Memory Patterns Research Articles

Helices of disaster memory: How forgetting and remembering influence tropical cyclone response in Mauritius

Tropical cyclones have had a considerable impact on Mauritius. Large cyclones are relatively rare, and in popular imagination are thought to hit Mauritius every 15 years. Yet it has been over 25 years since the last cyclone widely considered as ‘significant’. Critically, there is little known about the role of memory in responses to cyclones and details regarding responses to past cyclones in Mauritian history are scant.This article examines past experiences and impacts of cyclones in Mauritius, as well as contemporary perceptions of cyclone vulnerability and memories of historical cyclones. The analysis draws on both community interviews and archival research conducted in Mauritius and takes a longue durée approach. This approach combines an examination of both event and process with historical discourses in an effort to uncover the long-standing and slowly changing relationships between people and extreme events.The results reveal a number of repetitive patterns of responses that act out over the long term and repeat for many of the largest cyclones, indicating that tropical cyclone impact and recovery in Mauritius is strongly conditioned by complex, cultural, and place based memory (and forgetting). While these patterns could be characterised as cycles, the research instead presents a concept of ‘helices’ as a new conceptualisation of long term disaster memory patterns. This research is part of a growing literature arguing for the need to account for the historical processes fundamental to understanding vulnerability. This has implications for disaster risk reduction (including climate change adaptation) in Mauritius, other small islands, and elsewhere.

Attractor-state itinerancy in neural circuits with synaptic depression

Neural populations with strong excitatory recurrent connections can support bistable states in their mean firing rates. Multiple fixed points in a network of such bistable units can be used to model memory retrieval and pattern separation. The stability of fixed points may change on a slower timescale than that of the dynamics due to short-term synaptic depression, leading to transitions between quasi-stable point attractor states in a sequence that depends on the history of stimuli. To better understand these behaviors, we study a minimal model, which characterizes multiple fixed points and transitions between them in response to stimuli with diverse time- and amplitude-dependencies. The interplay between the fast dynamics of firing rate and synaptic responses and the slower timescale of synaptic depression makes the neural activity sensitive to the amplitude and duration of square-pulse stimuli in a nontrivial, history-dependent manner. Weak cross-couplings further deform the basins of attraction for different fixed points into intricate shapes. We find that while short-term synaptic depression can reduce the total number of stable fixed points in a network, it tends to strongly increase the number of fixed points visited upon repetitions of fixed stimuli. Our analysis provides a natural explanation for the system’s rich responses to stimuli of different durations and amplitudes while demonstrating the encoding capability of bistable neural populations for dynamical features of incoming stimuli.

Cultural patterns in autobiographical memory of childhood: Comparison of Chinese, Russian, and Uzbek samples

In the present study, I examined whether the regular patterns of variables that referred to mental representation of the entire childhood in young adults might be associated with the different types of cultural selves proposed by Kagitcibasi's model of family change. In this model, three types of cultural selves (heteronomous-related self, autonomous-separated self, and autonomous-related self) are merged with culturally specific styles of parenting and childhood experience. Chinese, Russian, and Uzbekistani participants (N = 439) visualized their childhood on timelines. The exploratory factor analysis suggested a three-factor solution. Factor 1 combined memories of achievements and vicarious memories; that is, memories representing events that happened to other people. In my point of view, in contrast to "we-memories," vicarious memories portray a readiness to view other people as a valuable part of one's own life, but in the context of well-defined self-boundaries. Therefore, they denote the kind of relatedness which does not contradict autonomy. Because Factor 1 was found to be the most articulated in the Chinese sample, it was linked to the autonomous-related self, with the focus on directive function of autobiographical memory. Factor 2 was composed of the abundance of recollections, the early age of first memory, and prolonged childhood. Due to the highest scores being achieved on Factor 2 in the Russian sample, it was attributed to the autonomous-separated self, employing predominantly a self-reflective function of autobiographical memory. Factor 3 consisted of memories of attending social groups, positive emotional bias, and a tendency to mention one's own birth. Taking into account that the Uzbeks achieved the highest scores on this factor, it was interpreted as a mnemonic database of a heteronomous-related self, predominantly associated with social bonding and emotion regulation functions. Taken together, the findings highlight the assumption that childhood memories reveal a cultural self.

