Emotional Episodic Memory Research Articles

The role of the amygdala in enhanced remembrance of negative episodes and acquired negativity of related neutral cues

Prior research on the interaction between emotion and episodic memory established that negatively charged events are better remembered compared to neutral events (i.e. enhanced remembrance), as well as that a priori neutral cues that were present in the environment during a negative event can attain aversive meaning by themselves (i.e. acquired negativity). Improved understanding the neural mechanisms that mediate enhanced remembrance of negative episodes and acquired negativity of related neutral cues may carry substantial clinical relevance, particularly in the context of posttraumatic pathophysiology. In order to address this point forty-nine healthy participants completed a novel fMRI task that involve the presentation of neutral pictures before and after a series of short neutral and aversive video-clips from which the neutral pictures were originally extracted, and a subsequent presentation of these pictures as cues for clip recall [termed, Picture-Clip-Picture-Recall (PCPR) task]. Behavioral results indicate that aversive clips were indeed better remembered compared to neutral clips (i.e. enhanced remembrance of negative episode) and that a priori neutral pictures that appeared in aversive clips were rated more negatively after relative to before the exposure to the aversive clips (i.e. acquired negativity of related neutral cues). Whole-brain fMRI analysis revealed that increased amygdala activation in response to pictures when presented as cues for clip recall predicted successful clip remembrance, particularly remembrance of aversive clips. This amygdala activation was also correlated with the magnitude of acquired negativity of the cues following their appearance in aversive clips. Taken together our findings implicate the PCPR as a novel, naturalistic, framework for investigating the neural interface of emotional episodic memory, while highlighting the role of the amygdala in enhanced remembrance of negative episodes and acquired negativity of related neutral cues. Clinical implications are discussed.

Δ9-Tetrahydrocannabinol at Retrieval Drives False Recollection of Neutral and Emotional Memories

BackgroundIt is well established that the main psychoactive constituent of cannabis, Δ9-tetrahydrocannabinol (THC), impairs episodic memory encoding and modulates emotional processing, but little is known about the impact of THC during the retrieval of emotional episodic memories. With the rise of cannabis to treat medical conditions, including those characterized by emotional and episodic memory disturbances, there is an urgent need to determine the effects of THC on memory accuracy and distortion. Here, we report the first study investigating the effects of THC during retrieval of neutral and emotional episodic memories. MethodsUsing a double-blind, placebo-controlled, within-subjects design, healthy volunteers (N = 23) viewed negative, neutral, and positive pictures (emotional memory task) and lists of semantically related words (false memory task). Forty-eight hours later, participants ingested a capsule containing either THC (15 mg) or placebo and completed tasks to test their memories for the previously studied pictures and words. ResultsTHC during retrieval did not reduce the number of correct responses to studied items. Instead, it robustly increased false recollection on both the emotional memory and false memory tasks. This effect was found for both neutral and emotional items. ConclusionsThese findings show that THC has adverse effects during memory retrieval, distorting both neutral and emotional memories. Coupled with THC’s known effects during encoding, these new retrieval findings are important in light of the spreading acceptance of cannabis.

Emerging Directions in Emotional Episodic Memory.

Building upon the existing literature on emotional memory, the present review examines emerging evidence from brain imaging investigations regarding four research directions: (1) Social Emotional Memory, (2) The Role of Emotion Regulation in the Impact of Emotion on Memory, (3) The Impact of Emotion on Associative or Relational Memory, and (4) The Role of Individual Differences in Emotional Memory. Across these four domains, available evidence demonstrates that emotion- and memory-related medial temporal lobe brain regions (amygdala and hippocampus, respectively), together with prefrontal cortical regions, play a pivotal role during both encoding and retrieval of emotional episodic memories. This evidence sheds light on the neural mechanisms of emotional memories in healthy functioning, and has important implications for understanding clinical conditions that are associated with negative affective biases in encoding and retrieving emotional memories.

Hierarchical emotional episodic memory for social human robot collaboration

For social human robot collaboration, robots need to effectively remember human experiences and manage emotional experiences as well as repetitive experiences. To implement these functions, the hierarchical emotional episodic memory, using deep adaptive resonance theory network, is proposed in this paper. The proposed memory not only learns emotional experiences, but also has the ability to anticipate future emotional situations. Two parameter modulation processes, delayed consolidation and instant update, are provided. These make emotional experiences reinforce faster, remain for longer, and become more stable and sensitive to analogous experiences. Simulation analysis is conducted to verify the proposed memory, and an experiment is carried out in a kitchen environment to demonstrate social human robot collaboration.

