Adaptive memory: Is the animacy effect on memory due to emotional arousal?

PubMed

Meinhardt, Martin J; Bell, Raoul; Buchner, Axel; Röer, Jan P

2018-05-07

Animate entities are often better remembered than inanimate ones. The proximal mechanisms underlying this animacy effect on recall are unclear. In two experiments, we tested whether the animacy effect is due to emotional arousal. Experiment 1 revealed that translations of the animate words used in the pioneering study of Nairne et al. (Psychological science, 24, 2099-2105, 2013) were perceived as being more arousing than translations of the inanimate words, suggesting that animacy might have been confounded with arousal in previous studies. In Experiment 2, new word lists were created in which the animate and inanimate words were matched on arousal (amongst several other dimensions), and participants were required to reproduce the animate and inanimate words in a free recall task. There was a tendency towards better memory for arousing items, but robust animacy effects were obtained even though animate and inanimate words were matched on arousal. Thus, while arousal may contribute to the animacy effect when it is not carefully controlled for, it cannot explain the memory advantage of animate items.

The effects of sleep on episodic memory in older and younger adults.

PubMed

Aly, Mariam; Moscovitch, Morris

2010-04-01

Evidence on sleep-dependent benefits for episodic memory remains elusive. Furthermore we know little about age-related changes on the effects of sleep on episodic memory. The study we report is the first to compare the effects of sleep on episodic memories in younger and older adults. Memories of stories and personal events were assessed following a retention interval that included sleep and following an equal duration of wakefulness. Both older and younger adults have superior memory following sleep compared to following wakefulness for both types of material. Amount of forgetting of personal events was less during wakefulness in older adults than in younger adults, possibly due to spontaneous rehearsal. Amount of time spent sleeping correlated highly with sleep benefit in older adults, suggesting that quantity of total sleep, and/or time spent in some stages of sleep, are important contributors to age-related differences in memory consolidation or protection from interference during sleep.

Research on memory management in embedded systems

NASA Astrophysics Data System (ADS)

Huang, Xian-ying; Yang, Wu

2005-12-01

Memory is a scarce resource in embedded system due to cost and size. Thus, applications in embedded systems cannot use memory randomly, such as in desktop applications. However, data and code must be stored into memory for running. The purpose of this paper is to save memory in developing embedded applications and guarantee running under limited memory conditions. Embedded systems often have small memory and are required to run a long time. Thus, a purpose of this study is to construct an allocator that can allocate memory effectively and bear a long-time running situation, reduce memory fragmentation and memory exhaustion. Memory fragmentation and exhaustion are related to the algorithm memory allocated. Static memory allocation cannot produce fragmentation. In this paper it is attempted to find an effective allocation algorithm dynamically, which can reduce memory fragmentation. Data is the critical part that ensures an application can run regularly, which takes up a large amount of memory. The amount of data that can be stored in the same size of memory is relevant with the selected data structure. Skills for designing application data in mobile phone are explained and discussed also.

The Effect of Working Memory Capacity Limitations on the Intuitive Assessment of Correlation: Amplification, Attenuation, or Both?

ERIC Educational Resources Information Center

Cahan, Sorel; Mor, Yaniv

2007-01-01

This article challenges Yaakov Kareev's (1995a, 2000) argument regarding the positive bias of intuitive correlation estimates due to working memory capacity limitations and its adaptive value. The authors show that, under narrow window theory's primacy effect assumption, there is a considerable between-individual variability of the effects of…

Nitrogen-doped partially reduced graphene oxide rewritable nonvolatile memory.

PubMed

Seo, Sohyeon; Yoon, Yeoheung; Lee, Junghyun; Park, Younghun; Lee, Hyoyoung

2013-04-23

As memory materials, two-dimensional (2D) carbon materials such as graphene oxide (GO)-based materials have attracted attention due to a variety of advantageous attributes, including their solution-processability and their potential for highly scalable device fabrication for transistor-based memory and cross-bar memory arrays. In spite of this, the use of GO-based materials has been limited, primarily due to uncontrollable oxygen functional groups. To induce the stable memory effect by ionic charges of a negatively charged carboxylic acid group of partially reduced graphene oxide (PrGO), a positively charged pyridinium N that served as a counterion to the negatively charged carboxylic acid was carefully introduced on the PrGO framework. Partially reduced N-doped graphene oxide (PrGODMF) in dimethylformamide (DMF) behaved as a semiconducting nonvolatile memory material. Its optical energy band gap was 1.7-2.1 eV and contained a sp2 C═C framework with 45-50% oxygen-functionalized carbon density and 3% doped nitrogen atoms. In particular, rewritable nonvolatile memory characteristics were dependent on the proportion of pyridinum N, and as the proportion of pyridinium N atom decreased, the PrGODMF film lost memory behavior. Polarization of charged PrGODMF containing pyridinium N and carboxylic acid under an electric field produced N-doped PrGODMF memory effects that followed voltage-driven rewrite-read-erase-read processes.

Nonvolatile Ferroelectric Memory Circuit Using Black Phosphorus Nanosheet-Based Field-Effect Transistors with P(VDF-TrFE) Polymer.

PubMed

Lee, Young Tack; Kwon, Hyeokjae; Kim, Jin Sung; Kim, Hong-Hee; Lee, Yun Jae; Lim, Jung Ah; Song, Yong-Won; Yi, Yeonjin; Choi, Won-Kook; Hwang, Do Kyung; Im, Seongil

2015-10-27

Two-dimensional van der Waals (2D vdWs) materials are a class of new materials that can provide important resources for future electronics and materials sciences due to their unique physical properties. Among 2D vdWs materials, black phosphorus (BP) has exhibited significant potential for use in electronic and optoelectronic applications because of its allotropic properties, high mobility, and direct and narrow band gap. Here, we demonstrate a few-layered BP-based nonvolatile memory transistor with a poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric top gate insulator. Experiments showed that our BP-based ferroelectric transistors operate satisfactorily at room temperature in ambient air and exhibit a clear memory window. Unlike conventional ambipolar BP transistors, our ferroelectric transistors showed only p-type characteristics due to the carbon-fluorine (C-F) dipole effect of the P(VDF-TrFE) layer, as well as the highest linear mobility value of 1159 cm(2) V(-1) s(-1) with a 10(3) on/off current ratio. For more advanced memory applications beyond unit memory devices, we implemented two memory inverter circuits, a resistive-load inverter circuit and a complementary inverter circuit, combined with an n-type molybdenum disulfide (MoS2) nanosheet. Our memory inverter circuits displayed a clear memory window of 15 V and memory output voltage efficiency of 95%.

Emigration, Generation, and Collective Memories: The Presence of the Past for Emigrants from the Former Soviet Union

ERIC Educational Resources Information Center

Corning, Amy D.

2010-01-01

Research on memory of public events consistently reveals generational effects, where individuals remember best the events from their "critical years" of adolescence and early adulthood--a phenomenon attributed to privileged encoding or retrieval of memories due to primacy of experience. Prior research, however, has not decoupled the…

Effects of Self-Paced Encoding and Practice on Age-Related Deficits in Binding Three Features

ERIC Educational Resources Information Center

Kinjo, Hikari

2010-01-01

Although much literature suggests that the age-related decline in episodic memory could be due to difficulties in binding features of information, previous studies focused mainly on memory of paired associations rather than memory of multiple bound features. In reality, however, there are many situations that require binding multiple features…

Emotional memory can be persistently weakened by suppressing cortisol during retrieval.

PubMed

Rimmele, Ulrike; Besedovsky, Luciana; Lange, Tanja; Born, Jan

2015-03-01

Cortisol's effects on memory follow an inverted U-shaped function such that memory retrieval is impaired with very low concentrations, presumably due to insufficient activation of high-affine mineralocorticoid receptors (MR), or with very high concentrations, due to predominant low-affine glucocorticoid receptor (GR) activation. Through corresponding changes in re-encoding, the retrieval effect of cortisol might translate into a persistent change of the retrieved memory. We tested whether partial suppression of morning cortisol synthesis by metyrapone, leading to intermediate, circadian nadir-like levels with presumed predominant MR activation, improves retrieval, particularly of emotional memory, and persistently changes the memory. In a randomized, placebo-controlled, double-blind, within-subject cross-over design, 18 men were orally administered metyrapone (1g) vs. placebo at 4:00 AM to suppress the morning cortisol rise. Retrieval of emotional and neutral texts and pictures (learned 3 days earlier) was assessed 4h after substance administration and a second time one week later. Metyrapone suppressed endogenous cortisol release to circadian nadir-equivalent levels at the time of retrieval testing. Contrary to our expectations, metyrapone significantly impaired free recall of emotional texts (p<.05), whereas retrieval of neutral texts or pictures remained unaffected. One week later, participants still showed lower memory for emotional texts in the metyrapone than placebo condition (p<.05). Our finding that suppressing morning cortisol to nadir-like concentrations not only impairs acute retrieval, but also persistently weakens emotional memories corroborates the concept that retrieval effects of cortisol produce persistent memory changes, possibly by affecting re-encoding. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Acute Alcohol Effects on Narrative Recall and Contextual Memory: An Examination of Fragmentary Blackouts

PubMed Central

Wetherill, Reagan R.; Fromme, Kim

2011-01-01

The present study examined the effects of alcohol consumption on narrative recall and contextual memory among individuals with and without a history of fragmentary blackouts in an attempt to better understand why some individuals experience alcohol-induced memory impairments whereas others do not, even at comparable blood alcohol concentrations (BACs). Standardized beverage (alcohol, no alcohol) administration procedures and neuropsychological assessments measured narrative recall and context memory performance before and after alcohol consumption in individuals with (n = 44) and without (n = 44) a history of fragmentary blackouts. Findings indicate acute alcohol intoxication led to impairments in free recall, but not next-day cued recall. Further, participants showed similar memory performance when sober, but individuals who consumed alcohol and had a positive history of fragmentary blackouts showed greater contextual memory impairments than those who had not previously experienced a fragmentary blackout. Thus, it appears that some individuals may have an inherent vulnerability to alcohol-induced memory impairments due to alcohol’s effects on contextual memory processes. PMID:21497445

Sleep promotes analogical transfer in problem solving.

PubMed

Monaghan, Padraic; Sio, Ut Na; Lau, Sum Wai; Woo, Hoi Kei; Linkenauger, Sally A; Ormerod, Thomas C

2015-10-01

Analogical problem solving requires using a known solution from one problem to apply to a related problem. Sleep is known to have profound effects on memory and information restructuring, and so we tested whether sleep promoted such analogical transfer, determining whether improvement was due to subjective memory for problems, subjective recognition of similarity across related problems, or by abstract generalisation of structure. In Experiment 1, participants were exposed to a set of source problems. Then, after a 12-h period involving sleep or wake, they attempted target problems structurally related to the source problems but with different surface features. Experiment 2 controlled for time of day effects by testing participants either in the morning or the evening. Sleep improved analogical transfer, but effects were not due to improvements in subjective memory or similarity recognition, but rather effects of structural generalisation across problems. Copyright © 2015 Elsevier B.V. All rights reserved.

Word frequency influences on the list length effect and associative memory in young and older adults.

PubMed

Badham, Stephen P; Whitney, Cora; Sanghera, Sumeet; Maylor, Elizabeth A

2017-07-01

Many studies show that age deficits in memory are smaller for information supported by pre-experimental experience. Many studies also find dissociations in memory tasks between words that occur with high and low frequencies in language, but the literature is mixed regarding the extent of word frequency effects in normal ageing. We examined whether age deficits in episodic memory could be influenced by manipulations of word frequency. In Experiment 1, young and older adults studied short and long lists of high- and low-frequency words for free recall. The list length effect (the drop in proportion recalled for longer lists) was larger in young compared to older adults and for high- compared to low-frequency words. In Experiment 2, young and older adults completed item and associative recognition memory tests with high- and low-frequency words. Age deficits were greater for associative memory than for item memory, demonstrating an age-related associative deficit. High-frequency words led to better associative memory performance whilst low-frequency words resulted in better item memory performance. In neither experiment was there any evidence for age deficits to be smaller for high- relative to low-frequency words, suggesting that word frequency effects on memory operate independently from effects due to cognitive ageing.

The hard fall effect: high working memory capacity leads to a higher, but less robust short-term memory performance.

PubMed

Thomassin, Noémylle; Gonthier, Corentin; Guerraz, Michel; Roulin, Jean-Luc

2015-01-01

Participants with a high working memory span tend to perform better than low spans in a variety of tasks. However, their performance is paradoxically more impaired when they have to perform two tasks at once, a phenomenon that could be labeled the "hard fall effect." The present study tested whether this effect exists in a short-term memory task, and investigated the proposal that the effect is due to high spans using efficient facilitative strategies under simple task conditions. Ninety-eight participants performed a spatial short-term memory task under simple and dual task conditions; stimuli presentation times either allowed for the use of complex facilitative strategies or not. High spans outperformed low spans only under simple task conditions when presentation times allowed for the use of facilitative strategies. These results indicate that the hard fall effect exists on a short-term memory task and may be caused by individual differences in strategy use.

Working memory dependence of spatial contextual cueing for visual search.

PubMed

Pollmann, Stefan

2018-05-10

When spatial stimulus configurations repeat in visual search, a search facilitation, resulting in shorter search times, can be observed that is due to incidental learning. This contextual cueing effect appears to be rather implicit, uncorrelated with observers' explicit memory of display configurations. Nevertheless, as I review here, this search facilitation due to contextual cueing depends on visuospatial working memory resources, and it disappears when visuospatial working memory is loaded by a concurrent delayed match to sample task. However, the search facilitation immediately recovers for displays learnt under visuospatial working memory load when this load is removed in a subsequent test phase. Thus, latent learning of visuospatial configurations does not depend on visuospatial working memory, but the expression of learning, as memory-guided search in repeated displays, does. This working memory dependence has also consequences for visual search with foveal vision loss, where top-down controlled visual exploration strategies pose high demands on visuospatial working memory, in this way interfering with memory-guided search in repeated displays. Converging evidence for the contribution of working memory to contextual cueing comes from neuroimaging data demonstrating that distinct cortical areas along the intraparietal sulcus as well as more ventral parieto-occipital cortex are jointly activated by visual working memory and contextual cueing. © 2018 The British Psychological Society.

Sub-efficacious doses of phosphodiesterase 4 and 5 inhibitors improve memory in a mouse model of Alzheimer's disease.

PubMed

Gulisano, Walter; Tropea, Maria Rosaria; Arancio, Ottavio; Palmeri, Agostino; Puzzo, Daniela

2018-06-06

Cyclic nucleotides cAMP and cGMP cooperate to ensure memory acquisition and consolidation. Increasing their levels by phosphodiesterase inhibitors (PDE-Is) enhanced cognitive functions and rescued memory loss in different models of aging and Alzheimer's disease (AD). However, side effects due to the high doses used limited their application in humans. Based on previous studies suggesting that combinations of sub-efficacious doses of cAMP- and cGMP-specific PDE-Is improved synaptic plasticity and memory in physiological conditions, here we aimed to study whether this treatment was effective to counteract the AD phenotype in APPswe mice. We found that a 3-week chronic treatment with a combination of sub-efficacious doses of the cAMP-specific PDE4-I roflumilast (0.01 mg/kg) and the cGMP-specific PDE5-I vardenafil (0.1 mg/kg) improved recognition, spatial and contextual fear memory. Importantly, the cognitive enhancement persisted for 2 months beyond administration. This long-lasting action, and the possibility to minimize side effects due to the low doses used, might open feasible therapeutic strategies against AD. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thinking about memories for everyday and shocking events: do people use ease-of-retrieval cues in memory judgments?

PubMed

Echterhoff, Gerald; Hirst, William

2006-06-01

Extant research shows that people use retrieval ease, a feeling-based cue, to judge how well they remember life periods. Extending this approach, we investigated the role of retrieval ease in memory judgments for single events. In Experiment 1, participants who were asked to recall many memories of an everyday event (New Year's Eve) rated retrieval as more difficult and judged their memory as worse than did participants asked to recall only a few memories. In Experiment 2, this ease-of-retrieval effect was found to interact with the shocking character of the remembered event: There was no effect when the event was highly shocking (i.e., learning about the attacks of September 11, 2001), whereas an effect was found when the event was experienced as less shocking (due either to increased distance to "9/11" or to the nonshocking nature of the event itself). Memory vividness accounted for additional variance in memory judgments, indicating an independent contribution of content-based cues in judgments of event memories.

The emotion-induced memory trade-off: more than an effect of overt attention?

PubMed

Steinmetz, Katherine R Mickley; Kensinger, Elizabeth A

2013-01-01

Although it has been suggested that many effects of emotion on memory are attributable to attention, in the present study we addressed the hypothesis that such effects may relate to a number of different factors during encoding or postencoding. One way to look at the effects of emotion on memory is by examining the emotion-induced memory trade-off, whereby enhanced memory for emotional items often comes at the cost of memory for surrounding background information. We present evidence that this trade-off cannot be explained solely by overt attention (measured via eyetracking) directed to the emotional items during encoding. Participants did not devote more overt attention to emotional than to neutral items when those items were selectively remembered (at the expense of their backgrounds). Only when participants were asked to answer true/false questions about the items and the backgrounds--a manipulation designed to affect both overt attention and poststimulus elaboration--was there a reduction in selective emotional item memory due to an increase in background memory. These results indicate that the allocation of overt visual attention during encoding is not sufficient to predict the occurrence of selective item memory for emotional items.

The Asymmetrical Effects of Divided Attention on Encoding and Retrieval Processes: A Different View Based on an Interference with the Episodic Register

PubMed Central

Guez, Jonathan; Naveh-Benjamin, Moshe

2013-01-01

In this study, we evaluate the conceptualization of encoding and retrieval processes established in previous studies that used a divided attention (DA) paradigm. These studies indicated that there were considerable detrimental effects of DA at encoding on later memory performance, but only minimal effects, if any, on divided attention at retrieval. We suggest that this asymmetry in the effects of DA on memory can be due, at least partially, to a confound between the memory phase (encoding and retrieval) and the memory requirements of the task (memory “for” encoded information versus memory “at” test). To control for this confound, we tested memory for encoded information and for retrieved information by introducing a second test that assessed memory for the retrieved information from the first test. We report the results of four experiments that use measures of memory performance, retrieval latency, and performance on the concurrent task, all of which consistently show that DA at retrieval strongly disrupts later memory for the retrieved episode, similarly to the effects of DA at encoding. We suggest that these symmetrical disruptive effects of DA at encoding and retrieval on later retrieval reflect a disruption of an episodic buffer (EB) or episodic register component (ER), rather than a failure of encoding or retrieval operations per se. PMID:24040249

MAO-A Phenotype Effects Response Sensitivity and the Parietal Old/New Effect during Recognition Memory

PubMed Central

Ross, Robert S.; Smolen, Andrew; Curran, Tim; Nyhus, Erika

2018-01-01

A critical problem for developing personalized treatment plans for cognitive disruptions is the lack of understanding how individual differences influence cognition. Recognition memory is one cognitive ability that varies from person to person and that variation may be related to different genetic phenotypes. One gene that may impact recognition memory is the monoamine oxidase A gene (MAO-A), which influences the transcription rate of MAO-A. Examination of how MAO-A phenotypes impact behavioral and event-related potentials (ERPs) correlates of recognition memory may help explain individual differences in recognition memory performance. Therefore, the current study uses electroencephalography (EEG) in combination with genetic phenotyping of the MAO-A gene to determine how well-characterized ERP components of recognition memory, the early frontal old/new effect, left parietal old/new effect, late frontal old/new effect, and the late posterior negativity (LPN) are impacted by MAO-A phenotype during item and source memory. Our results show that individuals with the MAO-A phenotype leading to increased transcription have lower response sensitivity during both item and source memory. Additionally, during item memory the left parietal old/new effect is not present due to increased ERP amplitude for correct rejections. The results suggest that MAO-A phenotype changes EEG correlates of recognition memory and influences how well individuals differentiate between old and new items. PMID:29487517

The asymmetrical effects of divided attention on encoding and retrieval processes: a different view based on an interference with the episodic register.

PubMed

Guez, Jonathan; Naveh-Benjamin, Moshe

2013-01-01

In this study, we evaluate the conceptualization of encoding and retrieval processes established in previous studies that used a divided attention (DA) paradigm. These studies indicated that there were considerable detrimental effects of DA at encoding on later memory performance, but only minimal effects, if any, on divided attention at retrieval. We suggest that this asymmetry in the effects of DA on memory can be due, at least partially, to a confound between the memory phase (encoding and retrieval) and the memory requirements of the task (memory "for" encoded information versus memory "at" test). To control for this confound, we tested memory for encoded information and for retrieved information by introducing a second test that assessed memory for the retrieved information from the first test. We report the results of four experiments that use measures of memory performance, retrieval latency, and performance on the concurrent task, all of which consistently show that DA at retrieval strongly disrupts later memory for the retrieved episode, similarly to the effects of DA at encoding. We suggest that these symmetrical disruptive effects of DA at encoding and retrieval on later retrieval reflect a disruption of an episodic buffer (EB) or episodic register component (ER), rather than a failure of encoding or retrieval operations per se.

Attention to Global Gist Processing Eliminates Age Effects in False Memories

ERIC Educational Resources Information Center

Odegard, Timothy N.; Holliday, Robyn E.; Brainerd, Charles J.; Reyna, Valerie F.

2008-01-01

Counterintuitive age increases have been reported for the Deese-Roediger-McDermott (DRM) false memory illusion. The current theoretical explanation of this effect assumes that it is due to age increases in spontaneous interconnection of DRM list words' meanings. To test this explanation, 11-year-olds and young adults studied DRM lists under…

Factors affecting reorganisation of memory encoding networks in temporal lobe epilepsy

PubMed Central

Sidhu, M.K.; Stretton, J.; Winston, G.P.; Symms, M.; Thompson, P.J.; Koepp, M.J.; Duncan, J.S.

2015-01-01

Summary Aims In temporal lobe epilepsy (TLE) due to hippocampal sclerosis reorganisation in the memory encoding network has been consistently described. Distinct areas of reorganisation have been shown to be efficient when associated with successful subsequent memory formation or inefficient when not associated with successful subsequent memory. We investigated the effect of clinical parameters that modulate memory functions: age at onset of epilepsy, epilepsy duration and seizure frequency in a large cohort of patients. Methods We studied 53 patients with unilateral TLE and hippocampal sclerosis (29 left). All participants performed a functional magnetic resonance imaging memory encoding paradigm of faces and words. A continuous regression analysis was used to investigate the effects of age at onset of epilepsy, epilepsy duration and seizure frequency on the activation patterns in the memory encoding network. Results Earlier age at onset of epilepsy was associated with left posterior hippocampus activations that were involved in successful subsequent memory formation in left hippocampal sclerosis patients. No association of age at onset of epilepsy was seen with face encoding in right hippocampal sclerosis patients. In both left hippocampal sclerosis patients during word encoding and right hippocampal sclerosis patients during face encoding, shorter duration of epilepsy and lower seizure frequency were associated with medial temporal lobe activations that were involved in successful memory formation. Longer epilepsy duration and higher seizure frequency were associated with contralateral extra-temporal activations that were not associated with successful memory formation. Conclusion Age at onset of epilepsy influenced verbal memory encoding in patients with TLE due to hippocampal sclerosis in the speech-dominant hemisphere. Shorter duration of epilepsy and lower seizure frequency were associated with less disruption of the efficient memory encoding network whilst longer duration and higher seizure frequency were associated with greater, inefficient, extra-temporal reorganisation. PMID:25616449

Effects of aging and divided attention on memory for items and their contexts.

PubMed

Craik, Fergus I M; Luo, Lin; Sakuta, Yuiko

2010-12-01

It is commonly found that memory for context declines disproportionately with aging, arguably due to a general age-related deficit in associative memory processes. One possible mechanism for such deficits is an age-related reduction in available processing resources. In two experiments we compared the effects of aging to the effects of division of attention in younger adults on memory for items and context. Using a technique proposed by Craik (1989), linear functions relating memory performance for items and their contexts were derived for a Young Full Attention group, a Young Divided Attention group, and an Older Adult group. Results suggested that the Old group showed an additional deficit in associative memory that was not mimicked by divided attention. It is speculated that both divided attention and aging are associated with a loss of available processing resources that may reflect inefficient frontal lobe functioning, whereas the additional age-related decrement in associative memory may reflect inefficient processing in medial-temporal regions. (c) 2010 APA, all rights reserved).

High-strain slide-ring shape-memory polycaprolactone-based polyurethane.

PubMed

Wu, Ruiqing; Lai, Jingjuan; Pan, Yi; Zheng, Zhaohui; Ding, Xiaobin

2018-06-06

To enable shape-memory polymer networks to achieve recoverable high deformability with a simultaneous high shape-fixity ratio and shape-recovery ratio, novel semi-crystalline slide-ring shape-memory polycaprolactone-based polyurethane (SR-SMPCLU) with movable net-points constructed by a topologically interlocked slide-ring structure was designed and fabricated. The SR-SMPCLU not only exhibited good shape fixity, almost complete shape recovery, and a fast shape-recovery speed, it also showed an outstanding recoverable high-strain capacity with 95.83% Rr under a deformation strain of 1410% due to the pulley effect of the topological slide-ring structure. Furthermore, the SR-SMPCLU system maintained excellent shape-memory performance with increasing the training cycle numbers at 45% and even 280% deformation strain. The effects of the slide-ring cross-linker content, deformation strain, and successive shape-memory cycles on the shape-memory performance were investigated. A possible mechanism for the shape-memory effect of the SR-SMPCLU system is proposed.

Mood induction effects on motor sequence learning and stop signal reaction time.

PubMed

Greeley, Brian; Seidler, Rachael D

2017-01-01

The neurobiological theory of positive affect proposes that positive mood states may benefit cognitive performance due to an increase of dopamine throughout the brain. However, the results of many positive affect studies are inconsistent; this may be due to individual differences. The relationship between dopamine and performance is not linear, but instead follows an inverted "U" shape. Given this, we hypothesized that individuals with high working memory capacity, a proxy measure for dopaminergic transmission, would not benefit from positive mood induction and in fact performance in dopamine-mediated tasks would decline. In contrast, we predicted that individuals with low working memory capacities would receive the most benefit after positive mood induction. Here, we explored the effect of positive affect on two dopamine-mediated tasks, an explicit serial reaction time sequence learning task and the stop signal task, predicting that an individual's performance is modulated not only by working memory capacity, but also on the type of mood. Improvements in explicit sequence learning from pre- to post-positive mood induction were associated with working memory capacity; performance declined in individuals with higher working memory capacities following positive mood induction, but improved in individuals with lower working memory capacities. This was not the case for negative or neutral mood induction. Moreover, there was no relationship between the change in stop signal reaction time with any of the mood inductions and individual differences in working memory capacity. These results provide partial support for the neurobiological theory of positive affect and highlight the importance of taking into account individual differences in working memory when examining the effects of positive mood induction.

On Using the Volatile Mem-Capacitive Effect of TiO2 Resistive Random Access Memory to Mimic the Synaptic Forgetting Process

NASA Astrophysics Data System (ADS)

Sarkar, Biplab; Mills, Steven; Lee, Bongmook; Pitts, W. Shepherd; Misra, Veena; Franzon, Paul D.

2018-02-01

In this work, we report on mimicking the synaptic forgetting process using the volatile mem-capacitive effect of a resistive random access memory (RRAM). TiO2 dielectric, which is known to show volatile memory operations due to migration of inherent oxygen vacancies, was used to achieve the volatile mem-capacitive effect. By placing the volatile RRAM candidate along with SiO2 at the gate of a MOS capacitor, a volatile capacitance change resembling the forgetting nature of a human brain is demonstrated. Furthermore, the memory operation in the MOS capacitor does not require a current flow through the gate dielectric indicating the feasibility of obtaining low power memory operations. Thus, the mem-capacitive effect of volatile RRAM candidates can be attractive to the future neuromorphic systems for implementing the forgetting process of a human brain.

The list-composition effect in memory for emotional and neutral pictures: Differential contribution of ventral and dorsal attention networks to successful encoding.

PubMed

Barnacle, Gemma E; Montaldi, Daniela; Talmi, Deborah; Sommer, Tobias

2016-09-01

The Emotional enhancement of memory (EEM) is observed in immediate free-recall memory tests when emotional and neutral stimuli are encoded and tested together ("mixed lists"), but surprisingly, not when they are encoded and tested separately ("pure lists"). Here our aim was to investigate whether the effect of list-composition (mixed versus pure lists) on the EEM is due to differential allocation of attention. We scanned participants with fMRI during encoding of semantically-related emotional (negative valence only) and neutral pictures. Analysis of memory performance data replicated previous work, demonstrating an interaction between list composition and emotional valence. In mixed lists, neural subsequent memory effects in the dorsal attention network were greater for neutral stimulus encoding, while neural subsequent memory effects for emotional stimuli were found in a region associated with the ventral attention network. These results imply that when life experiences include both emotional and neutral elements, memory for the latter is more highly correlated with neural activity representing goal-directed attention processing at encoding. Copyright © 2016. Published by Elsevier Ltd.

Biphasic effect of citral, a flavoring and scenting agent, on spatial learning and memory in rats.

PubMed

Yang, Zheqiong; Xi, Jinlei; Li, Jihong; Qu, Wen

2009-10-01

Although some central effects of citral have been reported, cognitive effects on spatial memory have not been investigated. The evidence showed that citral can regulate the synthesis of retinoic acid (RA), which exerts a vital function in the development and maintenance of spatial memory. In this study, we applied Morris water maze to test the effect of citral on animals' spatial learning and memory. To elucidate the mechanism of this effect, we also measured the retinoic acid concentration in rats' hippocampus by high performance liquid chromatography (HPLC). Our data implied biphasic effects of citral. The low dose (0.1 mg/kg) of citral improved the spatial learning capability, and enhanced the spatial reference memory of rats, whereas the high dose (1.0 mg/kg) was like to produce the opposite effects. Meanwhile, the low dose of citral increased the hippocampal retinoic acid concentration, while the high dose decreased it. Due to the quick elimination and non-bioaccumulation in the body, effects of citral on spatial memory in this study seemed to be indirect actions. The change in hippocampal retinoic acid concentration induced by different doses of citral might be responsible for the biphasic effect of citral on spatial learning and memory.

Reduced autobiographical memory specificity in bereaved Afghan adolescents.

PubMed

Neshat Doost, Hamid Taher; Yule, William; Kalantari, Mehrdad; Rezvani, Sayed Rohollah; Dyregrov, Atle; Jobson, Laura

2014-01-01

This study investigated the effect of bereavement (father death due to war in Afghanistan) on autobiographical memory specificity in Afghan adolescents living in Iran. Participants consisted of bereaved (n=70) and non-bereaved (n=33) Afghan adolescents. The measures included Farsi versions of the Autobiographical Memory Test, Mood and Feeling Questionnaire, Revised Children's Manifest Anxiety Scale, and Impact of Event Scale. Results indicated that the bereaved group retrieved a significantly lower proportion of specific memories and a significantly greater proportion of extended and categoric memories than the non-bereaved group. Additionally, depression symptoms and reduced autobiographical memory specificity were significantly correlated. These findings suggest that bereaved adolescents have impaired autobiographical memory specificity.

Working Memory in Children With Neurocognitive Effects From Sickle Cell Disease: Contributions of the Central Executive and Processing Speed

PubMed Central

Smith, Kelsey E.; Schatz, Jeffrey

2017-01-01

Children with sickle cell disease (SCD) are at risk for working memory deficits due to multiple disease processes. We assessed working memory abilities and related functions in 32 school-age children with SCD and 85 matched comparison children using Baddeley’s working memory model as a framework. Children with SCD performed worse than controls for working memory, central executive function, and processing/rehearsal speed. Central executive function was found to mediate the relationship between SCD status and working memory, but processing speed did not. Cognitive remediation strategies that focus on central executive processes may be important for remediating working memory deficits in SCD. PMID:27759435

Acute alcohol effects on narrative recall and contextual memory: an examination of fragmentary blackouts.