The Long Shadow of the Spanish Civil War

The Spanish Civil War (1936-1939) was one of the most devastating conflicts of the twentieth century, yet little is known about its long-term legacy. We show that the war had a long-lasting effect on social capital, voting behavior and collective memory. To this end we use geo-located data on historical mass graves, disaggregated modern-day survey data on trust, combined with modern electoral results. For econometric identification, we exploit deviations from the initial military plans of attack, using the historical (1931) highway network. We also employ a geographical Regression Discontinuity Design along the Aragon Front. Our results show a significant, negative and sizable relationship between political violence and generalized trust. We further decompose the trust results, finding negative effects of conflict on trust in institutions associated with the Civil War, but no effects when looking at trust on Post 1975 democratic institutions. We also find long-lasting results on voting during the Democratic Period (1977-2016), corresponding to the sided political repression implemented in the Aragon region. In terms of mechanisms — using a specialized survey on the Civil War, street names data and Francoist newsreels about the war — we find lower levels of political engagement and differential patterns of collective memory about this traumatic historical event.

Patterns of Memory in Askold Melnyczuk’s Novels as an Example of Ukrainian-American Émigré Fiction

Although Ukrainian emigration to North America is not a new phenomenon, the dilemmas of memory and amnesia remain crucial in Ukrainian-American émigré fiction. The paper focuses on selected novels by Askold Melnyczuk (What is Told and Ambassador of the Dead) and analyzes how traumatic memories and family stories of the past shape the American lives of Ukrainian emigrants. The discussion of the selected Ukrainian-American émigré novels focuses on the dilemmas of remembering and forgetting in the construction of both Ukrainian and American narratives of the past. The voluntary amnesia of the Ame- rican-born Ukrainians in Melnyczuk’s novels confronts their parents’ dependence on the past and their inability to abandon it emotionally. Memories of ‘the old country’ make them, similarly to Ada Kruk, ambassadors of the dead. The expression becomes a metaphoric definition of those wrapped by their repressed, fragmentary and sometimes inaccessible memories. Crucial events of European history of the 20th century are inscribed and personalized in the older generation’s stories which their children are reluctant to hear. For them, their parents’ memories became a burden and a shame. Using the concept of transgenerational memory, the paper explores the challenges of postmemory, and eventually its failure.

Financial stress spillover across Asian Countries

AbstractThis paper uses fractional integration techniques to explore the stochastic properties of the Financial Stress Indices (FSIs) of 10 Asian countries, further investigating the bilateral linkages between them to ascertain how financial stress spreads among countries in the region. For the FSIs of each country, the results show that all the estimated orders of integration are in the interval (0, 1) implying fractional integration and a long memory pattern. Thus, shocks will have transitory though long‐lasting effects. For the cross‐country spillovers of the FSIs, we find that convergence is satisfied in all cases with values of the differencing parameter around 0 and thus showing short memory behavior. It is worth noting that for the larger economies in the region, Japan and China, financial stress transmission between Japan and the smaller economies was faster than with respect to China. Overall, the results provide valuable information on the financial market activity of the countries in the region. To check for the robustness of the baseline results we also use systemic risk measures for these countries, CoVaR with the results showing evidence of fractional integration for the individual series, with all values of the differencing parameter in the range (0, 1). For convergence, there is a substantial reduction in the degree of integration, though the results are not as clear as with the FSIs.

