, Activation Likelihood Estimation (ALE) & Latent Dirichlet Allocation (LDA) to quantitatively assess the neural correlates of IF and to evaluate the degree of compatibility between the proposed neurobiological models and the existing brain imaging data. We found that IF involves the interaction of two networks, the main “core regions” consisting of a primarily right-lateralized frontal-parietal circuit that is activated irrespective of the paradigm used and sample characteristics and a second less constrained “supportive network” that involves frontal-hippocampal interactions when IF takes place. Additionally, our results support the validity of the inhibitory or thought suppression hypothesis. The presence of a neural signature of IF that is stable regardless of experimental paradigms is a promising finding that may open new venues for the development of effective clinical interventions.

Foreign Language Learning in Older Adults: Anatomical and Cognitive Markers of Vocabulary Learning Success

In recent years, foreign language learning (FLL) has been proposed as a possible cognitive intervention for older adults. However, the brain network and cognitive functions underlying FLL has remained largely unconfirmed in older adults. In particular, older and younger adults have markedly different cognitive profile—while older adults tend to exhibit decline in most cognitive domains, their semantic memory usually remains intact. As such, older adults may engage the semantic functions to a larger extent than the other cognitive functions traditionally considered the most important (e.g., working memory capacity and phonological awareness). Using anatomical measurements and a cognitive test battery, the present study examined this hypothesis in twenty cognitively normal older adults (58–69 years old), who participated in a two-month Italian learning programme. Results showed that the immediate learning success and long-term retention of Italian vocabularies were most consistently predicted by the anatomical measures of the left pars orbitalis and left caudal middle frontal cortex, which are implicated in semantic and episodic memory functions. Convergent evidence was also found based on the pattern of cognitive associations. Our results are consistent with a prominent role of semantic and episodic memory functions in vocabulary learning in older learners.

Functional connectivity between right-lateralized ventrolateral prefrontal cortex and insula mediates reappraisal's link to memory control

BACKGROUND

Memory control (MC) ability is critical for people's mental and physical health. Previous research had conceptually demonstrated that MC ability has close relationship with reappraisal. However, experimental evidence supporting the relationship was limited. Thus, in the present study, we investigated how MC and reappraisal are linked, both in behavior and in the brain.

METHODS

The habitual use of reappraisal was assessed by Emotion Regulation Questionnaire, and memory control ability was measured through directed forgetting task. Resting-state functional magnetic resonance imaging was used to test the seed-based functional connectivity in 181 healthy subjects.

RESULTS

Behavioral results revealed that more frequent reappraisal was associated with an enhanced ability to control negative memories. Resting-state seed-based functional connectivity showed that habitual use of reappraisal was positively related to the strength of functional connectivity between the right ventrolateral prefrontal cortex (VLPFC) and right insula. Most importantly, this functional connectivity mediated the effect of habitual use of reappraisal on control over negative memories.

LIMITATIONS

Present results mainly showed the habitual use of reappraisal was related with MC ability in negative items. Future study could further explore the relationship between MC ability of different categories of negative emotional memories and other kinds of ER strategies.

CONCLUSIONS

Our results support the notion that reappraisal provides opportunities for individuals to practice and enhance inhibitory control-a relationship underpinned by connectivity between the right VLPFC and right insula.

Post-retrieval Distortions of Self-Referential Negative Memory: Valence Consistency Enhances Gist-Directed False, While Non-negative Interference Generates More Intrusive Updates

According to the theory of reconsolidation, the contents of an original memory can be updated after reactivation with subsequent new learnings. However, there seems to be a lack of an appropriate behavioral paradigm to study the reconsolidation of explicit self-related memory, which is of great significance to further explore its cognitive neural mechanism in the future. In two separate experiments, we adapted a trial-by-trial interfering paradigm with a self-episodic simulation process and investigated (1) whether it is possible to reconsolidate negative memories under the new behavioral paradigm and (2) how the emotional valence of post-retrieval interference material affects the reconsolidation of negative memories. The results showed that the negative memories under trial-by-trial self-simulation can be degraded and updated via post-retrieval interference processes. Individuals whose original memories were reactivated by initial background cues and who were then presented with new interference situations were less able to recall original scenes and showed more memory intrusions on these scenes than those who had experienced new learning without reactivation or only reactivation without interference. Furthermore, the extent and manner of memory change/updating were greatly influenced by the characteristics of interference information. For memories with negative valences, new learning materials with the same valence produced superior interference effects in the form of lower correct recalls and more integrated false; whereas the neutral interference materials can cause more memory intrusion. Post-retrieval memory distortions of negative self-memory may underlie different functional mechanisms.

