Memory Inhibition Research Articles

A thalamic-hippocampal CA1 signal for contextual fear memory suppression, extinction, and discrimination

The adaptive regulation of fear memories is a crucial neural function that prevents inappropriate fear expression. Fear memories can be acquired through contextual fear conditioning (CFC) which relies on the hippocampus. The thalamic nucleus reuniens (NR) is necessary to extinguish contextual fear and innervates hippocampal CA1. However, the role of the NR-CA1 pathway in contextual fear is unknown. We developed a head-restrained virtual reality CFC paradigm, and demonstrate that mice can acquire and extinguish context-dependent fear responses. We found that inhibiting the NR-CA1 pathway following CFC lengthens the duration of fearful freezing epochs, increases fear generalization, and delays fear extinction. Using in vivo imaging, we recorded NR-axons innervating CA1 and found that NR-axons become tuned to fearful freezing following CFC. We conclude that the NR-CA1 pathway actively suppresses fear by disrupting contextual fear memory retrieval in CA1 during fearful freezing behavior, a process that also reduces fear generalization and accelerates extinction.

Higher visceral adipose tissue is associated with decreased memory suppression ability on food-related thoughts: A 1-year prospective ERP study

Memory about food and eating is crucial in regulating appetite and eating behaviors. Successfully stopping vivid imagination of delicious food could help reduce food craving and thus reduce the possibility of further intake. Memory inhibition is a cognitive process that involves intentional suppression of certain memories coming to consciousness. Successful memory suppression derives from inhibitory control. Although considerable work has consistently observed the impairment in motor or response inhibitory control among individuals with obesity, there has been a lack of investigation into the influence of bodyweight status on memory inhibitory control. To fill this gap, current study investigated behavioral and neurophysiological correlates of memory suppression in young women. Using Think/No-Think task and event-related potentials among 47 females, we found that participants with higher visceral adipose tissue (VAT) showed a tendency towards decreased suppression ability for memories related to food but not memories related to nonfood items. In depth analysis showed that decrease in the differences in P2 amplitudes between suppression vs. retrieval of food-related memories mediated the impairment of suppression ability by high VAT. We then tested whether individual differences in memory suppression ability as well as ERP correlates predicted future BMI or VAT change over 1-year follow-up. Results showed that P2 amplitudes when retrieving food-related memory could predict VAT change at 1-year follow-up among participants with healthy BMI. These observations suggest a hypersensitivity inference hypothesis underlying memory control impairments. To be specific, deficits in memory suppression may be in part resulted from elevated sensitivity to the cues coupling with food-related memory. It extends previous studies of memory suppression with food rewards and provides the first evidence to help understand the relationship between inhibitory control on food-related memory and obesity.

Thyroidectomy and PTU-Induced Hypothyroidism: Effect of L-Thyroxine on Suppression of Spatial and Non-Spatial Memory Related Signaling Molecules.

The calcium/calmodulin protein kinase II (CaMKII) signaling cascade is crucial for hippocampus-dependent learning and memory. Hypothyroidism impairs hippocampus- dependent learning and memory in adult rats, which can be prevented by simple replacement therapy with L-thyroxine (thyroxine, T4) treatment. In this study, we compared animal models of hypothyroidism induced by thyroidectomy and treatment with propylthiouracil (PTU) in terms of synaptic plasticity and the effect on underlying molecular mechanisms of spatial and non-spatial types of memory. Hypothyroidism was induced using thyroidectomy or treatment with propylthiouracil (PTU). L-thyroxin was used as replacement therapy. Synaptic plasticity was evaluated using in vivo electrophysiological recording. Training in the radial arm water maze (RAWM), where rats had to locate a hidden platform, generated spatial and non-spatial learning and memory. Western blotting measured signaling molecules in the hippocampal area CA1 area. Our findings show that thyroidectomy and PTU models are equally effective, as indicated by the identical plasma levels of thyroid stimulating hormone (TSH) and T4. The two models produced an identical degree of inhibition of synaptic plasticity as indicated by depression of long-term potentiation (LTP). For non-spatial memory, rats were trained to swim to a visible platform in an open swim field. Analysis of hippocampal area CA1 revealed that training, on both mazes, of control and thyroxine-treated hypothyroid rats, produced significant increases in the P-calcium calmodulin kinase II (P-CaMKII), protein kinase-C (PKCγ), calcineurin and calmodulin protein levels, but the training failed to induce such increases in untreated thyroidectomized rats. Thyroxine therapy prevented the deleterious effects of hypothyroidism at the molecular level.

