Emotional Memory Consolidation Research Articles

Heart Rate Variability During Rapid Eye Movement Sleep is Associated with Reduced Negative Memory Bias.

Emotional memories change over time, but the mechanisms supporting this change are not well understood. Sleep has been identified as one mechanism that supports memory consolidation, with sleep selectively benefitting negative emotional consolidation at the expense of neutral memories, with specific oscillatory events linked to this process. In contrast, the consolidation of neutral and positive memories, compared to negative memories, has been associated with increased vagally-mediated vagal heart rate variability (HRV) during wakefulness. However, how HRV during sleep contributes to emotional memory consolidation remains unexplored. We investigated how sleep oscillations and vagal contributions during sleep contribute to the consolidation of neutral and negative memories. Using a double-blind, placebo-controlled, within-subject, cross-over design, we examined the impact of pharmacological vagal suppression using zolpidem on overnight emotional memory consolidation. Thirty-two participants encoded neutral and negative pictures in the morning, followed by picture recognition tests before and after a night of sleep. Zolpidem or placebo was administered in the evening before overnight sleep, and participants were monitored with electroencephalography and electrocardiography. In the placebo condition, greater overnight improvement for neutral pictures was associated with higher vagal HRV in both Non-Rapid Eye Movement Slow Wave Sleep (NREM SWS) and REM. Additionally, the emotional memory tradeoff (i.e., difference between consolidation of neutral versus negative memories) was associated with higher vagal HRV during REM, but in this case, neutral memories were remembered better than negative memories, indicating a potential role for REM vagal HRV in promoting a positive memory bias overnight. Zolpidem, on the other hand, reduced vagal HRV during SWS, increased NREM sigma power, and eliminated the positive memory bias. Lastly, we used a stepwise linear mixed effects regression to determine how NREM sigma power and vagal HRV during REM independently explained the variance in the emotional memory tradeoff effect. We found that the addition of vagal HRV in combination with sleep significantly improved the model's fit. Overall, our results suggest that sleep brain oscillations and vagal signals synergistically interact in the overnight consolidation of emotional memories, with REM vagal HRV critically contributing to the positive memory bias.

Temporal dynamics of negative emotional memory reprocessing during sleep

Memory reprocessing during sleep is a well-established phenomenon in numerous studies. However, it is unclear whether the intensity of memory reprocessing is consistently maintained throughout the night or exhibits dynamic changes. This study investigates the temporal dynamics of negative emotional memory reprocessing during sleep, with a specific focus on slow oscillation (SO)-spindle coupling and its role in memory reprocessing. In the first experiment (N = 40, mean age = 22.5 years), we detected the negative emotional memory reprocessing strength in each sleep cycle, we found that the 2nd sleep cycle after negative emotional memory learning constitute the most sensitive window for memory reprocessing, furthermore, SO-spindle coupling signals in this window plays a role in stabilizing negative emotional memory. To verify the role of SO-spindle coupling in negative emotional memory reprocessing, we utilized transcranial alternating current stimulation (tACS) to disrupt SO-spindle coupling during the 2nd sleep cycle (N = 21, mean age = 19.3 years). Notably, the outcomes of the tACS intervention demonstrated a significant reduction in the recognition of negative emotional memories. These findings offer new insights into the mechanisms that regulate emotional memory consolidation during sleep and may have implications for addressing psychiatric disorders associated with pathological emotional memory.

A theoretical model of emotional processing in visual artmaking and art therapy

Current theoretical models of emotional processing rely mainly on detecting emotional processing through verbal, conscious, and cognitive processes. However, artmaking can potentially reveal embodied and implicit processes that may otherwise remain hidden in verbal expression. This paper attempts to close the scholarly gap by introducing a novel art-based emotional processing model that integrates emotional processing and art therapy literature, incorporating emotional meaning-making, awareness, acceptance, and memory consolidation. The art-based EP model explains the processes through which art creation may benefit emotional processing. It also elucidates the ways in which art therapy can be used to enhance therapeutic outcomes.

The Involvement of the Serotonergic System in Ketamine and Fluoxetine Combination-induced Cognitive Impairments in Mice.