MDMA Impairs Both the Encoding and Retrieval of Emotional Recollections.

The psychoactive drug ±3,4-methylenedioxymethamphetamine (MDMA) is increasingly used for its perceived emotional effects (eg, prosociality, empathy, psychotherapy), but surprisingly little research has been aimed at identifying the effect of the drug on emotional episodic memory in humans. Here, we report the first double-blind placebo-controlled study to examine the effects of MDMA on emotional memory separately during encoding and retrieval in healthy participants. Participants viewed emotionally negative, neutral, and positive pictures and their labels. Forty-eight hours later, they were given cued recollection and recognition memory tests designed to assess recollection and familiarity for the studied pictures. Participants were randomly assigned to one of three groups who received MDMA (1 mg/kg) either during encoding (Encoding group; N=20), retrieval (Retrieval group; N=20), or neither (Placebo group; N=20). Although MDMA administered at either phase did not affect overall memory accuracy, it did alter the recollection of details associated specifically with emotional memories as estimated using a dual process signal detection analysis of confidence judgments and subjective 'remember' judgments. In the Encoding group, MDMA reduced recollection estimates for negative and positive pictures but had little to no effect on neutral items or familiarity estimates. There was evidence for similar trends in the Retrieval group. These findings indicate that MDMA attenuates the encoding and retrieval of salient details from emotional events, consistent with the idea that its potential therapeutic effects for treating posttraumatic stress disorder are related to altering emotional memory.

Disruption of amygdala-entorhinal-hippocampal network in late-life depression.

Episodic memory deficits are evident in late-life depression (LLD) and are associated with subtle synaptic and neurochemical changes in the medial temporal lobes (MTL). However, the particular mechanisms by which memory impairment occurs in LLD are currently unknown. We tested older adults with (DS+) and without (DS-) depressive symptoms using high-resolution fMRI that is capable of discerning signals in hippocampal subfields and amygdala nuclei. Scanning was conducted during performance of an emotional discrimination task used previously to examine the relationship between depressive symptoms and amygdala-mediated emotional modulation of hippocampal pattern separation in young adults. We found that hippocampal dentate gyrus (DG)/CA3 activity was reduced during correct discrimination of negative stimuli and increased during correct discrimination of neutral items in DS+ compared to DS- adults. The extent of the latter increase was correlated with symptom severity. Furthermore, DG/CA3 and basolateral amygdala (BLA) activity predicted discrimination performance on negative trials, a relationship that depended on symptom severity. The impact of the BLA on depressive symptom severity was mediated by the DG/CA3 during discrimination of neutral items, and by the lateral entorhinal cortex (LEC) during false recognition of positive items. These results shed light on a novel mechanistic account for amygdala-hippocampal network changes and concurrent alterations in emotional episodic memory in LLD. The BLA-LEC-DG/CA3 network, which comprises a key pathway by which emotion modulates memory, is specifically implicated in LLD. © 2017 Wiley Periodicals, Inc.

Neutral mood induction during reconsolidation reduces accuracy, but not vividness and anxiety of emotional episodic memories

Background and objectivesConsolidated memories become labile upon reactivation and as a result have to go through reconsolidation to become re-stabilized. This property of memory may potentially be used to reduce the impact of highly negative episodic memories. Because detailed and vivid negative memories are mediated by high arousal, if arousal is lessened during reconsolidation, memory accuracy and vividness should diminish. In this study, we examined this hypothesis. MethodsParticipants (N = 72) viewed a stressful, suspenseful video on Day 1 to develop negative episodic memories. Then, 24–29 h later, they saw a brief reminder of the stressful video (or not), and then viewed a neutral, calming (or positive) video. Another 24–29 h later, participants were tested on the accuracy, vividness, and anxiety associated with their memory of the stressful video on Day 1. ResultsParticipants who watched the reminder and then the neutral video showed reduced memory accuracy compared to participants in the other groups. Despite the reduction in memory accuracy, their memory vividness and anxiety associated with the stressful video did not decrease. LimitationsThe use of undergraduates prevents generalizations to clinical populations. Also, the study did not test long-term memories that were more than 2 days old. ConclusionsNeutral mood induction during reconsolidation reduces the accuracy of highly negative episodic memories.

Olfactory memory networks: from emotional learning to social behaviors.

