Memory Resilience Research Articles

0081 The impact of sleep deficiency on spatial working and long-term memory in different rat models of sleep deprivation

Abstract Introduction A pressing issue in modern society, lack of sleep has detrimental health consequences, among which cognitive dysfunctions attract great attention. Although there is consensus about the harmful effects of insufficient sleep on vigilance and attention, there is still a debate about memory susceptibility to acute and chronic sleep deprivation. Which types of memory are more vulnerable remains unclear. We studied the susceptibility of spatial working and long-term memory to acute and chronic sleep deprivation in rats. Methods Male Wistar rats were deprived of sleep (SD) by placing cages on an orbital shaker. Animals were subjected to three patterns of SD: 1) acute SD (ASD) — continuous SD for 18 hours; 2) short sleep restriction (SSR) —cycles of 3-hour SD followed by 1 hour of sleep opportunity over 24 hours, with a total SD duration of 18 hours; 3) chronic sleep restriction (CSR) — SSR for 5 consecutive days. For each SD protocol, working spatial memory was assessed with the spontaneous alternation test in the Y-maze. Learning and long-term spatial memory were assessed in the Barnes maze test. Results ASD impaired spatial working memory, as assessed by spontaneous alternations in the Y-maze test, and decreased the level of locomotion/exploration (assessed by the number of arm entries). However, in SSR and CSR, 1-hour alternating sleep opportunities allowed for preventing working memory loss. The Barnes maze test demonstrated no changes in learning or spatial long-term memory under any tested SD conditions. Conclusion The results suggest that spatial working memory is the most vulnerable to continuous sleep loss. Even under a 5-day chronic sleep restriction, the negative effect disappears if rats are allowed to sleep during intermittent 1-hour intervals. It indicates the great importance of short sleep intervals that protect memory against sustained sleep restriction. The resilience of long-term memory to any of the tested sleep deprivation conditions implies that short-term and long-term memory systems diverge in their susceptibility to sleep deficiency. Support (if any) State assignment to the Institute of Evolutionary Physiology and Biochemistry; theme reg. no. АААА-А18-118012290427-7.

Climate Change and the Resilience of Collective Memories

Vernacular heritage sites encompass customs, practices, places, objects, artistic expressions, and values that are innate to a particular place and time. Climate knowledge of the particular place and time is embedded in vernacular settlements and lifestyles along with other environmental, cultural, and societal determinants of the place. Rebuilt, restored, and adapted, vernacular settlements evolved with changing climate, cultural practices, community aspirations, and a gradual influx of modernization and urbanization. However, its legacy —as represented by traditional houses from the pre-industrial period that were built by laypeople— is challenged by climate and disaster risks, e.g., loss of lands, food sources, water resources, intangible values, and displacement. Although the impacts of climate change combined with anthropic influences have been recognized as a threat to cultural heritage by scholars, this underappreciated form of cultural heritage has not been the focus of the integrated understanding risks of climate and disaster discussions. The aim of this dissertation, therefore, is to reveal the deteriorations caused by changing climate and anthropic interventions on vernacular heritage at both spatial planning decisions such as urban development projects and at local level practices such as maladaptation from the case of Fındıklı of Rize in Turkiye. The factors behind the deterioration of vernacular heritage sites under changing climate and the ways to achieve climate resilience are analysed through interviews with local people, the observations of on-site visits conducted in January and July 2019 in addition to mapping.

Predictors of Successful Memory Aging in Older Mexican Adults.