Cortical thickness in the right inferior frontal gyrus mediates age-related performance differences on an item-method directed forgetting task

Evidence suggests that older adults have difficulty relative to younger adults in forgetting irrelevant information. Here we sought to understand the physical basis of this deficit by investigating the relationship between cortical thickness and intentional forgetting, using an item-method directed forgetting task. We tested younger (n = 44) and older (n = 54) adults' memories for words that they were instructed to either remember or to forget, and then extracted cortical thickness values from brain regions previously shown, using functional neuroimaging, to be associated with memory suppression, including the right inferior frontal gyrus, the right postcentral gyrus and the left superior/middle frontal gyrus. Results from a parallel mediation model indicated that variations in cortical thickness in the right inferior frontal gyrus, but not the right postcentral gyrus or left superior/middle frontal gyrus, partially explained age-related differences in directed forgetting: older adults with thinner cortices in this area showed worse forgetting ability. This is the first study to explore how neuromorphological differences affect the ability to intentionally suppress items in memory. The results suggest that age-related differences in directed forgetting may be partly driven by cortical thickness in a brain structure known to be functionally involved in directed forgetting, and inhibitory control more broadly, supporting a contribution of deficient inhibition to this phenomenon.

Neuronal Signatures of Negative and Positive Schemas towards the Self and Others in Patients with Early Stage Schizophrenia

OBJECTIVE

The present study investigated the functional neuroanatomy underlying negative and positive schemas towards the self and others in patients with early stage schizophrenia spectrum disorders (SSDs) using a task-based fMRI procedure.

METHODS

This study included 50 patients with SSDs and 52 controls. The schema-evoking task consisted of four active conditions and neutral condition. Differences in brain activation were compared between the two groups. Correlation analysis was performed between task-related activation and psychopathology.

RESULTS

The SSD patients exhibited higher activity of the left middle and inferior frontal gyri under the negative-others minus neutral contrast as well as greater activation of the left superior and middle frontal gyri and right medial superior frontal gyrus under the positive- self minus neutral and positive-others minus neutral contrasts. Under the positive-others minus neutral contrast, negative correlation was observed between activity of the right inferior parietal gyrus and right angular and total score of the Positive and Negative Syndrome Scale (PANSS), whereas positive correlation between activity of the left middle cingulate gyrus and left/right precuneus and positive-others score of the Brief Core Schema Scales (BCSS).

CONCLUSION

The present findings suggest that the frontal brain regions of SSD patients are more sensitive to negative and positive schemas towards the self and/or others compared to those of controls.

Electrophysiological evidence of encoding in self-referential effect

Although the self-referential effect was widely supported by several previous studies, there was few event-related potential (ERP) evidence for the encoding mechanism of the self-referential effect. The present study employed ERPs to investigate whether the electrophysiological indices of the encoding processing could predict the retrieval processing in the self-referential paradigm. Behavioral results demonstrated better performance in the self-reference condition than other-reference condition. The N400 and LPP for the subsequent memory effect (the Dm effect) were observed in both self-referential and other-referential trials as shown in the ERP results of the encoding processing. Moreover, the self-referential information had higher amplitudes for subsequently remembered trials. The study also showed correlation between the ERP components in the encoding phase and those in retrieval. These findings suggest that the self-referential effect can be due to more effective encoding process, which in turn predicts better later recall performance.

Can self-referential information improve directed forgetting? Evidence from a multinomial processing tree model

A large body of research has shown that self-referential processing can enhance an individual’s memory of information. However, there are many arguments about how self-referential processing affects directed forgetting (DF). In this study, two experiments were designed to investigate the DF effect and its internal psychological mechanism under explicit and implicit referential conditions using the item-method DF paradigm combined with the storage-retrieval MPT model. We compare the difference in the DF effect between self-referential and other-referential conditions and explain the reasons for the difference. Our results suggest that the item-method DF effect is the result of a selective rehearsal mechanism and a retrieval inhibition mechanism working together. Both self-reference and other-reference can cause DF in explicit referential processing or implicit referential processing, although the DF effect is stronger under the self-referential condition. Furthermore, the memory advantage effect of implicit self-referential processing is stronger than that of explicit self-referential processing.

Decomposing item-method directed forgetting of emotional pictures: Equivalent costs and no benefits

Using an item-method directed forgetting task, we presented negative, neutral, and positive photographic pictures, one at a time, each followed by an instruction to remember or forget. We determined that the directed forgetting effect, defined as better subsequent recognition of to-be-remembered (TBR) items than to-be-forgotten (TBF) items, was equivalent across negative, neutral, and positive pictures. To disentangle the underlying costs (i.e., decrease in memory for TBF items) and benefits (i.e., increase in memory for TBR items), we compared recognition memory performance in the directed forgetting task to that of a novel within-subjects remember-all control condition (Experiment 1) and to a between-subjects remember-all control group (Experiment 2). We observed costs without benefits across all three emotions-negative, neutral, and positive-in both experiments. These results demonstrate that equivalent directed forgetting effects for emotional stimuli are not attributable to different underlying component processes. Instead, our results suggest that selection for encoding is accomplished in similar ways, regardless of emotional content.