EDITORIAL article Front. Behav. Neurosci., 17 February 2015Sec. Learning and Memory Volume 9 - 2015 | https://doi.org/10.3389/fnbeh.2015.00036

New learning following reactivation in the human brain: Targeting emotional memories through rapid serial visual presentation

Once reactivated, previously consolidated memories destabilize and have to be reconsolidated to persist, a process that might be altered non-invasively by interfering learning immediately after reactivation. Here, we investigated the influence of interference on brain correlates of reactivated episodic memories for emotional and neutral scenes using event-related potentials (ERPs). To selectively target emotional memories we applied a new reactivation method: rapid serial visual presentation (RSVP). RSVP leads to enhanced implicit processing (pop out) of the most salient memories making them vulnerable to disruption. In line, interference after reactivation of previously encoded pictures disrupted recollection particularly for emotional events. Furthermore, memory impairments were reflected in a reduced centro-parietal ERP old/new difference during retrieval of emotional pictures. These results provide neural evidence that emotional episodic memories in humans can be selectively altered through behavioral interference after reactivation, a finding with further clinical implications for the treatment of anxiety disorders.

DISC1 gene and affective psychopathology: A combined structural and functional MRI study

The gene Disrupted-In-Schizophrenia-1 (DISC1) has been indicated as a determinant of psychopathology, including affective disorders, and shown to influence prefrontal cortex (PFC) and hippocampus functioning, regions of major interest for affective disorders. We aimed to investigate whether DISC1 differentially modulates brain function during executive and memory processing, and morphology in regions relevant for depression and anxiety disorders (affective disorders). 128 participants, with (n = 103) and without (controls; n = 25) affective disorders underwent genotyping for Ser704Cys (with Cys-allele considered as risk-allele) and structural and functional (f) Magnetic Resonance Imaging (MRI) during visuospatial planning and emotional episodic memory tasks. For both voxel-based morphometry and fMRI analyses, we investigated the effect of genotype in controls and explored genotypeXdiagnosis interactions. Results are reported at p < 0.05 FWE small volume corrected. In controls, Cys-carriers showed smaller bilateral (para)hippocampal volumes compared with Ser-homozygotes, and lower activation in the anterior cingulate cortex (ACC) and dorsolateral PFC during visuospatial planning. In anxiety patients, Cys-carriers showed larger (para)hippocampal volumes and more ACC activation during visuospatial planning. In depressive patients, no effect of genotype was observed and overall, no effect of genotype on episodic memory processing was detected. We demonstrated that Ser704Cys-genotype influences (para)hippocampal structure and functioning the dorsal PFC during executive planning, most prominently in unaffected controls. Results suggest that presence of psychopathology moderates Ser704Cys effects.

A single bout of resistance exercise can enhance episodic memory performance

Acute aerobic exercise can be beneficial to episodic memory. This benefit may occur because exercise produces a similar physiological response as physical stressors. When administered during consolidation, acute stress, both physical and psychological, consistently enhances episodic memory, particularly memory for emotional materials. Here we investigated whether a single bout of resistance exercise performed during consolidation can produce episodic memory benefits 48h later. We used a one-leg knee extension/flexion task for the resistance exercise. To assess the physiological response to the exercise, we measured salivary alpha amylase (a biomarker of central norepinephrine), heart rate, and blood pressure. To test emotional episodic memory, we used a remember-know recognition memory paradigm with equal numbers of positive, negative, and neutral IAPS images as stimuli. The group that performed the exercise, the active group, had higher overall recognition accuracy than the group that did not exercise, the passive group. We found a robust effect of valence across groups, with better performance on emotional items as compared to neutral items and no difference between positive and negative items. This effect changed based on the physiological response to the exercise. Within the active group, participants with a high physiological response to the exercise were impaired for neutral items as compared to participants with a low physiological response to the exercise. Our results demonstrate that a single bout of resistance exercise performed during consolidation can enhance episodic memory and that the effect of valence on memory depends on the physiological response to the exercise.