PubMed

Wetherill, Reagan R; Fromme, Kim

2011-08-01

The present study examined the effects of alcohol consumption on narrative recall and contextual memory among individuals with and without a history of fragmentary blackouts in an attempt to better understand why some individuals experience alcohol-induced memory impairments whereas others do not, even at comparable blood alcohol concentrations (BACs). Standardized beverage (alcohol and no alcohol) administration procedures and neuropsychological assessments measured narrative recall and context memory performance before and after alcohol consumption in individuals with (n=44) and without (n=44) a history of fragmentary blackouts. Findings indicate that acute alcohol intoxication led to impairments in free recall, but not next-day cued recall. Further, participants showed similar memory performance when sober, but individuals who consumed alcohol and had a positive history of fragmentary blackouts showed greater contextual memory impairments than those who had not previously experienced a fragmentary blackout. Thus, it appears that some individuals may have an inherent vulnerability to alcohol-induced memory impairments due to alcohol's effects on contextual memory processes. Copyright © 2011 Elsevier Ltd. All rights reserved.

All of the above: When multiple correct response options enhance the testing effect.

PubMed

Bishara, Anthony J; Lanzo, Lauren A

2015-01-01

Previous research has shown that multiple choice tests often improve memory retention. However, the presence of incorrect lures often attenuates this memory benefit. The current research examined the effects of "all of the above" (AOTA) options. When such options are correct, no incorrect lures are present. In the first three experiments, a correct AOTA option on an initial test led to a larger memory benefit than no test and standard multiple choice test conditions. The benefits of a correct AOTA option occurred even without feedback on the initial test; for both 5-minute and 48-hour retention delays; and for both cued recall and multiple choice final test formats. In the final experiment, an AOTA question led to better memory retention than did a control condition that had identical timing and exposure to response options. However, the benefits relative to this control condition were similar regardless of the type of multiple choice test (AOTA or not). Results suggest that retrieval contributes to multiple choice testing effects. However, the extra testing effect from a correct AOTA option, rather than being due to more retrieval, might be due simply to more exposure to correct information.

Pathophysiology and Treatment of Memory Dysfunction after Traumatic Brain Injury

PubMed Central

Paterno, Rosalia; Folweiler, Kaitlin A.; Cohen, Akiva S.

2018-01-01

Memory is fundamental to everyday life, and cognitive impairments resulting from traumatic brain injury (TBI) have devastating effects on TBI survivors. A contributing component to memory impairments caused by TBI are alterations in the neural circuits associated with memory function. In this review, we aim to bring together experimental findings that characterize behavioral memory deficits and the underlying pathophysiology of memory-involved circuits after TBI. While there is little doubt that TBI causes memory and cognitive dysfunction, it is difficult to conclude which memory phase i.e., encoding, maintenance or retrieval is specifically altered by TBI. This is most likely due to variation in behavioral protocols and experimental models. Additionally we review a selection of experimental treatments that hold translational potential to mitigate memory dysfunction following injury. PMID:28500417

Within-session and one-week practice effects on a motor task in amnestic mild cognitive impairment.

PubMed

Schaefer, Sydney Y; Duff, Kevin

2017-06-01

Practice effects on neuropsychological tests, which are improvements in test scores due to repeated exposure to testing materials, are robust in healthy elders, but muted in older adults with cognitive disorders. Conversely, few studies have investigated practice effects on motor tasks involving procedural memory, particularly across test-retest periods exceeding 24 hours. The current study examined one-week practice effects on a novel upper extremity motor task in 54 older adults with amnestic mild cognitive impairment. Results indicate that these individuals with primary memory deficits did improve on this motor task within a brief training session as well as across one week. These practice effects were unrelated to demographic characteristics or global cognition. One-week practice effects were, however, negatively related to delayed memory function, with larger practice effects being associated with poorer delayed memory and potentially better visuospatial ability. The presence of longer term practice effects on a procedural motor task not only has implications for how longitudinal assessments with similar measures involving implicit memory might be interpreted, but may also inform future rehabilitative strategies for patients with more severe declarative memory deficits.

Corticosterone administration after a single-trial contextual fear conditioning does not influence the strength and specificity of recent and remote memory in rats.

PubMed

Bueno, Ana Paula A; de Paiva, Joselisa Péres Queiroz; Corrêa, Moisés Dos Santos; Tiba, Paula Ayako; Fornari, Raquel Vecchio

2017-03-15

It is well established that corticosterone (CORT) enhances memory consolidation of emotionally arousing experiences. Despite emotional memories being usually referred to as well remembered for long periods, there are no studies that have investigated the effects of CORT in modulating the duration and specificity of memory. In the present study, we trained Wistar rats in a single-trial contextual fear conditioning protocol and injected CORT (0.3, 1.0 or 3.0mg/kg), immediately after training, to investigate its effects on memory consolidation. Rats were tested 2 and 29days after the training session or only 29days after training to assess recent or remote memory. Our results show that animals tested for recent memory discriminated the training context from a novel one, while those tested only for remote memory generalized the fear response to both contexts. Animals tested for remote memory after being tested for recent memory were able to discriminate both contexts. These results support the literature regarding memory specificity and duration. However, CORT treatment, even at the dose of 1.0mg/kg that effectively enhanced the plasmatic hormone levels, did not affect the strength or the specificity of memory in either recent or remote memory tests. We hypothesize that the lack of effect of CORT treatment could be due to the low arousing training experience of the single-trial protocol which, despite being sufficient to induce significant recent and remote memory consolidation, may not be sufficient to allow the memory-enhancing effect of CORT. Copyright © 2017 Elsevier Inc. All rights reserved.

Modalities of memory: is reading lips like hearing voices?

PubMed

Maidment, David W; Macken, Bill; Jones, Dylan M

2013-12-01

Functional similarities in verbal memory performance across presentation modalities (written, heard, lipread) are often taken to point to a common underlying representational form upon which the modalities converge. We show here instead that the pattern of performance depends critically on presentation modality and different mechanisms give rise to superficially similar effects across modalities. Lipread recency is underpinned by different mechanisms to auditory recency, and while the effect of an auditory suffix on an auditory list is due to the perceptual grouping of the suffix with the list, the corresponding effect with lipread speech is due to misidentification of the lexical content of the lipread suffix. Further, while a lipread suffix does not disrupt auditory recency, an auditory suffix does disrupt recency for lipread lists. However, this effect is due to attentional capture ensuing from the presentation of an unexpected auditory event, and is evident both with verbal and nonverbal auditory suffixes. These findings add to a growing body of evidence that short-term verbal memory performance is determined by modality-specific perceptual and motor processes, rather than by the storage and manipulation of phonological representations. Copyright © 2013 Elsevier B.V. All rights reserved.

Factors that influence the generation of autobiographical memory conjunction errors

PubMed Central

Devitt, Aleea L.; Monk-Fromont, Edwin; Schacter, Daniel L.; Addis, Donna Rose

2015-01-01

The constructive nature of memory is generally adaptive, allowing us to efficiently store, process and learn from life events, and simulate future scenarios to prepare ourselves for what may come. However, the cost of a flexibly constructive memory system is the occasional conjunction error, whereby the components of an event are authentic, but the combination of those components is false. Using a novel recombination paradigm, it was demonstrated that details from one autobiographical memory may be incorrectly incorporated into another, forming autobiographical memory conjunction errors that elude typical reality monitoring checks. The factors that contribute to the creation of these conjunction errors were examined across two experiments. Conjunction errors were more likely to occur when the corresponding details were partially rather than fully recombined, likely due to increased plausibility and ease of simulation of partially recombined scenarios. Brief periods of imagination increased conjunction error rates, in line with the imagination inflation effect. Subjective ratings suggest that this inflation is due to similarity of phenomenological experience between conjunction and authentic memories, consistent with a source monitoring perspective. Moreover, objective scoring of memory content indicates that increased perceptual detail may be particularly important for the formation of autobiographical memory conjunction errors. PMID:25611492

Changing room cues reduces the effects of proactive interference in Clark's Nutcrackers, Nucifraga columbiana.

PubMed

Lewis, Jody L; Kamil, Alan C; Webbink, Kate E

2013-04-01

To determine what factors are important for minimizing interference effects in spatial memory, Clark's Nutcrackers, Nucifraga columbiana were tested for their spatial memory for two serial lists of locations per day. In this experiment two unique landmark sets were either different between List 1 and List 2 or the same. We found that Nutcrackers were most susceptible to interference when the landmark sets were the same. This study suggests that repeatedly testing animal memory in the same room, with the same cues, can hamper recall due to interference.

Would transcranial direct current stimulation (tDCS) enhance the effects of working memory training in older adults with mild neurocognitive disorder due to Alzheimer's disease: study protocol for a randomized controlled trial.

PubMed

Cheng, Calvin P W; Chan, Sandra S M; Mak, Arthur D P; Chan, Wai Chi; Cheng, Sheung Tak; Shi, Lin; Wang, Defeng; Lam, Linda Chiu-Wa

2015-10-24

There has been longstanding interesting in cognitive training for older adults with cognitive impairment. In this study, we will investigate the effects of working memory training, and explore augmentation strategies that could possibly consolidate the effects in older adults with mild neurocognitive disorder. Transcranial direct current stimulation (tDCS) has been demonstrated to affect the neuronal excitability and reported to enhance memory performance. As tDCS may also modulate cognitive function through changes in neuroplastic response, it would be adopted as an augmentation strategy for working memory training in the present study. This is a 4-week intervention double-blind randomized controlled trial (RCT) of tDCS. Chinese older adults (aged 60 to 90 years) with mild neurocognitive disorder due to Alzheimer's disease (DSM-5 criteria) would be randomized into a 4-week intervention of either tDCS-working memory (DCS-WM), tDCS-control cognitive training (DCS-CC), and sham tDCS-working memory (WM-CD) groups. The primary outcome would be working memory test - the n-back task performance and the Chinese version of the Alzheimer's Disease Assessment Scale - Cognitive Subscale (ADAS-Cog). Secondary outcomes would be test performance of specific cognitive domains and mood. Intention-to-treat analysis would be carried out. Changes of efficacy indicators with time and intervention would be tested with mixed effect models. This study adopts the theory of neuroplasticity to evaluate the potential cognitive benefits of non-invasive electrical brain stimulation, working memory training and dual stimulation in older adults at risk of cognitive decline. It would also examine the tolerability, program adherence and adverse effects of this novel intervention. Information would be helpful for further research of dementia prevention studies. ChiCTR-TRC- 14005036 Date of registration: 31 July 2014.

Adaptive memory: the survival-processing memory advantage is not due to negativity or mortality salience.

PubMed

Bell, Raoul; Röer, Jan P; Buchner, Axel

2013-05-01

Recent research has highlighted the adaptive function of memory by showing that imagining being stranded in the grasslands without any survival material and rating words according to their survival value in this situation leads to exceptionally good memory for these words. Studies examining the role of emotions in causing the survival-processing memory advantage have been inconclusive, but some studies have suggested that the effect might be due to negativity or mortality salience. In Experiments 1 and 2, we compared the survival scenario to a control scenario that implied imagining a hopeless situation (floating in outer space with dwindling oxygen supplies) in which only suicide can avoid the agony of choking to death. Although this scenario was perceived as being more negative than the survival scenario, the survival-processing memory advantage persisted. In Experiment 3, thinking about the relevance of words for survival led to better memory for these words than did thinking about the relevance of words for death. This survival advantage was found for concrete, but not for abstract, words. The latter finding is consistent with the assumption that the survival instructions encourage participants to think about many different potential uses of items to aid survival, which may be a particularly efficient form of elaborate encoding. Together, the results suggest that thinking about death is much less effective in promoting recall than is thinking about survival. Therefore, the survival-processing memory advantage cannot be satisfactorily explained by negativity or mortality salience.

The Effect of Midazolam and Propranolol on Fear Memory Reconsolidation in Ethanol-Withdrawn Rats: Influence of D-Cycloserine

PubMed Central

Ortiz, Vanesa; Giachero, Marcelo; Espejo, Pablo Javier; Molina, Víctor Alejandro

2015-01-01

Background: Withdrawal from chronic ethanol facilitates the formation of contextual fear memory and delays the onset to extinction, with its retrieval promoting an increase in ethanol consumption. Consequently, manipulations aimed to reduce these aversive memories, may be beneficial in the treatment of alcohol discontinuation symptoms. Related to this, pharmacological memory reconsolidation blockade has received greater attention due to its therapeutic potential. Methods: Here, we examined the effect of post-reactivation amnestic treatments such as Midazolam (MDZ, 3 mg/kg i.p) and Propranolol (PROP, 5 mg/kg i.p) on contextual fear memory reconsolidation in ethanol- withdrawn (ETOH) rats. Next, we examined whether the activation of N-methyl-D-aspartate (NMDA) receptors induced by d-cycloserine (DCS, 5 mg/kg i.p., a NMDA partial agonist) before memory reactivation can facilitate the disruptive effect of PROP and MDZ on fear memory in ETOH rats. Results: We observed a resistance to the disruptive effect of both MDZ and PROP following memory reactivation. Although intra-basolateral amygdala (BLA; 1.25 ug/side) and systemic PROP administration attenuated fear memory in DCS pre-treated ETOH rats, DCS/MDZ treatment did not affect memory in these animals. Finally, a decrease of both total and surface protein expression of the α1 GABAA receptor (GABAA-R) subunit in BLA was found in the ETOH rats. Conclusions: Ethanol withdrawal facilitated the formation of fear memory resistant to labilization post-reactivation. DCS administration promoted the disruptive effect of PROP on memory reconsolidation in ETOH rats. The resistance to MDZ’s disruptive effect on fear memory reconsolidation may be, at least in part, associated with changes in the GABAA-R composition induced by chronic ethanol administration/withdrawal. PMID:25617327

The effect of mood on false memory for emotional DRM word lists.

PubMed

Zhang, Weiwei; Gross, Julien; Hayne, Harlene

2017-04-01

In the present study, we investigated the effect of participants' mood on true and false memories of emotional word lists in the Deese-Roediger-McDermott (DRM) paradigm. In Experiment 1, we constructed DRM word lists in which all the studied words and corresponding critical lures reflected a specified emotional valence. In Experiment 2, we used these lists to assess mood-congruent true and false memory. Participants were randomly assigned to one of three induced-mood conditions (positive, negative, or neutral) and were presented with word lists comprised of positive, negative, or neutral words. For both true and false memory, there was a mood-congruent effect in the negative mood condition; this effect was due to a decrease in true and false recognition of the positive and neutral words. These findings are consistent with both spreading-activation and fuzzy-trace theories of DRM performance and have practical implications for our understanding of the effect of mood on memory.

Verbal short-term memory as an articulatory system: evidence from an alternative paradigm.

PubMed

Cheung, Him; Wooltorton, Lana

2002-01-01

In a series of experiments, the role of articulatory rehearsal in verbal [corrected] short-term memory was examined via a shadowing-plus-recall paradigm. In this paradigm, subjects shadowed a word target presented closely after an auditory memory list before they recalled the list. The phonological relationship between the shadowing target and the final item on the memory list was manipulated. Experiments 1 and 2 demonstrated that targets sounding similar to the list-final memory item generally took longer to shadow than unrelated targets. This inhibitory effect of phonological relatedness was more pronounced with tense- than lax-vowel pseudoword recall lists. The interaction between vowel tenseness and phonological relatedness was replicated in Experiment 3 using shorter lists of real words. In Experiment 4, concurrent articulation was applied during list learning to block rehearsal; consequently, neither the phonological relatedness effect nor its interaction with vowel tenseness emerged. Experiments 5 and 6 manipulated the occurrence frequencies and lexicality of the recall items, respectively, instead of vowel tenseness. Unlike vowel tenseness, these non-articulatory memory factors failed to interact with the phonological relatedness effect. Experiment 7 orthogonally manipulated the vowel tenseness and frequencies of the recall items; slowing in shadowing times due to phonological relatedness was modulated by vowel tenseness but not frequency. Taken together, these results suggest that under the present paradigm, the modifying effect of vowel tenseness on the magnitude of slowing in shadowing due to phonological relatedness is indicative of a prominent articulatory component in verbal short-term retention. The shadowing-plus-recall approach avoids confounding overt recall into internal memory processing, which is an inherent problem of the traditional immediate serial recall and span tasks.

Acute Sleep Deprivation Blocks Short- and Long-Term Operant Memory in Aplysia.

PubMed

Krishnan, Harini C; Gandour, Catherine E; Ramos, Joshua L; Wrinkle, Mariah C; Sanchez-Pacheco, Joseph J; Lyons, Lisa C

2016-12-01

Insufficient sleep in individuals appears increasingly common due to the demands of modern work schedules and technology use. Consequently, there is a growing need to understand the interactions between sleep deprivation and memory. The current study determined the effects of acute sleep deprivation on short and long-term associative memory using the marine mollusk Aplysia californica , a relatively simple model system well known for studies of learning and memory. Aplysia were sleep deprived for 9 hours using context changes and tactile stimulation either prior to or after training for the operant learning paradigm, learning that food is inedible (LFI). The effects of sleep deprivation on short-term (STM) and long-term memory (LTM) were assessed. Acute sleep deprivation prior to LFI training impaired the induction of STM and LTM with persistent effects lasting at least 24 h. Sleep deprivation immediately after training blocked the consolidation of LTM. However, sleep deprivation following the period of molecular consolidation did not affect memory recall. Memory impairments were independent of handling-induced stress, as daytime handled control animals demonstrated no memory deficits. Additional training immediately after sleep deprivation failed to rescue the induction of memory, but additional training alleviated the persistent impairment in memory induction when training occurred 24 h following sleep deprivation. Acute sleep deprivation inhibited the induction and consolidation, but not the recall of memory. These behavioral studies establish Aplysia as an effective model system for studying the interactions between sleep and memory formation. © 2016 Associated Professional Sleep Societies, LLC.

Blue Corn Tortillas: Effects on Learning and Spatial Memory in Rats.

PubMed

Aguirre López, L O; Chávez Servia, J L; Gómez Rodiles, C C; Beltrán Ramírez, J R; Bañuelos Pineda, J

2017-12-01

Consumption of pigmented corn has been associated with health benefits due to its flavonoid contents (mainly anthocyanins) and antioxidant ability. Therefore, the objective of this study was to determine the effect of blue corn tortilla (BM) consumption on memory and learning ability adult rats. Eighteen adult female rats were divided into three groups and fed for 38 consecutive days with commercial food (Control group) or the commercial food plus 6 g/day of either blue corn (BM) or white corn (WM) tortillas. Memory and learning capabilities were assessed using Barnes's labyrinth at the end of the feeding period. Short-and long-term memory was improved in the BM group, showing that consumption of blue maize tortillas improves learning and memory capabilities in adult rats.

Source Memory for Self and Other in Patients With Mild Cognitive Impairment due to Alzheimer’s Disease

PubMed Central

Deason, Rebecca G.; Budson, Andrew E.; Gutchess, Angela H.

2016-01-01

Objectives. The present study examined the role of enactment in source memory in a cognitively impaired population. As seen in healthy older adults, it was predicted that source memory in people with mild cognitive impairment due to Alzheimer’s disease (MCI-AD) would benefit from the self-reference aspect of enactment. Method. Seventeen participants with MCI-AD and 18 controls worked in small groups to pack a picnic basket and suitcase and were later tested for their source memory for each item. Results. For item memory, self-referencing improved corrected recognition scores for both MCI-AD and control participants. The MCI-AD group did not demonstrate the same benefit as controls in correct source memory for self-related items. However, those with MCI-AD were relatively less likely to misattribute new items to the self and more likely to misattribute new items to others when committing errors, compared with controls. Discussion. The enactment effect and self-referencing did not enhance accurate source memory more than other referencing for patients with MCI-AD. However, people with MCI-AD benefited in item memory and source memory, being less likely to falsely claim new items as their own, indicating some self-reference benefit occurs for people with MCI-AD. PMID:24904049

Source Memory for Self and Other in Patients With Mild Cognitive Impairment due to Alzheimer's Disease.

PubMed

Rosa, Nicole M; Deason, Rebecca G; Budson, Andrew E; Gutchess, Angela H

2016-01-01

The present study examined the role of enactment in source memory in a cognitively impaired population. As seen in healthy older adults, it was predicted that source memory in people with mild cognitive impairment due to Alzheimer's disease (MCI-AD) would benefit from the self-reference aspect of enactment. Seventeen participants with MCI-AD and 18 controls worked in small groups to pack a picnic basket and suitcase and were later tested for their source memory for each item. For item memory, self-referencing improved corrected recognition scores for both MCI-AD and control participants. The MCI-AD group did not demonstrate the same benefit as controls in correct source memory for self-related items. However, those with MCI-AD were relatively less likely to misattribute new items to the self and more likely to misattribute new items to others when committing errors, compared with controls. The enactment effect and self-referencing did not enhance accurate source memory more than other referencing for patients with MCI-AD. However, people with MCI-AD benefited in item memory and source memory, being less likely to falsely claim new items as their own, indicating some self-reference benefit occurs for people with MCI-AD. Published by Oxford University Press on behalf of the Gerontological Society of America 2014.

Limited Near and Far Transfer Effects of Jungle Memory Working Memory Training on Learning Mathematics in Children with Attentional and Mathematical Difficulties.

PubMed

Nelwan, Michel; Kroesbergen, Evelyn H

2016-01-01

The goal of this randomized controlled trial was to investigate whether Jungle Memory working memory training (JM) affects performance on working memory tasks, performance in mathematics and gains made on a mathematics training (MT) in school aged children between 9-12 years old ( N = 64) with both difficulties in mathematics, as well as attention and working memory. Children were randomly assigned to three groups and were trained in two periods: (1) JM first, followed by MT, (2) MT first, followed by JM, and (3) a control group that received MT only. Bayesian analyses showed possible short term effects of JM on near transfer measures of verbal working memory, but none on visual working memory. Furthermore, support was found for the hypothesis that children that received JM first, performed better after MT than children who did not follow JM first or did not train with JM at all. However, these effects could be explained at least partly by frequency of training effects, possibly due to motivational issues, and training-specific factors. Furthermore, it remains unclear whether the effects found on improving mathematics were actually mediated by gains in working memory. It is argued that JM might not train the components of working memory involved in mathematics sufficiently. Another possible explanation can be found in the training's lack of adaptivity, therefore failing to provide the children with tailored instruction and feedback. Finally, it was hypothesized that, since effect sizes are generally small, training effects are bound to a critical period in development.

Limited Near and Far Transfer Effects of Jungle Memory Working Memory Training on Learning Mathematics in Children with Attentional and Mathematical Difficulties

PubMed Central

Nelwan, Michel; Kroesbergen, Evelyn H.

2016-01-01

The goal of this randomized controlled trial was to investigate whether Jungle Memory working memory training (JM) affects performance on working memory tasks, performance in mathematics and gains made on a mathematics training (MT) in school aged children between 9–12 years old (N = 64) with both difficulties in mathematics, as well as attention and working memory. Children were randomly assigned to three groups and were trained in two periods: (1) JM first, followed by MT, (2) MT first, followed by JM, and (3) a control group that received MT only. Bayesian analyses showed possible short term effects of JM on near transfer measures of verbal working memory, but none on visual working memory. Furthermore, support was found for the hypothesis that children that received JM first, performed better after MT than children who did not follow JM first or did not train with JM at all. However, these effects could be explained at least partly by frequency of training effects, possibly due to motivational issues, and training-specific factors. Furthermore, it remains unclear whether the effects found on improving mathematics were actually mediated by gains in working memory. It is argued that JM might not train the components of working memory involved in mathematics sufficiently. Another possible explanation can be found in the training’s lack of adaptivity, therefore failing to provide the children with tailored instruction and feedback. Finally, it was hypothesized that, since effect sizes are generally small, training effects are bound to a critical period in development. PMID:27708595

Processing-in-Memory Enabled Graphics Processors for 3D Rendering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Chenhao; Song, Shuaiwen; Wang, Jing

2017-02-06

The performance of 3D rendering of Graphics Processing Unit that convents 3D vector stream into 2D frame with 3D image effects significantly impact users’ gaming experience on modern computer systems. Due to the high texture throughput in 3D rendering, main memory bandwidth becomes a critical obstacle for improving the overall rendering performance. 3D stacked memory systems such as Hybrid Memory Cube (HMC) provide opportunities to significantly overcome the memory wall by directly connecting logic controllers to DRAM dies. Based on the observation that texel fetches significantly impact off-chip memory traffic, we propose two architectural designs to enable Processing-In-Memory based GPUmore » for efficient 3D rendering.« less

Modeling and simulation of floating gate nanocrystal FET devices and circuits

NASA Astrophysics Data System (ADS)

Hasaneen, El-Sayed A. M.

The nonvolatile memory market has been growing very fast during the last decade, especially for mobile communication systems. The Semiconductor Industry Association International Technology Roadmap for Semiconductors states that the difficult challenge for nonvolatile semiconductor memories is to achieve reliable, low power, low voltage performance and high-speed write/erase. This can be achieved by aggressive scaling of the nonvolatile memory cells. Unfortunately, scaling down of conventional nonvolatile memory will further degrade the retention time due to the charge loss between the floating gate and drain/source contacts and substrate which makes conventional nonvolatile memory unattractive. Using nanocrystals as charge storage sites reduces dramatically the charge leakage through oxide defects and drain/source contacts. Floating gate nanocrystal nonvolatile memory, FG-NCNVM, is a candidate for future memory because it is advantageous in terms of high-speed write/erase, small size, good scalability, low-voltage, low-power applications, and the capability to store multiple bits per cell. Many studies regarding FG-NCNVMs have been published. Most of them have dealt with fabrication improvements of the devices and device characterizations. Due to the promising FG-NCNVM applications in integrated circuits, there is a need for circuit a simulation model to simulate the electrical characteristics of the floating gate devices. In this thesis, a FG-NCNVM circuit simulation model has been proposed. It is based on the SPICE BSIM simulation model. This model simulates the cell behavior during normal operation. Model validation results have been presented. The SPICE model shows good agreement with experimental results. Current-voltage characteristics, transconductance and unity gain frequency (fT) have been studied showing the effect of the threshold voltage shift (DeltaVth) due to nanocrystal charge on the device characteristics. The threshold voltage shift due to nanocrystal charge has a strong effect on the memory characteristics. Also, the programming operation of the memory cell has been investigated. The tunneling rate from quantum well channel to quantum dot (nanocrystal) gate is calculated. The calculations include various memory parameters, wavefunctions, and energies of quantum well channel and quantum dot gate. The use of floating gate nanocrystal memory as a transistor with a programmable threshold voltage has been demonstrated. The incorporation of FG-NCFETs to design programmable integrated circuit building blocks has been discussed. This includes the design of programmable current and voltage reference circuits. Finally, we demonstrated the design of tunable gain op-amp incorporating FG-NCFETs. Programmable integrated circuit building blocks can be used in intelligent analog and digital systems.

Memory effects in funnel ratchet of self-propelled particles

NASA Astrophysics Data System (ADS)

Hu, Cai-Tian; Wu, Jian-Chun; Ai, Bao-Quan

2017-05-01

The transport of self-propelled particles with memory effects is investigated in a two-dimensional periodic channel. Funnel-shaped barriers are regularly arrayed in the channel. Due to the asymmetry of the barriers, the self-propelled particles can be rectified. It is found that the memory effects of the rotational diffusion can strongly affect the rectified transport. The memory effects do not always break the rectified transport, and there exists an optimal finite value of correlation time at which the rectified efficiency takes its maximal value. We also find that the optimal values of parameters (the self-propulsion speed, the translocation diffusion coefficient, the rotational noise intensity, and the self-rotational diffusion coefficient) can facilitate the rectified transport. When introducing a finite load, particles with different self-propulsion speeds move to different directions and can be separated.

Single-trial evaluative conditioning can be moderated by instructed forgetting.

PubMed

Gast, Anne; Kattner, Florian

2016-09-01

Evaluative conditioning (EC) is a change in the valence of a conditioned stimulus (CS) due to previous pairing with an affective unconditioned stimulus (US). Several previous studies indicate that EC is related to memory of the CS-US pairs. Previous studies, however, typically cannot distinguish between the influence of CS-US knowledge during measurement and during encoding. In addition, by measuring rather than manipulating memory, they do not test the causal effect of memory on EC. The present study employed a "directed forgetting" procedure to the EC paradigm instructing participants to either forget or remember certain CS-US pairs. We found that EC effects after single learning trials were stronger for to-be-remembered than for to-be-forgotten pairs. Manipulation checks showed that the forgetting manipulation also successfully modulated memory for the target pairs and reduced both retroactive and proactive interference on memory for other pairs. Item-based analyses further demonstrated that the size of EC depended on CS-US memory. The results suggest that EC relies on available memory during measurement of the EC effect.

Effect of Atomic Layer Depositions (ALD)-Deposited Titanium Oxide (TiO2) Thickness on the Performance of Zr40Cu35Al15Ni10 (ZCAN)/TiO2/Indium (In)-Based Resistive Random Access Memory (RRAM) Structures

DTIC Science & Technology

2015-08-01

metal structures, memristors, resistive random access memory, RRAM, titanium dioxide, Zr40Cu35Al15Ni10, ZCAN, resistive memory, tunnel junction 16...TiO2 thickness ........................6 1 1. Introduction Resistive-switching memory elements based on metal-insulator-metal (MIM) diodes ...have attracted great interest due to their potential as components for simple, inexpensive, and high-density non-volatile storage devices. MIM diodes

Selective effects of acute alcohol intake on the prospective and retrospective components of a prospective-memory task with emotional targets.

PubMed

Walter, Nora T; Bayen, Ute J

2016-01-01

Prospective memory involves remembering to do something in the future and has a prospective component (remembering that something must be done) and a retrospective component (remembering what must be done and when it must be done). Initial studies reported an impairment in prospective-memory performance due to acute alcohol consumption. Retrospective-memory studies demonstrated that alcohol effects vary depending on the emotionality of the information that needs to be learned. The aim of the present study was to investigate possible differential effects of a mild acute alcohol dose (0.4 g/kg) on the prospective and retrospective components of prospective memory depending on cue valence. Seventy-five participants were allocated to an alcohol or placebo group and performed a prospective-memory task in which prospective-memory cue valence was manipulated (negative, neutral, positive). The multinomial model of event-based prospective memory (Smith and Bayen 2004) was used to measure alcohol and valence effects on the two prospective-memory components separately. Overall, no main effect of alcohol or valence on prospective-memory performance occurred. However, model-based analyses demonstrated a significantly higher retrospective component for positive compared with negative cues in the placebo group. In the alcohol group, the prospective component was weaker for negative than for neutral cues and the retrospective component was stronger for positive than for neutral cues. Group comparisons showed that the alcohol group had a significantly lower prospective component for negative cues and a lower retrospective component for neutral cues. This is the first study to demonstrate selective alcohol effects on prospective-memory components depending on prospective-memory cue valence.

Relations between emotion, memory, and attention: evidence from taboo stroop, lexical decision, and immediate memory tasks.

PubMed

MacKay, Donald G; Shafto, Meredith; Taylor, Jennifer K; Marian, Diane E; Abrams, Lise; Dyer, Jennifer R

2004-04-01

This article reports five experiments demonstrating theoretically coherent effects of emotion on memory and attention. Experiments 1-3 demonstrated three taboo Stroop effects that occur when people name the color of taboo words. One effect is longer color-naming times for taboo than for neutral words, an effect that diminishes with word repetition. The second effect is superior recall of taboo words in surprise memory tests following color naming. The third effect is better recognition memory for colors consistently associated with taboo words rather than with neutral words. None of these effects was due to retrieval factors, attentional disengagement processes, response inhibition, or strategic attention shifts. Experiments 4 and 5 demonstrated that taboo words impair immediate recall of the preceding and succeeding words in rapidly presented lists but do not impair lexical decision times. We argue that taboo words trigger specific emotional reactions that facilitate the binding of taboo word meaning to salient contextual aspects, such as occurrence in a task and font color in taboo Stroop tasks.