Related neural networks underlie suppression of emotion, memory, motor processes as identified by data-driven analysis

BackgroundGoal-directed behavior benefits from self-regulation of cognitive and affective processes, such as emotional reactivity, memory retrieval, and prepotent motor response. Dysfunction in self-regulation is a common characteristic of many psychiatric disorders, such as PTSD and ADHD. This study sought to determine whether common intrinsic connectivity networks (ICNs; e.g. default mode network) are involved in the regulation of emotion, motor, and memory processes, and if a data-driven approach using independent component analysis (ICA) would successfully identify such ICNs that contribute to inhibitory regulation.MethodsEighteen participants underwent neuroimaging while completing an emotion regulation (ER) task, a memory suppression (Think/No-Think; TNT) task, and a motor inhibition (Stop Signal; SS) task. ICA (CONN; MATLAB) was conducted on the neuroimaging data from each task and corresponding components were selected across tasks based on interrelated patterns of activation. Subsequently, ICNs were correlated with behavioral performance variables from each task.ResultsICA indicated a common medial prefrontal network, striatal network, and frontoparietal executive control network, as well as downregulation in task-specific ROIs.ConclusionsThese results illustrate that common ICNs were exhibited across three distinct inhibitory regulation tasks, as successfully identified through a data-driven approach (ICA).

Sequence-dependent heterochromatin formation in the human malaria parasite Plasmodium falciparum

The human malaria parasite Plasmodium falciparum represses transcription of the gene encoding AP2-G, which is the master regulator of germ cell differentiation, via heterochromatin condensation following histone H3 lysine 9 trimethylation (H3K9me3). Although H3K9me3-marked heterochromatin is typically constitutive and its establishment depends on the RNA interference (RNAi) pathway in fission yeast centromeres, malaria parasites lack molecular members essential for RNAi. We developed a strategy to assess heterochromatin establishment on artificial chromosomes introduced into P. falciparum. We show that a particular DNA sequence in the AP2-G promoter is able to induce de novo H3K9me3 nucleosome deposition. In addition, we also found that the AP2-G promoter contains a distinct element required in maintenance of the repression memory. Thus, we speculate that malaria parasites have evolutionarily acquired a sequence-dependent establishment system of non-constitutive, i.e. facultative, H3K9me3-marked heterochromatin.

Suppression and Memory for Childhood Traumatic Events: Trauma Symptoms and Non-Disclosure.

Self-reported lost memory of child sexual abuse (CSA) can be mistaken for "repressed memory." Based on our longitudinal studies of memory and disclosure in child maltreatment victims who are now adults, we discuss findings relevant to "repressed memory cases." We examined relations between self-report of temporarily lost memory of CSA (subjective forgetting) and memory accuracy for maltreatment-related experiences (objective memory). Across two studies involving separate samples, we find evidence for memory suppression rather than repression: (1) Most adults who claimed temporary lost memory of CSA reported memory suppression and clarified that they could have remembered the event if asked; (2) subjective forgetting was positively associated with accurate objective memory for maltreatment-related experiences. Subjective forgetting was also related to increased adult trauma symptoms and related to childhood non-disclosure of CSA. Moreover, trauma-related psychopathology mediated the relation between non-disclosure and subjective forgetting. Implications for psychological theory and repressed memory cases are discussed.

Classification of transient epileptic amnesia attacks: Two types of amnestic seizures, the pure amnesia type and partial amnesia type.

Transient epileptic amnesia (TEA) is a type of mesial temporal lobe epilepsy characterized by recurrent amnesia attacks. In 1998, Zeman et al. proposed the following diagnostic criteria for TEA: (1) recurrent, witnessed episodes of amnesia (TEA attacks); (2) other cognitive functions remain intact during attacks; and (3) evidence of epilepsy. It was also reported that patients with TEA often demonstrate two other types of memory symptoms: accelerated long-term forgetting (ALF) and autobiographical amnesia (AbA). Both ALF and AbA are persistent memory disorders, but transient epileptic seizures are not. We encountered two cases of TEA associated with two types of amnesia attacks. Therefore, we reviewed TEA cases in the literature to clarify the type of TEA attacks that occurred. Based on the extracted TEA cases, including our two cases, we found that there are two main types of TEA attacks, and we discussed their clinical features. We propose two main types of TEA attacks; that is, pure amnesia-type and partial amnesia-type seizures. Furthermore, we also propose that topographical amnesia mainly manifests as a type of amnesia attack, rather than as a chronic memory disturbance, such as ALF or AbA.

