Secondary Memory Research Articles

Component analysis of verbal versus spatial working memory training in adolescents with ADHD: A randomized, controlled trial

Adaptive training of working memory (WM) using the Cogmed-RM intervention has recently shown some efficacy as an alternative treatment for ADHD, but this intervention may not be optimally designed. A recent component analysis of WM has suggested that maintenance in primary memory (PM) appears to be largely intact whereas recall from secondary memory (SM) appears to be deficient in ADHD relative to age-matched controls. However, extrapolating from basic research, there is reason to believe that Cogmed-RM may target the PM component more than the SM component; though training with spatial exercises may target the SM component more than training with verbal exercises. To investigate, participants diagnosed with ADHD were randomly assigned to either a verbal training condition (n = 24) or a spatial training condition (n = 23) using a randomized, controlled design, and both groups were instructed to complete at least 20 days of training. The PM and SM components of WM were assessed immediately before and after training using both verbal and spatial free recall tasks. The main findings showed that both versions of the intervention enhanced the maintenance of information in PM regardless of test modality, but not the recall of information from SM. Therefore, the component of WM that is improved by Cogmed-RM is not the same component of WM that is deficient in ADHD.

A parallel solver for huge dense linear systems

HDSS (Huge Dense Linear System Solver) is a Fortran Application Programming Interface (API) to facilitate the parallel solution of very large dense systems to scientists and engineers. The API makes use of parallelism to yield an efficient solution of the systems on a wide range of parallel platforms, from clusters of processors to massively parallel multiprocessors. It exploits out-of-core strategies to leverage the secondary memory in order to solve huge linear systems O ( 100.000 ) . The API is based on the parallel linear algebra library PLAPACK, and on its Out-Of-Core (OOC) extension POOCLAPACK. Both PLAPACK and POOCLAPACK use the Message Passing Interface (MPI) as the communication layer and BLAS to perform the local matrix operations. The API provides a friendly interface to the users, hiding almost all the technical aspects related to the parallel execution of the code and the use of the secondary memory to solve the systems. In particular, the API can automatically select the best way to store and solve the systems, depending of the dimension of the system, the number of processes and the main memory of the platform. Experimental results on several parallel platforms report high performance, reaching more than 1 TFLOP with 64 cores to solve a system with more than 200 000 equations and more than 10 000 right-hand side vectors. New version program summary Program title: Huge Dense System Solver (HDSS) Catalogue identifier: AEHU_v1_1 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEHU_v1_1.html Program obtainable from: CPC Program Library, Queenʼs University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 87 062 No. of bytes in distributed program, including test data, etc.: 1 069 110 Distribution format: tar.gz Programming language: Fortran90, C Computer: Parallel architectures: multiprocessors, computer clusters Operating system: Linux/Unix Has the code been vectorized or parallelized?: Yes, includes MPI primitives. RAM: Tested for up to 190 GB Classification: 6.5 External routines: MPI ( http://www.mpi-forum.org/), BLAS ( http://www.netlib.org/blas/), PLAPACK ( http://www.cs.utexas.edu/~plapack/), POOCLAPACK ( ftp://ftp.cs.utexas.edu/pub/rvdg/PLAPACK/pooclapack.ps) (code for PLAPACK and POOCLAPACK is included in the distribution). Catalogue identifier of previous version: AEHU_v1_0 Journal reference of previous version: Comput. Phys. Comm. 182 (2011) 533 Does the new version supersede the previous version?: Yes Nature of problem: Huge scale dense systems of linear equations, A x = B , beyond standard LAPACK capabilities. Solution method: The linear systems are solved by means of parallelized routines based on the LU factorization, using efficient secondary storage algorithms when the available main memory is insufficient. Reasons for new version: In many applications we need to guarantee a high accuracy in the solution of very large linear systems and we can do it by using double-precision arithmetic. Summary of revisions: Version 1.1 • Can be used to solve linear systems using double-precision arithmetic. • New version of the initialization routine. The user can choose the kind of arithmetic and the values of several parameters of the environment. Running time: About 5 hours to solve a system with more than 200 000 equations and more than 10 000 right-hand side vectors using double-precision arithmetic on an eight-node commodity cluster with a total of 64 Intel cores.