Glutamatergic N-methyl-D-aspartate (NMDA) receptors play vital roles in memory formation. Changes in the activity of these receptors influence memory processes. Ketamine is a noncompetitive NMDA receptor antagonist drug with promising mood-altering and pain-reducing effects in low doses. These effects are believed to be related to altered serotonergic transmission. The present study investigated the involvement of the serotonergic system in low-dose ketamine administrations' effects on memory acquisition, consolidation, and retrieval processes. Sixty-four male BALB/c mice were used in this experiment and separated into 8t groups. Mice were treated subchronically with a selective serotonin reuptake inhibitor, fluoxetine, and a serotonin depletion agent, p-chlorophenylalanine (pCPA). A serotonin antagonist, methiothepin, and ketamine were acutely administered 60 minutes before or after the behavioral tests. A passive avoidance (PA) test measured emotional memory acquisition, consolidation, and retrieval processes. Hippocampi malondialdehyde (MDA) levels were analyzed, and histopathological examinations were performed. Ketamine alone did not significantly affect memory encoding processes in the PA test, while the ketamine-fluoxetine combination disrupted memory consolidation. Fluoxetine negatively affected the memory acquisition process, which was normalized during the consolidation and retrieval trials. Drug applications did not significantly alter hippocampal MDA levels. In all ketamine-applied groups, histopathologic alterations were evident. Low-dose ketamine administration induces neurodegeneration, and it also impairs memory functions when combined with fluoxetine, indicating increased serotonergic transmission may be involved in the memory-impairing and neurotoxic effects of ketamine.

Consolidation of emotional memory during waking rest depends on trait anxiety

A short period of eyes-closed waking rest improves long-term memory for recently learned information, including declarative, spatial, and procedural memory. However, the effect of rest on emotional memory consolidation remains unknown. This preregistered study aimed to establish whether post-encoding rest affects emotional memory and how anxiety levels might modulate this effect. Participants completed a modified version of the dot-probe attention task that involved reacting to and encoding word stimuli appearing underneath emotionally negative or neutral photos. We tested the effect of waking rest on memory for these words and pictures by manipulating the state that participants entered just after this task (rest vs. active wake). Trait anxiety levels were measured using the State-Trait Anxiety Inventory and examined as a covariate. Waking rest improved emotional memory consolidation for individuals high in trait anxiety. These results suggest that the beneficial effect of waking rest on memory extends into the emotional memory domain but depends on individual characteristics such as anxiety.

Musical Perception and Social Context in emotional memory consolidation

Musical Perception and Social Context in emotional memory consolidation

0067 The Effect of Aging on Emotional Memory Encoding and Consolidation over Sleep and Wake

0067 The Effect of Aging on Emotional Memory Encoding and Consolidation over Sleep and Wake

The impact of daytime sleep on emotional memory consolidation and reactivity

The impact of daytime sleep on emotional memory consolidation and reactivity

Age-related positivity effect in emotional memory consolidation from middle age to late adulthood.

While younger adults are more likely to attend to, process, and remember negative relative to positive information, healthy older adults show the opposite pattern. The current study evaluates when, exactly, this positivity shift begins, and how it influences memory performance for positive, negative, and neutral information. A total of 274 healthy early middle-aged (35-47), late middle-aged (48-59), and older adults (>59) viewed scenes consisting of a negative, positive, or a neutral object placed on a plausible neutral background, and rated each scene for its valence and arousal. After 12 h spanning a night of sleep (n = 137) or a day of wakefulness (n = 137), participants completed an unexpected memory test during which they were shown objects and backgrounds separately and indicated whether the scene component was the "same," "similar," or "new" to what they viewed during the study session. We found that both late middle-aged and older adults rated positive and neutral scenes more positively compared to early middle-aged adults. However, only older adults showed better memory for positive objects relative to negative objects, and a greater positive memory trade-off magnitude (i.e., remembering positive objects at the cost of their associated neutral backgrounds) than negative memory trade-off magnitude (i.e., remembering negative objects at the cost of their associated neutral backgrounds). Our findings suggest that while the positivity bias may not emerge in memory until older adulthood, a shift toward positivity in terms of processing may begin in middle age.