Increase in physiological inhibitory control results in better suppression of unwanted memories.

Forgetting or suppressing a memory with unwanted content is just as important as remembering a desirable one. In addition to emphasizing the role of inhibitory control in memory suppression processes, neuropsychological studies have indicated that an intentional inhibition targeting a brain area may exert its inhibitory effects in seemingly unrelated areas through a common inhibitory network. In this study, we aimed to investigate whether the suppression of unwanted memories can be strengthened by recruiting an inhibitory task that can be simultaneously performed with a memory suppression task. Therefore, we manipulated the level of urinary urgency-induced inhibition of participants (N = 180) and test its effect on the suppression of unwanted memories using a Think/No-Think (T/NT) task. The results of our study indicated that individuals with high levels of urinary urgency demonstrated greater memory suppression compared to those with low urinary urgency. Findings and their implications are discussed within the context of cognitive and clinical perspectives, and recommendations are made for future research.

Acan downregulation in parvalbumin GABAergic cells reduces spontaneous recovery of fear memories.

While persistence of fear memories is essential for survival, a failure to inhibit fear in response to harmless stimuli is a feature of anxiety disorders. Extinction training only temporarily suppresses fear memory recovery in adults, but it is highly effective in juvenile rodents. Maturation of GABAergic circuits, in particular of parvalbumin-positive (PV+) cells, restricts plasticity in the adult brain, thus reducing PV+ cell maturation could promote the suppression of fear memories following extinction training in adults. Epigenetic modifications such as histone acetylation control gene accessibility for transcription and help couple synaptic activity to changes in gene expression. Histone deacetylase 2 (Hdac2), in particular, restrains both structural and functional synaptic plasticity. However, whether and how Hdac2 controls the maturation of postnatal PV+ cells is not well understood. Here, we show that PV+- cell specific Hdac2 deletion limits spontaneous fear memory recovery in adult mice, while enhancing PV+ cell bouton remodeling and reducing perineuronal net aggregation around PV+ cells in prefrontal cortex and basolateral amygdala. Prefrontal cortex PV+ cells lacking Hdac2, show reduced expression of Acan, a critical perineuronal net component, which is rescued by Hdac2 re-expression. Pharmacological inhibition of Hdac2 before extinction training is sufficient to reduce both spontaneous fear memory recovery and Acan expression in wild-type adult mice, while these effects are occluded in PV+-cell specific Hdac2 conditional knockout mice. Finally, a brief knock-down of Acan expression mediated by intravenous siRNA delivery before extinction training but after fear memory acquisition is sufficient to reduce spontaneous fear recovery in wild-type mice. Altogether, these data suggest that controlled manipulation of PV+ cells by targeting Hdac2 activity, or the expression of its downstream effector Acan, promotes the long-term efficacy of extinction training in adults.

Control of contextual memory through interneuronal α5-GABAA receptors.

γ-Aminobutyric acid type A receptors that incorporate α5 subunits (α5-GABAARs) are highly enriched in the hippocampus and are strongly implicated in control of learning and memory. Receptors located on pyramidal neuron dendrites have long been considered responsible, but here we report that mice in which α5-GABAARs have been eliminated from pyramidal neurons (α5-pyr-KO) continue to form strong spatial engrams and that they remain as sensitive as their pseudo-wild-type (p-WT) littermates to etomidate-induced suppression of place cells and spatial engrams. By contrast, mice with selective knockout in interneurons (α5-i-KO) no longer exhibit etomidate-induced suppression of place cells. In addition, the strength of spatial engrams is lower in α5-i-KO mice than p-WT littermates under control conditions. Consistent with the established role of the hippocampus in contextual fear conditioning, α5-i-KO mice resisted etomidate's suppression of freezing to context, but so too did α5-pyr-KO mice, supporting a role for extra-hippocampal regions in the development of contextual fear memory. Overall, our results indicate that interneuronal α5-GABAARs serve a physiological role in promoting spatial learning and that they mediate suppression of hippocampus-dependent contextual memory by etomidate.

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.