Background Research suggests a significant association between increasing age and memory impairments. Nevertheless, for some individuals, memory performance stays within or above the normative values of younger subjects. This is known as successful memory aging and is associated with specific neurophysiological features and psychological and lifestyle-related variables. To date, little is known about the association between successful memory aging and intrinsic capacity (IC) defined as “the composite of all the physical and mental (including psychosocial) capacities that an individual can draw on at any point in time” and resilience. Hence, the aim of this study was to determine if longitudinal associations between IC and successful memory aging and resilience exist and to find differences in cognitive performance between Mexican older adults with successful memory aging, older adults with average memory, and older adults with memory impairment. Methods Longitudinal data from 590 individuals from the third wave (2012) and the Mex-Cog subsample (2016) of the Mexican Health and Aging Study was analysed. Subjects were classified into 3 groups: (1) older adults with successful memory aging (SUMA), (2) older adults with average memory (AVMA), and (3) older adults with memory impairment (IMA). Cognitive domains of orientation, language, attention, constructional praxis, and executive function were evaluated. IC and resilience were measured using items from the MHAS battery. Analysis of variance and multinomial logistic regressions were used to find differences in IC and resilience across the memory aging groups. Results ANOVAs showed significant differences across the three cognitive performance groups in all cognitive domains. Multinomial logistic regression analyses revealed that respondents with higher scores in the psychological and cognitive domains of IC at baseline were more likely to have successful memory aging in the subsequent wave of the study. More resilient subjects in 2012 were not more likely to become a SUMA in 2016. However, this could be a result of the way resilience was measured. Conclusion Our main findings suggest that intrinsic capacity could be used as a predictor of successful memory aging specifically in the psychological and the cognitive domains. More longitudinal studies are needed to further examine these associations.

Cognitive throughput and working memory raw scores consistently differentiate resilient and vulnerable groups to sleep loss.

Substantial individual differences exist in cognitive deficits due to sleep restriction (SR) and total sleep deprivation (TSD), with various methods used to define such neurobehavioral differences. We comprehensively compared numerous methods for defining cognitive throughput and working memory resiliency and vulnerability. Forty-one adults participated in a 13-day experiment: 2 baseline, 5 SR, 4 recovery, and one 36 h TSD night. The Digit Symbol Substitution Test (DSST) and Digit Span Test (DS) were administered every 2 h. Three approaches (Raw Score [average SR performance], Change from Baseline [average SR minus average baseline performance], and Variance [intraindividual variance of SR performance]), and six thresholds (±1 standard deviation, and the best/worst performing 12.5%, 20%, 25%, 33%, 50%) classified Resilient/Vulnerable groups. Kendall's tau-b correlations compared the group categorizations' concordance within and between DSST number correct and DS total number correct. Bias-corrected and accelerated bootstrapped t-tests compared group performance. . The approaches generally did not categorize the same participants into Resilient/Vulnerable groups within or between measures. The Resilient groups categorized by the Raw Score approach had significantly better DSST and DS performance across all thresholds on all study days, while the Resilient groups categorized by the Change from Baseline approach had significantly better DSST and DS performance for several thresholds on most study days. By contrast, the Variance approach showed no significant DSST and DS performance group differences. Various approaches to define cognitive throughput and working memory resilience/vulnerability to sleep loss are not synonymous. The Raw Score approach can be reliably used to differentiate resilient and vulnerable groups using DSST and DS performance during sleep loss.

F184. White Matter Structural Integrity and Working Memory Resilience to Stress in Schizophrenia

F184. White Matter Structural Integrity and Working Memory Resilience to Stress in Schizophrenia

The Capacity for Correlated Semantic Memories in the Cortex.

A statistical analysis of semantic memory should reflect the complex, multifactorial structure of the relations among its items. Still, a dominant paradigm in the study of semantic memory has been the idea that the mental representation of concepts is structured along a simple branching tree spanned by superordinate and subordinate categories. We propose a generative model of item representation with correlations that overcomes the limitations of a tree structure. The items are generated through “factors” that represent semantic features or real-world attributes. The correlation between items has its source in the extent to which items share such factors and the strength of such factors: if many factors are balanced, correlations are overall low; whereas if a few factors dominate, they become strong. Our model allows for correlations that are neither trivial nor hierarchical, but may reproduce the general spectrum of correlations present in a dataset of nouns. We find that such correlations reduce the storage capacity of a Potts network to a limited extent, so that the number of concepts that can be stored and retrieved in a large, human-scale cortical network may still be of order 107, as originally estimated without correlations. When this storage capacity is exceeded, however, retrieval fails completely only for balanced factors; above a critical degree of imbalance, a phase transition leads to a regime where the network still extracts considerable information about the cued item, even if not recovering its detailed representation: partial categorization seems to emerge spontaneously as a consequence of the dominance of particular factors, rather than being imposed ad hoc. We argue this to be a relevant model of semantic memory resilience in Tulving’s remember/know paradigms.