Air quality in London: evidence of persistence, seasonality and trends

The poor air quality in the London metropolis has sparked our interest in studying the time series dynamics of air pollutants in the city. The dataset consists of roadside and background air quality for seven standard pollutants: nitric oxide (NO), nitrogen dioxide (NO2), oxides of nitrogen (NOx), ozone (O3), particulate matter (PM10 and PM2.5) and sulphur dioxide (SO2), using fractional integration to investigate issues such as persistence, seasonality and time trends in the data. Though we notice a large degree of heterogeneity across pollutants and a persistent behaviour based on a long memory pattern is observed practically in all cases. Seasonality and decreasing linear trends are also found in some cases. The findings in the paper may serve as a guide to air pollution management and European Union (EU) policymakers.

Autobiographical memory as a latent vulnerability mechanism following childhood maltreatment: Association with future depression symptoms and prosocial behavior.

Childhood maltreatment is associated with altered neural reactivity during autobiographical memory (ABM) recall and a pattern of overgeneral memory (OGM). Altered ABM and OGM have been linked with psychopathology and poorer social functioning. The present study investigated the association between altered ABM and subsequent socio-emotional functioning (measured two years later) in a sample of adolescents with (N = 20; maltreatment group, MT) and without (N = 17; non-MT group) documented childhood maltreatment histories. At baseline, adolescents (aged 12.6 ± 1.45 years) were administered the Autobiographical Memory Test to measure OGM. Participants also recalled specific ABMs in response to emotionally valenced cue words during functional MRI. Adolescents in both groups underwent assessments measuring depressive symptoms and prosocial behavior at both timepoints. Regression analyses were carried out to predict outcome measures at follow-up controlling for baseline levels. In the MT group, greater OGM at baseline significantly predicted reduced prosocial behavior at follow-up and showed a trend level association with elevated depressive symptoms. Patterns of altered ABM-related brain activity did not significantly predict future psycho-social functioning. The current findings highlight the potential value of OGM as a cognitive mechanism that could be targeted to reduce risk of depression in adolescents with prior histories of maltreatment.

Royal Attire, Ceremonialism, and Performing Arts in the Kraton of Yogyakarta

Royal attire aspect as part of the process of fashion and identity is an interesting phenomenon for a study. Especially if that aspect is then intended as a special element in relation to the events of ceremonialism and performance art in Yogyakarta Palace. In this presentation, a phenomenon which is closely related to the development of attires in the event of ceremonialism and performance art in the palace. Ceremonialism itself is a formal pattern designed for strategic interests which is combined in a compromise manner through the presentation of performance art. As stored in archival and document sources, there are always a number of formal standard patterns applied in ceremonialism. The best sources that are still being treated in the Sultan's Palace are manuscript records such as planners, budgels, pranatan and so on. In addition, through the archival studies approach, it is also known that the pattern of formal memory is also well stored among society record keepers as an oral tradition. This archival studies approach then limits in the area of fashion studies in a variety of standard formal patterns when the Yogyakarta Kraton performing arts perform certain ceremonies.

CyNAPSE: A Low-power Reconfigurable Neural Inference Accelerator for Spiking Neural Networks

While neural network models keep scaling in depth and computational requirements, biologically accurate models are becoming more interesting for low-cost inference. Coupled with the need to bring more computation to the edge in resource-constrained embedded and IoT devices, specialized ultra-low power accelerators for spiking neural networks are being developed. Having a large variance in the models employed in these networks, these accelerators need to be flexible, user-configurable, performant and energy efficient. In this paper, we describe CyNAPSE, a fully digital accelerator designed to emulate neural dynamics of diverse spiking networks. Since the use case of our implementation is primarily concerned with energy efficiency, we take a closer look at the factors that could improve its energy consumption. We observe that while majority of its dynamic power consumption can be credited to memory traffic, its on-chip components suffer greatly from static leakage. Given that the event-driven spike processing algorithm is naturally memory-intensive and has a large number of idle processing elements, it makes sense to tackle each of these problems towards a more efficient hardware implementation. With a diverse set of network benchmarks, we incorporate a detailed study of memory patterns that ultimately informs our choice of an application-specific network-adaptive memory management strategy to reduce dynamic power consumption of the chip. Subsequently, we also propose and evaluate a leakage mitigation strategy for runtime control of idle power. Using both the RTL implementation and a software simulation of CyNAPSE, we measure the relative benefits of these undertakings. Results show that our adaptive memory management policy results in up to 22% more reduction in dynamic power consumption compared to conventional policies. The runtime leakage mitigation techniques show that up to 99.92% and at least 14% savings in leakage energy consumption is achievable in CyNAPSE hardware modules.