Current Perspective on Sleep and Emotion Regulation

This article explores the correlation between emotions and sleep. Sleep plays an essential role in regulating our emotions and cognitive processes. Extensive research demonstrates the intricate connection between sleep and emotional well-being. During sleep, the brain engages in vital activities that influence emotional memory consolidation, regulation, and cognitive functioning. Insufficient sleep or sleep deprivation has detrimental impacts on various brain functions related to emotions. These include impairments in working memory and attention, disruptions in dopamine function, and altered processing of aversive stimuli. Sleep deprivation can also influence different components of the emotion regulation process model. Furthermore, sleep abnormalities have been linked to several mental disorders, including post-traumatic stress disorder (PTSD) and major depression. Understanding the intricate relationship between sleep and emotions can provide valuable insights into developing effective interventions for individuals with sleep disorders or mental health conditions. Promoting healthy sleep habits and addressing sleep disturbances can improve emotional regulation and overall well-being. Additionally, exploring the reciprocal relationship between sleep and emotional processes can contribute to advancements in therapeutic interventions for mental health disorders, ultimately improving the quality of life for affected individuals.

Sleep and memory consolidation in healthy, neurotypical children, and adults: a summary of systematic reviews and meta-analyses.

This review systematically assesses the impact of sleep on memory and cognition in healthy individuals across different life stages. It specifically examines how sleep affects memory processes in children, adults, and older adults. The methodology involved a comprehensive literature search, starting with 46 known papers. Keywords and Mesh terms related to sleep and memory consolidation were derived using the Word Frequency Analysis tool in SR Accelerator and Mesh on Demand. A detailed search on PubMed yielded a large set of records. Classifier training on 4854 decisions, these were narrowed down to 1437 papers for full-text screening, culminating in 19 systematic reviews and meta-analyses. Sleep enhances memory consolidation, especially for complex declarative information. While the role of sleep in procedural memory consolidation in children remains less robust compared to declarative memory, findings suggest potential but inconsistent benefits. Sleep improves prospective memory consolidation and aids in complex associative memory tasks. Memory reactivation during sleep, specifically slow-wave sleep, and spindles are implicated in memory consolidation. Meta-analytic evidence suggests that while sleep benefits both emotional and neutral memory consolidation, there is no strong preferential effect of sleep on emotional memory in comparison to neutral memory. In older adults, there is a noticeable reduction in sleep-dependent memory consolidation, particularly for declarative memory, likely linked to a decline in slow-wave sleep. This suggests a decrease in the benefits of sleep for memory consolidation with aging. Overall, the review underscores the importance of sleep in memory processes across all ages, highlighting variations in its impact on different types of memory and across age groups. It points to future research directions for enhancing understanding and practical applications in clinical and educational settings.

The role and mechanisms of sleep on memory consolidation

In addition to its physiological functions, sleep also has a consolidating effect on memory, and current research has found sleep could promote the consolidation of declarative, procedural, and emotional memory. Possible mechanisms of sleep-enhanced memory include the the systemic consolidation theory, dual-process theory, the synaptic homeostasis theory, and the sequence hypothesis. In the future, more research need to examine the neural mechanisms of sleep-enhanced memory consolidation, and the use of simultaneous EEG-MRI will be a meaningful attempt to help us better understand the specific neural processes of sleep-enhanced memory consolidation.

P020 Exploring the Roles of Individual Rapid Eye Movement Sleep Parameters in Emotional Memory Processing