Protective Capacity of Memory CD8 + T Cells Is Dictated by Antigen Exposure History and Nature of the Infection

Infection or vaccination confers heightened resistance to pathogen rechallenge because of quantitative and qualitative differences between naive and primary memory T cells. Herein, we show that secondary (boosted) memory CD8+ T cells were better than primary memory CD8+ T cells in controlling some, but not all acute infections with diverse pathogens. However, secondary memory CD8+ T cells were less efficient than an equal number of primary memory cells at preventing chronic LCMV infection and are more susceptible to functional exhaustion. Importantly, localization of memory CD8+ T cells within lymph nodes, which is reduced by antigen restimulation, was critical for both viral control in lymph nodes and for the sustained CD8+ T cell response required to prevent chronic LCMV infection. Thus, repeated antigen stimulation shapes memory CD8+ T cell populations to either enhance or decrease per cell protective immunity in a pathogen-specific manner, a concept of importance in vaccine design against specific diseases.

Fully dynamic metric access methods based on hyperplane partitioning

Metric access methods based on hyperplane partitioning have the advantage, compared to the ball partitioning-based ones, that regions do not overlap. The price is less flexibility for controlling the tree shape, especially in the dynamic scenario, that is, upon insertions and deletions of objects. In this paper we introduce a technique called ghost hyperplanes, which enables fully dynamic data structures based on hyperplane partitioning. We apply the technique to Brin's GNAT static index, obtaining a dynamic variant called EGNAT, which in addition we adapt to secondary memory. We show experimentally that the EGNAT is competitive with the M-tree, the baseline for this scenario. We also apply the ghost hyperplane technique to Voronoi trees, obtaining a competitive dynamic structure for main memory.

Postpamięć jako marzenie senne – Achtung Zelig! Druga wojna Krzysztofa Gawronkiewicza i Krystiana Rosenberga

Postmemory in the popular culture on the example of the comic novel “Achtung Zelig! The Second War” by Krzysztof Gawronkiewicz & Krystian Rosenberg The comic book is a product of popculture. It got deeply rooted in American and Western European popular culture in the 1970s. In France, this type of sequential art told in pictorial stories was presented in daily papers and developed humorously-told threads of the plot. In the UK it won juvenile audience with its simple jokes, genre scenes and shortened and abridged versions of fables. In the United States, in turn, crude science fiction, horror or joke graphic stories were most popular. However, in the late 1990s these depictions increasingly started to develop into something of much different nature. On the one hand, popular culture embraced more and more different creative areas, wrestled with subject and themes that so far had been tackled only by more sophisticated literature (for example, war themes). On the other hand, the Polish reader had a better chance to experience new titles and pictorial stories from the West or other far-away cultures that represented high artistic skills and offered original and remarkable stories. This, in turn, created a new situation in which adult readers turned to comic books. Moreover, comic books became a subject of interests for academics beyond those who were professionally involved in documenting and understanding popular culture, i.e. for methodologists of history, modern culture anthropologists, researchers in literature and art historians. A particular type of comics is the one that presents historical and memory contents. Works of brilliant artists from different cultures such as, for example: Maus by Art Spiegelman, Persepolis by Mariane Satrapi, Achtung Zelig! by Krzysztof Gawronkiewicz and Krystian Rosenberg or Marzi by Marzena Sowa and Sylvain Savoia have become available on the Polish publishing market and have been widely reviewed and discussed academically. In the present article I am concentrating on the phenomenon postmemory. Analysing Achtung Zelig! by Gawronkiewicz and Rosenberg I am trying to show main trademarks postmemory: borrowing another person’s stories, phenomen of secondary memory, fetishization of the past.

The influence of levels of processing on recall from working memory and delayed recall tasks.