Regulation of memory storage through epigenetic alterations: a new role for RNA

A fundamental assumption in modern psychology and neuroscience is that memory is stored as physical changes in the brain. More than a century ago, the famous neuroanatomist Ramón Y Cajal (see the article entitled “Santiago Ramón y Cajal, the ultimate scientist?” in this issue of The Biochemist) postulated that changes in the strength of synaptic connections between neurons were the physical substrate for memory. Extensive experimental evidence has since established the dominance of this connectionist view, referred to as the “synaptic plasticity” model. However, although the synaptic plasticity model broadly accords with the results of neurobiological studies of learning and memory, it does not fully account for the extraordinary resilience of memory despite the significant loss of synapses during such phenomena as development, trauma and ageing. Here, we will focus on the newly discovered role of small non-coding RNAs (ncRNAs) as potential master regulators of learning-induced epigenesis, neuronal plasticity and, ultimately, memory. In support of this idea, recent data from our lab indicate that RNA can promote the transfer of long-term memory from a trained to an untrained (naïve) animal.

Hero, Champion of Social Justice, Benign Friend: Theodore Roosevelt in American Memory

Following scholarship that suggests that societies crave continuity in their collective memories, this article identifies recurring themes in American memories of Theodore Roosevelt as an intensely masculine leader, a champion of social justice, and a loveable character. Memories of Roosevelt since his death have not been static. Leftist scholars and activists have contributed to counter-memories of TR as chauvinist, racist, and a dangerous imperialist. The interplay between memories and counter-memories of Theodore Roosevelt suggests that while cultural pluralism enables a multiplicity of memories to flourish within American society, it does not ensure that counter-memories expand beyond those who generate them. The resilience of memories of Roosevelt as a hero, champion, and friend is indicative of durable qualities in Americans’ self-image.

Neurofascin Knock Down in the Basolateral Amygdala Mediates Resilience of Memory and Plasticity in the Dorsal Dentate Gyrus Under Stress.

Activation of the amygdala is one of the hallmarks of acute stress reactions and a central element of the negative impact of stress on hippocampus-dependent memory and cognition. Stress-induced psychopathologies, such as posttraumatic stress disorder, exhibit a sustained hyperactivity of the amygdala, triggered at least in part by deficits in GABAergic inhibition that lead to shifts in amygdalo-hippocampal interaction. Here, we have utilized lentiviral knock down of neurofascin to reduce GABAergic inhibition specifically at the axon initial segment (AIS) of principal neurons within the basolateral amygdala (BLA) of rats. Metaplastic effects of such a BLA modulation on hippocampal synaptic function were assessed using BLA priming prior to the induction of long-term potentiation (LTP) on dentate gyrus synapses in anesthetized rats in vivo. The knock down of neurofascin in the BLA prevented a priming-induced impairment on LTP maintenance in the dentate gyrus. At the behavioral level, a similar effect was observable, with neurofascin knock down preventing the detrimental impact of acute traumatic stress on hippocampus-dependent spatial memory retrieval in a water maze task. These findings suggest that reducing GABAergic inhibition specifically at the AIS synapses of the BLA alters amygdalo-hippocampal interactions such that it attenuates the adverse impact of acute stress exposure on cognition-related hippocampal functions.

Individuals’ Self-Defining Memories As Reflecting Their Strength and Weaknesses

The associations between attachment orientations, temperament, resilience, and various dimensions of self-defining memories were examined in 83 female Israeli adolescents and young adults. Resiliency and positive temperament were associated with positive qualities of memories, whereas negative emotionality and reactivity were associated with poor recollection quality. Lower levels of fearful attachment orientation were associated with interpersonal memories and mixed emotions in memories, and a profound-distrust attachment orientation was associated with life-threatening memories. The study highlights the contribution of these qualities to recollections and underscores the contribution to theory and practical implications.

Dorsoventral and Proximodistal Hippocampal Processing Account for the Influences of Sleep and Context on Memory (Re)consolidation: A Connectionist Model