Abstract Background Maladaptive emotional memory processing is thought to underpin intrusion symptoms experienced by individuals with post-traumatic stress disorder (PTSD). Curtailment of rapid eye movement sleep (REMS) impairs emotional memory consolidation (EMC) and is proposed to contribute to the development of PTSD. However, the effects of altered REMS quality remain less explored. The present study aims to investigate the potential ability of REM percentage, REM latency, and REMS fragmentation to predict EMC. Methods The study forms part of a larger study investigating the effects of suvorexant and temazepam on REMS and EMC. Healthy participants view a series of emotionally positive, negative and neutral images, undergo overnight polysomnography with a study drug or placebo, and are assessed for recognition 48 hours after viewing the images. REMS architecture metrics are derived from polysomnographic data. EMC is calculated based on signal detection theory (d′ = z(hit rate) − z(false alarm rate)). Results Data collection is ongoing with 11 participants’ data being collected. A one-way ANOVA reveals a main effect of valence, with positive and negative images being recognised better than the neutral (p(positive-neutral) = .039, p(negative-neutral) = .039). REMS parameters do not significantly predict EMC when accounting for image valence, possibly due to low statistical power. Discussion Given existing literature supporting the contribution of REMS on emotional memory processing, promoting high-quality REMS may help facilitate adaptive EMC. Further data is required to examine this effect.

The modulation of emotional memory consolidation by dream affect

IntroductionResearch in the field of cognitive neuroscience has focused on the role of sleep in various neurocognitive processes such as memory consolidation. However, an area that has not been adequately researched is the role of dreaming in this memory process. This study aimed to determine the relationship between affect experienced in dreams and emotional memory consolidation. Considering that REM dreams are laden with emotion and that emotion enhances memory, one possibility is that dream affect could also play a role in emotional memory consolidation. We hypothesised that greater dream-related affect would be associated with greater memory retention of emotional but not neutral information.Methods126 healthy participants, aged 18–35, were recruited for the online study, of which 103 participants had valid data (female: n =73). On the night of the study, participants viewed a series of pictures from the South African Affective Picture System (SA-APS) in an online session. Afterwards, they verbally recalled as many pictures as possible. The following morning, they were asked to recall any dreams and rate the emotional intensity of their dreams. Participants then again verbally recalled all the pictures that they could remember from the previous night.ResultsContrary to the prediction, dream-related affect, regardless of valence, did not predict memory consolidation of positive or negative information. Instead, increases in dream-related affect, and especially anxiety were predictive of better memory retention of all information. The findings also showed that an increase in negative affect in dreams predicted better memory retention of negative information.DiscussionOur results suggest that dream affect is an important modulator of memory consolidation processes occurring during sleep. Furthermore, increased negative affect may indicate which experiences are salient and require consolidation to form long-lasting memories that can guide future behaviour.ConclusionThese findings have implications for psychiatric disorders, such as major depression, which is characterised by negative affect and increased memory sensitivity to negative stimuli.

Emotional memory consolidation during sleep is associated with slow oscillation-spindle coupling strength in young and older adults.

Emotional memories are processed during sleep; however, the specific mechanisms are unclear. Understanding such mechanisms may provide critical insight into preventing and treating mood disorders. Consolidation of neutral memories is associated with the coupling of NREM sleep slow oscillations (SOs) and sleep spindles (SPs). Whether SO-SP coupling is likewise involved in emotional memory processing is unknown. Furthermore, there is an age-related emotional valence bias such that sleep consolidates and preserves reactivity to negative but not positive emotional memories in young adults and positive but not negative emotional memories in older adults. If SO-SP coupling contributes to the effect of sleep on emotional memory, then it may selectively support negative memory in young adults and positive memory in older adults. To address these questions, we examined whether emotional memory recognition and overnight change in emotional reactivity were associated with the strength of SO-SP coupling in young (n = 22) and older (n = 32) adults. In younger adults, coupling strength predicted negative but not positive emotional memory performance after sleep. In contrast, coupling strength predicted positive but not negative emotional memory performance after sleep in older adults. Coupling strength was not associated with emotional reactivity in either age group. Our findings suggest that SO-SP coupling may play a mechanistic role in sleep-dependent consolidation of emotional memories.

Does the brain sleep differently depending on intellectual abilities?