Too hard to forget? ERPs to remember, forget, and uninformative cues in the encoding phase of item-method directed forgetting

In item-method directed forgetting, worse memory performance occurs for to-be-forgotten (TBF) than for to-be-remembered (TBR) items. However, recently TBF items have been found to be recognized more accurately than uninformative (UI) items not associated with any specific task. Here, we compare ERPs elicited by cues signaling the remember or the forget instruction with those elicited by uninformative cues. Participants were presented with a series of complex pictures, each followed by a symbolic TBR, TBF, or UI cue. On a yes-no recognition test, accuracy was higher for TBR than for both TBF and UI items. However, TBF items were recognized more accurately than UI items. ERPs elicited by the TBR cue were larger than ERPs elicited by both TBF and UI cues at the frontal P2, the late frontal negativity, and the late parietal positivity complex. This is consistent with more attention capture, selective rehearsal, and long-term memory encoding of TBR. In contrast, both TBF and UI cues induced a larger frontal N2 than TBR cues. Critically, TBF elicited a larger late right-frontal positivity than both UI and TBR cues and a larger late parietal positivity than UI cues. Moreover, the late right-frontal positivity was correlated with better recognition performance. It may therefore reflect processing orientation rather than inhibition per se. Results suggest that, when compared to UI cues, both TBR and TBF cues are processed actively. Distinct processing is seen at right frontal and centroparietal positive ERPs that may mediate better subsequent recognition of TBF than of UI items.

Shared Mechanisms May Support Mnemonic Benefits from Self-Referencing and Emotion

The literatures on episodic memory for self-referential and emotional information have proceeded relatively independently, and most studies examining the effects of age on these memory processes have been interpreted within domain-specific frameworks. However, there is increasing evidence for shared mechanisms that contribute to episodic memory benefits in these two domains. We review this evidence and propose a model that incorporates overlapping as well as domain-specific contributions to episodic memory encoding of self-referential and emotional material. We discuss the implications for understanding the relatively intact memory of older adults for these classes of stimuli, and conclude with suggestions for future research to test key tenets and extensions of this shared-process model.

Cooperative and Competitive Contextual Effects on Social Cognitive and Empathic Neural Responses

We aimed to differentiate the neural responses to cooperative and competitive contexts, which are the two of the most important social contexts in human society. Healthy male college students were asked to complete a Tetris-like task requiring mental rotation skills under individual, cooperative, and competitive contexts in an fMRI scanner. While the participants completed the task, pictures of others experiencing pain evoking emotional empathy randomly appeared to capture contextual effects on empathic neural responses. Behavioral results indicated that, in the presence of cooperation, participants solved the tasks more accurately and quickly than what they did when in the presence of competition. The fMRI results revealed activations in the dorsolateral prefrontal cortex (dlPFC) and dorsomedial prefrontal cortex (dmPFC) related to executive functions and theory of mind when participants performed the task under both cooperative and competitive contexts, whereas no activation of such areas was observed in the individual context. Cooperation condition exhibited stronger neural responses in the ventromedial prefrontal cortex (vmPFC) and dmPFC than competition condition. Competition condition, however, showed marginal neural responses in the cerebellum and anterior insular cortex (AIC). The two social contexts involved stronger empathic neural responses to other's pain than the individual context, but no substantial differences between cooperation and competition were present. Regions of interest analyses revealed that individual's trait empathy modulated the neural activity in the state empathy network, the AIC, and the dorsal anterior cingulate cortex (dACC) depending on the social context. These results suggest that cooperation improves task performance and activates neural responses associated with reward and mentalizing. Furthermore, the interaction between trait- and state-empathy was explored by correlation analyses between individual's trait empathy score and changing empathic brain activations along with the exposure to the cooperative and competitive social contexts.