Polydopamine Particle-Filled Shape-Memory Polyurethane Composites with Fast Near-Infrared Light Responsibility.

PubMed

Yang, Li; Tong, Rui; Wang, Zhanhua; Xia, Hesheng

2018-03-25

A new kind of fast near-infrared (NIR) light-responsive shape-memory polymer composites was prepared by introducing polydopamine particles (PDAPs) into commercial shape-memory polyurethane (SMPU). The toughness and strength of the polydopamine-particle-filled polyurethane composites (SMPU-PDAPs) were significantly enhanced with the addition of PDAPs due to the strong interface interaction between PDAPs and polyurethane segments. Owing to the outstanding photothermal effect of PDAPs, the composites exhibit a rapid light-responsive shape-memory process in 60 s with a PDAPs content of 0.01 wt%. Due to the excellent dispersion and convenient preparation method, PDAPs have great potential to be used as high-efficiency and environmentally friendly fillers to obtain novel photoactive functional polymer composites. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Working memory, perceptual priming, and the perception of hierarchical forms: opposite effects of priming and working memory without memory refreshing.

PubMed

Kim, Jeong-Im; Humphreys, Glyn W

2010-08-01

Previous research has shown that stimuli held in working memory (WM) can influence spatial attention. Using Navon stimuli, we explored whether and how items in WM affect the perception of visual targets at local and global levels in compound letters. Participants looked for a target letter presented at a local or global level while holding a regular block letter as a memory item. An effect of holding the target's identity in WM was found. When memory items and targets were the same, performance was better than in a neutral condition when the memory item did not appear in the hierarchical letter (a benefit from valid cuing). When the memory item matched the distractor in the hierarchical stimulus, performance was worse than in the neutral baseline (a cost on invalid trials). These effects were greatest when the WM cue matched the global level of the hierarchical stimulus, suggesting that WM biases attention to the global level of form. Interestingly, in a no-memory priming condition, target perception was faster in the invalid condition than in the neutral baseline, reversing the effect in the WM condition. A further control experiment ruled out the effects of WM being due to participants' refreshing their memory from the hierarchical stimulus display. The data show that information in WM biases the selection of hierarchical forms, whereas priming does not. Priming alters the perceptual processing of repeated stimuli without biasing attention.

Cocaine Directly Impairs Memory Extinction and Alters Brain DNA Methylation Dynamics in Honey Bees.

PubMed

Søvik, Eirik; Berthier, Pauline; Klare, William P; Helliwell, Paul; Buckle, Edwina L S; Plath, Jenny A; Barron, Andrew B; Maleszka, Ryszard

2018-01-01

Drug addiction is a chronic relapsing behavioral disorder. The high relapse rate has often been attributed to the perseverance of drug-associated memories due to high incentive salience of stimuli learnt under the influence of drugs. Drug addiction has also been interpreted as a memory disorder since drug associated memories are unusually enduring and some drugs, such as cocaine, interfere with neuroepigenetic machinery known to be involved in memory processing. Here we used the honey bee (an established invertebrate model for epigenomics and behavioral studies) to examine whether or not cocaine affects memory processing independently of its effect on incentive salience. Using the proboscis extension reflex training paradigm we found that cocaine strongly impairs consolidation of extinction memory. Based on correlation between the observed effect of cocaine on learning and expression of epigenetic processes, we propose that cocaine interferes with memory processing independently of incentive salience by directly altering DNA methylation dynamics. Our findings emphasize the impact of cocaine on memory systems, with relevance for understanding how cocaine can have such an enduring impact on behavior.

Cocaine Directly Impairs Memory Extinction and Alters Brain DNA Methylation Dynamics in Honey Bees

PubMed Central

Søvik, Eirik; Berthier, Pauline; Klare, William P.; Helliwell, Paul; Buckle, Edwina L. S.; Plath, Jenny A.; Barron, Andrew B.; Maleszka, Ryszard

2018-01-01

Drug addiction is a chronic relapsing behavioral disorder. The high relapse rate has often been attributed to the perseverance of drug-associated memories due to high incentive salience of stimuli learnt under the influence of drugs. Drug addiction has also been interpreted as a memory disorder since drug associated memories are unusually enduring and some drugs, such as cocaine, interfere with neuroepigenetic machinery known to be involved in memory processing. Here we used the honey bee (an established invertebrate model for epigenomics and behavioral studies) to examine whether or not cocaine affects memory processing independently of its effect on incentive salience. Using the proboscis extension reflex training paradigm we found that cocaine strongly impairs consolidation of extinction memory. Based on correlation between the observed effect of cocaine on learning and expression of epigenetic processes, we propose that cocaine interferes with memory processing independently of incentive salience by directly altering DNA methylation dynamics. Our findings emphasize the impact of cocaine on memory systems, with relevance for understanding how cocaine can have such an enduring impact on behavior. PMID:29487536

Effects of age, gender, and stimulus presentation period on visual short-term memory.

PubMed

Kunimi, Mitsunobu

2016-01-01

This study focused on age-related changes in visual short-term memory using visual stimuli that did not allow verbal encoding. Experiment 1 examined the effects of age and the length of the stimulus presentation period on visual short-term memory function. Experiment 2 examined the effects of age, gender, and the length of the stimulus presentation period on visual short-term memory function. The worst memory performance and the largest performance difference between the age groups were observed in the shortest stimulus presentation period conditions. The performance difference between the age groups became smaller as the stimulus presentation period became longer; however, it did not completely disappear. Although gender did not have a significant effect on d' regardless of the presentation period in the young group, a significant gender-based difference was observed for stimulus presentation periods of 500 ms and 1,000 ms in the older group. This study indicates that the decline in visual short-term memory observed in the older group is due to the interaction of several factors.

Effects of Interfacial Fluorination on Performance Enhancement of High-k-Based Charge Trap Flash Memory

NASA Astrophysics Data System (ADS)

Wang, Chenjie; Huo, Zongliang; Liu, Ziyu; Liu, Yu; Cui, Yanxiang; Wang, Yumei; Li, Fanghua; Liu, Ming

2013-07-01

The effects of interfacial fluorination on the metal/Al2O3/HfO2/SiO2/Si (MAHOS) memory structure have been investigated. By comparing MAHOS memories with and without interfacial fluorination, it was identified that the deterioration of the performance and reliability of MAHOS memories is mainly due to the formation of an interfacial layer that generates excess oxygen vacancies at the interface. Interfacial fluorination suppresses the growth of the interfacial layer, which is confirmed by X-ray photoelectron spectroscopy depth profile analysis, increases enhanced program/erase efficiency, and improves data retention characteristics. Moreover, it was observed that fluorination at the SiO-HfO interface achieves a more effective performance enhancement than that at the HfO-AlO interface.

The Influence of Similarity on Visual Working Memory Representations

PubMed Central

Lin, Po-Han; Luck, Steven J.

2007-01-01

In verbal memory, similarity between items in memory often leads to interference and impaired memory performance. The present study sought to determine whether analogous interference effects would be observed in visual working memory by varying the similarity of the to-be-remembered objects in a color change-detection task. Instead of leading to interference and impaired performance, increased similarity among the items being held in memory led to improved performance. Moreover, when two similar colors were presented along with one dissimilar color, memory performance was better for the similar colors than for the dissimilar color. Similarity produced better performance even when the objects were presented sequentially and even when memory for the first item in the sequence was tested. These findings show that similarity does not lead to interference between representations in visual working memory. Instead, similarity may lead to improved task performance, possibly due to increased stability or precision of the memory representations during maintenance. PMID:19430536

Effects of aging and divided attention on recognition memory processes for single and associative information.

PubMed

Kinjo, Hikari

2011-04-01

In the divided attention paradigm to test age-related associative memory deficits, whether the effects of divided attention occur at encoding or retrieval has not been clarified, and the effect on retention has not been studied. This study explored whether and how much divided attention at either encoding, retention, or retrieval diminished accuracy in recognizing a single feature (object or location) and associated features (object+location) by 23 elderly people (13 women; M age = 70.6 yr., SD = 2.8) recruited from a neighborhood community circle, and 29 female college students (M age = 20.8 yr., SD = 1.1). The results showed a significant decline in memory performance for both age groups due to divided attention in location and associative memory at retention, suggesting that the retention process demands attentional resources. Overall, regardless of their relative deficiency in associative memory, older adults showed an effect of divided attention comparable to that of younger adults in a recognition task.

Stochastic memory: Memory enhancement due to noise

NASA Astrophysics Data System (ADS)

Stotland, Alexander; di Ventra, Massimiliano

2012-01-01

There are certain classes of resistors, capacitors, and inductors that, when subject to a periodic input of appropriate frequency, develop hysteresis loops in their characteristic response. Here we show that the hysteresis of such memory elements can also be induced by white noise of appropriate intensity even at very low frequencies of the external driving field. We illustrate this phenomenon using a physical model of memory resistor realized by TiO2 thin films sandwiched between metallic electrodes and discuss under which conditions this effect can be observed experimentally. We also discuss its implications on existing memory systems described in the literature and the role of colored noise.

Positive modulation of a neutral declarative memory by a threatening social event.

PubMed

Fernández, Rodrigo S; Bavassi, Luz; Campos, Jorge; Allegri, Ricardo F; Molina, Victor A; Forcato, Cecilia; Pedreira, María E

2015-12-01

Memories can be altered by negative or arousing experiences due to the activation of the stress-responsive sympatho-adrenal-medullary axis (SYM). Here, we used a neutral declarative memory that was acquired during multi-trial training to determine the effect of a threatening event on memory without emotional valence. To this end, participants received a new threatening social protocol before learning pairs of meaningless syllables and were tested either 15 min, 2 days or 8 days after acquisition. We first demonstrated that this threatening social situation activates not only the SYM axis (Experiment 1) and the hypothalamus-pituitary-adrenal axis (HPA; Experiment 2), but also, it improves the acquisition or early consolidation of the syllable pairs (Experiment 3). This improvement is not a transient effect; it can be observed after the memory is consolidated. Furthermore, this modulation increases the persistence of memory (Experiment 4). Thus, it is possible to affect memories with specific events that contain unrelated content and a different valence. Copyright © 2015 Elsevier Inc. All rights reserved.

The influence of strategic encoding on false memory in patients with mild cognitive impairment and Alzheimer's disease dementia.

PubMed

Tat, Michelle J; Soonsawat, Anothai; Nagle, Corinne B; Deason, Rebecca G; O'Connor, Maureen K; Budson, Andrew E

2016-11-01

Patients with Alzheimer's disease (AD) dementia exhibit high rates of memory distortions in addition to their impairments in episodic memory. Several investigations have demonstrated that when healthy individuals (young and old) engaged in an encoding strategy that emphasized the uniqueness of study items (an item-specific encoding strategy), they were able to improve their discrimination between old items and unstudied critical lure items in a false memory task. In the present study we examined if patients with AD could also improve their memory discrimination when engaging in an item-specific encoding strategy. Healthy older adult controls, patients with mild cognitive impairment (MCI) due to AD, and patients with mild AD dementia were asked to study lists of categorized words. In the Item-Specific condition, participants were asked to provide a unique detail or personal experience with each study item. In the Relational condition, they were asked to determine how each item in the list was related to the others. To assess the influence of both strategies, recall and recognition memory tests were administered. Overall, both patient groups exhibited poorer memory in both recall and recognition tests compared to controls. In terms of recognition, healthy older controls and patients with MCI due to AD exhibited improved memory discrimination in the Item-Specific condition compared to the Relational condition, whereas patients with AD dementia did not. We speculate that patients with MCI due to AD use intact frontal networks to effectively engage in this strategy. Published by Elsevier Inc.

The influence of strategic encoding on false memory in patients with mild cognitive impairment and Alzheimer’s disease dementia

PubMed Central

Tat, Michelle J.; Soonsawat, Anothai; Nagle, Corinne B.; Deason, Rebecca G.; O’Connor, Maureen K.; Budson, Andrew E.

2018-01-01

Patients with Alzheimer’s disease (AD) dementia exhibit high rates of memory distortions in addition to their impairments in episodic memory. Several investigations have demonstrated that when healthy individuals (young and old) engaged in an encoding strategy that emphasized the uniqueness of study items (an item-specific encoding strategy), they were able to improve their discrimination between old items and unstudied critical lure items in a false memory task. In the present study we examined if patients with AD could also improve their memory discrimination when engaging in an item-specific encoding strategy. Healthy older adult controls, patients with mild cognitive impairment (MCI) due to AD, and patients with mild AD dementia were asked to study lists of categorized words. In the Item-Specific condition, participants were asked to provide a unique detail or personal experience with each study item. In the Relational condition, they were asked to determine how each item in the list was related to the others. To assess the influence of both strategies, recall and recognition memory tests were administered. Overall, both patient groups exhibited poorer memory in both recall and recognition tests compared to controls. In terms of recognition, healthy older controls and patients with MCI due to AD exhibited improved memory discrimination in the Item-Specific condition compared to the Relational condition, whereas patients with AD dementia did not. We speculate that patients with MCI due to AD use intact frontal networks to effectively engage in this strategy. PMID:27643951

Acute exposure to blue wavelength light during memory consolidation improves verbal memory performance.

PubMed

Alkozei, Anna; Smith, Ryan; Dailey, Natalie S; Bajaj, Sahil; Killgore, William D S

2017-01-01

Acute exposure to light within the blue wavelengths has been shown to enhance alertness and vigilance, and lead to improved speed on reaction time tasks, possibly due to activation of the noradrenergic system. It remains unclear, however, whether the effects of blue light extend beyond simple alertness processes to also enhance other aspects of cognition, such as memory performance. The aim of this study was to investigate the effects of a thirty minute pulse of blue light versus placebo (amber light) exposure in healthy normally rested individuals in the morning during verbal memory consolidation (i.e., 1.5 hours after memory acquisition) using an abbreviated version of the California Verbal Learning Test (CVLT-II). At delayed recall, individuals who received blue light (n = 12) during the consolidation period showed significantly better long-delay verbal recall than individuals who received amber light exposure (n = 18), while controlling for the effects of general intelligence, depressive symptoms and habitual wake time. These findings extend previous work demonstrating the effect of blue light on brain activation and alertness to further demonstrate its effectiveness at facilitating better memory consolidation and subsequent retention of verbal material. Although preliminary, these findings point to a potential application of blue wavelength light to optimize memory performance in healthy populations. It remains to be determined whether blue light exposure may also enhance performance in clinical populations with memory deficits.

Recognition-induced forgetting is not due to category-based set size.

PubMed

Maxcey, Ashleigh M

2016-01-01

What are the consequences of accessing a visual long-term memory representation? Previous work has shown that accessing a long-term memory representation via retrieval improves memory for the targeted item and hurts memory for related items, a phenomenon called retrieval-induced forgetting. Recently we found a similar forgetting phenomenon with recognition of visual objects. Recognition-induced forgetting occurs when practice recognizing an object during a two-alternative forced-choice task, from a group of objects learned at the same time, leads to worse memory for objects from that group that were not practiced. An alternative explanation of this effect is that category-based set size is inducing forgetting, not recognition practice as claimed by some researchers. This alternative explanation is possible because during recognition practice subjects make old-new judgments in a two-alternative forced-choice task, and are thus exposed to more objects from practiced categories, potentially inducing forgetting due to set-size. Herein I pitted the category-based set size hypothesis against the recognition-induced forgetting hypothesis. To this end, I parametrically manipulated the amount of practice objects received in the recognition-induced forgetting paradigm. If forgetting is due to category-based set size, then the magnitude of forgetting of related objects will increase as the number of practice trials increases. If forgetting is recognition induced, the set size of exemplars from any given category should not be predictive of memory for practiced objects. Consistent with this latter hypothesis, additional practice systematically improved memory for practiced objects, but did not systematically affect forgetting of related objects. These results firmly establish that recognition practice induces forgetting of related memories. Future directions and important real-world applications of using recognition to access our visual memories of previously encountered objects are discussed.

Is Working Memory Training Effective?

ERIC Educational Resources Information Center

Shipstead, Zach; Redick, Thomas S.; Engle, Randall W.

2012-01-01

Working memory (WM) is a cognitive system that strongly relates to a person's ability to reason with novel information and direct attention to goal-relevant information. Due to the central role that WM plays in general cognition, it has become the focus of a rapidly growing training literature that seeks to affect broad cognitive change through…

Cross-cultural and gender differences in childhood amnesia.

PubMed

MacDonald, S; Uesiliana, K; Hayne, H

2000-11-01

In two experiments, we examined cross-cultural and gender differences in adults' earliest memories. To do this, we asked male and female adults from three cultural backgrounds (New Zealand European, New Zealand Maori, and Asian) to describe and date their earliest personal memory. Consistent with past research, Asian adults reported significantly later memories than European adults, however this effect was due exclusively to the extremely late memories reported by Asian females. Maori adults, whose traditional culture includes a strong emphasis on the past, reported significantly earlier memories than adults from the other two cultural groups. Across all three cultures, the memories reported by women contained more information than the memories reported by men. These findings support the view that the age and content of our earliest memories are influenced by a wide range of factors including our culture and our gender. These factors must be incorporated into any comprehensive theory of autobiographical memory.

The other-race effect does not rely on memory: Evidence from a matching task.

PubMed

Megreya, Ahmed M; White, David; Burton, A Mike

2011-08-01

Viewers are typically better at remembering faces from their own race than from other races; however, it is not yet established whether this effect is due to memorial or perceptual processes. In this study, UK and Egyptian viewers were given a simultaneous face-matching task, in which the target faces were presented upright or upside down. As with previous research using face memory tasks, participants were worse at matching other-race faces than own-race faces and showed a stronger face inversion effect for own-race faces. However, subjects' performance on own and other-race faces was highly correlated. These data provide strong evidence that difficulty in perceptual encoding of unfamiliar faces contributes substantially to the other-race effect and that accounts based entirely on memory cannot capture the full data. Implications for forensic settings are also discussed.

False memory in aging: effects of emotional valence on word recognition accuracy.

PubMed

Piguet, Olivier; Connally, Emily; Krendl, Anne C; Huot, Jessica R; Corkin, Suzanne

2008-06-01

Memory is susceptible to distortions. Valence and increasing age are variables known to affect memory accuracy and may increase false alarm production. Interaction between these variables and their impact on false memory was investigated in 36 young (18-28 years) and 36 older (61-83 years) healthy adults. At study, participants viewed lists of neutral words orthographically related to negative, neutral, or positive critical lures (not presented). Memory for these words was subsequently tested with a remember-know procedure. At test, items included the words seen at study and their associated critical lures, as well as sets of orthographically related neutral words not seen at study and their associated unstudied lures. Positive valence was shown to have two opposite effects on older adults' discrimination of the lures: It improved correct rejection of unstudied lures but increased false memory for critical lures (i.e., lures associated with words studied previously). Thus, increased salience triggered by positive valence may disrupt memory accuracy in older adults when discriminating among similar events. These findings likely reflect a source memory deficit due to decreased efficiency in cognitive control processes with aging.

Sleep-Dependent Synaptic Down-Selection (I): Modeling the Benefits of Sleep on Memory Consolidation and Integration

PubMed Central

Nere, Andrew; Hashmi, Atif; Cirelli, Chiara; Tononi, Giulio

2013-01-01

Sleep can favor the consolidation of both procedural and declarative memories, promote gist extraction, help the integration of new with old memories, and desaturate the ability to learn. It is often assumed that such beneficial effects are due to the reactivation of neural circuits in sleep to further strengthen the synapses modified during wake or transfer memories to different parts of the brain. A different possibility is that sleep may benefit memory not by further strengthening synapses, but rather by renormalizing synaptic strength to restore cellular homeostasis after net synaptic potentiation in wake. In this way, the sleep-dependent reactivation of neural circuits could result in the competitive down-selection of synapses that are activated infrequently and fit less well with the overall organization of memories. By using computer simulations, we show here that synaptic down-selection is in principle sufficient to explain the beneficial effects of sleep on the consolidation of procedural and declarative memories, on gist extraction, and on the integration of new with old memories, thereby addressing the plasticity-stability dilemma. PMID:24137153

On nonlinear finite element analysis in single-, multi- and parallel-processors

NASA Technical Reports Server (NTRS)

Utku, S.; Melosh, R.; Islam, M.; Salama, M.

1982-01-01

Numerical solution of nonlinear equilibrium problems of structures by means of Newton-Raphson type iterations is reviewed. Each step of the iteration is shown to correspond to the solution of a linear problem, therefore the feasibility of the finite element method for nonlinear analysis is established. Organization and flow of data for various types of digital computers, such as single-processor/single-level memory, single-processor/two-level-memory, vector-processor/two-level-memory, and parallel-processors, with and without sub-structuring (i.e. partitioning) are given. The effect of the relative costs of computation, memory and data transfer on substructuring is shown. The idea of assigning comparable size substructures to parallel processors is exploited. Under Cholesky type factorization schemes, the efficiency of parallel processing is shown to decrease due to the occasional shared data, just as that due to the shared facilities.

Testing enhances both encoding and retrieval for both tested and untested items.

PubMed

Cho, Kit W; Neely, James H; Crocco, Stephanie; Vitrano, Deana

2017-07-01

In forward testing effects, taking a test enhances memory for subsequently studied material. These effects have been observed for previously studied and tested items, a potentially item-specific testing effect, and newly studied untested items, a purely generalized testing effect. We directly compared item-specific and generalized forward testing effects using procedures to separate testing benefits due to encoding versus retrieval. Participants studied two lists of Swahili-English word pairs, with the second study list containing "new" pairs intermixed with the previously studied "old" pairs. Participants completed a review phase in which they took a cued-recall test on only the "old" pairs or restudied them. In Experiments 1a, 1b, and 2, the review phase was given either before or after the second study list. Testing benefited memory to the same degree for both "new" and "old" pairs, suggesting that there were no pair-specific benefits of testing. The larger benefit from testing when review was given before rather than after the second study list suggests that the memory enhancement was due to both testing-enhanced encoding and testing-enhanced retrieval. To better equate generalized testing effects for "new" and "old" pairs, Experiment 3 intermixed them in the review phase. A statistically significant pair-specific testing effect for "old" items was now observed. Overall, these results show that forward testing effects are due to both testing-enhanced encoding and retrieval effects and that direct, pair-specific forward testing benefits are considerably smaller than indirect, generalized forward testing benefits.

Novel conformal organic antireflective coatings for advanced I-line lithography

NASA Astrophysics Data System (ADS)

Deshpande, Shreeram V.; Nowak, Kelly A.; Fowler, Shelly; Williams, Paul; Arjona, Mikko

2001-08-01

Flash memory chips are playing a critical role in semiconductor devices due to increased popularity of hand held electronic communication devices such as cell phones and PDAs (personal Digital Assistants). Flash memory offers two primary advantages in semiconductor devices. First, it offers flexibility of in-circuit programming capability to reduce the loss from programming errors and to significantly reduce commercialization time to market for new devices. Second, flash memory has a double density memory capability through stacked gate structures which increases the memory capability and thus saves significantly on chip real estate. However, due to stacked gate structures the requirements for manufacturing of flash memory devices are significantly different from traditional memory devices. Stacked gate structures also offer unique challenges to lithographic patterning materials such as Bottom Anti-Reflective Coating (BARC) compositions used to achieve CD control and to minimize standing wave effect in photolithography. To be applicable in flash memory manufacturing a BARC should form a conformal coating on high topography of stacked gate features as well as provide the normal anti-reflection properties for CD control. In this paper we report on a new highly conformal advanced i-line BARC for use in design and manufacture of flash memory devices. Conformal BARCs being significantly thinner in trenches than the planarizing BARCs offer the advantage of reducing BARC overetch and thus minimizing resist thickness loss.

Self-Referential Information Alleviates Retrieval Inhibition of Directed Forgetting Effects-An ERP Evidence of Source Memory.

PubMed

Mao, Xinrui; Wang, Yujuan; Wu, Yanhong; Guo, Chunyan

2017-01-01

Directed forgetting (DF) assists in preventing outdated information from interfering with cognitive processing. Previous studies pointed that self-referential items alleviated DF effects due to the elaboration of encoding processes. However, the retrieval mechanism of this phenomenon remains unknown. Based on the dual-process framework of recognition, the retrieval of self-referential information was involved in familiarity and recollection. Using source memory tasks combined with event-related potential (ERP) recording, our research investigated the retrieval processes of alleviative DF effects elicited by self-referential information. The FN400 (frontal negativity at 400 ms) is a frontal potential at 300-500 ms related to familiarity and the late positive complex (LPC) is a later parietal potential at 500-800 ms related to recollection. The FN400 effects of source memory suggested that familiarity processes were promoted by self-referential effects without the modulation of to-be-forgotten (TBF) instruction. The ERP results of DF effects were involved with LPCs of source memory, which indexed retrieval processing of recollection. The other-referential source memory of TBF instruction caused the absence of LPC effects, while the self-referential source memory of TBF instruction still elicited the significant LPC effects. Therefore, our neural findings suggested that self-referential processing improved both familiarity and recollection. Furthermore, the self-referential processing advantage which was caused by the autobiographical retrieval alleviated retrieval inhibition of DF, supporting that the self-referential source memory alleviated DF effects.

Acute Sleep Deprivation Blocks Short- and Long-Term Operant Memory in Aplysia

PubMed Central

Krishnan, Harini C.; Gandour, Catherine E.; Ramos, Joshua L.; Wrinkle, Mariah C.; Sanchez-Pacheco, Joseph J.; Lyons, Lisa C.

2016-01-01

Study Objectives: Insufficient sleep in individuals appears increasingly common due to the demands of modern work schedules and technology use. Consequently, there is a growing need to understand the interactions between sleep deprivation and memory. The current study determined the effects of acute sleep deprivation on short and long-term associative memory using the marine mollusk Aplysia californica, a relatively simple model system well known for studies of learning and memory. Methods: Aplysia were sleep deprived for 9 hours using context changes and tactile stimulation either prior to or after training for the operant learning paradigm, learning that food is inedible (LFI). The effects of sleep deprivation on short-term (STM) and long-term memory (LTM) were assessed. Results: Acute sleep deprivation prior to LFI training impaired the induction of STM and LTM with persistent effects lasting at least 24 h. Sleep deprivation immediately after training blocked the consolidation of LTM. However, sleep deprivation following the period of molecular consolidation did not affect memory recall. Memory impairments were independent of handling-induced stress, as daytime handled control animals demonstrated no memory deficits. Additional training immediately after sleep deprivation failed to rescue the induction of memory, but additional training alleviated the persistent impairment in memory induction when training occurred 24 h following sleep deprivation. Conclusions: Acute sleep deprivation inhibited the induction and consolidation, but not the recall of memory. These behavioral studies establish Aplysia as an effective model system for studying the interactions between sleep and memory formation. Citation: Krishnan HC, Gandour CE, Ramos JL, Wrinkle MC, Sanchez-Pacheco JJ, Lyons LC. Acute sleep deprivation blocks short- and long-term operant memory in Aplysia. SLEEP 2016;39(12):2161–2171. PMID:27748243

Radiation Test Challenges for Scaled Commerical Memories

NASA Technical Reports Server (NTRS)

LaBel, Kenneth A.; Ladbury, Ray L.; Cohn, Lewis M.; Oldham, Timothy

2007-01-01

As sub-100nm CMOS technologies gather interest, the radiation effects performance of these technologies provide a significant challenge. In this talk, we shall discuss the radiation testing challenges as related to commercial memory devices. The focus will be on complex test and failure modes emerging in state-of-the-art Flash non-volatile memories (NVMs) and synchronous dynamic random access memories (SDRAMs), which are volatile. Due to their very high bit density, these device types are highly desirable for use in the natural space environment. In this presentation, we shall discuss these devices with emphasis on considerations for test and qualification methods required.

The strain and thermal induced tunable charging phenomenon in low power flexible memory arrays with a gold nanoparticle monolayer

NASA Astrophysics Data System (ADS)

Zhou, Ye; Han, Su-Ting; Xu, Zong-Xiang; Roy, V. A. L.

2013-02-01

The strain and temperature dependent memory effect of organic memory transistors on plastic substrates has been investigated under ambient conditions. The gold (Au) nanoparticle monolayer was prepared and embedded in an atomic layer deposited aluminum oxide (Al2O3) as the charge trapping layer. The devices exhibited low operation voltage, reliable memory characteristics and long data retention time. Experimental analysis of the programming and erasing behavior at various bending states showed the relationship between strain and charging capacity. Thermal-induced effects on these memory devices have also been analyzed. The mobility shows ~200% rise and the memory window increases from 1.48 V to 1.8 V when the temperature rises from 20 °C to 80 °C due to thermally activated transport. The retention capability of the devices decreases with the increased working temperature. Our findings provide a better understanding of flexible organic memory transistors under various operating temperatures and validate their applications in various areas such as temperature sensors, temperature memory or advanced electronic circuits. Furthermore, the low temperature processing procedures of the key elements (Au nanoparticle monolayer and Al2O3 dielectric layer) could be potentially integrated with large area flexible electronics.The strain and temperature dependent memory effect of organic memory transistors on plastic substrates has been investigated under ambient conditions. The gold (Au) nanoparticle monolayer was prepared and embedded in an atomic layer deposited aluminum oxide (Al2O3) as the charge trapping layer. The devices exhibited low operation voltage, reliable memory characteristics and long data retention time. Experimental analysis of the programming and erasing behavior at various bending states showed the relationship between strain and charging capacity. Thermal-induced effects on these memory devices have also been analyzed. The mobility shows ~200% rise and the memory window increases from 1.48 V to 1.8 V when the temperature rises from 20 °C to 80 °C due to thermally activated transport. The retention capability of the devices decreases with the increased working temperature. Our findings provide a better understanding of flexible organic memory transistors under various operating temperatures and validate their applications in various areas such as temperature sensors, temperature memory or advanced electronic circuits. Furthermore, the low temperature processing procedures of the key elements (Au nanoparticle monolayer and Al2O3 dielectric layer) could be potentially integrated with large area flexible electronics. Electronic supplementary information (ESI) available: UV-vis spectrum of Au nanoparticle aqueous solution, transfer characteristics of the transistors without inserting an Au nanoparticle monolayer, AFM image of the pentacene layer, transfer characteristics at different program voltages and memory windows with respect to the P/E voltage. See DOI: 10.1039/c2nr32579a

Short-term memory across eye blinks.

PubMed

Irwin, David E

2014-01-01

The effect of eye blinks on short-term memory was examined in two experiments. On each trial, participants viewed an initial display of coloured, oriented lines, then after a retention interval they viewed a test display that was either identical or different by one feature. Participants kept their eyes open throughout the retention interval on some blocks of trials, whereas on others they made a single eye blink. Accuracy was measured as a function of the number of items in the display to determine the capacity of short-term memory on blink and no-blink trials. In separate blocks of trials participants were instructed to remember colour only, orientation only, or both colour and orientation. Eye blinks reduced short-term memory capacity by approximately 0.6-0.8 items for both feature and conjunction stimuli. A third, control, experiment showed that a button press during the retention interval had no effect on short-term memory capacity, indicating that the effect of an eye blink was not due to general motoric dual-task interference. Eye blinks might instead reduce short-term memory capacity by interfering with attention-based rehearsal processes.