Recent research in working memory has highlighted the similarities involved in retrieval from complex span tasks and episodic memory tasks, suggesting that these tasks are influenced by similar memory processes. In the present article, the authors manipulated the level of processing engaged when studying to-be-remembered words during a reading span task (Experiment 1) and an operation span task (Experiment 2) in order to assess the role of retrieval from secondary memory during complex span tasks. Immediate recall from both span tasks was greater for items studied under deep processing instructions compared with items studied under shallow processing instructions regardless of trial length. Recall was better for deep than for shallow levels of processing on delayed recall tests as well. These data are consistent with the primary-secondary memory framework, which suggests that to-be-remembered items are displaced from primary memory (i.e., the focus of attention) during the processing phases of complex span tasks and therefore must be retrieved from secondary memory.

Revealing list-level control in the Stroop task by uncovering its benefits and a cost.

Interference is reduced in mostly incongruent relative to mostly congruent lists. Classic accounts of this list-wide proportion congruence effect assume that list-level control processes strategically modulate word reading. Contemporary accounts posit that reliance on the word is modulated poststimulus onset by item-specific information (e.g., proportion congruency of the word). To adjudicate between these accounts, we used novel designs featuring neutral trials. In two experiments, we showed that the list-wide proportion congruence effect is accompanied by a change in neutral trial color-naming performance. Because neutral words have no item-specific bias, this pattern can be attributed to list-level control. Additionally, we showed that list-level attenuation of word reading led to a cost to performance on a secondary prospective memory task but only when that task required processing of the irrelevant, neutral word. These findings indicate that the list-wide proportion congruence effect at least partially reflects list-level control and challenge purely item-specific accounts of this effect.

Differential Role of “Signal 3” Inflammatory Cytokines in Regulating CD8 T Cell Expansion and Differentiation in vivo

Following an infection, naïve CD8 T cells are stimulated by dendritic cells (DC) displaying pathogen-derived peptides on MHC class I molecules (signal 1) and costimulatory molecules (signal 2). Additionally, pathogen-induced inflammatory cytokines also act directly on the responding CD8 T cells to regulate their expansion and differentiation. In particular, both type I interferons (IFNs) and IL-12 have been described as critical survival signals (signal 3) for optimal CD8 T cell accumulation during the expansion phase. Furthermore, expansion in numbers of antigen-specific CD8 T cells is coupled with their acquisition of effector functions to combat the infection. However, it still remains unclear whether these same cytokines also regulate the effector/memory differentiation program of the CD8 T cell response in vivo. Here, we demonstrate that defective signaling by either type I IFNs or IL-12 to the responding CD8 T cells impairs maximal expansion in response to DC immunization + CpG ODN, but neither of these cytokines is essential to regulate the effector/memory differentiation program. In addition, lack of direct IL-12 signaling to CD8 T cells accelerates the development of central memory phenotype in both primary and secondary antigen-specific memory CD8 T cells.

The nature and position of processing determines why forgetting occurs in working memory tasks

The effect of potentially distracting processing within working memory was examined by varying the nature and position of processing across conditions of a Brown-Peterson-like task. Separate groups of participants carried out verbal or visuospatial processing operations on identical stimuli, while retaining lists of to-be-remembered words. The number of words presented either before or after the processing interval was varied systematically. Results showed that although verbal processing was no more demanding than visuospatial processing, it led to greater forgetting. However, forgetting was confined to items presented prior to processing, and the difference in degree of forgetting shown by the two groups was maximal when four items occurred before processing. Temporal isolation effects were more marked in the verbal processing group. These findings indicate that individuals can keep active a limited number of items in primary memory during processing, unless processing blocks rehearsal, in which case retrieval occurs from secondary memory.

Contribution of strategy use to performance on complex and simple span tasks

Simple and complex span tasks are widely thought to measure related but separable memory constructs. Recently, however, research has demonstrated that simple and complex span tasks may tap, in part, the same construct because both similarly predict performance on measures of fluid intelligence (Gf) when the number of items retrieved from secondary memory (SM) is equated (Unsworth & Engle, Journal of Memory and Language 54:68-80 2006). Two studies (n = 105 and n = 152) evaluated whether retrieval from SM is influenced by individual differences in the use of encoding strategies during span tasks. Results demonstrated that, after equating the number of items retrieved from SM, simple and complex span performance similarly predicted Gf performance, but rates of effective strategy use did not mediate the span-Gf relationships. Moreover, at the level of individual differences, effective strategy use was more highly related to complex span performance than to simple span performance. Thus, even though individual differences in effective strategy use influenced span performance on trials that required retrieval from SM, strategic behavior at encoding cannot account for the similarities between simple and complex span tasks.