The context in which learning occurs is sufficient to reconsolidate stored memories and neuronal reactivation may be crucial to memory consolidation during sleep. The mechanisms of context-dependent and sleep-dependent memory (re)consolidation are unknown but involve the hippocampus. We simulated memory (re)consolidation using a connectionist model of the hippocampus that explicitly accounted for its dorsoventral organization and for CA1 proximodistal processing. Replicating human and rodent (re)consolidation studies yielded the following results. (1) Semantic overlap between memory items and extraneous learning was necessary to explain experimental data and depended crucially on the recurrent networks of dorsal but not ventral CA3. (2) Stimulus-free, sleep-induced internal reactivations of memory patterns produced heterogeneous recruitment of memory items and protected memories from subsequent interference. These simulations further suggested that the decrease in memory resilience when subjects were not allowed to sleep following learning was primarily due to extraneous learning. (3) Partial exposure to the learning context during simulated sleep (i.e., targeted memory reactivation) uniformly increased memory item reactivation and enhanced subsequent recall. Altogether, these results show that the dorsoventral and proximodistal organization of the hippocampus may be important components of the neural mechanisms for context-based and sleep-based memory (re)consolidations.

Memory Resilience to Alzheimer's Genetic Risk: Sex Effects in Predictor Profiles.

Apolipoprotein E (APOE) ɛ4 and Clusterin (CLU) C alleles are risk factors for Alzheimer's disease (AD) and episodic memory (EM) decline. Memory resilience occurs when genetically at-risk adults perform at high and sustained levels. We investigated whether (a) memory resilience to AD genetic risk is predicted by biological and other risk markers and (b) the prediction profiles vary by sex and AD risk variant. Using a longitudinal sample of nondemented adults (n = 642, aged 53-95) we focused on memory resilience (over 9 years) to 2 AD risk variants (APOE, CLU). Growth mixture models classified resilience. Random forest analysis, stratified by sex, tested the predictive importance of 22 nongenetic risk factors from 5 domains (n = 24-112). For both sexes, younger age, higher education, stronger grip, and everyday novel cognitive activity predicted memory resilience. For women, 9 factors from functional, health, mobility, and lifestyle domains were also predictive. For men, only fewer depressive symptoms was an additional important predictor. The prediction profiles were similar for APOE and CLU. Although several factors predicted resilience in both sexes, a greater number applied only to women. Sex-specific mechanisms and intervention targets are implied.

The Resilience of Memory, Truth, and Justice Processes

The Resilience of Memory, Truth, and Justice Processes

MEMORY RESILIENCE IN CARRIERS OF ALZHEIMER'S GENETIC RISK: PREDICTORS VARY FOR FEMALE AND MALE OLDER ADULTS

MEMORY RESILIENCE IN CARRIERS OF ALZHEIMER'S GENETIC RISK: PREDICTORS VARY FOR FEMALE AND MALE OLDER ADULTS

‘Speaking to, with and about’: Cherbourg women’s memory of domestic work as activist counter-memory

This article considers distinctive mediums of memory emerging from the traumatic history of Aboriginal women’s experiences as domestic workers in Queensland, Australia throughout the nineteenth and twentieth centuries. One is the exhibition Many Threads presented in 2014 at the Ration Shed Museum in the Aboriginal community of Cherbourg in southern Queensland. The other is the collaborative memoir Auntie Rita by Jackie Huggins and Rita Huggins, which recounts Rita’s life through a dialogue between mother and daughter. The article uses a reading of Jackie’s voice, as consciously activist and feminist, as a way in to understanding the testimonial memory of other Cherbourg women. In remembering, interpreting and presenting their experiences as domestic workers, alongside those of their mothers, grandmothers, aunts and sisters, Cherbourg women are actively intervening in historical and contemporary discourses that seek to limit their representation to that of victims and their community as intrinsically dysfunctional. Instead, through yarning, writing and sewing, Cherbourg women are generating memories, and memory communities, of resistance, strength, resilience, creativity and survival. The paper argues that this memory work is a vital form of counter-memory, which disturbs and unsettles normative Australian representations.

The Role of the Medial Prefrontal Cortex in the Conditioning and Extinction of Fear.