Experimental study of three-dimensional fin-channel charge trapping flash memories with titanium nitride and polycrystalline silicon gates

NASA Astrophysics Data System (ADS)

Liu, Yongxun; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Ishikawa, Yuki; Mizubayashi, Wataru; Morita, Yukinori; Migita, Shinji; Ota, Hiroyuki; Masahara, Meishoku

2014-01-01

Three-dimensional (3D) fin-channel charge trapping (CT) flash memories with different gate materials of physical-vapor-deposited (PVD) titanium nitride (TiN) and n+-polycrystalline silicon (poly-Si) have successfully been fabricated by using (100)-oriented silicon-on-insulator (SOI) wafers and orientation-dependent wet etching. Electrical characteristics of the fabricated flash memories including statistical threshold voltage (Vt) variability, endurance, and data retention have been comparatively investigated. It was experimentally found that a larger memory window and a deeper erase are obtained in PVD-TiN-gated metal-oxide-nitride-oxide-silicon (MONOS)-type flash memories than in poly-Si-gated poly-Si-oxide-nitride-oxide-silicon (SONOS)-type memories. The larger memory window and deeper erase of MONOS-type flash memories are contributed by the higher work function of the PVD-TiN metal gate than of the n+-poly-Si gate, which is effective for suppressing electron back tunneling during erase operation. It was also found that the initial Vt roll-off due to the short-channel effect (SCE) is directly related to the memory window roll-off when the gate length (Lg) is scaled down to 46 nm or less.

The Effects of Feedback on Memory Strategies of Younger and Older Adults

PubMed Central

Zhang, Fan; Zhang, Xin; Luo, Meng; Geng, Haiyan

2016-01-01

Existing literature suggests that feedback could effectively reduce false memories in younger adults. However, it is unclear whether memory performance in older adults also might be affected by feedback. The current study tested the hypothesis that older adults can use immediate feedback to adjust their memory strategy, similar to younger adults, but after feedback is removed, older adults may not be able to maintain using the memory strategy. Older adults will display more false memories than younger adults due to a reduction in attentional resources. In Study 1, both younger and older adults adjusted gist processing and item-specific processing biases based on the feedback given (i.e., biased and objective feedback). In Study 2 after the feedback was removed, only younger adults with full attention were able to maintain the feedback-shaped memory strategy; whereas, both younger adults with divided attention and older adults had increased false memories after feedback was removed. The findings suggest that environmental support helps older adults as well as younger adults to adopt a memory strategy that demands high attentional resources, but when the support is removed, older adults can no longer maintain such a strategy. PMID:28033327

Memory Effects on Movement Behavior in Animal Foraging

PubMed Central

Bracis, Chloe; Gurarie, Eliezer; Van Moorter, Bram; Goodwin, R. Andrew

2015-01-01

An individual’s choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems. PMID:26288228

Memory Effects on Movement Behavior in Animal Foraging.

PubMed

Bracis, Chloe; Gurarie, Eliezer; Van Moorter, Bram; Goodwin, R Andrew

2015-01-01

An individual's choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.

The Effects of Feedback on Memory Strategies of Younger and Older Adults.

PubMed

Zhang, Fan; Zhang, Xin; Luo, Meng; Geng, Haiyan

2016-01-01

Existing literature suggests that feedback could effectively reduce false memories in younger adults. However, it is unclear whether memory performance in older adults also might be affected by feedback. The current study tested the hypothesis that older adults can use immediate feedback to adjust their memory strategy, similar to younger adults, but after feedback is removed, older adults may not be able to maintain using the memory strategy. Older adults will display more false memories than younger adults due to a reduction in attentional resources. In Study 1, both younger and older adults adjusted gist processing and item-specific processing biases based on the feedback given (i.e., biased and objective feedback). In Study 2 after the feedback was removed, only younger adults with full attention were able to maintain the feedback-shaped memory strategy; whereas, both younger adults with divided attention and older adults had increased false memories after feedback was removed. The findings suggest that environmental support helps older adults as well as younger adults to adopt a memory strategy that demands high attentional resources, but when the support is removed, older adults can no longer maintain such a strategy.

Self-Referential Information Alleviates Retrieval Inhibition of Directed Forgetting Effects—An ERP Evidence of Source Memory

PubMed Central

Mao, Xinrui; Wang, Yujuan; Wu, Yanhong; Guo, Chunyan

2017-01-01

Directed forgetting (DF) assists in preventing outdated information from interfering with cognitive processing. Previous studies pointed that self-referential items alleviated DF effects due to the elaboration of encoding processes. However, the retrieval mechanism of this phenomenon remains unknown. Based on the dual-process framework of recognition, the retrieval of self-referential information was involved in familiarity and recollection. Using source memory tasks combined with event-related potential (ERP) recording, our research investigated the retrieval processes of alleviative DF effects elicited by self-referential information. The FN400 (frontal negativity at 400 ms) is a frontal potential at 300–500 ms related to familiarity and the late positive complex (LPC) is a later parietal potential at 500–800 ms related to recollection. The FN400 effects of source memory suggested that familiarity processes were promoted by self-referential effects without the modulation of to-be-forgotten (TBF) instruction. The ERP results of DF effects were involved with LPCs of source memory, which indexed retrieval processing of recollection. The other-referential source memory of TBF instruction caused the absence of LPC effects, while the self-referential source memory of TBF instruction still elicited the significant LPC effects. Therefore, our neural findings suggested that self-referential processing improved both familiarity and recollection. Furthermore, the self-referential processing advantage which was caused by the autobiographical retrieval alleviated retrieval inhibition of DF, supporting that the self-referential source memory alleviated DF effects. PMID:29066962

Alteration in Memory and Electroencephalogram Waves with Sub-acute Noise Stress in Albino Rats and Safeguarded by Scoparia dulcis.

PubMed

Loganathan, Sundareswaran; Rathinasamy, Sheeladevi

2016-01-01

Noise stress has different effects on memory and novelty and the link between them with an electroencephalogram (EEG) has not yet been reported. To find the effect of sub-acute noise stress on the memory and novelty along with EEG and neurotransmitter changes. Eight-arm maze (EAM) and Y-maze to analyze the memory and novelty by novel object test. Four groups of rats were used: Control, control treated with Scoparia dulcis extract, noise exposed, and noise exposed which received Scoparia extract. The results showed no marked difference observed between control and control treated with Scoparia extract on EAM, Y-maze, novel object test, and EEG in both prefrontal and occipital region, however, noise stress exposed rats showed significant increase in the reference memory and working memory error in EAM and latency delay, triad errors in Y-maze, and prefrontal and occipital EEG frequency rate with the corresponding increase in plasma corticosterone and epinephrine, and significant reduction in the novelty test, and significant reduction in the novelty test, amplitude of prefrontal, occipital EEG, and acetylcholine. These noise stress induced changes in EAM, Y-maze, novel object test, and neurotransmitters were significantly prevented when treated with Scoparia extract and these changes may be due to the normalizing action of Scoparia extract on the brain, which altered due to noise stress. Noise stress exposure causes EEG, behavior, and neurotransmitter alteration in the frontoparietal and occipital regions mainly involved in planning and recognition memoryOnly the noise stress exposed animals showed the significant alteration in the EEG, behavior, and neurotransmittersHowever, these noise stress induced changes in EEG behavior and neurotransmitters were significantly prevented when treated with Scoparia extractThese changes may be due to the normalizing action of Scoparia dulcis (adoptogen) on the brain which altered by noise stress. Abbreviations used: EEG: Electroencephalogram, dB: Decibel, EPI: Epinephrine, ACH: Acetylcholine, EAM: Eight-arm maze.

Alteration in Memory and Electroencephalogram Waves with Sub-acute Noise Stress in Albino Rats and Safeguarded by Scoparia dulcis

PubMed Central

Loganathan, Sundareswaran; Rathinasamy, Sheeladevi

2016-01-01

Background: Noise stress has different effects on memory and novelty and the link between them with an electroencephalogram (EEG) has not yet been reported. Objective: To find the effect of sub-acute noise stress on the memory and novelty along with EEG and neurotransmitter changes. Materials and Methods: Eight-arm maze (EAM) and Y-maze to analyze the memory and novelty by novel object test. Four groups of rats were used: Control, control treated with Scoparia dulcis extract, noise exposed, and noise exposed which received Scoparia extract. Results: The results showed no marked difference observed between control and control treated with Scoparia extract on EAM, Y-maze, novel object test, and EEG in both prefrontal and occipital region, however, noise stress exposed rats showed significant increase in the reference memory and working memory error in EAM and latency delay, triad errors in Y-maze, and prefrontal and occipital EEG frequency rate with the corresponding increase in plasma corticosterone and epinephrine, and significant reduction in the novelty test, and significant reduction in the novelty test, amplitude of prefrontal, occipital EEG, and acetylcholine. Conclusion: These noise stress induced changes in EAM, Y-maze, novel object test, and neurotransmitters were significantly prevented when treated with Scoparia extract and these changes may be due to the normalizing action of Scoparia extract on the brain, which altered due to noise stress. SUMMARY Noise stress exposure causes EEG, behavior, and neurotransmitter alteration in the frontoparietal and occipital regions mainly involved in planning and recognition memoryOnly the noise stress exposed animals showed the significant alteration in the EEG, behavior, and neurotransmittersHowever, these noise stress induced changes in EEG behavior and neurotransmitters were significantly prevented when treated with Scoparia extractThese changes may be due to the normalizing action of Scoparia dulcis (adoptogen) on the brain which altered by noise stress. Abbreviations used: EEG: Electroencephalogram, dB: Decibel, EPI: Epinephrine, ACH: Acetylcholine, EAM: Eight-arm maze PMID:27041862

Odors as effective retrieval cues for stressful episodes.

PubMed

Wiemers, Uta S; Sauvage, Magdalena M; Wolf, Oliver T

2014-07-01

Olfactory information seems to play a special role in memory due to the fast and direct processing of olfactory information in limbic areas like the amygdala and the hippocampus. This has led to the assumption that odors can serve as effective retrieval cues for autobiographic memories, especially emotional memories. The current study sought to investigate whether an olfactory cue can serve as an effective retrieval cue for memories of a stressful episode. A total of 95 participants were exposed to a psychosocial stressor or a well matching but not stressful control condition. During both conditions were visual objects present, either bound to the situation (central objects) or not (peripheral objects). Additionally, an ambient odor was present during both conditions. The next day, participants engaged in an unexpected object recognition task either under the influence of the same odor as was present during encoding (congruent odor) or another odor (non-congruent odor). Results show that stressed participants show a better memory for all objects and especially for central visual objects if recognition took place under influence of the congruent odor. An olfactory cue thus indeed seems to be an effective retrieval cue for stressful memories. Copyright © 2013 Elsevier Inc. All rights reserved.

Memory Reactivation Enables Long-Term Prevention of Interference.

PubMed

Herszage, Jasmine; Censor, Nitzan

2017-05-22

The ability of the human brain to successively learn or perform two competing tasks constitutes a major challenge in daily function. Indeed, exposing the brain to two different competing memories within a short temporal offset can induce interference, resulting in deteriorated performance in at least one of the learned memories [1-4]. Although previous studies have investigated online interference and its effects on performance [5-13], whether the human brain can enable long-term prevention of future interference is unknown. To address this question, we utilized the memory reactivation-reconsolidation framework [2, 12] stemming from studies at the synaptic level [14-17], according to which reactivation of a memory enables its update. In a set of experiments, using the motor sequence learning task [18] we report that a unique pairing of reactivating the original memory (right hand) in synchrony with novel memory trials (left hand) prevented future interference between the two memories. Strikingly, these effects were long-term and observed a month following reactivation. Further experiments showed that preventing future interference was not due to practice per se, but rather specifically depended on a limited time window induced by reactivation of the original memory. These results suggest a mechanism according to which memory reactivation enables long-term prevention of interference, possibly by creating an updated memory trace integrating original and novel memories during the reconsolidation time window. The opportunity to induce a long-term preventive effect on memories may enable the utilization of strategies optimizing normal human learning, as well as recovery following neurological insults. Copyright © 2017 Elsevier Ltd. All rights reserved.

A semi-floating gate memory based on van der Waals heterostructures for quasi-non-volatile applications

NASA Astrophysics Data System (ADS)

Liu, Chunsen; Yan, Xiao; Song, Xiongfei; Ding, Shijin; Zhang, David Wei; Zhou, Peng

2018-05-01

As conventional circuits based on field-effect transistors are approaching their physical limits due to quantum phenomena, semi-floating gate transistors have emerged as an alternative ultrafast and silicon-compatible technology. Here, we show a quasi-non-volatile memory featuring a semi-floating gate architecture with band-engineered van der Waals heterostructures. This two-dimensional semi-floating gate memory demonstrates 156 times longer refresh time with respect to that of dynamic random access memory and ultrahigh-speed writing operations on nanosecond timescales. The semi-floating gate architecture greatly enhances the writing operation performance and is approximately 106 times faster than other memories based on two-dimensional materials. The demonstrated characteristics suggest that the quasi-non-volatile memory has the potential to bridge the gap between volatile and non-volatile memory technologies and decrease the power consumption required for frequent refresh operations, enabling a high-speed and low-power random access memory.

A facilitative effect of negative affective valence on working memory.

PubMed

Gotoh, Fumiko; Kikuchi, Tadashi; Olofsson, Ulrich

2010-06-01

Previous studies have shown that negatively valenced information impaired working memory performance due to an attention-capturing effect. The present study examined whether negative valence could also facilitate working memory. Affective words (negative, neutral, positive) were used as retro-cues in a working memory task that required participants to remember colors at different spatial locations on a computer screen. Following the cue, a target detection task was used to either shift attention to a different location or keep attention at the same location as the retro-cue. Finally, participants were required to discriminate the cued color from a set of distractors. It was found that negative cues yielded shorter response times (RTs) in the attention-shift condition and longer RTs in the attention-stay condition, compared with neutral and positive cues. The results suggest that negative affective valence may enhance working memory performance (RTs), provided that attention can be disengaged.

Phosphodiesterase 10A inhibition attenuates sleep deprivation-induced deficits in long-term fear memory.

PubMed

Guo, Lengqiu; Guo, Zhuangli; Luo, Xiaoqing; Liang, Rui; Yang, Shui; Ren, Haigang; Wang, Guanghui; Zhen, Xuechu

2016-12-02

Sleep, particularly rapid eye movement (REM) sleep, is implicated in the consolidation of emotional memories. In the present study, we investigated the protective effects of a phosphodiesterase 10A (PDE10A) inhibitor MP-10 on deficits in long-term fear memory induced by REM sleep deprivation (REM-SD). REM-SD caused deficits in long-term fear memory, however, MP-10 administration ameliorated the deleterious effects of REM-SD on long term fear memory. Brain-derived neurotropic factor (BDNF) and phosphorylated cAMP response element-binding protein (pCREB) were altered in specific brain regions associated with learning and memory in REM-SD rats. Accordingly, REM-SD caused a significant decrease of pCREB in hippocampus and striatum and a significant decrease of BDNF in the hippocampus, striatum and amygdala, however, MP-10 reversed the effects of REM-SD in a dose-dependent manner. Our findings suggest that REM-SD disrupts the consolidation of long-term fear memory and that administration of MP-10 protects the REM-SD-induced deficits in fear memory, which may be due to the MP-10-induced expression of BDNF in the hippocampus, striatum and amygdala, and phosphorylation of CREB in the hippocampus and striatum. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Source memory enhancement for emotional words.

PubMed

Doerksen, S; Shimamura, A P

2001-03-01

The influence of emotional stimuli on source memory was investigated by using emotionally valenced words. The words were colored blue or yellow (Experiment 1) or surrounded by a blue or yellow frame (Experiment 2). Participants were asked to associate the words with the colors. In both experiments, emotionally valenced words elicited enhanced free recall compared with nonvalenced words; however, recognition memory was not affected. Source memory for the associated color was also enhanced for emotional words, suggesting that even memory for contextual information is benefited by emotional stimuli. This effect was not due to the ease of semantic clustering of emotional words because semantically related words were not associated with enhanced source memory, despite enhanced recall (Experiment 3). It is suggested that enhancement resulted from facilitated arousal or attention, which may act to increase organization processes important for source memory.

Mechanical properties and shape memory effect of thermal-responsive polymer based on PVA

NASA Astrophysics Data System (ADS)

Lin, Liulan; Zhang, Lingfeng; Guo, Yanwei

2018-01-01

In this study, the effect of content of glutaraldehyde (GA) on the shape memory behavior of a shape memory polymer based on polyvinyl alcohol chemically cross-linked with GA was investigated. Thermal-responsive shape memory composites with three different GA levels, GA-PVA (3 wt%, 5 wt%, 7 wt%), were prepared by particle melting, mold forming and freeze-drying technique. The mechanical properties, thermal properties and shape memory behavior were measured by differential scanning calorimeter, physical bending test and cyclic thermo-mechanical test. The addition of GA to PVA led to a steady shape memory transition temperature and an improved mechanical compressive strength. The composite with 5 wt% of GA exhibited the best shape recoverability. Further increase in the crosslinking agent content of GA would reduce the recovery force and prolong the recovery time due to restriction in the movement of the soft PVA chain segments. These results provide important information for the study on materials in 4D printing.

Nonvolatile memory characteristics of organic thin film transistors using poly(2-hydroxyethyl methacrylate)-based polymer multilayer dielectric

NASA Astrophysics Data System (ADS)

Chen, Ying-Chih; Su, Yan-Kuin; Yu, Hsin-Chieh; Huang, Chun-Yuan; Huang, Tsung-Syun

2011-10-01

A wide hysteresis width characteristic (memory window) was observed in the organic thin film transistors (OTFTs) using poly(2-hydroxyethyl methacrylate) (PHEMA)-based polymer multilayers. In this study, a strong memory effect was also found in the pentacene-based OTFTs and the electric characteristics were improved by introducing PHEMA/poly(methyl methacrylate) (PMMA)/PHEMA trilayer to replace the conventional PHEMA monolayer or PMMA/PHEMA and PHEMA/PMMA bilayer as the dielectric layers of OTFTs. The memory effect was originated from the electron trapping and slow polarization of the dielectrics. The hydroxyl (-OH) groups inside the polymer dielectric were the main charge storage sites of the electrons. This charge-storage phenomenon could lead to a wide flat-band voltage shift (memory window, △VFB = 22 V) which is essential for the OTFTs' memory-related applications. Moreover, the fabricated transistors also exhibited significant switchable channel current due to the charge-storage and slow charge relaxation.

Suppression of Neurotoxic Lesion-Induced Seizure Activity: Evidence for a Permanent Role for the Hippocampus in Contextual Memory

PubMed Central

Sparks, Fraser T.; Lehmann, Hugo; Hernandez, Khadaryna; Sutherland, Robert J.

2011-01-01

Damage to the hippocampus (HPC) using the excitotoxin N-methyl-D-aspartate (NMDA) can cause retrograde amnesia for contextual fear memory. This amnesia is typically attributed to loss of cells in the HPC. However, NMDA is also known to cause intense neuronal discharge (seizure activity) during the hours that follow its injection. These seizures may have detrimental effects on retrieval of memories. Here we evaluate the possibility that retrograde amnesia is due to NMDA-induced seizure activity or cell damage per se. To assess the effects of NMDA induced activity on contextual memory, we developed a lesion technique that utilizes the neurotoxic effects of NMDA while at the same time suppressing possible associated seizure activity. NMDA and tetrodotoxin (TTX), a sodium channel blocker, are simultaneously infused into the rat HPC, resulting in extensive bilateral damage to the HPC. TTX, co-infused with NMDA, suppresses propagation of seizure activity. Rats received pairings of a novel context with foot shock, after which they received NMDA-induced, TTX+NMDA-induced, or no damage to the HPC at a recent (24 hours) or remote (5 weeks) time point. After recovery, the rats were placed into the shock context and freezing was scored as an index of fear memory. Rats with an intact HPC exhibited robust memory for the aversive context at both time points, whereas rats that received NMDA or NMDA+TTX lesions showed a significant reduction in learned fear of equal magnitude at both the recent and remote time points. Therefore, it is unlikely that observed retrograde amnesia in contextual fear conditioning are due to disruption of non-HPC networks by propagated seizure activity. Moreover, the memory deficit observed at both time points offers additional evidence supporting the proposition that the HPC has a continuing role in maintaining contextual memories. PMID:22110648

Factors that influence the generation of autobiographical memory conjunction errors.

PubMed

Devitt, Aleea L; Monk-Fromont, Edwin; Schacter, Daniel L; Addis, Donna Rose

2016-01-01

The constructive nature of memory is generally adaptive, allowing us to efficiently store, process and learn from life events, and simulate future scenarios to prepare ourselves for what may come. However, the cost of a flexibly constructive memory system is the occasional conjunction error, whereby the components of an event are authentic, but the combination of those components is false. Using a novel recombination paradigm, it was demonstrated that details from one autobiographical memory (AM) may be incorrectly incorporated into another, forming AM conjunction errors that elude typical reality monitoring checks. The factors that contribute to the creation of these conjunction errors were examined across two experiments. Conjunction errors were more likely to occur when the corresponding details were partially rather than fully recombined, likely due to increased plausibility and ease of simulation of partially recombined scenarios. Brief periods of imagination increased conjunction error rates, in line with the imagination inflation effect. Subjective ratings suggest that this inflation is due to similarity of phenomenological experience between conjunction and authentic memories, consistent with a source monitoring perspective. Moreover, objective scoring of memory content indicates that increased perceptual detail may be particularly important for the formation of AM conjunction errors.

Serial position effects in free memory recall--An ERP-study.

PubMed

Wiswede, Daniel; Rüsseler, Jascha; Münte, Thomas F

2007-05-01

Event-related brain potentials (ERPs) elicited by recalled and non-recalled words were recorded from 18 female subjects to investigate primacy and recency effects in free memory recall. The typical pattern of a serial position curve (SPC) was obtained with words presented at first and final positions in a list recalled better than words presented in the middle of a list. A marked positivity is seen in the ERPs for words on Primacy, but not on Recency positions at frontocentral electrodes. In contrast, ERP amplitudes on parietal electrodes resemble the SPC seen in behavioral data: P300 amplitude is largest for words on Primacy and Recency positions and attenuated on Plateau positions. Furthermore, subjects with a clear Primacy effect in behavioral data show a distinct frontal positive slow wave for Primacy words only, whereas subjects without a clear primacy effect show a frontal "difference due to subsequent memory" (DM) effect for Primacy and Plateau words. These results are discussed in the framework of working memory and distinctiveness.

[Cognitive aging mechanism of signaling effects on the memory for procedural sentences].

PubMed

Yamamoto, Hiroki; Shimada, Hideaki

2006-08-01

The aim of this study was to clarify the cognitive aging mechanism of signaling effects on the memory for procedural sentences. Participants were 60 younger adults (college students) and 60 older adults. Both age groups were assigned into two groups; half of each group was presented with procedural sentences with signals that highlighted their top-level structure and the other half with procedural sentences without them. Both groups were requested to perform the sentence arrangement task and the reconstruction task. Each task was composed of procedural sentences with or without signals. Results indicated that signaling supported changes in strategy utilization during the successive organizational processes and that changes in strategy utilization resulting from signaling improved the memory for procedural sentences. Moreover, age-related factors interfered with these signaling effects. This study clarified the cognitive aging mechanism of signaling effects in which signaling supports changes in the strategy utilization during organizational processes at encoding and this mediation promotes memory for procedural sentences, though disuse of the strategy utilization due to aging restrains their memory for procedural sentences.

A review on shape memory alloys with applications to morphing aircraft

NASA Astrophysics Data System (ADS)

Barbarino, S.; Saavedra Flores, E. I.; Ajaj, R. M.; Dayyani, I.; Friswell, M. I.

2014-06-01

Shape memory alloys (SMAs) are a unique class of metallic materials with the ability to recover their original shape at certain characteristic temperatures (shape memory effect), even under high applied loads and large inelastic deformations, or to undergo large strains without plastic deformation or failure (super-elasticity). In this review, we describe the main features of SMAs, their constitutive models and their properties. We also review the fatigue behavior of SMAs and some methods adopted to remove or reduce its undesirable effects. SMAs have been used in a wide variety of applications in different fields. In this review, we focus on the use of shape memory alloys in the context of morphing aircraft, with particular emphasis on variable twist and camber, and also on actuation bandwidth and reduction of power consumption. These applications prove particularly challenging because novel configurations are adopted to maximize integration and effectiveness of SMAs, which play the role of an actuator (using the shape memory effect), often combined with structural, load-carrying capabilities. Iterative and multi-disciplinary modeling is therefore necessary due to the fluid-structure interaction combined with the nonlinear behavior of SMAs.

Cognitive decline impairs financial and health literacy among community-based older persons without dementia

PubMed Central

Boyle, Patricia A.; Yu, Lei; Wilson, Robert S.; Segawa, Eisuke; Buchman, Aron S.; Bennett, David A.

2013-01-01

Literacy is an important determinant of health and well-being across the lifespan but is critical in aging, when many influential health and financial decisions are made. Prior studies suggest that older persons exhibit lower literacy than younger persons, particularly in the domains of financial and health literacy, but the reasons why remain unknown. The objectives of this study were to: a) examine pathways linking diverse resources (i.e., education, word knowledge, cognitive function, and decision making style) to health and financial literacy among older persons and determine the extent to which the relation of age with literacy represents a direct effect versus an indirect effect due to decrements in specific cognitive functions (i.e., executive functions and episodic memory), and b) test the hypothesis that declines in executive function and episodic memory are associated with lower literacy among older persons without dementia. 645 community-based older persons without dementia underwent detailed assessments of diverse resources, including education, word knowledge, cognitive function (i.e., executive function, episodic memory) and decision making style (i.e., risk aversion), and completed a measure of literacy that included items similar to those assessed in the Health and Retirement Study, such as numeracy, financial concepts such as compound inflation and knowledge of stocks and bonds, and important health concepts such as understanding of drug risk and Medicare Part D. Path analysis revealed a strong effect of age on literacy, with about half of the effect of age on literacy due to decrements in executive functions and episodic memory. In addition, executive function had an indirect effect on literacy via decision making style (i.e., risk aversion), and education and word knowledge had independent effects on literacy. Finally, among (n=447) persons with repeated cognitive assessments available for up to 14 years, regression analysis supported the association of multiple resources with literacy; moreover, more rapid declines in executive function and episodic memory over an average of 6.4 years prior to the literacy assessment predicted lower literacy scores (p’s<0.02), but rate of decline in word knowledge did not. These findings suggest that diverse individual resources contribute to financial and health literacy and lower literacy in old age is partially due to declines in executive function and episodic memory. PMID:23957225

Cognitive decline impairs financial and health literacy among community-based older persons without dementia.

PubMed

Boyle, Patricia A; Yu, Lei; Wilson, Robert S; Segawa, Eisuke; Buchman, Aron S; Bennett, David A

2013-09-01

Literacy is an important determinant of health and well-being across the life span but is critical in aging, when many influential health and financial decisions are made. Prior studies suggest that older persons exhibit lower literacy than younger persons, particularly in the domains of financial and health literacy, but the reasons why remain unknown. The objectives of this study were to: (a) examine pathways linking diverse resources (i.e., education, word knowledge, cognitive function, and decision making style) to health and financial literacy among older persons and determine the extent to which the relation of age with literacy represents a direct effect versus an indirect effect due to decrements in specific cognitive functions (i.e., executive functions and episodic memory); and (b) test the hypothesis that declines in executive function and episodic memory are associated with lower literacy among older persons without dementia. Six-hundred and forty-five community-based older persons without dementia underwent detailed assessments of diverse resources, including education, word knowledge, cognitive function (i.e., executive function, episodic memory) and decision making style (i.e., risk aversion), and completed a measure of literacy that included items similar to those used in the Health and Retirement Study, such as numeracy, financial concepts such as compound inflation and knowledge of stocks and bonds, and important health concepts such as understanding of drug risk and Medicare Part D. Path analysis revealed a strong effect of age on literacy, with about half of the effect of age on literacy due to decrements in executive functions and episodic memory. In addition, executive function had an indirect effect on literacy via decision making style (i.e., risk aversion), and education and word knowledge had independent effects on literacy. Finally, among (n = 447) persons with repeated cognitive assessments available for up to 14 years, regression analysis supported the association of multiple resources with literacy; moreover, more rapid declines in executive function and episodic memory over an average of 6.4 years prior to the literacy assessment predicted lower literacy scores (ps < 0.02), but rate of decline in word knowledge did not. These findings suggest that diverse individual resources contribute to financial and health literacy and lower literacy in old age is partially due to declines in executive function and episodic memory.

Exploration of the Memory Effect on the Photon-Assisted Tunneling via a Single Quantum Dot:. a Generalized Floquet Theoretical Approach

NASA Astrophysics Data System (ADS)

Chen, Hsing-Ta; Ho, Tak-San; Chu, Shih-I.

The generalized Floquet approach is developed to study memory effect on electron transport phenomena through a periodically driven single quantum dot in an electrode-multi-level dot-electrode nanoscale quantum device. The memory effect is treated using a multi-function Lorentzian spectral density (LSD) model that mimics the spectral density of each electrode in terms of multiple Lorentzian functions. For the symmetric single-function LSD model involving a single-level dot, the underlying single-particle propagator is shown to be related to a 2×2 effective time-dependent Hamiltonian that includes both the periodic external field and the electrode memory effect. By invoking the generalized Van Vleck (GVV) nearly degenerate perturbation theory, an analytical Tien-Gordon-like expression is derived for arbitrary order multi-photon resonance d.c. tunneling current. Numerically converged simulations and the GVV analytical results are in good agreement, revealing the origin of multi-photon coherent destruction of tunneling and accounting for the suppression of the staircase jumps of d.c. current due to the memory effect. Specially, a novel blockade phenomenon is observed, showing distinctive oscillations in the field-induced current in the large bias voltage limit.

Gender-Specific Differences in the Relationship between Autobiographical Memory and Intertemporal Choice in Older Adults

PubMed Central

Seinstra, Maayke; Grzymek, Katharina; Kalenscher, Tobias

2015-01-01

As the population of older adults grows, their economic choices will have increasing impact on society. Research on the effects of aging on intertemporal decisions shows inconsistent, often opposing results, indicating that yet unexplored factors might play an essential role in guiding one's choices. Recent studies suggest that episodic future thinking, which is based on the same neural network involved in episodic memory functions, leads to reductions in discounting of future rewards. As episodic memory functioning declines with normal aging, but to greatly variable degrees, individual differences in delay discounting might be due to individual differences in the vitality of this memory system in older adults. We investigated this hypothesis, using a sample of healthy older adults who completed an intertemporal choice task as well as two episodic memory tasks. We found no clear evidence for a relationship between episodic memory performance and delay discounting in older adults. However, when additionally considering gender differences, we found an interaction effect of gender and autobiographical memory on delay discounting: while men with higher memory scores showed less delay discounting, women with higher memory scores tended to discount the future more. We speculate that this gender effect might stem from the gender-specific use of different modal representation formats (i.e. temporal or visual) during assessment of intertemporal choice options. PMID:26335426

Loads and loads and loads: the influence of prospective load, retrospective load, and ongoing task load in prospective memory.

PubMed

Meier, Beat; Zimmermann, Thomas D

2015-01-01

In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load (OTL) can affect prospective memory performance. The existence of multiple target events increases prospective load (PL) and adding complexity to the to-be-remembered action increases retrospective load (RL). In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of PL on costs in the ongoing task for categorical targets (Experiment 2), but not for specific targets (Experiment 1). RL and OTL both affected remembering the retrospective component of the prospective memory task. We suggest that PL can enhance costs in the ongoing task due to additional monitoring requirements. RL and OTL seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially.

Loads and loads and loads: the influence of prospective load, retrospective load, and ongoing task load in prospective memory

PubMed Central

Meier, Beat; Zimmermann, Thomas D.