An efficient strategy for storing and searching binary trees in WORM external memory

Consider the problem of searching and storing a massive binary tree in WORM (Write Once Read Many) secondary memory. Tree nodes are organized in pages, each of which contains a fixed number of nodes. Pages are transferred to primary memory as the tree is traversed. This work presents a new strategy for paging that aims to decrease the amount of unused space in each page as well as to reduce the total number of pages required to store the tree while also reduce the number of pages accessed for searching. The algorithm employs an efficient strategy based on bin packing for allocating unbalanced trees. Experimental results are reported comparing the performance of two bin-packing heuristics, as well as other paging strategies and B-trees. Results confirm the superior performance of the proposed approach both in terms of the number of page transfers required for searching and the page filling percentage.

Monoterpenoid extract of sage (Salvia lavandulaefolia) with cholinesterase inhibiting properties improves cognitive performance and mood in healthy adults

Extracts of sage (Salvia officinalis/lavandulaefolia) with terpenoid constituents have previously been shown to inhibit cholinesterase and improve cognitive function. The current study combined an in vitro investigation of the cholinesterase inhibitory properties and phytochemical constituents of a S. lavandulaefolia essential oil, with a double-blind, placebo-controlled, balanced crossover study assessing the effects of a single dose on cognitive performance and mood. In this latter investigation 36 healthy participants received capsules containing either 50 µL of the essential oil or placebo on separate occasions, 7 days apart. Cognitive function was assessed using a selection of computerized memory and attention tasks and the Cognitive Demand Battery before the treatment and 1-h and 4-h post-dose. The essential oil was a potent inhibitor of human acetylcholinesterase (AChE) and consisted almost exclusively of monoterpenoids. Oral consumption lead to improved performance of secondary memory and attention tasks, most notably at the 1-h post-dose testing session, and reduced mental fatigue and increased alertness which were more pronounced 4-h post-dose. These results extend previous observations of improved cognitive performance and mood following AChE inhibitory sage extracts and suggest that the ability of well-tolerated terpenoid-containing extracts to beneficially modulate cholinergic function and cognitive performance deserves further attention.

Secondary Immunization Generates Clonally Related Antigen-Specific Plasma Cells and Memory B Cells

Rechallenge with T cell-dependent Ags induces memory B cells to re-enter germinal centers (GCs) and undergo further expansion and differentiation into plasma cells (PCs) and secondary memory B cells. It is currently not known whether the expanded population of memory B cells and PCs generated in secondary GCs are clonally related, nor has the extent of proliferation and somatic hypermutation of their precursors been delineated. In this study, after secondary tetanus toxoid (TT) immunization, TT-specific PCs increased 17- to 80-fold on days 6-7, whereas TT-specific memory B cells peaked (delayed) on day 14 with a 2- to 22-fold increase. Molecular analyses of V(H)DJ(H) rearrangements of individual cells revealed no major differences of gene usage and CDR3 length between TT-specific PCs and memory B cells, and both contained extensive evidence of somatic hypermutation with a pattern consistent with GC reactions. This analysis identified clonally related TT-specific memory B cells and PCs. Within clusters of clonally related cells, sequences shared a number of mutations but also could contain additional base pair changes. The data indicate that although following secondary immunization PCs can derive from memory B cells without further somatic hypermutation, in some circumstances, likely within GC reactions, asymmetric mutation can occur. These results suggest that after the fate decision to differentiate into secondary memory B cells or PCs, some committed precursors continue to proliferate and mutate their V(H) genes.

Fast and Compact Web Graph Representations

Compressed graph representations, in particular for Web graphs, have become an attractive research topic because of their applications in the manipulation of huge graphs in main memory. The state of the art is well represented by the WebGraph project, where advantage is taken of several particular properties of Web graphs to offer a trade-off between space and access time. In this paper we show that the same properties can be exploited with a different and elegant technique that builds on grammar-based compression. In particular, we focus on Re-Pair and on Ziv-Lempel compression, which, although cannot reach the best compression ratios of WebGraph, achieve much faster navigation of the graph when both are tuned to use the same space. Moreover, the technique adapts well to run on secondary memory and in distributed scenarios. As a byproduct, we introduce an approximate Re-Pair version that works efficiently with severely limited main memory.