Exhibitions on Soviet Repressions at the Moscow NGO Memorial (2011–2021): Transforming Family Memory into Cultural Memory

ABSTRACT The article analyzes the curation of the history of Soviet repressions at the temporary exhibitions organized by the International Memorial NGO in Moscow from 2011 to 2021. Compared with other Russian museums, Memorial relies mainly on family archives and family memories. The repressions are treated as a collective experience that affected not only victims, those executed or imprisoned, but also their relatives and descendants. Seen from this perspective, the carceral past is directly linked to today’s population. The article explores the various ways in which Memorial draws on families’ memories of repression to create a museum statement.

Classification accuracy of the event‐related potentials‐based Brain Fingerprinting and its robustness to direct‐suppression and thought‐substitution countermeasures

AbstractResearch on the accuracy of Brain Fingerprinting (BFP) has produced mixed outcomes: some report 99.9% and others report lower. Furthermore, no studies have measured the susceptibility of BFP to countermeasures. In Experiment‐1, we report the accurate classification of 15 of the 16 subjects, tested on their own real‐life autobiographical incidents; and 14 of the 15 other subjects, tested on another subject's real‐life autobiographical incidents. In Experiment‐2, 16 subjects of Experiment‐1, who were tested on their own real‐life incidents, participated in the BFP test again, but this time employing either direct‐suppression or thought‐substitution (n = 8 each) countermeasures. We report that neither direct‐suppression nor thought‐substitution was effective at concealing information that BFP was designed to reveal. We assert that BFP is a highly accurate, albeit not perfect, concealed‐knowledge detection technology and that it is resistant to memory suppression and thought substitution countermeasures in the context of autobiographical incidents.

Memory Zero

Abstract The repression of memory as a result of trauma from war and social divisions is often an experience that obscures or intensifies personal histories. This is especially true between generations. The Memory Zero project is an attempt to bridge this gap through drawn impressions from intergenerational family stories collaged with image and text searches to locate their approximate times and places. Together this creates, hopefully, a fuller historical and affective context. For this, I drew from family stories and histories in England and Poland before and after World War l. In this way the personal and historical approximations merge into their own continuum, greater than their parts.

Principal component analysis suggests multiple dimensions of memory inhibition that are differentially affected by age.

Cognitive inhibition is among the executive functions that decline early in the course of normal aging. Failures to be able to inhibit irrelevant information from memory may represent an essential factor of age-associated memory impairment. While a variety of elaborate behavioral tasks have been developed that presumably all index memory inhibition, the extent to which these different tasks measure the same underlying cognitive construct that declines with age has not been well explored. In the current study, 100 and 75 cognitively healthy younger (n = 71; age = 30.7 ± 5.4 years, 56.7% female) and older (n = 104, age = 69.3 ± 5.9 years, 66.2% female) adults with equivalent educational attainment performed three computer-based memory inhibition tasks: the Retrieval Induced Forgetting task, the Suppress task, and the Directed Forgetting task. We conducted a principal component analysis using scores derived from different components of these tasks to explore whether and how the tasks relate to one another. We further investigated how age, sex and education, along with, in a subsample of the participants, a neuropsychological measure of episodic memory, impacted both the task scores individually, and the principal components derived from the exploratory analysis. We identified 3 distinct sources of variability which represent potentially independent cognitive processes: memory retrieval facilitation, and two memory inhibition processes that distinguished themselves by the degree of volitional initiation of memory suppression. Only the memory retrieval component correlated with a neuropsychologically-derived episodic memory score, and both memory inhibition principal components were age dependent. Our findings provide support for a distinction in memory suppression processes between those 'instructed' to be performed and those which happen without explicit instruction. This distinction adds nuance to the dichotomous classification of controlled vs. automatic inhibitory mechanisms, which have been shown in previous work to vary as a function of the degree of frontal involvement. Our findings further demonstrate that while both of these measures of inhibition were affected by age, the episodic memory component was not, suggesting that inhibitory impairments may precede memory deficits in healthy aging.

Suffering into patrimony: dealing with communist repression in postcommunist Romania

Analyses of communist repression in post-communist Romania focused on anticommunism and its totemic figures. Laws, institutions and people promote this perspective, transforming the suffering of the formerly politically persecuted into a patrimony meant to be preserved and passed on. On the official level, the anticommunist paradigm gained momentum in December 2006 when the communist regime was condemned as ‘criminal and illegitimate’. However, a majority of the population have not embraced the official approach to communism as the fallen regime still acts as a ‘millieu de memoire’ (as defined by Pierre Nora). My article deals with the main institutions and laws which aimed at promoting and transmitting the memory of repression in post-communist Romania. Analyzing the memory politics as regards the communist repression might provide fresh insight into the ongoing process of building a cultural memory through selection, reconstruction and adjusting figures, deeds, and memorial items.