To compare the children's sleep electroencephalogram according to their intellectual profile. Children were grouped according to their Wechsler Intelligence Scale for Children (WISC) scores (17 with normal intelligence quotient [IQ, NIQ] and 24 with high IQ [HIQ]). Comparisons of spectral power between groups and its relationship with WISC scores were assessed using analyses of variance and linear regression models, adjusted for age and sex. Children with HIQ had more rapid eye movement (REM) sleep, especially late at night, and more power in slow-frequency bands during REM sleep than those with NIQ. There were also positive associations between the processing speed index and the spectral power in β bands in NREM sleep, and with the spectral power in α, σ, β, and γ bands in REM sleep, with different associations between groups. The enhanced power in slow bands during REM sleep in children with HIQ overlaps with that of typical REM sleep oscillations thought to be involved in emotional memory consolidation. The dissimilar relationships between spectral power and WISC scores in NIQ and HIQ groups may underlie functional differences in brain activity related to cognitive efficiency, questioning the direction of the relationship between sleep and cognitive functioning.

0069 Effects of Depression and Anxiety Symptoms on Sleep-Dependent Consolidation of Emotional Memory in College Students

Abstract Introduction Depression and anxiety have been associated with emotional memory biases, disturbed sleep, and cognitive deficits. The goal of the present study is to investigate the effects of elevated levels of depressive and anxiety symptoms on sleep physiology and sleep-dependent consolidation of emotional memory and reactivity over a mid-day nap in young college students. Methods Data collection is ongoing, preliminary analyses are based on 34 participants (26F, 7M, 1 non-binary, 18-27 yrs). Based on well-validated depression and anxiety scales, participants were classified into high (n=10) vs low (n=24) symptom groups. Participants studied negative and neutral picture stimuli and rated them on the dimensions of valence and arousal. Recognition memory was tested after a 5 hr interval which included a high-density EEG monitored 90 min nap. Results We do not observe any group differences in memory accuracy (d’) or in selectivity for emotional stimuli. In the entire sample, depressive symptoms correlate with decision criterion (C) for negative stimuli (r = -0.357, p=.04), such that individuals with higher depressive symptoms have a more liberal responding bias for negative stimuli. Napping is associated with a decrease in arousal ratings across all participants (F(1,32)=5.43, p=.03), and the high mood symptom group rate stimuli as more arousing (F(1,32)=13.96, p<.001). Further, high levels of trait anxiety is associated with more negative valence ratings post-nap (r = -0.350, p=.03). Conclusion The effects of a mid-day nap on memory consolidation and reactivity for emotional stimuli are similar between individuals with high vs low levels of mood symptoms, but heightened levels of depression and anxiety are associated with altered response bias and higher emotional reactivity. Future plans involve comparisons of NREM oscillations between groups and investigation of their relations with task performance. Support (if any) Iowa Neuroscience Institute “2021 Ideas Lab” Award (Baran)

Dose-Dependent Atrophy in Bilateral Amygdalae and Nuclei After Brain Radiation Therapy and Its Association With Mood and Memory Outcomes on a Longitudinal Clinical Trial

Amygdalae, bilateral almond-shaped structures located anterior to the hippocampi, are critical to limbic system functions of emotional processing and memory consolidation. The amygdalae are heterogeneous, composed of multiple nuclei with distinct structural and functional properties. We prospectively assessed associations between longitudinal changes in amygdala morphometry, including component nuclei, and functional outcomes in primary brain tumor patients receiving radiation therapy (RT). On a prospective longitudinal trial, patients (n=63) underwent high-resolution volumetric brain MRI and testing for mood (Beck Depression Inventory [BDI]; Beck Anxiety Inventory [BAI]), memory (BVMT-Total/Delayed Recall; HVLT-Total/Delayed Recall) and health-related quality of life (hrQOL) outcomes (FACT-Br Social/Emotional Well-being) at baseline, 3, 6, and 12-months post-RT. Amygdalae, including eight nuclei, were auto-segmented bilaterally using validated techniques. Linear mixed effects models assessed longitudinal change in amygdalae/nuclei volumes, and association with dose and outcomes. Wilcoxon rank sum tests compared amygdala volume change between subject groups with worse and stable outcomes at each timepoint. We found atrophy in the right amygdala at 6 months (p=0.001) and the left amygdala at 12 months (p=0.046). Higher dose was associated with atrophy of the left amygdala (p=0.013) at 12 months. Right amygdala showed dose-dependent atrophy at 6 months (p=0.016) and 12 months (p=0.001). Worse BVMT-Total, HVLT-Total and HVLT-Delayed performance was associated with smaller left lateral (p= 0.014, p=0.004, p=0.007) and left basal (p=0.034, p=0.016, p=0.026) nuclei volumes. Increased anxiety at 6 months was associated with greater combined (p=0.031) and right (p=0.007) amygdala atrophy. Greater left amygdala atrophy (p=0.038) was noted in patients with decreased emotional well-being at 12 months. Bilateral amygdalae and nuclei undergo time- and dose-dependent atrophy after brain RT. Atrophy in amygdalae and specific nuclei was associated with poorer memory, mood, and emotional well-being. Amygdalae-sparing treatment planning may preserve neurocognitive and neuropsychiatric outcomes in this population.