Poster #M11 LONG-TERM EFFECTS OF NEONATAL MK-801 TREATMENT ON PROTEIN TRANSLATION SIGNAL PATHWAY IN THE RAT FRONTAL CORTEX

The gene Disrupted-In-Schizophrenia-1 (DISC1) has been indicated as a determinant of psychopathology, including affective disorders, and shown to influence prefrontal cortex (PFC) and hippocampus functioning, regions of major interest for affective disorders. We aimed to investigate whether DISC1 differentially modulates brain function during executive and memory processing, and morphology in regions relevant for depression and anxiety disorders (affective disorders). 128 participants, with (n = 103) and without (controls; n = 25) affective disorders underwent genotyping for Ser704Cys (with Cys-allele considered as risk-allele) and structural and functional (f) Magnetic Resonance Imaging (MRI) during visuospatial planning and emotional episodic memory tasks. For both voxel-based morphometry and fMRI analyses, we investigated the effect of genotype in controls and explored genotypeXdiagnosis interactions. Results are reported at p < 0.05 FWE small volume corrected. In controls, Cys-carriers showed smaller bilateral (para)hippocampal volumes compared with Ser-homozygotes, and lower activation in the anterior cingulate cortex (ACC) and dorsolateral PFC during visuospatial planning. In anxiety patients, Cys-carriers showed larger (para)hippocampal volumes and more ACC activation during visuospatial planning. In depressive patients, no effect of genotype was observed and overall, no effect of genotype on episodic memory processing was detected. We demonstrated that Ser704Cys-genotype influences (para)hippocampal structure and functioning the dorsal PFC during executive planning, most prominently in unaffected controls. Results suggest that presence of psychopathology moderates Ser704Cys effects.

An electroconvulsive therapy procedure impairs reconsolidation of episodic memories in humans

Despite accumulating evidence for a reconsolidation process in animals, support in humans, especially for episodic memory, is limited. Using a within-subjects manipulation, we found that a single application of electroconvulsive therapy following memory reactivation in patients with unipolar depression disrupted reactivated, but not non-reactivated, memories for an emotional episode in a time-dependent manner. Our results provide evidence for reconsolidation of emotional episodic memories in humans.

β-Adrenergic blockade during reactivation reduces the subjective feeling of remembering associated with emotional episodic memories

In contrast to neutral events, emotionally arousing events often are remembered vividly and with great detail. Although generally adaptive to survival, this emotional memory enhancement may contribute to psychopathology. Blocking the arousal-related noradrenergic activity with a β blocker shortly after learning prevents the emotional enhancement of memory. In the present experiment, we tested in 48 healthy subjects whether the administration of the β blocker propranolol before the reactivation of already consolidated emotional episodic memories may interfere with their reconsolidation and, thus, reduce the subsequent feeling of remembering associated with these memories. Our results show that propranolol before reactivation abolished the superior memory for emotional relative to neutral stimuli and decreased ‘remember’ judgments for emotional items, suggesting that β-adrenergic blockade during reactivation made emotional memories comparable to neutral memories.

Neural Signature of Reconsolidation Impairments by Propranolol in Humans

The retrieval of consolidated memories may result in their destabilization, requiring a restabilization process called reconsolidation. During reconsolidation, memories become sensitive to psychological and pharmacological modifications again, thus providing an opportunity to alter unwanted memories. Although such reconsolidation manipulations might open the door to novel treatment approaches for psychiatric disorders such as posttraumatic stress disorder, the brain mechanisms underlying reconsolidation processes in humans are completely unknown. Here, we asked whether a β-adrenergic receptor antagonist might interfere with the reconsolidation of emotional episodic memories and what brain mechanisms are involved in these effects. Healthy participants were administered the β-adrenergic receptor antagonist propranolol or a placebo before they reactivated previously learned neutral and emotional material. Recognition memory was tested 24 hours later. Functional magnetic resonance images were collected during reactivation and recognition testing. Propranolol during reactivation specifically reduced the subsequent memory for emotional pictures; memory for neutral pictures remained unaffected. This emotional memory impairment was associated with significantly increased activity in the amygdala and the hippocampus for correctly recognized pictures at test. Most interestingly, the same structures were active (but not modulated by propranolol) during memory reactivation. Memory reactivation alone or propranolol without reactivation had no effect on subsequent memory. Our results demonstrate how the consequences of memory reconsolidation processes are represented in the human brain, suggesting that the brain areas that are recruited during reactivation undergo changes in activity that are associated with subsequent memory recall.