Alcohol, to think or not to think? Brain hyperconnectivity during alcohol memory suppression in young binge drinkers

Alcohol, to think or not to think? Brain hyperconnectivity during alcohol memory suppression in young binge drinkers

Kepribadian Ganda Tokoh Claire Dalam Novel Misteri Alter Ego Karya Arin Daniswara

This study aims to describe the form of multiple personalities, the factors causing the emergence of multiple personalities, and the impact of multiple personalities in the novel Misteri Alter Ego by Arin Daniswara. This research is literary research with a descriptive method. The data of this research are in the form of words, phrases, clauses, or sentences taken from dialogues and narrative quotes contained in the novel. The research instrument is the researcher herself, assisted by tables containing research indicators. The researcher as an instrument plays a role in analyzing the data obtained and interpreting the data. Data collection techniques are reading and understanding novels, conducting literature studies, determining characters, and finding and recording data found in novels. The data validation technique is the triangulation technique. Data analysis techniques, namely, classifying and analyzing data, interpreting data, and concluding data analysis. The results of the research are: (1) the form of the split personality the character Claire in the Misteri Alter Ego novel by Arin Daniswara is divided into two, namely the host and the evil personality. (2) the factors that cause the emergence of multiple personalities in Claire's character in the novel Misteri Alter Ego by Arin Daniswara consist of two factors, namely trauma from physical violence and trauma from sexual harassment. (3) the impact of the multiple personality traits of Claire in Arin Daniswara's Misteri Alter Ego novel includes partial amnesia, guilt, depression, and suicidal tendencies.

Attentional capture mediates the emergence and suppression of intrusive memories.

Intrusive memories hijack consciousness and their control may lead to forgetting. However, the contribution of reflexive attention to qualifying a memory signal as interfering is unknown. We used machine learning to decode the brain's electrical activity and pinpoint the otherwise hidden emergence of intrusive memories reported during a memory suppression task. Importantly, the algorithm was trained on an independent attentional model of visual activity, mimicking either the abrupt and interfering appearance of visual scenes into conscious awareness or their deliberate exploration. Intrusion of memories into conscious awareness were decoded above chance. The decoding accuracy increased when the algorithm was trained using a model of reflexive attention. Conscious detection of intrusive activity decoded from the brain signal was central to the future silencing of suppressed memories and laterforgetting. Unwanted memories require the reflexive orienting of attention and access to consciousness to be suppressed effectively by inhibitory control.

Neural bases of motivated forgetting of autobiographical memories

ABSTRACT It is important for mental health to be able to control unwanted intrusive memories. Previous studies suggest that middle frontal gyrus (MFG) down regulates pathways underlie the suppression of retrieval of general memories. However, the neural basis of motivated forgetting of autobiographical memories is unclear. Therefore, this study used two samples to explore the neural mechanisms of motivated forgetting of self-referential memories. Every participant provided 40 life events (20 negative and 20 neutral) from their past personal experience, and then completed the Think/No-Think task while undergoing functional magnetic resonance imaging (fMRI). The first sample showed a significant reduction in recall in the No-Think condition relative to the Think condition. Attempting to exclude negative autobiographical memories from awareness was associated with increased activity in the right MFG, superior frontal gyrus (SFG), and inferior frontal gyrus (IFG), while reduced activity was observed in the bilateral Brodmann areas BA18 and BA19, bilateral medial prefrontal cortex (mPFC), bilateral precuneus, bilateral post cingulate cortex (PCC), the left parahippocampus, and the left hippocampus. Functional connectivity analyses showed that the right MFG projected into the bilateral mPFC, bilateral precuneus, and bilateral middle occipital gyrus (MOG) for negative autobiographical memories. The second sample replicated the results of the first sample at both the behavioral and brain levels. These results suggest that retrieval suppression of autobiographical memories involve the pathway between the MFG and the mPFC and precuneus to exclude self-referential memories. These results reveal how people engage in motivated forgetting of negative events in their daily lives.