Simulated Cataract and Low Contrast Stimuli Impair Cognitive Performance in Older Adults: Implications for Neuropsychological Assessment and Everyday Function

ABSTRACT Objective: To investigate how age-related declines in vision (particularly contrast sensitivity), simulated using cataract-goggles and low-contrast stimuli, influence the accuracy and speed of cognitive test performance in older adults. An additional aim was to investigate whether declines in vision differentially affect secondary more than primary memory. Method: Using a fully within-subjects design, 50 older drivers aged 66–87 years completed two tests of cognitive performance – letter matching (perceptual speed) and symbol recall (short-term memory) – under different viewing conditions that degraded visual input (low-contrast stimuli, cataract-goggles, and low-contrast stimuli combined with cataract-goggles, compared with normal viewing). However, presentation time was also manipulated for letter matching. Visual function, as measured using standard charts, was taken into account in statistical analyses. Results: Accuracy and speed for cognitive tasks were significantly impaired when visual input was degraded. Furthermore, cognitive performance was positively associated with contrast sensitivity. Presentation time did not influence cognitive performance, and visual gradation did not differentially influence primary and secondary memory. Conclusion: Age-related declines in visual function can impact on the accuracy and speed of cognitive performance, and therefore the cognitive abilities of older adults may be underestimated in neuropsychological testing. It is thus critical that visual function be assessed prior to testing, and that stimuli be adapted to older adults' sensory capabilities (e.g., by maximising stimuli contrast).

Healthy middle-aged individuals are vulnerable to cognitive deficits as a result of increased arterial stiffness

Whilst pulse pressure and pulse wave velocity have been shown to predict cognitive outcomes, the relationship between arterial stiffness and cognition has not yet been explored in an entirely healthy nonclinical population. Furthermore, the effects of arterial stiffness on cognition are yet to be examined with computerized cognitive test batteries sensitive to subtle differences in cognitive performance. The aim of the present study was to examine the relationship between arterial stiffness (pulse pressure and augmentation index) and specific domains of cognitive performance in a healthy middle-aged sample. INDIVIDUALS AND METHOD: The sample comprised 92 healthy individuals, aged between 40 and 65 years, with no history of cardiovascular disease, diabetes, stroke, hypertension, smoking and were free from medication. The cognitive drug research (CDR) computerized system was implemented to assess domains of cognitive performance, whereas pulse pressure and augmentation index were determined centrally by a noninvasive SphygmoCor device. Pulse pressure was an independent predictor of both episodic secondary memory performance (beta = -0.27, R change = 0.07, P < 0.05) and speed of memory retrieval (beta = 0.24, R change = 0.06, P < 0.05). Augmentation index was also an independent predictor of speed of memory (beta = 0.27, R change = 0.07, P < 0.01). Working memory, power of attention and continuity of attention were not predicted by pulse pressure or augmentation index. It was concluded that healthy middle-aged adults are vulnerable to memory deficits as a result of normal increases in pulse pressure associated with ageing.

Repetitive Antigen Stimulation Induces Stepwise Transcriptome Diversification but Preserves a Core Signature of Memory CD8+ T Cell Differentiation

Repetitive antigen stimulation by prime-boost vaccination or pathogen reencounter increases memory CD8(+) T cell numbers, but the impact on memory CD8(+) T cell differentiation is unknown. Here we showed that repetitive antigen stimulations induced accumulation of memory CD8(+) T cells with uniform effector memory characteristics. However, genome-wide microarray analyses revealed that each additional antigen challenge resulted in the differential regulation of several hundred new genes in the ensuing memory CD8(+) T cell populations and, therefore, in stepwise diversification of CD8(+) T cell transcriptomes. Thus, primary and repeatedly stimulated (secondary, tertiary, and quaternary) memory CD8(+) T cells differed substantially in their molecular signature while sharing expression of a small group of genes and biological pathways, which may constitute a core signature of memory differentiation. These results reveal the complex regulation of memory CD8(+) T cell differentiation and identify potential new molecular targets to dissect the function of memory cells generated by repeated antigen stimulation.