2015-01-01

In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load (OTL) can affect prospective memory performance. The existence of multiple target events increases prospective load (PL) and adding complexity to the to-be-remembered action increases retrospective load (RL). In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of PL on costs in the ongoing task for categorical targets (Experiment 2), but not for specific targets (Experiment 1). RL and OTL both affected remembering the retrospective component of the prospective memory task. We suggest that PL can enhance costs in the ongoing task due to additional monitoring requirements. RL and OTL seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially. PMID:26082709

Interference due to shared features between action plans is influenced by working memory span.

PubMed

Fournier, Lisa R; Behmer, Lawrence P; Stubblefield, Alexandra M

2014-12-01

In this study, we examined the interactions between the action plans that we hold in memory and the actions that we carry out, asking whether the interference due to shared features between action plans is due to selection demands imposed on working memory. Individuals with low and high working memory spans learned arbitrary motor actions in response to two different visual events (A and B), presented in a serial order. They planned a response to the first event (A) and while maintaining this action plan in memory they then executed a speeded response to the second event (B). Afterward, they executed the action plan for the first event (A) maintained in memory. Speeded responses to the second event (B) were delayed when it shared an action feature (feature overlap) with the first event (A), relative to when it did not (no feature overlap). The size of the feature-overlap delay was greater for low-span than for high-span participants. This indicates that interference due to overlapping action plans is greater when fewer working memory resources are available, suggesting that this interference is due to selection demands imposed on working memory. Thus, working memory plays an important role in managing current and upcoming action plans, at least for newly learned tasks. Also, managing multiple action plans is compromised in individuals who have low versus high working memory spans.

Improving the Performance of Electrically Activated NiTi Shape Memory Actuators by Pre-Aging

NASA Astrophysics Data System (ADS)

Rathmann1, Christian; Fleczok1, Benjamin; Otibar1, Dennis; Kuhlenkötter, Bernd

2017-06-01

Shape memory alloys possess an array of unique functional properties which are influenced by a complex interaction of different factors. Due to thermal sensitivity, slight changes in temperature may cause the properties to change significantly. This poses a huge challenge especially for the use of shape memory alloys as actuators. The displacement is the key performance indicator, which has to be of equal or better quality compared to conventional actuators. One problem of shape memory alloys is the change in functional fatigue in the first cycles, which makes it rather difficult to design the actuator. Therefore, the reduction of this shakedown effect is crucial. For this reason, this paper investigates the effect of electrical heat treatment as a method for pre-aging. This topic has so far been little investigated so that the investigations focus on identifying important factors and effects by using the design of experiments.

Isolating Age-Group Differences in Working Memory Load-Related Neural Activity: Assessing the Contribution of Working Memory Capacity Using a Partial-Trial fMRI Method

PubMed Central

Bennett, Ilana J.; Rivera, Hannah G.; Rypma, Bart

2013-01-01

Previous studies examining age-group differences in working memory load-related neural activity have yielded mixed results. When present, age-group differences in working memory capacity are frequently proposed to underlie these neural effects. However, direct relationships between working memory capacity and working memory load-related activity have only been observed in younger adults. These relationships remain untested in healthy aging. Therefore, the present study examined patterns of working memory load-related activity in 22 younger and 20 older adults and assessed the contribution of working memory capacity to these load-related effects. Participants performed a partial-trial delayed response item recognition task during functional magnetic resonance imaging. In this task, participants encoded either 2 or 6 letters, maintained them during a delay, and then indicated whether a probe was present in the memory set. Behavioral results revealed faster and more accurate responses to load 2 versus 6, with age-group differences in this load condition effect for the accuracy measure. Neuroimaging results revealed one region (medial superior frontal gyrus) that showed age-group differences in load-related activity during the retrieval period, with less (greater) neural activity for the low versus high load condition in younger (older) adults. Furthermore, for older adults, load-related activity did not vary as a function of working memory capacity. Thus, working memory-related activity varies with healthy aging, but these patterns are not due solely to working memory capacity. Neurocognitive aging theories that feature capacity will need to account for these results. PMID:23357076

Emotionally arousing pictures increase blood glucose levels and enhance recall.

PubMed

Blake, T M; Varnhagen, C K; Parent, M B

2001-05-01

Arousal enhances memory in human participants and this enhancing effect is likely due to the release of peripheral epinephrine. As epinephrine does not readily enter the brain, one way that peripheral epinephrine may enhance memory is by increasing circulating blood glucose levels. The present study investigated the possibility that emotionally arousing color pictures would improve memory and elevate blood glucose levels in human participants. Blood glucose levels were measured before, 15 min, and 30 min after male university students viewed 60 emotionally arousing or relatively neutral pictures. Participants viewed each picture for 6 s and then had 10 s to rate the arousal (emotional intensity) and valence (pleasantness) of each picture. A free-recall memory test was given 30 min after the last picture was viewed. Although the emotionally arousing and neutral picture sets were given comparable valence ratings, participants who viewed the emotionally arousing pictures rated the pictures as being more arousing, recalled more pictures, and had higher blood glucose levels after viewing the pictures than did participants who viewed the neutral pictures. These findings indicate that emotionally arousing pictures increase blood glucose levels and enhance memory, and that this effect is not due to differences in the degree of pleasantness of the stimuli. These findings support the possibility that increases in circulating blood glucose levels in response to emotional arousal may be part of the biological mechanism that allows emotional arousal to enhance memory. Copyright 2001 Academic Press.

Comparative effect of coffee robusta and coffee arabica (Qahwa) on memory and attention.

PubMed

Alharbi, Waheeb D M; Azmat, Aisha; Ahmed, Muhammad

2018-04-13

The comparative effects of coffee robusta and coffee arabica (Qahwa) on different attention and memory related assignments were measured in a double-blind study of 300 healthy young adult women who were randomly assigned to one of three different drinks: Group I (coffee robusta sachet dissolved in 100 ml of hot water): Group II (coffee arabica): and group III (100 ml water only). Cognitive function was assessed by standardized tests. Several monitoring cognitive tests and tasks were specifically chosen and performed to investigate the comparative effects of coffee robusta (CR) and coffee arabica (Qahwa; AC) on sleepiness (sleep and clear headed scale), attention (trail A & B, symbol digit, letter cancellation), general cognitive ability (stroop test) and memory (card test). Data was interpreted by analysis of variance (ANOVA). The present study revealed that coffee robusta has beneficial effects on attention, general cognitive ability and memory. Higher though non-significant cognitive scores were associated with coffee robusta consumption. Although, consumption of coffee arabica (Qahwa) has significant effects (P < 0.05) on sleepiness, attention, general cognitive ability and memory and it significantly improve reaction time and correct responses. Since different tasks were related to the sustained attention and working memory processes, results would suggest that coffee arabica (qahwa) could increase the memory and efficiency of the attentional system might be due to the presence of chlorogenic acids (CGA) which are found in less quantity in coffee robusta. However, more studies using larger samples and different tasks are necessary to better understand the effects of coffee robusta and arabica (Qahwa) on attention and memory.

Word Imageability Enhances Association-memory by Increasing Hippocampal Engagement.

PubMed

Caplan, Jeremy B; Madan, Christopher R

2016-10-01

The hippocampus is thought to support association-memory, particularly when tested with cued recall. One of the most well-known and studied factors that influences accuracy of verbal association-memory is imageability; participants remember pairs of high-imageability words better than pairs of low-imageability words. High-imageability words are also remembered better in tests of item-memory. However, we previously found that item-memory effects could not explain the enhancement in cued recall, suggesting that imageability enhances association-memory strength. Here we report an fMRI study designed to ask, what is the role of the hippocampus in the memory advantage for associations due to imageability? We tested two alternative hypotheses: (1) Recruitment Hypothesis: High-imageability pairs are remembered better because they recruit the underlying hippocampal association-memory function more effectively. Alternatively, (2) Bypassing Hypothesis: Imageability functions by making the association-forming process easier, enhancing memory in a way that bypasses the hippocampus, as has been found, for example, with explicit unitization imagery strategies. Results found, first, hippocampal BOLD signal was greater during study and recall of high- than low-imageability word pairs. Second, the difference in activity between recalled and forgotten pairs showed a main effect, but no significant interaction with imageability, challenging the bypassing hypothesis, but consistent with the predictions derived from the recruitment hypothesis. Our findings suggest that certain stimulus properties, like imageability, may leverage, rather than avoid, the associative function of the hippocampus to support superior association-memory.

The effect of encoding condition on free recall in Parkinson's disease: incidental and intentional memory are equally affected.

PubMed

Ellfolk, Ulla; Huurinainen, Salla; Joutsa, Juho; Karrasch, Mira

2012-01-01

Free recall memory deficits are common at early stages of Parkinson's disease (PD). As most studies have used intentional memory tasks, there is little information on how non-intentional, incidental encoding conditions affect memory performance in PD. We studied possible differences between PD patients and controls on free recall using incidental and intentional visual memory tasks. Free recall was examined in relation to attentive/executive functioning and subjective memory complaints. A total of 29 non-demented, medicated PD patients (age 60, disease duration 19 months) and 29 healthy controls (age 61) participated in the study. Incidental free recall was studied using a memory-modification of the Boston naming test (Memo-BNT) and intentional free recall with the 20 Objects test. There was a significant main effect for group due to worse free recall performances in the PD group. No statistically significant interaction between group and encoding condition was observed. The free recall deficit in the PD group was related to cognitive/psychomotor slowing, but not to attentive/executive task demands, or to subjective memory complaints. The results indicate that PD patients are impaired on free recall irrespective of encoding condition.

Training Working Memory in Adolescents Using Serious Game Elements: Pilot Randomized Controlled Trial

PubMed Central

Gladwin, Thomas E; Peeters, Margot; Prins, Pier J M; Wiers, Reinout W

2018-01-01

Background Working memory capacity has been found to be impaired in adolescents with various psychological problems, such as addictive behaviors. Training of working memory capacity can lead to significant behavioral improvements, but it is usually long and tedious, taxing participants’ motivation to train. Objective This study aimed to evaluate whether adding game elements to the training could help improve adolescents’ motivation to train while improving cognition. Methods A total of 84 high school students were allocated to a working memory capacity training, a gamified working memory capacity training, or a placebo condition. Working memory capacity, motivation to train, and drinking habits were assessed before and after training. Results Self-reported evaluations did not show a self-reported preference for the game, but participants in the gamified working memory capacity training condition did train significantly longer. The game successfully increased motivation to train, but this effect faded over time. Working memory capacity increased equally in all conditions but did not lead to significantly lower drinking, which may be due to low drinking levels at baseline. Conclusions We recommend that future studies attempt to prolong this motivational effect, as it appeared to fade over time. PMID:29792294

Judgment and memory performance for emotional stimuli in patients with alcoholic Korsakoff syndrome.

PubMed

Labudda, Kirsten; Todorovski, Saso; Markowitsch, Hans J; Brand, Matthias

2008-02-01

In this study we investigated whether alcoholic Korsakoff patients are impaired in categorizing neutral and emotional stimuli according to their valence and whether memory performance for this material is reduced. In a group of Korsakoff patients and a comparison group two experimental tasks--one containing emotional and neutral pictures and the other containing words-were administered. Results showed that patients had difficulties in affective judgments due to problems in classifying neutral stimuli. Memory for emotional and neutral material was impaired to a similar degree. Thus, the facilitating effect of emotional valence on memory performance is absent in Korsakoff patients.

Vitamin K2 Improves Anxiety and Depression but not Cognition in Rats with Metabolic Syndrome: a Role of Blood Glucose?

PubMed

Gancheva, Silvia M; Zhelyazkova-Savova, Maria D

2016-12-01

The metabolic syndrome is a socially important disorder of energy utilization and storage, recognized as a factor predisposing to the development of depression, anxiety and cognitive impairment in humans. In the present study we examined the effects of vitamin K2 on the behavior of rats with metabolic syndrome and looked for relationships with the effects on blood sugar. Male Wistar rats were divided in four groups: a control group on a regular rat chow, a metabolic syndrome (MS) group fed a high-fat high-fructose diet, a control group treated with vitamin K2 and a MS group treated with vitamin K2. Vitamin K2 was given by gavage. At the end of the study (after 10 weeks) behavioral tests were performed and fasting blood glucose was measured. Anxiety was determined using the social interaction test and depression was assessed by the Porsolt test. Memory effects were estimated by the object recognition test. Correlations between fasting blood glucose and behavioral performance were analyzed. The rats from the MS group had elevated blood glucose. They had anxiety, depression and memory deficit. Vitamin K2 normalized blood glucose, reduced anxiety and depression, but did not improve memory. Time of social interaction (inverse index of anxiety) and memory recognition were negatively correlated with blood glucose in the untreated rats but the immobility time (measure of depression) was not. When vitamin K2-treated rats were added, the correlation of blood glucose with the time of social interaction was kept, but the one with the recognition memory was lost. It might be that the anxiolytic effect of vitamin K2 in this setting is at least partly due to its effects on blood glucose, while the anti-depressant effect is glucose-independent. The present study demonstrated that vitamin K2 prevented the development of anxiety and depression, but did not improve the memory deficit caused by the dietary manipulation in an experimental model of metabolic syndrome. It might be that the anxiolytic effect of vitamin K2 is at least partly due to its effects on blood glucose, while the antidepressant effect is glucose-independent.

Processing Strategy and PI Effects in Recognition Memory of Word Lists.

ERIC Educational Resources Information Center

Hodge, Milton H.; Britton, Bruce K.

Previous research by A. I. Schulman argued that an observed systematic decline in recognition memory in long word lists was due to the build-up of input and output proactive interference (PI). It also suggested that input PI resulted from process automatization; that is, each list item was processed or encoded in much the same way, producing a set…

Effects of Target Probability and Memory Demands on the Vigilance of Adults with and without Mental Retardation.

ERIC Educational Resources Information Center

Tomporowski, Phillip D.; Tinsley, Veronica

1994-01-01

The vigilance of young adults with and without mild mental retardation (MR) was compared, with subjects performing two memory demanding, cognitively based tests. The vigilance decrement of MR adults declined more rapidly than did the vigilance of non-MR adults, due to an interaction between target detectability and response bias, and poor target…

The protective effects of brief mindfulness meditation training.

PubMed

Banks, Jonathan B; Welhaf, Matthew S; Srour, Alexandra

2015-05-01

Mindfulness meditation has gained a great deal of attention in recent years due to the variety of physical and psychological benefits, including improved working memory, decreased mind wandering and reduced impact of stress on working memory. The current study examined a 1-week at home mindfulness meditation intervention compared to an active control intervention. Results suggest that mindfulness meditation does not increase working memory or decrease mind wandering but does prevent stress related working memory impairments. Mindfulness meditation appears to alter the factors that impair working memory such that the negative impact of mind wandering on working memory was only evident at higher levels of negative affect. The use of cognitive mechanism words in narratives of stressful events did not differ by condition but predicted poorer working memory in the control condition. The results support the use of an at home mindfulness meditation intervention for reducing stress-related impairments. Copyright © 2015 Elsevier Inc. All rights reserved.

Procedural Learning and Memory Rehabilitation in Korsakoff's Syndrome - a Review of the Literature.

PubMed

Oudman, Erik; Nijboer, Tanja C W; Postma, Albert; Wijnia, Jan W; Van der Stigchel, Stefan

2015-06-01

Korsakoff's syndrome (KS) is a chronic neuropsychiatric disorder caused by alcohol abuse and thiamine deficiency. Patients with KS show restricted autonomy due to their severe declarative amnesia and executive disorders. Recently, it has been suggested that procedural learning and memory are relatively preserved in KS and can effectively support autonomy in KS. In the present review we describe the available evidence on procedural learning and memory in KS and highlight advances in memory rehabilitation that have been demonstrated to support procedural memory. The specific purpose of this review was to increase insights in the available tools for successful memory rehabilitation and give suggestions how to apply these tools in clinical practice to increase procedural learning in KS. Current evidence suggests that when memory rehabilitation is adjusted to the specific needs of KS patients, this will increase their ability to learn procedures and their typically compromised autonomy gets enhanced.

Visual short-term memory: activity supporting encoding and maintenance in retinotopic visual cortex.

PubMed

Sneve, Markus H; Alnæs, Dag; Endestad, Tor; Greenlee, Mark W; Magnussen, Svein

2012-10-15

Recent studies have demonstrated that retinotopic cortex maintains information about visual stimuli during retention intervals. However, the process by which transient stimulus-evoked sensory responses are transformed into enduring memory representations is unknown. Here, using fMRI and short-term visual memory tasks optimized for univariate and multivariate analysis approaches, we report differential involvement of human retinotopic areas during memory encoding of the low-level visual feature orientation. All visual areas show weaker responses when memory encoding processes are interrupted, possibly due to effects in orientation-sensitive primary visual cortex (V1) propagating across extrastriate areas. Furthermore, intermediate areas in both dorsal (V3a/b) and ventral (LO1/2) streams are significantly more active during memory encoding compared with non-memory (active and passive) processing of the same stimulus material. These effects in intermediate visual cortex are also observed during memory encoding of a different stimulus feature (spatial frequency), suggesting that these areas are involved in encoding processes on a higher level of representation. Using pattern-classification techniques to probe the representational content in visual cortex during delay periods, we further demonstrate that simply initiating memory encoding is not sufficient to produce long-lasting memory traces. Rather, active maintenance appears to underlie the observed memory-specific patterns of information in retinotopic cortex. Copyright © 2012 Elsevier Inc. All rights reserved.

Rumination mediates the relationship between overgeneral autobiographical memory and depression in patients with major depressive disorder.

PubMed

Liu, Yansong; Yu, Xinnian; Yang, Bixiu; Zhang, Fuquan; Zou, Wenhua; Na, Aiguo; Zhao, Xudong; Yin, Guangzhong

2017-03-21

Overgeneral autobiographical memory has been identified as a risk factor for the onset and maintenance of depression. However, little is known about the underlying mechanisms that might explain overgeneral autobiographical memory phenomenon in depression. The purpose of this study was to test the mediation effects of rumination on the relationship between overgeneral autobiographical memory and depressive symptoms. Specifically, the mediation effects of brooding and reflection subtypes of rumination were examined in patients with major depressive disorder. Eighty-seven patients with major depressive disorder completed the 17-item Hamilton Depression Rating Scale, Ruminative Response Scale, and Autobiographical Memory Test. Bootstrap mediation analysis for simple and multiple mediation models through the PROCESS macro was applied. Simple mediation analysis showed that rumination significantly mediated the relationship between overgeneral autobiographical memory and depression symptoms. Multiple mediation analyses showed that brooding, but not reflection, significantly mediated the relationship between overgeneral autobiographical memory and depression symptoms. Our results indicate that global rumination partly mediates the relationship between overgeneral autobiographical memory and depressive symptoms in patients with major depressive disorder. Furthermore, the present results suggest that the mediating role of rumination in the relationship between overgeneral autobiographical memory and depression is mainly due to the maladaptive brooding subtype of rumination.

Investigating the origins of high multilevel resistive switching in forming free Ti/TiO2-x-based memory devices through experiments and simulations

NASA Astrophysics Data System (ADS)

Bousoulas, P.; Giannopoulos, I.; Asenov, P.; Karageorgiou, I.; Tsoukalas, D.

2017-03-01

Although multilevel capability is probably the most important property of resistive random access memory (RRAM) technology, it is vulnerable to reliability issues due to the stochastic nature of conducting filament (CF) creation. As a result, the various resistance states cannot be clearly distinguished, which leads to memory capacity failure. In this work, due to the gradual resistance switching pattern of TiO2-x-based RRAM devices, we demonstrate at least six resistance states with distinct memory margin and promising temporal variability. It is shown that the formation of small CFs with high density of oxygen vacancies enhances the uniformity of the switching characteristics in spite of the random nature of the switching effect. Insight into the origin of the gradual resistance modulation mechanisms is gained by the application of a trap-assisted-tunneling model together with numerical simulations of the filament formation physical processes.

Direct Observation of Conducting Filaments in Tungsten Oxide Based Transparent Resistive Switching Memory.

PubMed

Qian, Kai; Cai, Guofa; Nguyen, Viet Cuong; Chen, Tupei; Lee, Pooi See

2016-10-05

Transparent nonvolatile memory has great potential in integrated transparent electronics. Here, we present highly transparent resistive switching memory using stoichiometric WO 3 film produced by cathodic electrodeposition with indium tin oxide electrodes. The memory device demonstrates good optical transmittance, excellent operative uniformity, low operating voltages (+0.25 V/-0.42 V), and long retention time (>10 4 s). Conductive atomic force microscopy, ex situ transmission electron microscopy, and X-ray photoelectron spectroscopy experiments directly confirm that the resistive switching effects occur due to the electric field-induced formation and annihilation of the tungsten-rich conductive channel between two electrodes. Information on the physical and chemical nature of conductive filaments offers insightful design strategies for resistive switching memories with excellent performances. Moreover, we demonstrate the promising applicability of the cathodic electrodeposition method for future resistive memory devices.

The ferromagnetic shape-memory effect in Ni Mn Ga

NASA Astrophysics Data System (ADS)

Marioni, M. A.; O'Handley, R. C.; Allen, S. M.; Hall, S. R.; Paul, D. I.; Richard, M. L.; Feuchtwanger, J.; Peterson, B. W.; Chambers, J. M.; Techapiesancharoenkij, R.

2005-04-01

Active materials have long been used in the construction of sensors and devices. Examples are piezo-electric ceramics and shape memory alloys. The more recently developed ferromagnetic shape-memory alloys (FSMAs) have received considerable attention due to their large magnetic field-induced, reversible strains (up to 10%). In this article, we review the basic physical characteristics of the FSMA Ni-Mn-Ga (crystallography, thermal, mechanical and magnetic behavior). Also, we present some of the works currently under way in the areas of pulse-field and acoustic-assisted actuation, and vibration energy absorption.

Dynamic interactions between visual working memory and saccade target selection

PubMed Central

Schneegans, Sebastian; Spencer, John P.; Schöner, Gregor; Hwang, Seongmin; Hollingworth, Andrew

2014-01-01

Recent psychophysical experiments have shown that working memory for visual surface features interacts with saccadic motor planning, even in tasks where the saccade target is unambiguously specified by spatial cues. Specifically, a match between a memorized color and the color of either the designated target or a distractor stimulus influences saccade target selection, saccade amplitudes, and latencies in a systematic fashion. To elucidate these effects, we present a dynamic neural field model in combination with new experimental data. The model captures the neural processes underlying visual perception, working memory, and saccade planning relevant to the psychophysical experiment. It consists of a low-level visual sensory representation that interacts with two separate pathways: a spatial pathway implementing spatial attention and saccade generation, and a surface feature pathway implementing color working memory and feature attention. Due to bidirectional coupling between visual working memory and feature attention in the model, the working memory content can indirectly exert an effect on perceptual processing in the low-level sensory representation. This in turn biases saccadic movement planning in the spatial pathway, allowing the model to quantitatively reproduce the observed interaction effects. The continuous coupling between representations in the model also implies that modulation should be bidirectional, and model simulations provide specific predictions for complementary effects of saccade target selection on visual working memory. These predictions were empirically confirmed in a new experiment: Memory for a sample color was biased toward the color of a task-irrelevant saccade target object, demonstrating the bidirectional coupling between visual working memory and perceptual processing. PMID:25228628

Ego Depletion Does Not Interfere With Working Memory Performance.

PubMed

Singh, Ranjit K; Göritz, Anja S

2018-01-01

Ego depletion happens if exerting self-control reduces a person's capacity to subsequently control themselves. Previous research has suggested that ego depletion not only interferes with subsequent self-control but also with working memory. However, recent meta-analytical evidence casts doubt onto this. The present study tackles the question if ego depletion does interfere with working memory performance. We induced ego depletion in two ways: using an e-crossing task and using a Stroop task. We then measured working memory performance using the letter-number sequencing task. There was no evidence of ego depletion interfering with working memory performance. Several aspects of our study render this null finding highly robust. We had a large and heterogeneous sample of N = 1,385, which provided sufficient power. We deployed established depletion tasks from two task families (e-crossing task and Stroop), thus making it less likely that the null finding is due to a specific depletion paradigm. We derived several performance scores from the working memory task and ran different analyses to maximize the chances of finding an effect. Lastly, we controlled for two potential moderators, the implicit theories about willpower and dispositional self-control capacity, to ensure that a possible effect on working memory is not obscured by an interaction effect. In sum, this experiment strengthens the position that ego depletion works but does not affect working memory performance.

Ego Depletion Does Not Interfere With Working Memory Performance

PubMed Central

Singh, Ranjit K.; Göritz, Anja S.

2018-01-01

Ego depletion happens if exerting self-control reduces a person’s capacity to subsequently control themselves. Previous research has suggested that ego depletion not only interferes with subsequent self-control but also with working memory. However, recent meta-analytical evidence casts doubt onto this. The present study tackles the question if ego depletion does interfere with working memory performance. We induced ego depletion in two ways: using an e-crossing task and using a Stroop task. We then measured working memory performance using the letter-number sequencing task. There was no evidence of ego depletion interfering with working memory performance. Several aspects of our study render this null finding highly robust. We had a large and heterogeneous sample of N = 1,385, which provided sufficient power. We deployed established depletion tasks from two task families (e-crossing task and Stroop), thus making it less likely that the null finding is due to a specific depletion paradigm. We derived several performance scores from the working memory task and ran different analyses to maximize the chances of finding an effect. Lastly, we controlled for two potential moderators, the implicit theories about willpower and dispositional self-control capacity, to ensure that a possible effect on working memory is not obscured by an interaction effect. In sum, this experiment strengthens the position that ego depletion works but does not affect working memory performance. PMID:29706923

Chess knowledge predicts chess memory even after controlling for chess experience: Evidence for the role of high-level processes.

PubMed

Lane, David M; Chang, Yu-Hsuan A

2018-04-01

The expertise effect in memory for chess positions is one of the most robust effects in cognitive psychology. One explanation of this effect is that chess recall is based on the recognition of familiar patterns and that experts have learned more and larger patterns. Template theory and its instantiation as a computational model are based on this explanation. An alternative explanation is that the expertise effect is due, in part, to stronger players having better and more conceptual knowledge, with this knowledge facilitating memory performance. Our literature review supports the latter view. In our experiment, a sample of 79 chess players were given a test of memory for chess positions, a test of declarative chess knowledge, a test of fluid intelligence, and a questionnaire concerning the amount of time they had played nontournament chess and the amount of time they had studied chess. We determined the numbers of tournament games the players had played from chess databases. Chess knowledge correlated .67 with chess memory and accounted for 16% of the variance after controlling for chess experience. Fluid intelligence accounted for an additional 13% of the variance. These results support the conclusion that both high-level conceptual processing and low-level recognition of familiar patterns play important roles in memory for chess positions.

The acute and medium-term effects of treatment with electroconvulsive therapy on memory in patients with major depressive disorder.

PubMed

Maric, N P; Stojanovic, Z; Andric, S; Soldatovic, I; Dolic, M; Spiric, Z

2016-03-01

Current literature provides insufficient information on the degree of cognitive impairment during and after electroconvulsive therapy (ECT), mostly due to the fact that applied tests lacked sensitivity and flexibility. Our goal was to evaluate cognitive functioning in adult depressed patients treated with bi-temporal ECT, using tests sensitive for detection of possible acute and medium-term memory changes. Thirty adult patients with major depressive disorder, treated with a course of bi-temporal ECT, underwent clinical and cognitive measurements three times: at baseline, immediately after a course of ECT, and 1 month later. For cognition assessment, we used learning and visual, spatial and figural memory tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Bi-temporal ECT has proven to be an effective treatment. The linear mixed model, used to analyze changes in depression severity and patients' cognitive performances over time and to assess dynamic correlations between aforementioned features, did not show any significant memory impairment as a potential acute or medium-term ECT effect. However, it yielded significant improvement on visual memory and learning at the follow-up, which positively correlated with the improvement of depression. Good progress is being made in the search for ECT-related acute and medium-term cognitive side-effects by using the tests sensitive to detect memory dysfunction with parallel forms of the tasks (to counter practice effects on repeat testing). Our results on learning and memory in relation to ECT during treatment of depression did not bring forth any prolonged and significant bi-temporal ECT-related memory deficit.

Triazolam and zolpidem: effects on human memory and attentional processes.

PubMed

Mintzer, M Z; Griffiths, R R

1999-05-01

The imidazopyridine hypnotic zolpidem may produce less memory and cognitive impairment than classic benzodiazepines, due to its relatively low binding affinity for the benzodiazepine receptor subtypes found in areas of the brain which are involved in learning and memory. The study was designed to compare the acute effects of single oral doses of zolpidem (5, 10, 20 mg/70 kg) and the benzodiazepine hypnotic triazolam (0.125, 0.25, and 0.5 mg/70 kg) on specific memory and attentional processes. Drug effects on memory for target (i.e., focal) information and contextual information (i.e., peripheral details surrounding a target stimulus presentation) were evaluated using a source monitoring paradigm, and drug effects on selective attention mechanisms were evaluated using a negative priming paradigm, in 18 healthy volunteers in a double-blind, placebo-controlled, crossover design. Triazolam and zolpidem produced strikingly similar dose-related effects on memory for target information. Both triazolam and zolpidem impaired subjects' ability to remember whether a word stimulus had been presented to them on the computer screen or whether they had been asked to generate the stimulus based on an antonym cue (memory for the origin of a stimulus, which is one type of contextual information). The results suggested that triazolam, but not zolpidem, impaired memory for the screen location of picture stimuli (spatial contextual information). Although both triazolam and zolpidem increased overall reaction time in the negative priming task, only triazolam increased the magnitude of negative priming relative to placebo. The observed differences between triazolam and zolpidem have implications for the cognitive and pharmacological mechanisms underlying drug-induced deficits in specific memory and attentional processes, as well for the cognitive and brain mechanisms underlying these processes.

The electrophysiological correlates of recent and remote recollection.

PubMed

Roberts, J S; Tsivilis, D; Mayes, A R

2013-09-01

Research using event related potentials (ERPs) to explore recognition memory has linked late parietal old/new effects to the recollection of episodic information. In the vast majority of these studies, the retrieval phase immediately follows encoding and consequently, very little is known about the ERP correlates of long term recollection. This is despite the fact that in other areas of the memory literature there is considerable interest in consolidation theories and the way episodic memory changes over time. The present study explored the idea that consolidation and forgetting processes operating over a moderate retention interval can alter the ERP markers of recollection memory. A remember/know test probed memory for stimuli studied either 15 minutes (recent memory) or 1 week (remote memory) prior to the test phase. Results revealed an attenuated late parietal effect for remote compared to recent remember responses, a finding that remained significant even when these recognition judgments were matched for reaction time. Experiments 2a and 2b identified characteristic differences between recent and remote recognition at the behavioural level. The 1 week delay produced an overall decline in recognition confidence and a dramatic loss of episodic detail. These behavioural changes are thought to underlie the ERP effects reported in the first experiment. The results highlight that although the neural basis of memory may exhibit significant changes as the length of the retention interval increases, it is important to consider the extent to which this is a direct effect of time or an indirect effect due to changes in memory quality, such as the amount of detail that can be recollected. © 2013 Elsevier Ltd. All rights reserved.