Self-Referential Information Alleviates Retrieval Inhibition of Directed Forgetting Effects-An ERP Evidence of Source Memory

Directed forgetting (DF) assists in preventing outdated information from interfering with cognitive processing. Previous studies pointed that self-referential items alleviated DF effects due to the elaboration of encoding processes. However, the retrieval mechanism of this phenomenon remains unknown. Based on the dual-process framework of recognition, the retrieval of self-referential information was involved in familiarity and recollection. Using source memory tasks combined with event-related potential (ERP) recording, our research investigated the retrieval processes of alleviative DF effects elicited by self-referential information. The FN400 (frontal negativity at 400 ms) is a frontal potential at 300–500 ms related to familiarity and the late positive complex (LPC) is a later parietal potential at 500–800 ms related to recollection. The FN400 effects of source memory suggested that familiarity processes were promoted by self-referential effects without the modulation of to-be-forgotten (TBF) instruction. The ERP results of DF effects were involved with LPCs of source memory, which indexed retrieval processing of recollection. The other-referential source memory of TBF instruction caused the absence of LPC effects, while the self-referential source memory of TBF instruction still elicited the significant LPC effects. Therefore, our neural findings suggested that self-referential processing improved both familiarity and recollection. Furthermore, the self-referential processing advantage which was caused by the autobiographical retrieval alleviated retrieval inhibition of DF, supporting that the self-referential source memory alleviated DF effects.

Directed forgetting of negative performed actions is difficult: A behavioural study

Strong evidence suggests that both performing actions and emotional stimuli can enhance memory by capturing attention. However, the synergetic effect of the two factors on directed forgetting has not been assessed. In this study, we used an item-method directed forgetting paradigm to examine the forgetting of emotional materials depending on whether actions were performed. The results showed that action performance influenced the directed forgetting of emotional words. Specifically, when actions were performed there was a directed forgetting effect for neutral and positive words but not for negative words. In comparison, for verbal tasks, directed forgetting was observed for all words. The elaborative encoding prior to the remember/forget instructions and the influence of negative emotion on attentional inhibition after the presentation of the instructions together suggest that it is more difficult to intentionally forget negative performed actions.

Abnormal brain activation during directed forgetting of negative memory in depressed patients

The frequent occurrence of uncontrollable negative thoughts and memories is a troubling aspect of depression. Thus, knowledge on the mechanism underlying intentional forgetting of these thoughts and memories is crucial to develop an effective emotion regulation strategy for depressed individuals. Behavioral studies have demonstrated that depressed participants cannot intentionally forget negative memories. However, the neural mechanism underlying this process remains unclear. In this study, participants completed the directed forgetting task in which they were instructed to remember or forget neutral or negative words. Standard univariate analysis based on the General Linear Model showed that the depressed participants have higher activation in the inferior frontal gyrus (IFG), superior frontal gyrus (SFG), superior parietal gyrus (SPG), and inferior temporal gyrus (ITG) than the healthy individuals. The results indicated that depressed participants recruited more frontal and parietal inhibitory control resources to inhibit the TBF items, but the attempt still failed because of negative bias. We also used the Support Vector Machine to perform multivariate pattern classification based on the brain activation during directed forgetting. The pattern of brain activity in directed forgetting of negative words allowed correct group classification with an overall accuracy of 75% (P=0.012). The brain regions which are critical for this discrimination showed abnormal activation when depressed participants were attempting to forget negative words. These results indicated that the abnormal neural circuitry when depressed individuals tried to forget the negative words might provide neurobiological markers for depression.

Psychosocial versus physiological stress - Meta-analyses on deactivations and activations of the neural correlates of stress reactions

Stress is present in everyday life in various forms and situations. Two stressors frequently investigated are physiological and psychosocial stress. Besides similar subjective and hormonal responses, it has been suggested that they also share common neural substrates. The current study used activation-likelihood-estimation meta-analysis to test this assumption by integrating results of previous neuroimaging studies on stress processing. Reported results are cluster-level FWE corrected. The inferior frontal gyrus (IFG) and the anterior insula (AI) were the only regions that demonstrated overlapping activation for both stressors. Analysis of physiological stress showed consistent activation of cognitive and affective components of pain processing such as the insula, striatum, or the middle cingulate cortex. Contrarily, analysis across psychosocial stress revealed consistent activation of the right superior temporal gyrus and deactivation of the striatum. Notably, parts of the striatum appeared to be functionally specified: the dorsal striatum was activated in physiological stress, whereas the ventral striatum was deactivated in psychosocial stress. Additional functional connectivity and decoding analyses further characterized this functional heterogeneity and revealed higher associations of the dorsal striatum with motor regions and of the ventral striatum with reward processing. Based on our meta-analytic approach, activation of the IFG and the AI seems to indicate a global neural stress reaction. While physiological stress activates a motoric fight-or-flight reaction, during psychosocial stress attention is shifted towards emotion regulation and goal-directed behavior, and reward processing is reduced. Our results show the significance of differentiating physiological and psychosocial stress in neural engagement. Furthermore, the assessment of deactivations in addition to activations in stress research is highly recommended.