Differential effects of acute exercise on emotional memory in men and women.

Exercise may change emotional memory, which is associated with the induction of mental disorders such as depression and anxiety. This effect of exercise may be influenced by exercise-induced cortisol release. Depending on sex, cortisol exerts differential effects on emotional memory consolidation. However, whether acute exercise and exercise-induced cortisol release have sex-dependent effects on emotional memory has not been established. Therefore, first, we aimed to determine the effects of acute exercise on emotional memory, separately for men and women, in a within-subjects design. Second, we aimed to examine whether the effects of acute exercise on emotional memory are related to the effects of exercise-induced cortisol release, separately for men and women. Sixteen healthy men and 15 healthy women were presented with positive and negative emotional images, followed by either rest or a vigorous-intensity cycling exercise condition using a within-subjects design on separate days. Salivary cortisol was measured before presenting the emotional images presentation and 20 min after each intervention. Emotional memory was assessed two days later. Vigorous-intensity exercise decreased emotional memory in women, whereas there was no change in men after rest or exercise. Cortisol levels increased after exercise intervention in both men and women, although there was no association between cortisol levels and emotional memory. These findings demonstrate that the effect of a single bout of vigorous-intensity exercise on emotional memory differs between men and women and is associated with decreased emotional memory in women.

Regulation of dendritic spines in the amygdala following sleep deprivation.

The amygdala is a hub of emotional circuits involved in the regulation of cognitive and emotional behaviors and its critically involved in emotional reactivity, stress regulation, and fear memory. Growing evidence suggests that the amygdala plays a key role in the consolidation of emotional memories during sleep. Neuroimaging studies demonstrated that the amygdala is selectively and highly activated during rapid eye movement sleep (REM) and sleep deprivation induces emotional instability and dysregulation of the emotional learning process. Regulation of dendritic spines during sleep represents a morphological correlate of memory consolidation. Several studies indicate that dendritic spines are remodeled during sleep, with evidence for broad synaptic downscaling and selective synaptic upscaling in several cortical areas and the hippocampus. Currently, there is a lack of information regarding the regulation of dendritic spines in the amygdala during sleep. In the present work, we investigated the effect of 5 h of sleep deprivation on dendritic spines in the mouse amygdala. Our data demonstrate that sleep deprivation results in differential dendritic spine changes depending on both the amygdala subregions and the morphological subtypes of dendritic spines. We observed decreased density of mushroom spines in the basolateral amygdala of sleep deprived mice, together with increased neck length and decreased surface area and volume. In contrast, we observed greater densities of stubby spines in sleep deprived mice in the central amygdala, indicating that downscaling selectively occurs in this spine type. Greater neck diameters for thin spines in the lateral and basolateral nuclei of sleep deprived mice, and decreases in surface area and volume for mushroom spines in the basolateral amygdala compared to increases in the cental amygdala provide further support for spine type-selective synaptic downscaling in these areas during sleep. Our findings suggest that sleep promotes synaptic upscaling of mushroom spines in the basolateral amygdala, and downscaling of selective spine types in the lateral and central amygdala. In addition, we observed decreased density of phosphorylated cofilin immunoreactive and growth hormone immunoreactive cells in the amygdala of sleep deprived mice, providing further support for upscaling of dendritic spines during sleep. Overall, our findings point to region-and spine type-specific changes in dendritic spines during sleep in the amygdala, which may contribute to consolidation of emotional memories during sleep.