Cognitive and memory training in adults at risk of dementia: A Systematic Review

PubMed Central

2011-01-01

Background Effective non-pharmacological cognitive interventions to prevent Alzheimer's dementia or slow its progression are an urgent international priority. The aim of this review was to evaluate cognitive training trials in individuals with mild cognitive impairment (MCI), and evaluate the efficacy of training in memory strategies or cognitive exercises to determine if cognitive training could benefit individuals at risk of developing dementia. Methods A systematic review of eligible trials was undertaken, followed by effect size analysis. Cognitive training was differentiated from other cognitive interventions not meeting generally accepted definitions, and included both cognitive exercises and memory strategies. Results Ten studies enrolling a total of 305 subjects met criteria for cognitive training in MCI. Only five of the studies were randomized controlled trials. Meta-analysis was not considered appropriate due to the heterogeneity of interventions. Moderate effects on memory outcomes were identified in seven trials. Cognitive exercises (relative effect sizes ranged from .10 to 1.21) may lead to greater benefits than memory strategies (.88 to -1.18) on memory. Conclusions Previous conclusions of a lack of efficacy for cognitive training in MCI may have been influenced by not clearly defining the intervention. Our systematic review found that cognitive exercises can produce moderate-to-large beneficial effects on memory-related outcomes. However, the number of high quality RCTs remains low, and so further trials must be a priority. Several suggestions for the better design of cognitive training trials are provided. PMID:21942932

A hybrid ferroelectric-flash memory cells

NASA Astrophysics Data System (ADS)

Park, Jae Hyo; Byun, Chang Woo; Seok, Ki Hwan; Kim, Hyung Yoon; Chae, Hee Jae; Lee, Sol Kyu; Son, Se Wan; Ahn, Donghwan; Joo, Seung Ki

2014-09-01

A ferroelectric-flash (F-flash) memory cells having a metal-ferroelectric-nitride-oxynitride-silicon structure are demonstrated, and the ferroelectric materials were perovskite-dominated Pb(Zr,Ti)O3 (PZT) crystallized by Pt gate electrode. The PZT thin-film as a blocking layer improves electrical and memorial performance where programming and erasing mechanism are different from the metal-ferroelectric-insulator-semiconductor device or the conventional silicon-oxide-nitride-oxide-silicon device. F-flash cells exhibit not only the excellent electrical transistor performance, having 442.7 cm2 V-1 s-1 of field-effect mobility, 190 mV dec-1 of substhreshold slope, and 8 × 105 on/off drain current ratio, but also a high reliable memory characteristics, having a large memory window (6.5 V), low-operating voltage (0 to -5 V), faster P/E switching speed (50/500 μs), long retention time (>10 years), and excellent fatigue P/E cycle (>105) due to the boosting effect, amplification effect, and energy band distortion of nitride from the large polarization. All these characteristics correspond to the best performances among conventional flash cells reported so far.

Isolating age-group differences in working memory load-related neural activity: assessing the contribution of working memory capacity using a partial-trial fMRI method.

PubMed

Bennett, Ilana J; Rivera, Hannah G; Rypma, Bart

2013-05-15

Previous studies examining age-group differences in working memory load-related neural activity have yielded mixed results. When present, age-group differences in working memory capacity are frequently proposed to underlie these neural effects. However, direct relationships between working memory capacity and working memory load-related activity have only been observed in younger adults. These relationships remain untested in healthy aging. Therefore, the present study examined patterns of working memory load-related activity in 22 younger and 20 older adults and assessed the contribution of working memory capacity to these load-related effects. Participants performed a partial-trial delayed response item recognition task during functional magnetic resonance imaging. In this task, participants encoded either 2 or 6 letters, maintained them during a delay, and then indicated whether a probe was present in the memory set. Behavioral results revealed faster and more accurate responses to load 2 versus 6, with age-group differences in this load condition effect for the accuracy measure. Neuroimaging results revealed one region (medial superior frontal gyrus) that showed age-group differences in load-related activity during the retrieval period, with less (greater) neural activity for the low versus high load condition in younger (older) adults. Furthermore, for older adults, load-related activity did not vary as a function of working memory capacity. Thus, working memory-related activity varies with healthy aging, but these patterns are not due solely to working memory capacity. Neurocognitive aging theories that feature capacity will need to account for these results. Copyright © 2013 Elsevier Inc. All rights reserved.

Long-term effects of brief hypoxia due to cardiac arrest: Hippocampal reductions and memory deficits.

PubMed

Stamenova, Vess; Nicola, Raneen; Aharon-Peretz, Judith; Goldsher, Dorith; Kapeliovich, Michael; Gilboa, Asaf

2018-05-01

To examine the effects of brief hypoxia (<7 min) due to cardiac arrest on the integrity of the brain and performance on memory and executive functions tasks. Patients after out-of-hospital cardiac arrest (CA) (n = 9), who were deemed neurologically intact on discharge, were compared to matched patients with myocardial infarction (MI) (n = 9). A battery of clinical and experimental memory and executive functions neuropsychological tests were administered and MRI scans for all patients were collected. Measures of subcortical and cortical volumes and cortical thickness were obtained using FreeSurfer. Manual segmentations of the hippocampus were also performed. APACHE-II scores were calculated based on metrics collected at admission to ICCU for all patients. Significant differences between the two groups were observed on several verbal memory tests. Both hippocampi were significantly reduced (p < 0.05) in the CA patients, relative to MI patients. Hippocampal subfields segmentation showed significantly reduced presubiculum volumes bilaterally. CA patients had on average 10% reduction in volumes bilaterally across hippocampal subfields. No cortical thickness differences survived correction. Significant correlations were observed in the CA group only between the hippocampal volumes and performance on verbal memory tasks, including recollection. Hippocampal volumes and several memory measures (but not other cognitive domains) were strongly correlated with APACHE-II scores on admission in the CA group, but not in the MI group CONCLUSIONS: Chronic patients with cardiac arrest who were discharged from hospital in "good neurological condition" showed an average of 10% reduction in hippocampal volume bilaterally and significant verbal memory deficits relative to matched controls with myocardial infarction, suggesting even brief hypoxic periods suffice to lead to specific hippocampal damage. Copyright © 2018 Elsevier B.V. All rights reserved.

Light sensitivity of a one transistor-one capacitor memory cell when used as a micromirror actuator in projector applications

NASA Astrophysics Data System (ADS)

Huffman, James Douglas

2001-11-01

The most important issue facing the future business success of the Digital Micromirror Device or DMD™ produced by Texas Instruments is the cost of the actual device. As the business and consumer markets call for higher resolution displays, the array size will have to be increased to incorporate more pixels. The manufacturing costs associated with building these higher resolution displays follow an exponential relation with the number of pixels due to yield loss and reduced number of chips per silicon wafer. Each pixel is actuated by electrostatics that are provided by a memory cell that is built in the underlying silicon substrate. One way to decrease cost of the wafer is to change the memory cell architecture from a static random access configuration or SRAM to a dynamic random access configuration or DRAM. This change has the benefits of having fewer components per area and a lower metal density. This reduction in the component count and metal density has a dramatic effect on the yield of the memory array by reducing the particle sensitivity of the underlying cell. The main drawback to using a DRAM configuration in a display application is the light sensitivity of a charge storage device built in the silicon substrate. As the photons pass through the mechanical micromirrors and illuminate the DRAM cell, the effective electrostatic potential of the memory element used for the mirror actuation is reduced. This dissertation outlines the issues associated with the light sensitivity of a DRAM memory cell as the actuation element for a micromirror. The concept of charge depletion on a silicon capacitor due to recombination of photogenerated carriers is explored and experimentally verified. The effects of the reduced potential on the capacitor on the micromirror are also explored. Optical modeling is used to determine the incoming photon flux to determine the benefits of adding a charge recombination region as part of the DRAM memory cell. Several options are explored to reduce the effect of the incoming photons on the potential of the memory cell. The results will show that a 1T1C memory cell with N-type recombination regions and maximum light shielding is sufficient for a projector application.

Why two heads apart are better than two heads together: multiple mechanisms underlie the collaborative inhibition effect in memory.

PubMed

Barber, Sarah J; Harris, Celia B; Rajaram, Suparna

2015-03-01

Although a group of people working together remembers more than any one individual, they recall less than their predicted potential. This finding is known as collaborative inhibition and is generally thought to arise due to retrieval disruption. However, there is growing evidence that is inconsistent with the retrieval disruption account, suggesting that additional mechanisms also contribute to collaborative inhibition. In the current studies, we examined 2 alternate mechanisms: retrieval inhibition and retrieval blocking. To identify the contributions of retrieval disruption, retrieval inhibition, and retrieval blocking, we tested how collaborative recall of entirely unshared information influences subsequent individual recall and individual recognition memory. If collaborative inhibition is due solely to retrieval disruption, then there should be a release from the negative effects of collaboration on subsequent individual recall and recognition tests. If it is due to retrieval inhibition, then the negative effects of collaboration should persist on both individual recall and recognition memory tests. Finally, if it is due to retrieval blocking, then the impairment should persist on subsequent individual free recall, but not recognition, tests. Novel to the current study, results suggest that retrieval inhibition plays a role in the collaborative inhibition effect. The negative effects of collaboration persisted on a subsequent, always-individual, free-recall test (Experiment 1) and also on a subsequent, always-individual, recognition test (Experiment 2). However, consistent with the retrieval disruption account, this deficit was attenuated (Experiment 1). Together, these results suggest that, in addition to retrieval disruption, multiple mechanisms play a role in collaborative inhibition. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Recollective performance advantages for implicit memory tasks.

PubMed

Sheldon, Signy A M; Moscovitch, Morris

2010-10-01

A commonly held assumption is that processes underlying explicit and implicit memory are distinct. Recent evidence, however, suggests that they may interact more than previously believed. Using the remember-know procedure the current study examines the relation between recollection, a process thought to be exclusive to explicit memory, and performance on two implicit memory tasks, lexical decision and word stem completion. We found that, for both implicit tasks, words that were recollected were associated with greater priming effects than were words given a subsequent familiarity rating or words that had been studied but were not recognised (misses). Broadly, our results suggest that non-voluntary processes underlying explicit memory also benefit priming, a measure of implicit memory. More specifically, given that this benefit was due to a particular aspect of explicit memory (recollection), these results are consistent with some strength models of memory and with Moscovitch's (2008) proposal that recollection is a two-stage process, one rapid and unconscious and the other more effortful and conscious.

Not sensitive, yet less biased: A signal detection theory perspective on mindfulness, attention, and recognition memory.

PubMed

Rosenstreich, Eyal; Ruderman, Lital

2016-07-01

The practice of mindfulness has been argued to increase attention control and improve memory performance. However, it was recently suggested that the effect of mindfulness on memory may be due to a shift in response-bias, rather than to an increase in memory-sensitivity. The present study examined the mindfulness-attention-memory triad. Participants filled in the five-facets of mindfulness questionnaire, and completed two recognition blocks; in the first attention was full, whereas in the second attention was divided during the encoding of information. It was found that the facet of non-judging (NJ) moderated the impact of attention on memory, such that responses of high NJ participants were less biased and remained constant even when attention was divided. Facets of mindfulness were not associated with memory sensitivity. These findings suggest that mindfulness may affect memory through decision making processes, rather than through directing attentional resources to the encoding of information. Copyright © 2016 Elsevier Inc. All rights reserved.

Language and memory abilities of internationally adopted children from China: evidence for early age effects.

PubMed

Delcenserie, Audrey; Genesee, Fred

2014-11-01

The goal of the present study was to examine if internationally adopted (IA) children from China (M = 10;8) adopted by French-speaking families exhibit lags in verbal memory in addition to lags in verbal abilities documented in previous studies (Gauthier & Genesee, 2011). Tests assessing verbal and non-verbal memory, language, non-verbal cognitive ability, and socio-emotional development were administered to thirty adoptees. Their results were compared to those of thirty non-adopted monolingual French-speaking children matched on age, gender, and socioeconomic status. The IA children scored significantly lower than the controls on language, verbal short-term memory, verbal working memory, and verbal long-term memory. No group differences were found on non-verbal memory, non-verbal cognitive ability, and socio-emotional development, suggesting language-specific difficulties. Despite extended exposure to French, adoptees may experience language difficulties due to limitations in verbal memory, possibly as a result of their delayed exposure to that language and/or attrition of the birth language.

Learning and memory performance in a cohort of clinically referred breast cancer survivors: the role of attention versus forgetting in patient-reported memory complaints.

PubMed

Root, James C; Ryan, Elizabeth; Barnett, Gregory; Andreotti, Charissa; Bolutayo, Kemi; Ahles, Tim

2015-05-01

While forgetfulness is widely reported by breast cancer survivors, studies documenting objective memory performance yield mixed, largely inconsistent, results. Failure to find consistent, objective memory issues may be due to the possibility that cancer survivors misattribute their experience of forgetfulness to primary memory issues rather than to difficulties in attention at the time of learning. To clarify potential attention issues, factor scores for Attention Span, Learning Efficiency, Delayed Memory, and Inaccurate Memory were analyzed for the California Verbal Learning Test-Second Edition (CVLT-II) in 64 clinically referred breast cancer survivors with self-reported cognitive complaints; item analysis was conducted to clarify specific contributors to observed effects, and contrasts between learning and recall trials were compared with normative data. Performance on broader cognitive domains is also reported. The Attention Span factor, but not Learning Efficiency, Delayed Memory, or Inaccurate Memory factors, was significantly affected in this clinical sample. Contrasts between trials were consistent with normative data and did not indicate greater loss of information over time than in the normative sample. Results of this analysis suggest that attentional dysfunction may contribute to subjective and objective memory complaints in breast cancer survivors. These results are discussed in the context of broader cognitive effects following treatment for clinicians who may see cancer survivors for assessment. Copyright © 2014 John Wiley & Sons, Ltd.

Emotional arousal and memory after deep encoding.

PubMed

Leventon, Jacqueline S; Camacho, Gabriela L; Ramos Rojas, Maria D; Ruedas, Angelica

2018-05-22

Emotion often enhances long-term memory. One mechanism for this enhancement is heightened arousal during encoding. However, reducing arousal, via emotion regulation (ER) instructions, has not been associated with reduced memory. In fact, the opposite pattern has been observed: stronger memory for emotional stimuli encoded with an ER instruction to reduce arousal. This pattern may be due to deeper encoding required by ER instructions. In the current research, we examine the effects of emotional arousal and deep-encoding on memory across three studies. In Study 1, adult participants completed a writing task (deep-encoding) for encoding negative, neutral, and positive picture stimuli, whereby half the emotion stimuli had the ER instruction to reduce the emotion. Memory was strong across conditions, and no memory enhancement was observed for any condition. In Study 2, adult participants completed the same writing task as Study 1, as well as a shallow-encoding task for one-third of negative, neutral, and positive trials. Memory was strongest for deep vs. shallow encoding trials, with no effects of emotion or ER instruction. In Study 3, adult participants completed a shallow-encoding task for negative, neutral, and positive stimuli, with findings indicating enhanced memory for negative emotional stimuli. Findings suggest that deep encoding must be acknowledged as a source of memory enhancement when examining manipulations of emotion-related arousal. Copyright © 2018. Published by Elsevier B.V.

High-Performance Flexible Organic Nano-Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles.

PubMed

Jung, Ji Hyung; Kim, Sunghwan; Kim, Hyeonjung; Park, Jongnam; Oh, Joon Hak

2015-10-07

Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I(on)/I(off)) of ≈2.98 × 10(3), and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe2O4 NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high-performance organic memory devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Parallel effects of memory set activation and search on timing and working memory capacity.

PubMed

Schweickert, Richard; Fortin, Claudette; Xi, Zhuangzhuang; Viau-Quesnel, Charles

2014-01-01

Accurately estimating a time interval is required in everyday activities such as driving or cooking. Estimating time is relatively easy, provided a person attends to it. But a brief shift of attention to another task usually interferes with timing. Most processes carried out concurrently with timing interfere with it. Curiously, some do not. Literature on a few processes suggests a general proposition, the Timing and Complex-Span Hypothesis: A process interferes with concurrent timing if and only if process performance is related to complex span. Complex-span is the number of items correctly recalled in order, when each item presented for study is followed by a brief activity. Literature on task switching, visual search, memory search, word generation and mental time travel supports the hypothesis. Previous work found that another process, activation of a memory set in long term memory, is not related to complex-span. If the Timing and Complex-Span Hypothesis is true, activation should not interfere with concurrent timing in dual-task conditions. We tested such activation in single-task memory search task conditions and in dual-task conditions where memory search was executed with concurrent timing. In Experiment 1, activating a memory set increased reaction time, with no significant effect on time production. In Experiment 2, set size and memory set activation were manipulated. Activation and set size had a puzzling interaction for time productions, perhaps due to difficult conditions, leading us to use a related but easier task in Experiment 3. In Experiment 3 increasing set size lengthened time production, but memory activation had no significant effect. Results here and in previous literature on the whole support the Timing and Complex-Span Hypotheses. Results also support a sequential organization of activation and search of memory. This organization predicts activation and set size have additive effects on reaction time and multiplicative effects on percent correct, which was found.

A categorical recall strategy does not explain animacy effects in episodic memory.

PubMed

VanArsdall, Joshua E; Nairne, James S; Pandeirada, Josefa N S; Cogdill, Mindi

2017-04-01

Animate stimuli are better remembered than matched inanimate stimuli in free recall. Three experiments tested the hypothesis that animacy advantages are due to a more efficient use of a categorical retrieval cue. Experiment 1 developed an "embedded list" procedure that was designed to disrupt participants' ability to perceive category structure at encoding; a strong animacy effect remained. Experiments 2 and 3 employed animate and inanimate word lists consisting of tightly constrained categories (four-footed animals and furniture). Experiment 2 failed to find an animacy advantage when the categorical structure was readily apparent, but the advantage returned in Experiment 3 when the embedded list procedure was employed using the same target words. These results provide strong evidence against an organizational account of the animacy effect, indicating that the animacy effect in episodic memory is probably due to item-specific factors related to animacy.

Memory effects in the afterglow: open questions on long-lived species and the role of surface processes

NASA Astrophysics Data System (ADS)

Petrovic, Z. Lj; Markovic, V. Lj; Pejovic, M. M.; Gocic, S. R.

2001-06-01

The memory effect, the phenomenon that some active species survive very long afterglow periods and affect subsequent breakdown, was observed more than 40 years ago. The effects have been observed even over periods of several hours. Attempts to explain the memory effect in nitrogen were mostly based on hypothetical metastables and on the A3Σ state. However, such explanations had to neglect some quenching processes which are known to be very effective under the conditions of the experiments. The explanation based on atoms remaining from the previous discharge and recombining on the cathode to produce initial electrons was shown to be fully consistent with all the experimental data for nitrogen including a wide range of pressures and the addition of oxygen impurities. The memory effect was also shown to be sensitive to the work function of the cathode material. Thus, an attempt was made to use the memory effect as a diagnostic tool to establish the data on the dominant loss of nitrogen atoms from the discharge which is recombination on the walls of the tube. However, a possible role of higher vibrational levels has not been fully addressed, mainly due to the shortage of data. On the other hand, the memory effect which was observed for rare gases cannot be explained on the basis of the standard data unless the presence of molecular impurities is invoked. Another open issue would be the role of charges accumulated on the glass surfaces and whether those may be released to the gas phase. The aim of this paper is to summarize the achievements of the model based on atom recombination and to point out how the breakdown model associated with the memory effect may be completed and how it may be applied in practical discharges.

The beneficial effect of testing: an event-related potential study

PubMed Central

Bai, Cheng-Hua; Bridger, Emma K.; Zimmer, Hubert D.; Mecklinger, Axel

2015-01-01

The enhanced memory performance for items that are tested as compared to being restudied (the testing effect) is a frequently reported memory phenomenon. According to the episodic context account of the testing effect, this beneficial effect of testing is related to a process which reinstates the previously learnt episodic information. Few studies have explored the neural correlates of this effect at the time point when testing takes place, however. In this study, we utilized the ERP correlates of successful memory encoding to address this issue, hypothesizing that if the benefit of testing is due to retrieval-related processes at test then subsequent memory effects (SMEs) should resemble the ERP correlates of retrieval-based processing in their temporal and spatial characteristics. Participants were asked to learn Swahili-German word pairs before items were presented in either a testing or a restudy condition. Memory performance was assessed immediately and 1-day later with a cued recall task. Successfully recalling items at test increased the likelihood that items were remembered over time compared to items which were only restudied. An ERP subsequent memory contrast (later remembered vs. later forgotten tested items), which reflects the engagement of processes that ensure items are recallable the next day were topographically comparable with the ERP correlate of immediate recollection (immediately remembered vs. immediately forgotten tested items). This result shows that the processes which allow items to be more memorable over time share qualitatively similar neural correlates with the processes that relate to successful retrieval at test. This finding supports the notion that testing is more beneficial than restudying on memory performance over time because of its engagement of retrieval processes, such as the re-encoding of actively retrieved memory representations. PMID:26441577

Dose-response effect of black maca (Lepidium meyenii) in mice with memory impairment induced by ethanol.

PubMed

Rubio, Julio; Yucra, Sandra; Gasco, Manuel; Gonzales, Gustavo F

2011-10-01

Previous studies have shown that black variety of maca has beneficial effects on learning and memory in experimental animal models. The present study aimed to determine whether the hydroalcoholic extract of black maca (BM) showed a dose-response effect in mice treated with ethanol 20% (EtOH) as a model of memory impairment. Mice were divided in the following groups: control, EtOH, ascorbic acid (AA) and 0.125, 0.25, 0.50 and 1.00 g/kg of BM plus EtOH. All treatments were orally administered for 28 days. Open field test was performed to determine locomotor activity and water Morris maze was done to determine spatial memory. Also, total polyphenol content in the hydroalcoholic extract of BM was determined (0.65 g pyrogallol/100 g). Mice treated with EtOH took more time to find the hidden platform than control during escape acquisition trials; meanwhile, AA and BM reversed the effect of EtOH. In addition, AA and BM ameliorated the deleterious effect of EtOH during the probe trial. Correlation analyses showed that the effect of BM a dose-dependent behavior. Finally, BM improved experimental memory impairment induced by ethanol in a dose-response manner due, in part, to its content of polyphenolic compounds.

Enhanced magnetic hysteresis in Ni-Mn-Ga single crystal and its influence on magnetic shape memory effect

NASA Astrophysics Data System (ADS)

Heczko, O.; Drahokoupil, J.; Straka, L.

2015-05-01

Enhanced magnetic hysteresis due to boron doping in combination with magnetic shape memory effect in Ni-Mn-Ga single crystal results in new interesting functionality of magnetic shape memory (MSM) alloys such as mechanical demagnetization. In Ni50.0Mn28.5Ga21.5 single crystal, the boron doping increased magnetic coercivity from few Oe to 270 Oe while not affecting the transformation behavior and 10 M martensite structure. However, the magnetic field needed for MSM effect also increased in doped sample. The magnetic behavior is compared to undoped single crystal of similar composition. The evidence from the X-ray diffraction, magnetic domain structure, magnetization loops, and temperature evolution of the magnetic coercivity points out that the enhanced hysteresis is caused by stress-induced anisotropy.

Working memory span capacity improved by a D2 but not D1 receptor family agonist.

PubMed

Tarantino, Isadore S; Sharp, Richard F; Geyer, Mark A; Meves, Jessica M; Young, Jared W

2011-06-01

Patients with schizophrenia exhibit poor working memory (WM). Although several subcomponents of WM can be measured, evidence suggests the primary subcomponent affected in schizophrenia is span capacity (WMC). Indeed, the NIMH-funded MATRICS initiative recommended assaying the WMC when assessing the efficacy of a putative therapeutic for FDA approval. Although dopamine D1 receptor agonists improve delay-dependent memory in animals, evidence for improvements in WMC due to dopamine D1 receptor activation is limited. In contrast, the dopamine D2-family agonist bromocriptine improves WMC in humans. The radial arm maze (RAM) can be used to assess WMC, although complications due to ceiling effects or strategy confounds have limited its use. We describe a 12-arm RAM protocol designed to assess whether the dopamine D1-family agonist SKF 38393 (0, 1, 3, and 10 mg/kg) or bromocriptine (0, 1, 3, and 10 mg/kg) could improve WMC in C57BL/6N mice (n=12) in cross-over designs. WMC increased and strategy usage decreased with training. The dopamine D1 agonist SKF 38393 had no effect on WMC or long-term memory. Bromocriptine decreased WMC errors, without affecting long-term memory, consistent with human studies. These data confirm that WMC can be measured in mice and reveal drug effects that are consistent with reported effects in humans. Future research is warranted to identify the subtype of the D2-family of receptors responsible for the observed improvement in WMC. Finally, this RAM procedure may prove useful in developing animal models of deficient WMC to further assess putative treatments for the cognitive deficits in schizophrenia. Copyright © 2011 Elsevier B.V. All rights reserved.

Dynamic effects of memory in a cobweb model with competing technologies

NASA Astrophysics Data System (ADS)

Agliari, Anna; Naimzada, Ahmad; Pecora, Nicolò

2017-02-01

We analyze a simple model based on the cobweb demand-supply framework with costly innovators and free imitators and study the endogenous dynamics of price and firms' fractions in a homogeneous good market. The evolutionary selection between technologies depends on a performance measure in which a memory parameter is introduced. The resulting dynamics is then described by a two-dimensional map. In addition to the locally stabilizing effect due to the presence of memory, we show the existence of a double stability threshold which entails for different dynamic scenarios occurring when the memory parameter takes extreme values (i.e. when consideration of the last profit realization prevails or it is too much neglected). The eventuality of different coexisting attractors as well as the structure of the basins of attraction that characterizes the path dependence property of the model with memory is shown. In particular, through global analysis we also illustrate particular bifurcations sequences that may increase the complexity of the related basins of attraction.

Preventing the Return of Fear Using Reconsolidation Update Mechanisms Depends on the Met-Allele of the Brain Derived Neurotrophic Factor Val66Met Polymorphism.

PubMed

Asthana, Manish Kumar; Brunhuber, Bettina; Mühlberger, Andreas; Reif, Andreas; Schneider, Simone; Herrmann, Martin J

2016-06-01

Memory reconsolidation is the direct effect of memory reactivation followed by stabilization of newly synthesized proteins. It has been well proven that neural encoding of both newly and reactivated memories requires synaptic plasticity. Brain derived neurotrophic factor (BDNF) has been extensively investigated regarding its role in the formation of synaptic plasticity and in the alteration of fear memories. However, its role in fear reconsolidation is still unclear; hence, the current study has been designed to investigate the role of the BDNF val66met polymorphism (rs6265) in fear memory reconsolidation in humans. An auditory fear-conditioning paradigm was conducted, which comprised of three stages (acquisition, reactivation, and spontaneous recovery). One day after fear acquisition, the experimental group underwent reactivation of fear memory followed by the extinction training (reminder group), whereas the control group (non-reminder group) underwent only extinction training. On day 3, both groups were subjected to spontaneous recovery of earlier learned fearful memories. The treat-elicited defensive response due to conditioned threat was measured by assessing the skin conductance response to the conditioned stimulus. All participants were genotyped for rs6265. The results indicate a diminishing effect of reminder on the persistence of fear memory only in the Met-allele carriers, suggesting a moderating effect of the BDNF polymorphism in fear memory reconsolidation. Our findings suggest a new role for BDNF gene variation in fear memory reconsolidation in humans. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Comparison of adult age differences in verbal and visuo-spatial memory: the importance of 'pure', parallel and validated measures.

PubMed

Kemps, Eva; Newson, Rachel

2006-04-01

The study compared age-related decrements in verbal and visuo-spatial memory across a broad elderly adult age range. Twenty-four young (18-25 years), 24 young-old (65-74 years), 24 middle-old (75-84 years) and 24 old-old (85-93 years) adults completed parallel recall and recognition measures of verbal and visuo-spatial memory from the Doors and People Test (Baddeley, Emslie & Nimmo-Smith, 1994). These constituted 'pure' and validated indices of either verbal or visuo-spatial memory. Verbal and visuo-spatial memory declined similarly with age, with a steeper decline in recall than recognition. Unlike recognition memory, recall performance also showed a heightened decline after the age of 85. Age-associated memory loss in both modalities was largely due to working memory and executive function. Processing speed and sensory functioning (vision, hearing) made minor contributions to memory performance and age differences in it. Together, these findings demonstrate common, rather than differential, age-related effects on verbal and visuo-spatial memory. They also emphasize the importance of using 'pure', parallel and validated measures of verbal and visuo-spatial memory in memory ageing research.

Neural effects of cognitive control load on auditory selective attention

PubMed Central

Sabri, Merav; Humphries, Colin; Verber, Matthew; Liebenthal, Einat; Binder, Jeffrey R.; Mangalathu, Jain; Desai, Anjali

2014-01-01

Whether and how working memory disrupts or alters auditory selective attention is unclear. We compared simultaneous event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) responses associated with task-irrelevant sounds across high and low working memory load in a dichotic-listening paradigm. Participants performed n-back tasks (1-back, 2-back) in one ear (Attend ear) while ignoring task-irrelevant speech sounds in the other ear (Ignore ear). The effects of working memory load on selective attention were observed at 130-210 msec, with higher load resulting in greater irrelevant syllable-related activation in localizer-defined regions in auditory cortex. The interaction between memory load and presence of irrelevant information revealed stronger activations primarily in frontal and parietal areas due to presence of irrelevant information in the higher memory load. Joint independent component analysis of ERP and fMRI data revealed that the ERP component in the N1 time-range is associated with activity in superior temporal gyrus and medial prefrontal cortex. These results demonstrate a dynamic relationship between working memory load and auditory selective attention, in agreement with the load model of attention and the idea of common neural resources for memory and attention. PMID:24946314

Verbal Memory Performance and Reduced Cortical Thickness of Brain Regions Along the Uncinate Fasciculus in Young Adult Cannabis Users

PubMed Central

Levar, Nina; Francis, Alan N.; Smith, Matthew J.; Ho, Wilson C.; Gilman, Jodi M.

2018-01-01

Abstract Introduction: Memory impairment is one of the most commonly reported effects of cannabis use, especially among those who initiate use earlier, perhaps due to the effects of delta-9- tetrahydrocannabinol on cannabinoid (CB1) receptors in the brain. Studies have increasingly investigated whether cannabis use is associated with impairments in verbal memory, and with alterations in brain structures underlying verbal memory. The uncinate fasciculus (UF), a long-range white matter tract, connects regions with densely localized CB1 receptors that are important in verbal memory. This study investigated the impact of cannabis use on UF structures and its association with memory performance in young adult cannabis users (CU) and non-using controls (CON). Materials and Methods: Nineteen CU and 22 CON completed a verbal memory task and a neuroimaging protocol, in which diffusion tensor imaging and structural scans were collected. We compared memory performance, diffusion and tractography measures of the UF, and cortical thickness of regions connected by the UF, between CU and CON. In regions showing a significant group effect, we also examined associations between verbal memory performance, cortical thickness, and age of onset of cannabis use. Results: Compared to non-users, CU had worse memory performance, decreased fiber bundle length in the UF, and decreased cortical thickness of brain regions along the UF such as the entorhinal cortex and fusiform gyrus. Verbal memory performance was significantly associated with age of onset of cannabis use, indicating that those who initiated cannabis use at an earlier age performed worse. Cortical thickness of the entorhinal cortex was significantly correlated with age of first use and memory performance. Conclusion: This study provides evidence that cannabis use, especially when initiated at a young age, may be associated with worse verbal memory and altered neural development along the UF. Reductions in cortical thickness in regions implicated in memory processes may underlie weaknesses in verbal memory performance. PMID:29607411

Duration of memory of dominance relationships in a group living cichlid

NASA Astrophysics Data System (ADS)

Hotta, Takashi; Takeyama, Tomohiro; Jordan, Lyndon Alexander; Kohda, Masanori

2014-09-01

Animal contests are costly and tend to escalate when rivals have similar competitive abilities. Individuals that remember dominance relationships with rivals may avoid repeated agonistic interactions and hence avoid the costs of repeated escalation of contests. However, it can be difficult to experimentally disentangle the effects of memory from those of loser effects (losers behaving subordinately due to prior defeats). Here, we test whether loser effects or individual memory mediate contest behaviour in the African cichlid, Julidochromis transcriptus. We find that on days 3 and 5 after initial contests, losers display subordinate behaviour to contest winners but not to novel contestants. However, this effect disappears after 7 days, at which time losers do not display subordinate behaviour to either rival. These results show that (1) this fish can recall a previously dominant contestant for up to 5 days and (2) as no subordinate displays were shown to the novel contestant, there are no evidences for loser effects in this species. Such short-term memory of past interactions may have broad significance in social species with repeated interactions.