Differential effects of the aromas of Salvia species on memory and mood

This study investigated the potential for the aromas of the essential oils of Salvia species to affect cognition and mood in healthy adults. Research has demonstrated that orally administered Salvia officinalis and Salvia lavandulaefolia are capable of modulating cognition and mood. The active compounds in the herbal products might also be present in the aromas and so produce similar effects. In an independent groups design, three conditions, S. officinalis aroma, S. lavandulaefolia aroma and no aroma were employed. One hundred and thirty-five healthy volunteers acted as participants, with 45 in each condition. Cognitive performance was assessed via the Cognitive Drug Research (CDR) System. Bond-Lader mood scales measured the participants' mood on three dimensions before and after the cognitive tasks. Data analysis revealed that the S. officinalis aroma group performed significantly better than the control group on the quality of memory and secondary memory primary outcome factors from the test battery. The Alert mood measure displayed significant differences between both aromas and the control condition. These findings suggest that the aromas of essential oils of Salvia species reproduce some but not all of the effects found following oral herb administration, and that interesting dissociations occur between subjective and objective responses.

Modulating numbers and phenotype of CD8+ T cells in secondary immune responses

Prime-boost regimens are frequently used to increase the number of memory CD8(+) T cells and thus the protective capacity of experimental vaccinations; however, it is currently unknown how the frequency and phenotype of primary (1 degrees ) memory CD8(+) T cells impact the quantity and phenotype of secondary (2 degrees ) memory CD8(+) T-cell populations. Here, we show that 2 degrees infections of mice that received different 1 degrees infections and/or immunizations generated similar numbers of 2 degrees effector and memory CD8(+) T cells. Remarkably, this result was independent of the numbers and phenotype of 1 degrees memory CD8(+) T cells present at the time of rechallenge. However, after adoptive transfer of low numbers of 1 degrees memory CD8(+) T cells, a linear correlation between 1 degrees memory CD8(+) T-cell input and 2 degrees memory CD8(+) T-cell numbers was observed. These data suggest that, above a very low threshold, boosting of 1 degrees memory CD8(+) T-cell populations elicits 2 degrees immune responses of similar magnitude. Therefore, our study has important implications for the design of prime-boost regimens that aim to generate protective CD8(+) T-cell-mediated immunity.

A Bounded and Adaptive Memory-Based Approach to Mine Frequent Patterns From Very Large Databases

Most of the existing methods to solve the problem of association rules mining (ARM) rely on special data structures to project the database (either totally or partially) in the primary memory. Traditionally, these data structures reside in the main memory and rely on the existing paging mechanism of the virtual memory manager (VMM) to handle the storage problem when they go out of the primary memory. Typically, VMM stores the overloaded data into the secondary memory based on some preassumed memory usage criteria. However, this direct and unplanned use of virtual memory results in an unpredictable behavior or thrashing, as depicted by some of the works described in the literature. This problem is tackled in this paper by presenting an ARM model capable of mining a transactional database, regardless of its size and without relying on the underlying VMM; the proposed approach could use only a bounded portion of the primary memory and this gives the opportunity to assign other parts of the main memory to other tasks with different priority. In other words, we propose a specialized memory management system which caters to the needs of the ARM model in such a way that the proposed data structure is constructed in the available allocated primary memory first. If at any point the structure grows out of the allocated memory quota, it is forced to be partially saved on secondary memory. The secondary memory version of the structure is accessed in a block-by-block basis so that both the spatial and temporal localities of the I/O access are optimized. Thus, the proposed framework takes control of the virtual memory access and hence manages the required virtual memory in an optimal way to the best benefit of the mining process to be served. Several clever data structures are used to facilitate these optimizations. Our method has the additional advantage that other tasks of different priorities may run concurrently with the main mining task with as little interference as possible because we do not rely on the default paging mechanism of the VMM. The reported test results demonstrate the applicability and effectiveness of the proposed approach.