Artificial Neural Network Simulations of Human Learning Suggest the Presence of Metastable Attractors in Visual Memory

The attractor hypothesis states that knowledge is encoded as topologically-defined, stable configurations of connected cell assemblies. Irrespective to its original state, a network encoding new information will thus self-organize to reach the necessary stable state. To investigate memory structure, a multimodular neural network architecture, termed Magnitron, has been developed. Magnitron is a biologically-inspired cognitive architecture that simulates digit recognition. It implements perceptual input, human visual long-term memory in the ventral visual pathway and, to a lesser extent, working memory processes. To test the attractor hypothesis a Monte Carlo simulation of 10,000 individuals has been run. Each simulated learner was trained in recognizing the ten digits from novice to expert stage. The results replicate several features of human learning. First, they show that random connectivity in long-term visual memory accounts for novices’ performance. Second, the learning curves revealed that Magnitron simulates the well-known psychological power law of practice. Third, after learning took place, performance departed from chance level and reached a minimum target of 95% of correct hits; hence simulating human performance in children (i.e., when digits are learned). Magnitron also replicates biological findings. In line with research using voxel-based morphometry, Magnitron showed that matter density increases while training is taken place. Crucially, the spatial analysis of the connectivity patterns in long-term visual memory supported the hypothesis of a stable attractor. The significance of these results regarding memory theory is discussed.

Reframing the Past: Justice, Guilt, and Consolidation in East and West Germany after Nazism

AbstractOnly a minority of Germans involved in Nazi crimes were prosecuted after the war, and the transnational history of trials is only beginning to be explored. Even less well understood are the ways in which those who were tainted by complicity reframed their personal life stories. Millions had been willing facilitators, witting beneficiaries, or passive (and perhaps unhappily helpless) witnesses of Nazi persecution; many had been actively involved in sustaining Nazi rule; perhaps a quarter of a million had personally killed Jewish civilians, and several million had direct knowledge of genocide. How did these people re-envision their own lives after Nazism? And how did they reinterpret their own former behaviors—their actions and inaction—in light of public confrontations with Nazi crimes and constructions of “perpetrators” in trials? Going beyond well-trodden debates about “overcoming the past,” this paper explores patterns of personal memory among East and West Germans after Nazism.

Abstract A14: Modeling drug combination sensitivity with Hopfield networks and transcriptomics data

Abstract The Hopfield neural network model is one of the simplest models able to mathematically implement Waddington’s interpretation of normal and anomalous cell phenotypes as dynamical attractors of epigenetic landscapes. Here, we propose a computational approach based on Hopfield’s associative memories that integrate gene expression data and gene interactome networks in (1) a model representing the dynamics and control of disease progression in multiple myeloma (MM), and (2) a model describing the control of angiogenesis. The MM model is built using single-cell RNA-seq data from bone marrow aspirates of MM patients as well as patients diagnosed with monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM), two medical conditions that often progress to full MM. We identify different clusters of MGUS, SMM, and MM cells, map them to Hopfield associative memory patterns, and model the dynamics of transition between the different patterns. The model is then used to identify combinations of genes whose simultaneous inhibition is associated with delayed disease progression. In the angiogenesis control model, we use single-cell RNA-seq data to predict specific combinations of targets for inhibition that could induce a cellular transition from tip-like to stalk-like endothelial cells, inhibiting the formation of capillary sprouts in blood vessels. The model generates novel hypotheses for combinations that could complement standard VEGF inhibitors and lead to a more efficient control of angiogenesis in cancer. Citation Format: Carlo Piermarocchi, Sergii Domanskyi, Alex Hakansson, Giovanni Paternostro. Modeling drug combination sensitivity with Hopfield networks and transcriptomics data [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr A14.