Aeroelastic flutter enhancement by exploiting the combined use of shape memory alloys and nonlinear piezoelectric circuits

NASA Astrophysics Data System (ADS)

Sousa, Vagner Candido de; Silva, Tarcísio Marinelli Pereira; De Marqui Junior, Carlos

2017-10-01

In this paper, the combined effects of semi-passive control using shunted piezoelectric material and passive pseudoelastic hysteresis of shape memory springs on the aerolastic behavior of a typical section is investigated. An aeroelastic model that accounts for the presence of both smart materials employed as mechanical energy dissipation devices is presented. The Brinson model is used to simulate the shape memory material. New expressions for the modeling of the synchronized switch damping on inductor technique (developed for enhanced piezoelectric damping) are presented, resulting in better agreement with experimental data. The individual effects of each nonlinear mechanism on the aeroelastic behavior of the typical section are first verified. Later, the combined effects of semi-passive piezoelectric control and passive shape memory alloy springs on the post-critical behavior of the system are discussed in details. The range of post-flutter airflow speeds with stable limit cycle oscillations is significantly increased due to the combined effects of both sources of energy dissipation, providing an effective and autonomous way to modify the behavior of aeroelastic systems using smart materials.

Memory effects on adsorption tubes for mercury vapor measurement in ambient air: elucidation, quantification, and strategies for mitigation of analytical bias.

PubMed

Brown, Richard J C; Kumar, Yarshini; Brown, Andrew S; Kim, Ki-Hyun

2011-09-15

The short- and long-term memory effects associated with measurements of mercury vapor in air using gold-coated silica adsorption tubes have been described. Data are presented to quantify these effects and to determine their dependence on certain relevant measurement parameters, such as number of heating cycles used for each analysis, age of adsorption tube, mass of mercury on adsorption tube, and the length of time between analyses. The results suggest that the long-term memory effect is due to absorption of mercury within the bulk gold in the adsorption tube, which may only be fully liberated by allowing enough time for this mercury to diffuse to the gold surface. The implications of these effects for air quality networks making these measurements routinely has been discussed, and recommendations have been made to ensure any measurement bias is minimized.

One bout of open skill exercise improves cross-modal perception and immediate memory in healthy older adults who habitually exercise.

PubMed

O'Brien, Jessica; Ottoboni, Giovanni; Tessari, Alessia; Setti, Annalisa

2017-01-01

One single bout of exercise can be associated with positive effects on cognition, due to physiological changes associated with muscular activity, increased arousal, and training of cognitive skills during exercise. While the positive effects of life-long physical activity on cognitive ageing are well demonstrated, it is not well established whether one bout of exercise is sufficient to register such benefits in older adults. The aim of this study was to test the effect of one bout of exercise on two cognitive processes essential to daily life and known to decline with ageing: audio-visual perception and immediate memory. Fifty-eight older adults took part in a quasi-experimental design study and were divided into three groups based on their habitual activity (open skill exercise (mean age = 69.65, SD = 5.64), closed skill exercise, N = 18, 94% female; sedentary activity-control group, N = 21, 62% female). They were then tested before and after their activity (duration between 60 and 80 minutes). Results showed improvement in sensitivity in audio-visual perception in the open skill group and improvements in one of the measures of immediate memory in both exercise groups, after controlling for baseline differences including global cognition and health. These findings indicate that immediate benefits for cross-modal perception and memory can be obtained after open skill exercise. However, improvements after closed skill exercise may be limited to memory benefits. Perceptual benefits are likely to be associated with arousal, while memory benefits may be due to the training effects provided by task requirements during exercise. The respective role of qualitative and quantitative differences between these activities in terms of immediate cognitive benefits should be further investigated. Importantly, the present results present the first evidence for a modulation of cross-modal perception by exercise, providing a plausible avenue for rehabilitation of cross-modal perception deficits, which are emerging as a significant contributor to functional decline in ageing.

Beneficial effect of commercial Rhodiola extract in rats with scopolamine-induced memory impairment on active avoidance.

PubMed

Vasileva, Liliya V; Getova, Damianka P; Doncheva, Nina D; Marchev, Andrey S; Georgiev, Milen I

2016-12-04

Rhodiola rosea L., family Crassulaceae also known as Golden Root or Arctic root is one of the most widely used medicinal plants with effect on cognitive dysfunction, psychological stress and depression. The aim of the study was to examine the effect of a standardized commercial Rhodiola extract on learning and memory processes in naive rats as well as its effects in rats with scopolamine-induced memory impairment. Sixty male Wistar rats were used in the study. The experiment was conducted in two series - on naive rats and on rats with scopolamine-induced model of impaired memory. The active avoidance test was performed in an automatic conventional shuttle box set-up. The criteria used were the number of conditional stimuli (avoidances), the number of unconditioned stimuli (escapes) as well as the number of intertrial crossings. The chemical fingerprinting of the standardized commercial Rhodiola extract was performed by means of nuclear magnetic resonance (NMR). Naive rats treated with standardized Rhodiola extract increased the number of avoidances during the learning session and memory retention test compared to the controls. Rats with scopolamine-induced memory impairment treated with Rhodiola extract showed an increase in the number of avoidances during the learning session and on the memory tests compared to the scopolamine group. The other two parameters were not changed in rats treated with the extract of Rhodiola in the two series. It was found that the studied Rhodiola extract exerts a beneficial effect on learning and memory processes in naive rats and rats with scopolamine-induced memory impairment. The observed effect is probably due to multiple underlying mechanisms including its modulating effect on acetylcholine levels in the brain and MAO-inhibitory activity leading to stimulation of the monoamines' neurotransmission. In addition the pronounced stress-protective properties of Rhodiola rosea L. could also play a role in the improvement of cognitive functions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Sleep-Effects on Implicit and Explicit Memory in Repeated Visual Search

PubMed Central

Assumpcao, Leonardo; Gais, Steffen

2013-01-01

In repeated visual search tasks, facilitation of reaction times (RTs) due to repetition of the spatial arrangement of items occurs independently of RT facilitation due to improvements in general task performance. Whereas the latter represents typical procedural learning, the former is a kind of implicit memory that depends on the medial temporal lobe (MTL) memory system and is impaired in patients with amnesia. A third type of memory that develops during visual search is the observers’ explicit knowledge of repeated displays. Here, we used a visual search task to investigate whether procedural memory, implicit contextual cueing, and explicit knowledge of repeated configurations, which all arise independently from the same set of stimuli, are influenced by sleep. Observers participated in two experimental sessions, separated by either a nap or a controlled rest period. In each of the two sessions, they performed a visual search task in combination with an explicit recognition task. We found that (1) across sessions, MTL-independent procedural learning was more pronounced for the nap than rest group. This confirms earlier findings, albeit from different motor and perceptual tasks, showing that procedural memory can benefit from sleep. (2) Likewise, the sleep group compared with the rest group showed enhanced context-dependent configural learning in the second session. This is a novel finding, indicating that the MTL-dependent, implicit memory underlying contextual cueing is also sleep-dependent. (3) By contrast, sleep and wake groups displayed equivalent improvements in explicit recognition memory in the second session. Overall, the current study shows that sleep affects MTL-dependent as well as MTL-independent memory, but it affects different, albeit simultaneously acquired, forms of MTL-dependent memory differentially. PMID:23936363

The strain and thermal induced tunable charging phenomenon in low power flexible memory arrays with a gold nanoparticle monolayer.

PubMed

Zhou, Ye; Han, Su-Ting; Xu, Zong-Xiang; Roy, V A L

2013-03-07

The strain and temperature dependent memory effect of organic memory transistors on plastic substrates has been investigated under ambient conditions. The gold (Au) nanoparticle monolayer was prepared and embedded in an atomic layer deposited aluminum oxide (Al(2)O(3)) as the charge trapping layer. The devices exhibited low operation voltage, reliable memory characteristics and long data retention time. Experimental analysis of the programming and erasing behavior at various bending states showed the relationship between strain and charging capacity. Thermal-induced effects on these memory devices have also been analyzed. The mobility shows ~200% rise and the memory window increases from 1.48 V to 1.8 V when the temperature rises from 20 °C to 80 °C due to thermally activated transport. The retention capability of the devices decreases with the increased working temperature. Our findings provide a better understanding of flexible organic memory transistors under various operating temperatures and validate their applications in various areas such as temperature sensors, temperature memory or advanced electronic circuits. Furthermore, the low temperature processing procedures of the key elements (Au nanoparticle monolayer and Al(2)O(3) dielectric layer) could be potentially integrated with large area flexible electronics.

Sleep enhances false memories depending on general memory performance.

PubMed

Diekelmann, Susanne; Born, Jan; Wagner, Ullrich

2010-04-02

Memory is subject to dynamic changes, sometimes giving rise to the formation of false memories due to biased processes of consolidation or retrieval. Sleep is known to benefit memory consolidation through an active reorganization of representations whereas acute sleep deprivation impairs retrieval functions. Here, we investigated whether sleep after learning and sleep deprivation at retrieval enhance the generation of false memories in a free recall test. According to the Deese, Roediger, McDermott (DRM) false memory paradigm, subjects learned lists of semantically associated words (e.g., "night", "dark", "coal", etc.), lacking the strongest common associate or theme word (here: "black"). Free recall was tested after 9h following a night of sleep, a night of wakefulness (sleep deprivation) or daytime wakefulness. Compared with memory performance after a retention period of daytime wakefulness, both post-learning nocturnal sleep as well as acute sleep deprivation at retrieval significantly enhanced false recall of theme words. However, these effects were only observed in subjects with low general memory performance. These data point to two different ways in which sleep affects false memory generation through semantic generalization: one acts during consolidation on the memory trace per se, presumably by active reorganization of the trace in the post-learning sleep period. The other is related to the recovery function of sleep and affects cognitive control processes of retrieval. Both effects are unmasked when the material is relatively weakly encoded. Crown Copyright 2009. Published by Elsevier B.V. All rights reserved.

Performance Evaluation and Improvement of Ferroelectric Field-Effect Transistor Memory

NASA Astrophysics Data System (ADS)

Yu, Hyung Suk

Flash memory is reaching scaling limitations rapidly due to reduction of charge in floating gates, charge leakage and capacitive coupling between cells which cause threshold voltage fluctuations, short retention times, and interference. Many new memory technologies are being considered as alternatives to flash memory in an effort to overcome these limitations. Ferroelectric Field-Effect Transistor (FeFET) is one of the main emerging candidates because of its structural similarity to conventional FETs and fast switching speed. Nevertheless, the performance of FeFETs have not been systematically compared and analyzed against other competing technologies. In this work, we first benchmark the intrinsic performance of FeFETs and other memories by simulations in order to identify the strengths and weaknesses of FeFETs. To simulate realistic memory applications, we compare memories on an array structure. For the comparisons, we construct an accurate delay model and verify it by benchmarking against exact HSPICE simulations. Second, we propose an accurate model for FeFET memory window since the existing model has limitations. The existing model assumes symmetric operation voltages but it is not valid for the practical asymmetric operation voltages. In this modeling, we consider practical operation voltages and device dimensions. Also, we investigate realistic changes of memory window over time and retention time of FeFETs. Last, to improve memory window and subthreshold swing, we suggest nonplanar junctionless structures for FeFETs. Using the suggested structures, we study the dimensional dependences of crucial parameters like memory window and subthreshold swing and also analyze key interference mechanisms.

Modulation of Memory by Vestibular Lesions and Galvanic Vestibular Stimulation

PubMed Central

Smith, Paul F.; Geddes, Lisa H.; Baek, Jean-Ha; Darlington, Cynthia L.; Zheng, Yiwen

2010-01-01

For decades it has been speculated that there is a close association between the vestibular system and spatial memories constructed by areas of the brain such as the hippocampus. While many animal studies have been conducted which support this relationship, only in the last 10 years have detailed quantitative studies been carried out in patients with vestibular disorders. The majority of these studies suggest that complete bilateral vestibular loss results in spatial memory deficits that are not simply due to vestibular reflex dysfunction, while the effects of unilateral vestibular damage are more complex and subtle. Very recently, reports have emerged that sub-threshold, noisy galvanic vestibular stimulation can enhance memory in humans, although this has not been investigated for spatial memory as yet. These studies add to the increasing evidence that suggests a connection between vestibular sensory information and memory in humans. PMID:21173897

High-performance black phosphorus top-gate ferroelectric transistor for nonvolatile memory applications

NASA Astrophysics Data System (ADS)

Lee, Young Tack; Hwang, Do Kyung; Choi, Won Kook

2016-10-01

Two-dimensional (2D) van der Waals (vdW) atomic crystals have been extensively studied and significant progress has been made. The newest 2D vdW material, called black phosphorus (BP), has attracted considerable attention due to its unique physical properties, such as its being a singlecomponent material like graphene, and its having a high mobility and direct band gap. Here, we report on a high-performance BP nanosheet based ferroelectric field effect transistor (FeFET) with a poly(vinylidenefluoride-trifluoroethylene) top-gate insulator for a nonvolatile memory application. The BP FeFETs show the highest linear hole mobility of 563 cm2/Vs and a clear memory window of more than 15 V. For more advanced nonvolatile memory circuit applications, two different types of resistive-load and complementary ferroelectric memory inverters were implemented, which showed distinct memory on/off switching characteristics.

The shape-memory effect in ionic elastomers: fixation through ionic interactions.

PubMed

González-Jiménez, Antonio; Malmierca, Marta A; Bernal-Ortega, Pilar; Posadas, Pilar; Pérez-Aparicio, Roberto; Marcos-Fernández, Ángel; Mather, Patrick T; Valentín, Juan L

2017-04-19

Shape-memory elastomers based on a commercial rubber cross-linked by both ionic and covalent bonds have been developed. The elastomeric matrix was a carboxylated nitrile rubber (XNBR) vulcanized with magnesium oxide (MgO) providing ionic interactions that form hierarchical structures. The so-named ionic transition is used as the unique thermal transition responsible for the shape-memory effect (SME) in these elastomers. These ionic interactions fix the temporary shape due to their behavior as dynamic cross-links with temperature changes. Covalent cross-links were incorporated with the addition of different proportions of dicumyl peroxide (DCP) to the ionic elastomer to establish and recover the permanent shape. In this article, the SME was modulated by modifying the degree of covalent cross-linking, while keeping the ionic contribution constant. In addition, different programming parameters, such as deformation temperature, heating/cooling rate, loading/unloading rate and percentage of tensile strain, were evaluated for their effects on shape-memory behavior.

Electric-field-controlled interface dipole modulation for Si-based memory devices.

PubMed

Miyata, Noriyuki

2018-05-31

Various nonvolatile memory devices have been investigated to replace Si-based flash memories or emulate synaptic plasticity for next-generation neuromorphic computing. A crucial criterion to achieve low-cost high-density memory chips is material compatibility with conventional Si technologies. In this paper, we propose and demonstrate a new memory concept, interface dipole modulation (IDM) memory. IDM can be integrated as a Si field-effect transistor (FET) based memory device. The first demonstration of this concept employed a HfO 2 /Si MOS capacitor where the interface monolayer (ML) TiO 2 functions as a dipole modulator. However, this configuration is unsuitable for Si-FET-based devices due to its large interface state density (D it ). Consequently, we propose, a multi-stacked amorphous HfO 2 /1-ML TiO 2 /SiO 2 IDM structure to realize a low D it and a wide memory window. Herein we describe the quasi-static and pulse response characteristics of multi-stacked IDM MOS capacitors and demonstrate flash-type and analog memory operations of an IDM FET device.

Priming in implicit memory tasks: prior study causes enhanced discriminability, not only bias.

PubMed

Zeelenberg, René; Wagenmakers, Eric-Jan M; Raaijmakers, Jeroen G W

2002-03-01

R. Ratcliff and G. McKoon (1995, 1996, 1997; R. Ratcliff, D. Allbritton, & G. McKoon, 1997) have argued that repetition priming effects are solely due to bias. They showed that prior study of the target resulted in a benefit in a later implicit memory task. However, prior study of a stimulus similar to the target resulted in a cost. The present study, using a 2-alternative forced-choice procedure, investigated the effect of prior study in an unbiased condition: Both alternatives were studied prior to their presentation in an implicit memory task. Contrary to a pure bias interpretation of priming, consistent evidence was obtained in 3 implicit memory tasks (word fragment completion, auditory word identification, and picture identification) that performance was better when both alternatives were studied than when neither alternative was studied. These results show that prior study results in enhanced discriminability, not only bias.

Loss and persistence of implicit memory for sound: evidence from auditory stream segregation context effects.

PubMed

Snyder, Joel S; Weintraub, David M

2013-07-01

An important question is the extent to which declines in memory over time are due to passive loss or active interference from other stimuli. The purpose of the present study was to determine the extent to which implicit memory effects in the perceptual organization of sound sequences are subject to loss and interference. Toward this aim, we took advantage of two recently discovered context effects in the perceptual judgments of sound patterns, one that depends on stimulus features of previous sounds and one that depends on the previous perceptual organization of these sounds. The experiments measured how listeners' perceptual organization of a tone sequence (test) was influenced by the frequency separation, or the perceptual organization, of the two preceding sequences (context1 and context2). The results demonstrated clear evidence for loss of context effects over time but little evidence for interference. However, they also revealed that context effects can be surprisingly persistent. The robust effects of loss, followed by persistence, were similar for the two types of context effects. We discuss whether the same auditory memories might contain information about basic stimulus features of sounds (i.e., frequency separation), as well as the perceptual organization of these sounds.

Crystallographic Characterization on Polycrystalline Ni-Mn-Ga Alloys with Strong Preferred Orientation.

PubMed

Li, Zongbin; Yang, Bo; Zou, Naifu; Zhang, Yudong; Esling, Claude; Gan, Weimin; Zhao, Xiang; Zuo, Liang

2017-04-27

Heusler type Ni-Mn-Ga ferromagnetic shape memory alloys can demonstrate excellent magnetic shape memory effect in single crystals. However, such effect in polycrystalline alloys is greatly weakened due to the random distribution of crystallographic orientation. Microstructure optimization and texture control are of great significance and challenge to improve the functional behaviors of polycrystalline alloys. In this paper, we summarize our recent progress on the microstructure control in polycrystalline Ni-Mn-Ga alloys in the form of bulk alloys, melt-spun ribbons and thin films, based on the detailed crystallographic characterizations through neutron diffraction, X-ray diffraction and electron backscatter diffraction. The presented results are expected to offer some guidelines for the microstructure modification and functional performance control of ferromagnetic shape memory alloys.

Effects of spacing of item repetitions in continuous recognition memory: does item retrieval difficulty promote item retention in older adults?

PubMed

Kılıç, Aslı; Hoyer, William J; Howard, Marc W

2013-01-01

BACKGROUND/STUDY CONTEXT: Older adults exhibit an age-related deficit in item memory as a function of the length of the retention interval, but older adults and young adults usually show roughly equivalent benefits due to the spacing of item repetitions in continuous memory tasks. The current experiment investigates the seemingly paradoxical effects of retention interval and spacing in young and older adults using a continuous recognition memory procedure. Fifty young adults and 52 older adults gave memory confidence ratings to words that were presented once (P1), twice (P2), or three times (P3), and the effects of the lag length and retention interval were assessed at P2 and at P3, respectively. Response times at P2 were disproportionately longer for older adults than for younger adults as a function of the number of items occurring between P1 and P2, suggestive of age-related loss in item memory. Ratings of confidence in memory responses revealed that older adults remembered fewer items at P2 with a high degree of certainty. Confidence ratings given at P3 suggested that young and older adults derived equivalent benefits from the spacing between P1 and P2. Findings of this study support theoretical accounts that suggest that recursive reminding and/or item retrieval difficulty promote item retention in older adults.

The effect of Vitamin E on learning and memory deficits in intrahippocampal kainate-induced temporal lobe epilepsy in rats.

PubMed

Kiasalari, Zahra; Khalili, Mohsen; Shafiee, Samaneh; Roghani, Mehrdad

2016-01-01

Since temporal lobe epilepsy (TLE) is associated with learning and memory impairment, we investigated the beneficial effect of Vitamin E on the impaired learning and memory in the intrahippocampal kainate model of TLE in rats. Rats were divided into sham, Vitamin E-treated sham, kainate, and Vitamin E-treated kainate. Intrahippocampal kainate was used for induction of epilepsy. Vitamin E was injected intraperitoneal (i.p.) at a dose of 200 mg/kg/day started 1 week before surgery until 1 h presurgery. Initial and step-through latencies in the passive avoidance test and alternation behavior percentage in Y-maze were finally determined in addition to measurement of some oxidative stress markers. Kainate injection caused a higher severity and rate of seizures and deteriorated learning and memory performance in passive avoidance paradigm and spontaneous alternation as an index of spatial recognition memory in Y-maze task. Intrahippocampal kainate also led to the elevation of malondialdehyde (MDA) and nitrite and reduced activity of superoxide dismutase (SOD). Vitamin E pretreatment significantly attenuated severity and incidence rate of seizures, significantly improved retrieval and recall in passive avoidance, did not ameliorate spatial memory deficit in Y-maze, and lowered MDA and enhanced SOD activity. Vitamin E improves passive avoidance learning and memory and part of its beneficial effect is due to its potential to mitigate hippocampal oxidative stress.

Acute effects of exergames on cognitive function of institutionalized older persons: a single-blinded, randomized and controlled pilot study.

PubMed

Monteiro-Junior, Renato Sobral; da Silva Figueiredo, Luiz Felipe; Maciel-Pinheiro, Paulo de Tarso; Abud, Erick Lohan Rodrigues; Braga, Ana Elisa Mendes Montalvão; Barca, Maria Lage; Engedal, Knut; Nascimento, Osvaldo José M; Deslandes, Andrea Camaz; Laks, Jerson

2017-06-01

Improvements on balance, gait and cognition are some of the benefits of exergames. Few studies have investigated the cognitive effects of exergames in institutionalized older persons. To assess the acute effect of a single session of exergames on cognition of institutionalized older persons. Nineteen institutionalized older persons were randomly allocated to Wii (WG, n = 10, 86 ± 7 year, two males) or control groups (CG, n = 9, 86 ± 5 year, one male). The WG performed six exercises with virtual reality, whereas CG performed six exercises without virtual reality. Verbal fluency test (VFT), digit span forward and digit span backward were used to evaluate semantic memory/executive function, short-term memory and work memory, respectively, before and after exergames and Δ post- to pre-session (absolute) and Δ % (relative) were calculated. Parametric (t independent test) and nonparametric (Mann-Whitney test) statistics and effect size were applied to tests for efficacy. VFT was statistically significant within WG (-3.07, df = 9, p = 0.013). We found no statistically significant differences between the two groups (p > 0.05). Effect size between groups of Δ % (median = 21 %) showed moderate effect for WG (0.63). Our data show moderate improvement of semantic memory/executive function due to exergames session. It is possible that cognitive brain areas are activated during exergames, increasing clinical response. A single session of exergames showed no significant improvement in short-term memory, working memory and semantic memory/executive function. The effect size for verbal fluency was promising, and future studies on this issue should be developed. RBR-6rytw2.

Aversive olfactory associative memory loses odor specificity over time

PubMed Central

König, Christian; Antwi-Adjei, Emmanuel; Ganesan, Mathangi; Kilonzo, Kasyoka; Viswanathan, Vignesh; Durairaja, Archana; Voigt, Anne

2017-01-01

ABSTRACT Avoiding associatively learned predictors of danger is crucial for survival. Aversive memories can, however, become counter-adaptive when they are overly generalized to harmless cues and contexts. In a fruit fly odor–electric shock associative memory paradigm, we found that learned avoidance lost its specificity for the trained odor and became general to novel odors within a day of training. We discuss the possible neural circuit mechanisms of this effect and highlight the parallelism to over-generalization of learned fear behavior after an incubation period in rodents and humans, with due relevance for post-traumatic stress disorder. PMID:28468811

In Search of Decay in Verbal Short-Term Memory

PubMed Central

Berman, Marc G.; Jonides, John; Lewis, Richard L.

2014-01-01

Is forgetting in the short term due to decay with the mere passage of time, interference from other memoranda, or both? Past research on short-term memory has revealed some evidence for decay and a plethora of evidence showing that short-term memory is worsened by interference. However, none of these studies has directly contrasted decay and interference in short-term memory in a task that rules out the use of rehearsal processes. In this article the authors present a series of studies using a novel paradigm to address this problem directly, by interrogating the operation of decay and interference in short-term memory without rehearsal confounds. The results of these studies indicate that short-term memories are subject to very small decay effects with the mere passage of time but that interference plays a much larger role in their degradation. The authors discuss the implications of these results for existing models of memory decay and interference. PMID:19271849

In search of decay in verbal short-term memory.

PubMed

Berman, Marc G; Jonides, John; Lewis, Richard L

2009-03-01

Is forgetting in the short term due to decay with the mere passage of time, interference from other memoranda, or both? Past research on short-term memory has revealed some evidence for decay and a plethora of evidence showing that short-term memory is worsened by interference. However, none of these studies has directly contrasted decay and interference in short-term memory in a task that rules out the use of rehearsal processes. In this article the authors present a series of studies using a novel paradigm to address this problem directly, by interrogating the operation of decay and interference in short-term memory without rehearsal confounds. The results of these studies indicate that short-term memories are subject to very small decay effects with the mere passage of time but that interference plays a much larger role in their degradation. The authors discuss the implications of these results for existing models of memory decay and interference. (c) 2009 APA, all rights reserved

Valence modulates source memory for faces.

PubMed

Bell, Raoul; Buchner, Axel

2010-01-01

Previous studies in which the effects of emotional valence on old-new discrimination and source memory have been examined have yielded highly inconsistent results. Here, we present two experiments showing that old-new face discrimination was not affected by whether a face was associated with disgusting, pleasant, or neutral behavior. In contrast, source memory for faces associated with disgusting behavior (i.e., memory for the disgusting context in which the face was encountered) was consistently better than source memory for other types of faces. This data pattern replicates the findings of studies in which descriptions of cheating, neutral, and trustworthy behavior were used, which findings were previously ascribed to a highly specific cheater detection module. The present results suggest that the enhanced source memory for faces of cheaters is due to a more general source memory advantage for faces associated with negative or threatening contexts that may be instrumental in avoiding the negative consequences of encounters with persons associated with negative or threatening behaviors.

[Pain and emotional dysregulation: Cellular memory due to pain].

PubMed

Narita, Minoru; Watanabe, Moe; Hamada, Yusuke; Tamura, Hideki; Ikegami, Daigo; Kuzumaki, Naoko; Igarashi, Katsuhide

2015-08-01

Genetic factors are involved in determinants for the risk of psychiatric disorders, and neurological and neurodegenerative diseases. Chronic pain stimuli and intense pain have effects at a cellular and/or gene expression level, and will eventually induce "cellular memory due to pain", which means that tissue damage, even if only transient, can elicit epigenetically abnormal transcription/translation and post-translational modification in related cells depending on the degree or kind of injury or associated conditions. Such cell memory/transformation due to pain can cause an abnormality in a fundamental intracellular response, such as a change in the three-dimensional structure of DNA, transcription, or translation. On the other hand, pain is a multidimensional experience with sensory-discriminative and motivational-affective components. Recent human brain imaging studies have examined differences in activity in the nucleus accumbens between controls and patients with chronic pain, and have revealed that the nucleus accumbens plays a role in predicting the value of a noxious stimulus and its offset, and in the consequent changes in the motivational state. In this review, we provide a very brief overview of a comprehensive understanding of chronic pain associated with emotional dysregulation due to transcriptional regulation, epigenetic modification and miRNA regulation.

Prediction of amyloid-β pathology in amnestic mild cognitive impairment with neuropsychological tests.

PubMed

Bahar-Fuchs, Alex; Villemagne, Victor; Ong, Kevin; Chetélat, Gaël; Lamb, Fiona; Reininger, Cornelia B; Woodward, Michael; Rowe, Christopher C

2013-01-01

Assessment of disease biomarkers, particularly the in vivo assessment of amyloid-β (Aβ) burden with positron emission tomography (PET), is gradually becoming central to the diagnosis of mild cognitive impairment (MCI) due to Alzheimer's disease (AD). However, the incorporation of biomarker evidence to the diagnostic process is currently restricted mainly to research settings. The identification of memory measures that are associated with Aβ is of clinical relevance as this may enhance the confidence in making a diagnosis of MCI due to AD in clinical settings. Forty one persons with amnestic MCI underwent Aβ imaging with (18)F-Florbetaben PET, magnetic resonance imaging, and a comprehensive neuropsychological assessment. All measures of episodic memory were significantly correlated with Aβ burden, but regression analyses revealed a strong and selective association between story recall and Aβ over and beyond the effects of age, education, global cognition, hippocampal volume, or other memory tests. Analyses of sensitivity and specificity of memory measures to detect high versus low Aβ scans suggested that word-list recall performed better when high sensitivity was preferred, whereas story recall performed better when high specificity was preferred. In conclusion, a measure of story recall may increase the confidence in making a diagnosis of MCI due to AD in clinical settings.

Memantine augmentation in clozapine-refractory schizophrenia: a randomized, double-blind, placebo-controlled crossover study.

PubMed

Veerman, S R T; Schulte, P F J; Smith, J D; de Haan, L

2016-07-01

Dysfunction of neuroplasticity due to N-methyl-d-aspartate (NMDA) receptor hypofunction may be a causal factor for memory and executive dysfunctioning in schizophrenia. Deregulation of NMDA transmission in the prefrontal cortex may also explain negative and positive symptoms. Clozapine augmentation with memantine targets altered NMDA receptor-mediated neurotransmission in schizophrenia and showed substantial beneficial effects on several symptom domains in a small proof-of-concept study. We evaluate effects of memantine add-on treatment to clozapine for memory and executive function, and negative and positive symptoms in schizophrenia. Clozapine-treated patients with refractory schizophrenia were randomly assigned to 12 weeks of double-blind adjunctive treatment with memantine (n = 26) or placebo (n = 26). Crossover occurred after a 2-week placebo wash-out period. Primary endpoints were change from baseline to 12 weeks treatment and 14 weeks to 26 weeks treatment on memory and executive function using the Cambridge Neuropsychological Test Automated Battery (CANTAB), Positive and Negative Syndrome Scale (PANSS), and Clinical Global Impression Severity Scale (CGI-S). Side effects were assessed using the Liverpool University Neuroleptic Side-Effect Rating Scale. When compared with placebo, memantine improved a composite memory score comprising verbal recognition memory and paired associates learning task scores on the CANTAB (effect size = 0.30) and PANSS negative subscale score (effect size = 0.29). Side effects were mild and transient. In patients with clozapine-treated refractory schizophrenia, memantine addition significantly improved verbal and visual memory and negative symptoms without serious adverse effects. These results justify further investigations on long-term memantine augmentation to clozapine in treatment-resistant schizophrenia.

The effect of cognitive load on hemispheric asymmetries in true and false memory.

PubMed

Tat, Michael J; Azuma, Tamiko

2016-01-01

Studies examining hemispheric asymmetries in false memory have shown that the right hemisphere (RH) is more susceptible to false memories compared to the left hemisphere (LH). Theories suggest that hemispheric asymmetries in true and false memory may be due to differences in representational coding and the use of top-down mechanisms in each hemisphere. In the current study, the Deese-Roediger-McDermott false memory paradigm was used in conjunction with divided visual field presentation to examine the role of top-down mechanisms in hemispheric asymmetries of true and false memory. In Experiment 1, participants studied lists of related words while completing secondary cognitive load tasks. In Experiment 2, the secondary tasks were administered during memory retrieval instead of memory encoding. Results revealed that cognitive loads imposed during the study phase influenced veridical memory in the LH more than the RH, but cognitive loads imposed during retrieval did not influence veridical memory in either hemisphere. Surprisingly, false memory rates were not influenced by cognitive loads and were higher in the LH. These data provide evidence that, at least for veridical memory, top-down control mechanisms are used more readily for the encoding of information into memory in the LH compared to the RH.