Immediate recall influences the effects of pre-encoding stress on emotional episodic long-term memory consolidation in healthy young men

The stress-associated activation of the hypothalamus–pituitary–adrenal axis influences memory. Several studies have supported the notion that post-learning stress enhances memory consolidation, while pre-retrieval stress impairs retrieval. Findings regarding the effects of pre-encoding stress, in contrast, have been rather inconsistent. In the current two studies, the impact of an immediate retrieval task on these effects was explored. In the first study, 24 healthy young male participants were exposed to a psychosocial laboratory stressor (Trier Social Stress Test) or a control condition before viewing positive, negative, and neutral photographs, which were accompanied by a brief narrative. Immediate as well as delayed (24 h later) free recall was assessed. Stress was expected to enhance emotional long-term memory without affecting immediate recall performance. Stress caused a significant increase in salivary cortisol concentrations but had no significant effects on immediate or delayed retrieval performance, even though a trend toward poorer memory of the stress group was apparent. Based on these findings, the second experiment tested the hypothesis that the beneficial effects of stress on emotional long-term memory performance might be abolished by an immediate recall test. In the second study (n = 32), the same design was used, except for the omission of the immediate retrieval test. This time stressed participants recalled significantly more negative photographs compared to the control group. The present study indicates that an immediate retrieval attempt of material studied after stress exposure can prevent or even reverse the beneficial effects of pre-encoding stress on emotional long-term memory consolidation.

Affective psychotherapy in post-traumatic reactions guided by affective neuroscience: memory reconsolidation and play.

This paper reviews the affective neuroscience dealing with the effects of traumatic events. We give an overview of the normal fear reactions, the pathological fear reaction, and the character of emotional episodic memories. We find that both emotions and emotional memories are a tripartite unit of sensory information, autonomic reaction, and motor impulse (the PRM complex). We propose that emotions and movements are part and parcel of the same complex. This is our main finding from the review of affective neuroscience, and from here we focus on psychotherapy with post-trauma reactions. The finding of the process of memory reconsolidation opens up a new treatment approach: affective psychotherapy focused on reconsolidation. The meaning of reconsolidation is that an emotional memory, when retrieved and being active, will rest in a labile form, amenable to change, for a brief period of time, until it reconsolidates in the memory. This leads us to the conclusion that emotions, affects, must be evoked during the treatment session and that positive emotion must come first, because safety must be part of the new memories. In the proposed protocol of affective psychotherapy based on reconsolidation the emotional episodic memory is relived in a safe and positive setting, focused in turn on the sensory experience, the autonomic reaction, and the motor impulse. Then it is followed by a fantasy of a different positive version of the same event. All in all treatment should provide a series of new memories without fear related to the original event. With the focus on the motor program, and the actions, there is a natural link to art therapy and to the mode of play, which can rehearse and fantasize new positive actions.

Acute effects of alcohol on memory: Impact of emotional context and serial position

Although the amnestic effects of alcohol in humans are well known, its effects on emotional memory are unclear. In this study, using a randomized double-blind placebo-controlled design, we examine narrative emotional episodic memory in healthy human female volunteers ( n = 32) who received either a single dose of alcohol (0.6 g/kg), or a placebo and then viewed neutral story elements presented in either a neutral or emotional context. Memory was tested for gist and detail of the neutral elements 3 days later in a surprise recognition test. Since alcohol modulates GABAergic neurotransmission and may exert its effects on emotion through the limbic system, we predicted that acute alcohol treatment would reduce the expected emotional memory-advantage for gist, leaving detail memory relatively unaffected. Furthermore, given previous findings showing that ‘primacy’ memory is enhanced by physiological arousal, we predicted that reduced arousal produced by alcohol would have the opposite effect and impair primacy memory relative to the middle or ‘recency’ sections of the narrative. Emotional arousal was expected to oppose this effect, so impaired primacy memory following alcohol was only expected in the neutral version of the narrative. Although there was a main effect of story phase (though not of story version), contrary to expectations, alcohol impaired primacy memory for emotionally encoded neutral material. The results suggest that under certain circumstances emotional context or physiological arousal make memories labile and susceptible to disruption through pharmacological manipulation during encoding.

Investigation of sex differences in emotional episodic memory in schizophrenia patients: an fMRI study

Investigation of sex differences in emotional episodic memory in schizophrenia patients: an fMRI study

Towards Understanding Emotion's Effects on Memory

Emotion can exert powerful influences on memory for events. The recent surge of behavioral and functional neuroimaging studies of emotional episodic memory has produced a wealth of new findings and theoretical approaches. Kensinger (2009) reviews recent studies, focusing on two key questions: what factors determine the particular aspects of an event that will be influenced by emotion, and, what is the role of valence in modulating emotional memory effects? This commentary touches on some points raised in this thought-provoking and timely review and attempts to place them in a broader context.