Memory and Oral Testimony in Agatha Christie’s Elephants Can Remember

Detection is a serious venture that depends heavily on oral testimonies and evidence. While partaking in the process of detection, the detective and the ones who testify put their capacity to think and memorise to test. Oral testimonies of people who witness or narrate the same event may vary due to the variations in the person- specific performance of the faculty of memory. The various functions of memory will also define and re- define a person’s knowledge about another person or an event. This paper is an attempt to trace such patterns of memory and oral testimony that decides the course of the detection of an event that happened much earlier, as portrayed in Agatha Christie’s Elephants Can Remember.Detection is a serious venture that depends heavily on oral testimonies and evidence. While partaking in the process of detection, the detective and the ones who testify put their capacity to think and memorise to test. Oral testimonies of people who witness or narrate the same event may vary due to the variations in the person- specific performance of the faculty of memory. The various functions of memory will also define and re- define a person’s knowledge about another person or an event. This paper is an attempt to trace such patterns of memory and oral testimony that decides the course of the detection of an event that happened much earlier, as portrayed in Agatha Christie’s Elephants Can Remember.

Enhanced cortical specialization to distinguish older and newer memories in highly superior autobiographical memory

There is a growing consensus on the role played by the hippocampus and the medial prefrontal cortex in autobiographical memory. However, it is not clear whether and how these key regions play a central role in enabling forms of enhanced memory, such as highly superior autobiographical memory (HSAM). Here, we investigated the role of the hippocampus, the ventromedial (vmPFc) and dorsomedial (dmPFc) prefrontal cortices in discriminating older vs newer autobiographical events in a group of rare individuals with HSAM through multivoxel pattern analysis of functional neuroimaging data. During fMRI scanning, participants with HSAM and normal memory controls were asked to recollect remote and more recent events. We found a stronger neural signature of older vs newer autobiographical memories within the vmPFc of HSAM subjects as compared to controls. In this brain region, the discriminability between the multivariate neural patterns of the two types of memories increased as a function of the temporal distance that separated older and newer events in HSAM subjects. Comparable neural patterns of older vs newer memories were found instead within the dmPFc and hippocampus of both groups. Overall, these findings highlight for the first time that HSAM relies on enhanced vmPFc specialization to represent past experiences, therefore contributing to uncover the neurobiological mechanisms potentially enabling enhanced forms of memory. Implications of the current findings for the extant models of autobiographical memory are discussed.

Narrando a própria morte: os relatos de experiências de quase-morte como narrativas de sentido

A morte é um fenômeno que revela importantes aspectos socioculturais. As ciências sociais, em especial a antropologia, já demonstraram o potencial desse fenômeno para além dos seus aspectos biológicos. Neste artigo, a morte serve de tema para a reflexão sobre experiências, narrativas e sentidos. Com base emrelatos de Experiências de Quase-Morte (EQM), o autor descreve como são construídas narrativas de sentidos, como novos arranjos emocionais e cognitivos são expressos narrativamente e como muito da cultura é compartilhada pelo que se diz. Nesse sentido, o argumento central deste artigo consiste em compreender como um fenômeno biológico, no presente caso, a morte, é ressignificado, ganhando novos contornos e aspectos essencialmente culturais. Evidencia-se ao fim, que as narrativas de quase-morte sãorelatos que guardam relações importantes com as concepções cosmológicas, envolvendo aspectos como memória, percepção simbólica e padrões emocionais. Entrevistas em profundidade compõem o material teórico do artigo.