Once acquired, a fearful memory can persist for a lifetime. Although learned fear can be extinguished, extinction memories are fragile. The resilience of fear memories to extinction may contribute to the maintenance of disorders of fear and anxiety, including post-traumatic stress disorder (PTSD). As such, considerable effort has been placed on understanding the neural circuitry underlying the acquisition, expression, and extinction of emotional memories in rodent models as well as in humans. A triad of brain regions, including the prefrontal cortex, hippocampus, and amygdala, form an essential brain circuit involved in fear conditioning and extinction. Within this circuit, the prefrontal cortex is thought to exert top-down control over subcortical structures to regulate appropriate behavioral responses. Importantly, a division of labor has been proposed in which the prelimbic (PL) and infralimbic (IL) subdivisions of the medial prefrontal cortex (mPFC) regulate the expression and suppression of fear in rodents, respectively. Here, we critically review the anatomical and physiological evidence that has led to this proposed dichotomy of function within mPFC. We propose that under some conditions, the PL and IL act in concert, exhibiting similar patterns of neural activity in response to aversive conditioned stimuli and during the expression or inhibition of conditioned fear. This may stem from common synaptic inputs, parallel downstream outputs, or cortico-cortical interactions. Despite this functional covariation, these mPFC subdivisions may still be coding for largely opposing behavioral outcomes, with PL biased towards fear expression and IL towards suppression.

The Malleability of Memory and Irish Republican Memory Entrepreneurship: A Case Study of the ‘Loughgall Martyrs’

This article is a case study of Irish republican memory entrepreneurship that critically examines the collective memory of the ‘Loughgall Martyrs’. Critiquing the ‘malleability of memory’, it interrogates attempts at remoulding the memory of the ‘Loughgall Martyrs’ in tandem with ‘memory politics’ in modern Irish republicanism and transitioning Northern Ireland. It examines the reinterpretation of the Loughgall memory by Sinn Fein to support their current strategy in the transition of Northern Ireland and conversely how traditionalists use the resilience of memory to contest reinterpretation. Particular examination is given to the emergence of the 1916 societies as a platform for localised resistance to political use of the memory of the men by Sinn Fein. It also examines how the memory of the ‘Loughgall Martyrs’ has been imbibed with assertions of victimhood that feed into wider contestation over the past in the North of Ireland.

COMeT+: Continuous Online Memory Testing with Multi-Threading Extension

Today’s computers have gigabytes of main memory due to improved DRAM density. As density increases, smaller bit cells become more susceptible to errors. With an increase in error susceptibility, the need for memory resiliency also increases. Self-testing of memory health can proactively check for errors to improve resiliency. This paper describes a software-only self-test to continuously test memory. We present the challenges and design for an approach, called Continuous Online Memory Testing with Multi-threading Extension (COMeT+), that targets chip multiprocessors. COMeT+ tests memory health simultaneously with execution of single and multi-threaded applications in anticipation of allocation requests. The approach guarantees that memory is tested within a fixed time interval to limit exposure to lurking errors. We developed and evaluated an implementation of COMeT+. On the SPEC CPU2006 and the PARSEC benchmarks, COMeT+ has a low 4% average performance overhead. On the PARSEC benchmarks, the effect of TLB shootdowns on application performance due to additional page migrations caused by COMeT+ was insignificant. When emulated errors were injected into physical memory, applications executed 1.13x to 4.41x longer with COMeT+ than without it.

Resilient Optically Connected Memory Systems Using Dynamic Bit-Steering [Invited

Resilience is becoming an increasingly critical performance requirement for future large-scale computing systems. In data center and high-performance computing systems with many thousands of nodes, errors in main memory can be a significant source of failures. As a result, large-scale memory systems must employ advanced error detection and correction techniques to mitigate failures. Memory devices are primarily designed for density, optimizing memory capacity and throughput, rather than resilience. A strict focus on memory performance instead of resilience risks undermining the overall stability of next-generation computers. In this work, we leverage an optically connected memory system to optimize both memory performance and resilience. A multicast-capable optical interconnection network replaces the traditional electronic bus between a processor and its main memory, allowing for a novel error-correction technique based on dynamic bit-steering. As compared to an electronically connected approach, we demonstrate significantly higher memory bandwidths and reduced latencies, in addition to a 700× improvement in resilience.

Defining immune memory resilience: implications for vaccine development

Expert Rev. Vaccines 9(4), 351–353 (2010) “…the effectiveness of the immune memory induced, rather than the magnitude of the primary immune response, is of utmost importance for the designs of effective vaccines.” The generation of antigen (Ag)-specific immune memory that can be restimulated upon subsequent encounter of the same Ag is one of the hallmarks of adaptive immunity. Vaccines are generally designed to induce such immune memory, which is recalled during infection, resulting in a rapid and augmented immune restimulation that protects the host. Hence, the effectiveness of the immune memory induced, rather than the magnitude of the primary immune response, is of utmost importance for the designs of effective vaccines.