Towards General-Purpose Acceleration: Finding Structure in Irregularity

Programmable hardware accelerators (e.g., vector processors, GPUs) have been extremely successful at targeting algorithms with regular control and memory patterns to achieve order-of-magnitude performance and energy efficiency improvements. However, they perform far under the peak on important irregular algorithms, like those from graph processing, database querying, genomics, advanced machine learning, and others. This work posits that the primary culprit is specific forms of irregular control flow and memory access. By capturing the problematic behavior at a domain-agnostic level, we propose an accelerator that is sufficiently general, matches domain-specific accelerator performance, and significantly outperforms traditional CPUs and GPUs.

Encoding Membrane-Potential-Based Memory within a Microbial Community.

Cellular membrane potential plays a key role in the formation and retrieval of memories in the metazoan brain, but it remains unclear whether such memory can also be encoded in simpler organisms like bacteria. Here, we show that single-cell-level memory patterns can be imprinted in bacterial biofilms by light-induced changes in the membrane potential. We demonstrate that transient optical perturbations generate a persistent and robust potassium-channel-mediated change in the membrane potential of bacteria within the biofilm. The light-exposed cells respond in an anti-phase manner, relative to unexposed cells, to both natural and induced oscillations in extracellular ion concentrations. This anti-phase response, which persists for hours following the transient optical stimulus, enables a direct single-cell resolution visualization of spatial memory patterns within the biofilm. The ability to encode robust and persistent membrane-potential-based memory patterns could enable computations within prokaryotic communities and suggests a parallel between neurons and bacteria.

SIRT1 activation by resveratrol reverses atrophy of apical dendrites of hippocampal CA1 pyramidal neurons and neurobehavioral impairments in moderate grade hepatic encephalopathy rats

A preliminary observation about resveratrol (RSV) dependent normalization of inflammatory and apoptotic factors in the cortex of hyperammonemic rat model of moderate grade hepatic encephalopathy (MoHE) led us to evaluate whether RSV is ultimately able to confer neuroprotection against MoHE pathogenesis and that it does so by activating its bonafide molecular target SIRT1. The present study compared the profile of relevant neurobehavioral pattern vs neuromorphometry of hippocampal CA1 neurons and SIRT1 activity in the hippocampus of the chronic liver failure (CLF) model of moderate grade HE (MoHE) rats induced by administration of 100 mg/kg body weight of thioacetamide i.p. for 10 days and in the CLF/MoHE rats treated with 10 mg/kg body weight RSV i.p. for 7 days. As compared to the control group rats, the MoHE rats showed significantly deranged pattern of memory and motor functions on MWM and rota rod tests, respectively. These behavioural deficits were associated with a significant reduction in apical dendrite length and number of branching points in the CA1 pyramidal neurons. Interestingly, all these parameters were found to be recovered back to their normal levels in the MoHE rats treated with RSV. Concordantly, MoHE associated declined SIRT1 activity in the hippocampus could be normalized back due to RSV treatment to those MoHE rats. Our findings suggest that RSV is able to normalize MoHE associated memory impairments and motor deficits vis a vis reversal of CA1 dendritic atrophy via SIRT1 activation.

Neural mechanisms supporting emotional and self-referential information processing and encoding in older and younger adults.

Emotion and self-referential information can both enhance memory, but whether they do so via common mechanisms across the adult lifespan remains underexplored. To address this gap, the current study directly compared, within the same fMRI paradigm, the encoding of emotionally salient and self-referential information in older adults and younger adults. Behavioral results replicated the typical patterns of better memory for emotional than neutral information and for self-referential than non-self-referential materials; these memory enhancements were present for younger and older adults. In neural activity, young and older adults showed similar modulation by emotion, but there were substantial age differences in the way self-referential processing affected neural recruitment. Contrary to our hypothesis, we found little evidence for overlap in the neural mechanisms engaged for emotional and self-referential processing. These results reveal that—just as in cognitive domains—older adults can show similar performance to younger adults in socioemotional domains even though the two age groups engage distinct neural mechanisms. These findings demonstrate the need for future research delving into the neural mechanisms supporting older adults’ memory benefits for socioemotional material.