Personalized and not general suggestion produces false autobiographical memories and suggestion-consistent behavior.

PubMed

Scoboria, Alan; Mazzoni, Giuliana; Jarry, Josée L; Bernstein, Daniel M

2012-01-01

Suggesting false childhood events produces false autobiographical beliefs, memories and suggestion-consistent behavior. The mechanisms by which suggestion affects behavior are not understood, and whether false beliefs and memories are necessary for suggestions to impact behavior remains unexplored. We examined the relative effects of providing a personalized suggestion (suggesting that an event occurred to the person in the past), and/or a general suggestion (suggesting that an event happened to others in the past). Participants (N=122) received a personalized suggestion, a general suggestion, both or neither, about childhood illness due to spoiled peach yogurt. The personalized suggestion resulted in false beliefs, false memories, and suggestion-consistent behavioral intentions immediately after the suggestion. One week or one month later participants completed a taste test that involved eating varieties of crackers and yogurts. The personalized suggestion led to reduced consumption of only peach yogurt, and those who reported a false memory showed the most eating suppression. This effect on behavior was equally strong after one week and one month, showing a long lived influence of the personalized suggestion. The general suggestion showed no effects. Suggestions that convey personal information about a past event produce false autobiographical memories, which in turn impact behavior. Copyright © 2011 Elsevier B.V. All rights reserved.

Similarity-based distortion of visual short-term memory is due to perceptual averaging.

PubMed

Dubé, Chad; Zhou, Feng; Kahana, Michael J; Sekuler, Robert

2014-03-01

A task-irrelevant stimulus can distort recall from visual short-term memory (VSTM). Specifically, reproduction of a task-relevant memory item is biased in the direction of the irrelevant memory item (Huang & Sekuler, 2010a). The present study addresses the hypothesis that such effects reflect the influence of neural averaging under conditions of uncertainty about the contents of VSTM (Alvarez, 2011; Ball & Sekuler, 1980). We manipulated subjects' attention to relevant and irrelevant study items whose similarity relationships were held constant, while varying how similar the study items were to a subsequent recognition probe. On each trial, subjects were shown one or two Gabor patches, followed by the probe; their task was to indicate whether the probe matched one of the study items. A brief cue told subjects which Gabor, first or second, would serve as that trial's target item. Critically, this cue appeared either before, between, or after the study items. A distributional analysis of the resulting mnemometric functions showed an inflation in probability density in the region spanning the spatial frequency of the average of the two memory items. This effect, due to an elevation in false alarms to probes matching the perceptual average, was diminished when cues were presented before both study items. These results suggest that (a) perceptual averages are computed obligatorily and (b) perceptual averages are relied upon to a greater extent when item representations are weakened. Implications of these results for theories of VSTM are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Effects of Different Electrode Types for Obtaining Surface Machining Shape on Shape Memory Alloy Using Electrochemical Machining

NASA Astrophysics Data System (ADS)

Choi, S. G.; Kim, S. H.; Choi, W. K.; Moon, G. C.; Lee, E. S.

2017-06-01

Shape memory alloy (SMA) is important material used for the medicine and aerospace industry due to its characteristics called the shape memory effect, which involves the recovery of deformed alloy to its original state through the application of temperature or stress. Consumers in modern society demand stability in parts. Electrochemical machining is one of the methods for obtained these stabilities in parts requirements. These parts of shape memory alloy require fine patterns in some applications. In order to machine a fine pattern, the electrochemical machining method is suitable. For precision electrochemical machining using different shape electrodes, the current density should be controlled precisely. And electrode shape is required for precise electrochemical machining. It is possible to obtain precise square holes on the SMA if the insulation layer controlled the unnecessary current between electrode and workpiece. If it is adjusting the unnecessary current to obtain the desired shape, it will be a great contribution to the medical industry and the aerospace industry. It is possible to process a desired shape to the shape memory alloy by micro controlling the unnecessary current. In case of the square electrode without insulation layer, it derives inexact square holes due to the unnecessary current. The results using the insulated electrode in only side show precise square holes. The removal rate improved in case of insulated electrode than others because insulation layer concentrate the applied current to the machining zone.

Pharmacological preconditioning by milrinone: memory preserving and neuroprotective effect in ischemia-reperfusion injury in mice.

PubMed

Saklani, Reetu; Jaggi, Amteshwar; Singh, Nirmal

2010-07-01

We tested the neuroprotective effect of milrinone, a phosphodiesterase III inhibitor, in pharmacological preconditioning. Bilateral carotid artery occlusion for 12 min followed by reperfusion for 24 h produced ischemia-reperfusion (I/R) cerebral injury in male Swiss albino mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using the Morris water maze test, and motor coordination was evaluated using the inclined beam walking test, rota-rod test, and lateral push test. Milrinone (50 microg/kg & 100 microg/kg i.v.) was administered 24 h before surgery in a separate group of animals to induce pharmacological preconditioning. I/R increased cerebral infarct size and impaired memory and motor coordination. Milrinone treatment significantly decreased cerebral infarct size and reversed I/R-induced impairments in memory and motor coordination. This neuroprotective effect was blocked by ruthenium red (3 mg/kg, s.c.), an intracellular ryanodine receptor blocker. These findings indicate that milrinone preconditioning exerts a marked neuroprotective effect on the ischemic brain, putatively due to increased intracellular calcium levels activating calcium-sensitive signal transduction cascades.

Non-Markovian Complexity in the Quantum-to-Classical Transition

PubMed Central

Xiong, Heng-Na; Lo, Ping-Yuan; Zhang, Wei-Min; Feng, Da Hsuan; Nori, Franco

2015-01-01

The quantum-to-classical transition is due to environment-induced decoherence, and it depicts how classical dynamics emerges from quantum systems. Previously, the quantum-to-classical transition has mainly been described with memory-less (Markovian) quantum processes. Here we study the complexity of the quantum-to-classical transition through general non-Markovian memory processes. That is, the influence of various reservoirs results in a given initial quantum state evolving into one of the following four scenarios: thermal state, thermal-like state, quantum steady state, or oscillating quantum nonstationary state. In the latter two scenarios, the system maintains partial or full quantum coherence due to the strong non-Markovian memory effect, so that in these cases, the quantum-to-classical transition never occurs. This unexpected new feature provides a new avenue for the development of future quantum technologies because the remaining quantum oscillations in steady states are decoherence-free. PMID:26303002

Memory in a fractional-order cardiomyocyte model alters properties of alternans and spontaneous activity

NASA Astrophysics Data System (ADS)

Comlekoglu, T.; Weinberg, S. H.

2017-09-01

Cardiac memory is the dependence of electrical activity on the prior history of one or more system state variables, including transmembrane potential (Vm), ionic current gating, and ion concentrations. While prior work has represented memory either phenomenologically or with biophysical detail, in this study, we consider an intermediate approach of a minimal three-variable cardiomyocyte model, modified with fractional-order dynamics, i.e., a differential equation of order between 0 and 1, to account for history-dependence. Memory is represented via both capacitive memory, due to fractional-order Vm dynamics, that arises due to non-ideal behavior of membrane capacitance; and ionic current gating memory, due to fractional-order gating variable dynamics, that arises due to gating history-dependence. We perform simulations for varying Vm and gating variable fractional-orders and pacing cycle length and measure action potential duration (APD) and incidence of alternans, loss of capture, and spontaneous activity. In the absence of ionic current gating memory, we find that capacitive memory, i.e., decreased Vm fractional-order, typically shortens APD, suppresses alternans, and decreases the minimum cycle length (MCL) for loss of capture. However, in the presence of ionic current gating memory, capacitive memory can prolong APD, promote alternans, and increase MCL. Further, we find that reduced Vm fractional order (typically less than 0.75) can drive phase 4 depolarizations that promote spontaneous activity. Collectively, our results demonstrate that memory reproduced by a fractional-order model can play a role in alternans formation and pacemaking, and in general, can greatly increase the range of electrophysiological characteristics exhibited by a minimal model.

The functional neuroanatomy of verbal memory in Alzheimer's disease: [18F]-Fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) correlates of recency and recognition memory.

PubMed

Staffaroni, Adam M; Melrose, Rebecca J; Leskin, Lorraine P; Riskin-Jones, Hannah; Harwood, Dylan; Mandelkern, Mark; Sultzer, David L

2017-09-01

The objective of this study was to distinguish the functional neuroanatomy of verbal learning and recognition in Alzheimer's disease (AD) using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word Learning task. In 81 Veterans diagnosed with dementia due to AD, we conducted a cluster-based correlation analysis to assess the relationships between recency and recognition memory scores from the CERAD Word Learning Task and cortical metabolic activity measured using [ 18 F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET). AD patients (Mini-Mental State Examination, MMSE mean = 20.2) performed significantly better on the recall of recency items during learning trials than of primacy and middle items. Recency memory was associated with cerebral metabolism in the left middle and inferior temporal gyri and left fusiform gyrus (p < .05 at the corrected cluster level). In contrast, recognition memory was correlated with metabolic activity in two clusters: (a) a large cluster that included the left hippocampus, parahippocampal gyrus, entorhinal cortex, anterior temporal lobe, and inferior and middle temporal gyri; (b) the bilateral orbitofrontal cortices (OFC). The present study further informs our understanding of the disparate functional neuroanatomy of recency memory and recognition memory in AD. We anticipated that the recency effect would be relatively preserved and associated with temporoparietal brain regions implicated in short-term verbal memory, while recognition memory would be associated with the medial temporal lobe and possibly the OFC. Consistent with our a priori hypotheses, list learning in our AD sample was characterized by a reduced primacy effect and a relatively spared recency effect; however, recency memory was associated with cerebral metabolism in inferior and lateral temporal regions associated with the semantic memory network, rather than regions associated with short-term verbal memory. The correlates of recognition memory included the medial temporal lobe and OFC, replicating prior studies.

Gender differences in memory for objects and their locations: a study on automatic versus controlled encoding and retrieval contexts.

PubMed

De Goede, Maartje; Postma, Albert

2008-04-01

Object-location memory is the only spatial task where female subjects have been shown to outperform males. This result is not consistent across all studies, and may be due to the combination of the multi-component structure of object location memory with the conditions under which different studies were done. Possible gender differences in object location memory and its component object identity memory were assessed in the present study. In order to disentangle these two components, an object location memory task (in which objects had to be relocated in daily environments), and a separate object identity recognition task were carried out. This study also focused on the conditions under which object locations were encoded and retrieved. Only half of the participants were aware of the fact that object locations had to be retrieved later on. Moreover, by applying the 'process dissociation procedure' to the object location memory assessments and the 'remember-know' paradigm to the object identity measure, the amount of explicit (conscious) and implicit (unconscious) retrieval was estimated for each component. In general, females performed better than males on the object location memory task. However, when controlled for object identity memory, females no longer outperformed males, whereas they did not obtain a higher general object identity memory score, nor did they have more explicit or implicit recollection of the object identities. These complicated effects might stem from a difference between males and females, in the way locations or associations between objects and locations are retrieved. In general, participants had more explicit (conscious) recollection than implicit (unconscious) recollection. No effect of encoding context was found, nor any interaction effect of gender, encoding and retrieval context.

White matter lesions and the cholinergic deficit in aging and mild cognitive impairment.

PubMed

Richter, Nils; Michel, Anne; Onur, Oezguer A; Kracht, Lutz; Dietlein, Markus; Tittgemeyer, Marc; Neumaier, Bernd; Fink, Gereon R; Kukolja, Juraj

2017-05-01

In Alzheimer's disease (AD), white matter lesions (WMLs) are associated with an increased risk of progression from mild cognitive impairment (MCI) to dementia, while memory deficits have, at least in part, been linked to a cholinergic deficit. We investigated the relationship between WML load assessed with the Scheltens scale, cerebral acetylcholinesterase (AChE) activity measured with [ 11 C]N-methyl-4-piperidyl acetate PET, and neuropsychological performance in 17 patients with MCI due to AD and 18 cognitively normal older participants. Only periventricular, not nonperiventricular, WML load negatively correlated with AChE activity in both groups. Memory performance depended on periventricular and total WML load across groups. Crucially, AChE activity predicted memory function better than WML load, gray matter atrophy, or age. The effects of WML load on memory were fully mediated by AChE activity. Data suggest that the contribution of WML to the dysfunction of the cholinergic system in MCI due to AD depends on WML distribution. Pharmacologic studies are warranted to explore whether this influences the response to cholinergic treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Antidepressant Effect and Recognition Memory Improvement of Two Novel Plant Extract Combinations - Antistress I and Anti-stress II on Rats Subjected to a Model of Mild Chronic Stress.

PubMed

Kandilarov, Ilin K; Zlatanova, Hristina I; Georgieva-Kotetarova, Maria T; Kostadinova, Ivanka I; Katsarova, Mariana N; Dimitrova, Stela Z; Lukanov, Ludmil K; Sadakov, Ferit

2018-03-01

Chronic stress is one of the main factors which lead to depression - a psychiatric disorder affecting millions of people and predicted to be the second ranked cause of premature death in 2020. Depression is often associated with cognitive disturbances and memory deficit. Plant based therapy could be effective in the treatment of mild to moderate depression due to its low level of adverse reaction, its good tolerability and compliance. 72 male Wistar rats, divided in 9 groups were given orally for 8 weeks two combinations of dry plant extracts - Antistress I and Antistress II and five individual dry extracts obtained from Serratula coronata, Hypericum perforatum, Valeriana officinalis, Crataegus monogyna and Melissa officinalis. The animals were exposed to a chronic unpredictable mild stress for 8 weeks. The depression-like symptoms were evaluated with Forced swim test while the assessment of the memory deficit was performed with Novel object recognition test. Antistress II demonstrates antidepressant effect while Antistress I doesn't improve the depressive-like symptoms. The individual extracts of Hypericum perforatum and Valeriana officinalis also possess antidepressant properties. Antistress II improves the cognition as well as the individual extracts of Hypericum perforatum, Valeriana officinalis and especially Serratula coronata. Dry extract from Serratula tend to have the best effect regarding the recognition memory. The effect of Antistress I on memory deficit is negligible. Antistress II possesses antidepressant effect and improves the recognition memory while Antistress I doesn't demonstrate any of the above-described effects.

Enhancing cognition with video games: a multiple game training study.

PubMed

Oei, Adam C; Patterson, Michael D

2013-01-01

Previous evidence points to a causal link between playing action video games and enhanced cognition and perception. However, benefits of playing other video games are under-investigated. We examined whether playing non-action games also improves cognition. Hence, we compared transfer effects of an action and other non-action types that required different cognitive demands. We instructed 5 groups of non-gamer participants to play one game each on a mobile device (iPhone/iPod Touch) for one hour a day/five days a week over four weeks (20 hours). Games included action, spatial memory, match-3, hidden- object, and an agent-based life simulation. Participants performed four behavioral tasks before and after video game training to assess for transfer effects. Tasks included an attentional blink task, a spatial memory and visual search dual task, a visual filter memory task to assess for multiple object tracking and cognitive control, as well as a complex verbal span task. Action game playing eliminated attentional blink and improved cognitive control and multiple-object tracking. Match-3, spatial memory and hidden object games improved visual search performance while the latter two also improved spatial working memory. Complex verbal span improved after match-3 and action game training. Cognitive improvements were not limited to action game training alone and different games enhanced different aspects of cognition. We conclude that training specific cognitive abilities frequently in a video game improves performance in tasks that share common underlying demands. Overall, these results suggest that many video game-related cognitive improvements may not be due to training of general broad cognitive systems such as executive attentional control, but instead due to frequent utilization of specific cognitive processes during game play. Thus, many video game training related improvements to cognition may be attributed to near-transfer effects.

Allium sativum L. Improves Visual Memory and Attention in Healthy Human Volunteers

PubMed Central

Tasnim, Sara; Haque, Parsa Sanjana; Bari, Md. Sazzadul; Hossain, Md. Monir; Islam, Sardar Mohd. Ashraful; Shahriar, Mohammad; Bhuiyan, Mohiuddin Ahmed; Bin Sayeed, Muhammad Shahdaat

2015-01-01

Studies have shown that Allium sativum L. (AS) protects amyloid-beta peptide-induced apoptosis, prevents oxidative insults to neurons and synapses, and thus prevent Alzheimer's disease progression in experimental animals. However, there is no experimental evidence in human regarding its putative role in memory and cognition. We have studied the effect of AS consumption by healthy human volunteers on visual memory, verbal memory, attention, and executive function in comparison to control subjects taking placebo. The study was conducted over five weeks and twenty volunteers of both genders were recruited and divided randomly into two groups: A (AS) and B (placebo). Both groups participated in the 6 computerized neuropsychological tests of the Cambridge Neuropsychological Test Automated Battery (CANTAB) twice: at the beginning and after five weeks of the study. We found statistically significant difference (p < 0.05) in several parameters of visual memory and attention due to AS ingestion. We also found statistically nonsignificant (p > 0.05) beneficial effects on verbal memory and executive function within a short period of time among the volunteers. Study for a longer period of time with patients suffering from neurodegenerative diseases might yield more relevant results regarding the potential therapeutic role of AS. PMID:26351508

An Implementation Method of the Fractional-Order PID Control System Considering the Memory Constraint and its Application to the Temperature Control of Heat Plate

NASA Astrophysics Data System (ADS)

Sasano, Koji; Okajima, Hiroshi; Matsunaga, Nobutomo

Recently, the fractional order PID (FO-PID) control, which is the extension of the PID control, has been focused on. Even though the FO-PID requires the high-order filter, it is difficult to realize the high-order filter due to the memory limitation of digital computer. For implementation of FO-PID, approximation of the fractional integrator and differentiator are required. Short memory principle (SMP) is one of the effective approximation methods. However, there is a disadvantage that the approximated filter with SMP cannot eliminate the steady-state error. For this problem, we introduce the distributed implementation of the integrator and the dynamic quantizer to make the efficient use of permissible memory. The objective of this study is to clarify how to implement the accurate FO-PID with limited memories. In this paper, we propose the implementation method of FO-PID with memory constraint using dynamic quantizer. And the trade off between approximation of fractional elements and quantized data size are examined so as to close to the ideal FO-PID responses. The effectiveness of proposed method is evaluated by numerical example and experiment in the temperature control of heat plate.

Anticholinergic drug use is associated with episodic memory decline in older adults without dementia.

PubMed

Papenberg, Goran; Bäckman, Lars; Fratiglioni, Laura; Laukka, Erika J; Fastbom, Johan; Johnell, Kristina

2017-07-01

Anticholinergic drug use is common in older adults and has been related to increased dementia risk. This suggests that users of these drugs may experience accelerated cognitive decline. So far, however, longitudinal data on this topic are absent and the available evidence is inconclusive with respect to effects on specific cognitive domains due to suboptimal control of confounding variables. We investigated whether anticholinergic medication use is associated with cognitive decline over 6 years in a population-based study of older adults (aged 60-90; n = 1473) without dementia. We found that users (n = 29) declined more on episodic memory over 6 years compared to nonusers (n = 1418). These results were independent of age, sex, education, overall drug intake, physical activity, depression, cardiovascular risk burden, and cardiovascular disease. By contrast, anticholinergic drug use was unrelated to performance in processing speed, semantic memory, short-term memory, verbal fluency, and global cognition (the Mini-Mental-State Examination). Our results suggest that effects of anticholinergics may be particularly detrimental to episodic memory in older adults, which supports the assertion that the cholinergic system plays an important role in episodic memory formation. Copyright © 2017 Elsevier Inc. All rights reserved.

Neural effects of cognitive control load on auditory selective attention.

PubMed

Sabri, Merav; Humphries, Colin; Verber, Matthew; Liebenthal, Einat; Binder, Jeffrey R; Mangalathu, Jain; Desai, Anjali

2014-08-01

Whether and how working memory disrupts or alters auditory selective attention is unclear. We compared simultaneous event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) responses associated with task-irrelevant sounds across high and low working memory load in a dichotic-listening paradigm. Participants performed n-back tasks (1-back, 2-back) in one ear (Attend ear) while ignoring task-irrelevant speech sounds in the other ear (Ignore ear). The effects of working memory load on selective attention were observed at 130-210ms, with higher load resulting in greater irrelevant syllable-related activation in localizer-defined regions in auditory cortex. The interaction between memory load and presence of irrelevant information revealed stronger activations primarily in frontal and parietal areas due to presence of irrelevant information in the higher memory load. Joint independent component analysis of ERP and fMRI data revealed that the ERP component in the N1 time-range is associated with activity in superior temporal gyrus and medial prefrontal cortex. These results demonstrate a dynamic relationship between working memory load and auditory selective attention, in agreement with the load model of attention and the idea of common neural resources for memory and attention. Copyright © 2014 Elsevier Ltd. All rights reserved.

Degrading emotional memories induced by a virtual reality paradigm.

PubMed

Cuperus, Anne A; Laken, Maarten; van den Hout, Marcel A; Engelhard, Iris M

2016-09-01

In Eye Movement and Desensitization and Reprocessing (EMDR) therapy, a dual-task approach is used: patients make horizontal eye movements while they recall aversive memories. Studies showed that this reduces memory vividness and/or emotionality. A strong explanation is provided by working memory theory, which suggests that other taxing dual-tasks are also effective. Experiment 1 tested whether a visuospatial task which was carried out while participants were blindfolded taxes working memory. Experiment 2 tested whether this task degrades negative memories induced by a virtual reality (VR) paradigm. In experiment 1, participants responded to auditory cues with or without simultaneously carrying out the visuospatial task. In experiment 2, participants recalled negative memories induced by a VR paradigm. The experimental group simultaneously carried out the visuospatial task, and a control group merely recalled the memories. Changes in self-rated memory vividness and emotionality were measured. The slowing down of reaction times due to the visuospatial task indicated that its cognitive load was greater than the load of the eye movements task in previous studies. The task also led to reductions in emotionality (but not vividness) of memories induced by the VR paradigm. Weaknesses are that only males were tested in experiment 1, and the effectiveness of the VR fear/trauma induction was not assessed with ratings of mood or intrusions in experiment 2. The results suggest that the visuospatial task may be applicable in clinical settings, and the VR paradigm may provide a useful method of inducing negative memories. Copyright © 2016 Elsevier Ltd. All rights reserved.

Errors made by animals in memory paradigms are not always due to failure of memory.

PubMed

Wilkie, D M; Willson, R J; Carr, J A

1999-01-01

It is commonly assumed that errors in animal memory paradigms such as delayed matching to sample, radial mazes, and food-cache recovery are due to failures in memory for information necessary to perform the task successfully. A body of research, reviewed here, suggests that this is not always the case: animals sometimes make errors despite apparently being able to remember the appropriate information. In this paper a case study of this phenomenon is described, along with a demonstration of a simple procedural modification that successfully reduced these non-memory errors, thereby producing a better measure of memory.

Modeling recall memory for emotional objects in Alzheimer's disease.

PubMed

Sundstrøm, Martin

2011-07-01

To examine whether emotional memory (EM) of objects with self-reference in Alzheimer's disease (AD) can be modeled with binomial logistic regression in a free recall and an object recognition test to predict EM enhancement. Twenty patients with AD and twenty healthy controls were studied. Six objects (three presented as gifts) were shown to each participant. Ten minutes later, a free recall and a recognition test were applied. The recognition test had target-objects mixed with six similar distracter objects. Participants were asked to name any object in the recall test and identify each object in the recognition test as known or unknown. The total of gift objects recalled in AD patients (41.6%) was larger than neutral objects (13.3%) and a significant EM recall effect for gifts was found (Wilcoxon: p < .003). EM was not found for recognition in AD patients due to a ceiling effect. Healthy older adults scored overall higher in recall and recognition but showed no EM enhancement due to a ceiling effect. A logistic regression showed that likelihood of emotional recall memory can be modeled as a function of MMSE score (p < .014) and object status (p < .0001) as gift or non-gift. Recall memory was enhanced in AD patients for emotional objects indicating that EM in mild to moderate AD although impaired can be provoked with strong emotional load. The logistic regression model suggests that EM declines with the progression of AD rather than disrupts and may be a useful tool for evaluating magnitude of emotional load.

FN400 and LPC memory effects for concrete and abstract words

PubMed Central

Stróżak, Paweł; Bird, Christopher W.; Corby, Krystin; Frishkoff, Gwen; Curran, Tim

2016-01-01

According to dual-process models, recognition memory depends on two neurocognitive mechanisms: familiarity, which has been linked to the "frontal N400" (FN400) effect in studies using event-related potentials (ERPs), and recollection, which is reflected by changes in the late positive complex (LPC). Recently, there has been some debate over the relationship between FN400 familiarity effects and N400 semantic effects. According to one view, these effects are one and the same. Proponents of this view have suggested that the frontal distribution of the FN400 could be due to stimulus concreteness: recognition memory experiments commonly use highly imageable or concrete words (or pictures), which elicit semantic ERPs with a frontal distribution. In the present study we tested this claim using a recognition memory paradigm in which subjects memorized concrete and abstract nouns; half of the words changed font color between study and test. FN400 and LPC old/new effects were observed for abstract, as well as concrete words, and were stronger over right hemisphere electrodes for concrete words. However, there was no difference in anteriority of the FN400 effect for the two word types. These findings challenge the notion that the frontal distribution of the FN400 old/new effect is fully explained by stimulus concreteness. PMID:27463978

Crystallographic Characterization on Polycrystalline Ni-Mn-Ga Alloys with Strong Preferred Orientation

PubMed Central

Li, Zongbin; Yang, Bo; Zou, Naifu; Zhang, Yudong; Esling, Claude; Gan, Weimin; Zhao, Xiang; Zuo, Liang

2017-01-01

Heusler type Ni-Mn-Ga ferromagnetic shape memory alloys can demonstrate excellent magnetic shape memory effect in single crystals. However, such effect in polycrystalline alloys is greatly weakened due to the random distribution of crystallographic orientation. Microstructure optimization and texture control are of great significance and challenge to improve the functional behaviors of polycrystalline alloys. In this paper, we summarize our recent progress on the microstructure control in polycrystalline Ni-Mn-Ga alloys in the form of bulk alloys, melt-spun ribbons and thin films, based on the detailed crystallographic characterizations through neutron diffraction, X-ray diffraction and electron backscatter diffraction. The presented results are expected to offer some guidelines for the microstructure modification and functional performance control of ferromagnetic shape memory alloys. PMID:28772826

Neuroprotective effect of curcumin on okadaic acid induced memory impairment in mice.

PubMed

Rajasekar, N; Dwivedi, Subhash; Tota, Santosh Kumar; Kamat, Pradeep Kumar; Hanif, Kashif; Nath, Chandishwar; Shukla, Rakesh

2013-09-05

Okadaic acid (OKA) has been observed to cause memory impairment in human subjects having seafood contaminated with dinoflagellate (Helicondria okadai). OKA induces tau hyperphosphorylation and oxidative stress leading to memory impairment as our previous study has shown. Curcumin a natural antioxidant has demonstrated neuroprotection in various models of neurodegeneration. However, the effect of curcumin has not been explored in OKA induced memory impairment. Therefore, present study evaluated the effect of curcumin on OKA (100ng, intracerebrally) induced memory impairment in male Swiss albino mice as evaluated in Morris water maze (MWM) and passive avoidance tests (PAT). OKA administration resulted in memory impairment with a decreased cerebral blood flow (CBF) (measured by laser doppler flowmetry), ATP level and increased mitochondrial (Ca(2+))i, neuroinflammation (increased TNF-α, IL-1β, COX-2 and GFAP), oxidative-nitrosative stress, increased Caspase-9 and cholinergic dysfunction (decreased AChE activity/expression and α7 nicotinic acetylcholine receptor expression) in cerebral cortex and hippocampus of mice brain. Oral administration of curcumin (50mg/kg) for 13 days significantly improved memory function in both MWM and PAT along with brain energy metabolism, CBF and cholinergic function. It decreased mitochondrial (Ca(2+))i, and ameliorated neuroinflammation and oxidative-nitrostative stress in different brain regions of OKA treated mice. Curcumin also inhibited astrocyte activation as evidenced by decreased GFAP expression. This neuroprotective effect of curcumin is due to its potent anti-oxidant action thus confirming previous studies. Therefore, use of curcumin should be encouraged in people consuming sea food (contaminated with dinoflagellates) to prevent cognitive impairment. © 2013 Elsevier B.V. All rights reserved.

Appearance-based first impressions and person memory.

PubMed

Bell, Raoul; Mieth, Laura; Buchner, Axel

2015-03-01

Previous research has demonstrated that people preferentially remember reputational information that is emotionally incongruent to their expectations, but it has left open the question of the generality of this effect. Three conflicting hypotheses were proposed: (a) The effect is restricted to information relevant to reciprocal social exchange. (b) The effect is most pronounced for emotional (approach-and-avoidance-relevant) information. (c) The effect is due to a general tendency of the cognitive system to attend to unexpected and novel information regardless of its (emotional) content. Here, we varied the type of to-be-remembered person information across experiments. To stimulate expectations, we selected faces whose facial appearance was rated as pleasant or disgusting (Experiments 1 and 2), as intelligent or unintelligent (Experiment 3), or as being that of a lawyer or a farmer (Experiment 4). These faces were paired with behavior descriptions that violated or confirmed these appearance-based 1st impressions. Source memory for the association between the faces and the descriptions was assessed with surprise memory tests. The results show that people are willing to form various social expectations based on facial appearance alone, and they support the hypothesis that the classification of the faces in the memory test is biased by schema-congruent guessing. Source memory was generally enhanced for information violating appearance-based social expectations. In sum, the results show that person memory is consistently affected by different kinds of social expectations, supporting the idea that the mechanisms determining memory performance generalize beyond exchange-relevant reputational and emotional information. PsycINFO Database Record (c) 2015 APA, all rights reserved.

Gone for 60 seconds: reactivation length determines motor memory degradation during reconsolidation.

PubMed

de Beukelaar, Toon T; Woolley, Daniel G; Wenderoth, Nicole

2014-10-01

When a stable memory is reactivated it becomes transiently labile and requires restabilization, a process known as reconsolidation. Animal studies have convincingly demonstrated that during reconsolidation memories are modifiable and can be erased when reactivation is followed by an interfering intervention. Few studies have been conducted in humans, however, and results are inconsistent regarding the extent to which a memory can be degraded. We used a motor sequence learning paradigm to show that the length of reactivation constitutes a crucial boundary condition determining whether human motor memories can be degraded. In our first experiment, we found that a short reactivation (less than 60 sec) renders the memory labile and susceptible to degradation through interference, while a longer reactivation does not. In our second experiment, we reproduce these results and show a significant linear relationship between the length of memory reactivation and the detrimental effect of the interfering task performed afterwards, i.e., the longer the reactivation, the smaller the memory loss due to interference. Our data suggest that reactivation via motor execution activates a time-dependent process that initially destabilizes the memory, which is then followed by restabilization during further practice.

Genistein improves spatial learning and memory in male rats with elevated glucose level during memory consolidation.

PubMed

Kohara, Yumi; Kawaguchi, Shinichiro; Kuwahara, Rika; Uchida, Yutaro; Oku, Yushi; Yamashita, Kimihiro

2015-03-01

Cognitive dysfunction due to higher blood glucose level has been reported previously. Genistein (GEN) is a phytoestrogen that we hypothesized might lead to improved memory, despite elevated blood glucose levels at the time of memory consolidation. To investigate this hypothesis, we compared the effects of orally administered GEN on the central nervous system in normal versus glucose-loaded adult male rats. A battery of behavioral assessments was carried out. In the MAZE test, which measured spatial learning and memory, the time of normal rats was shortened by GEN treatment compared to the vehicle group, but only in the early stages of testing. In the glucose-loaded group, GEN treatment improved performance as mazes were advanced. In the open-field test, GEN treatment delayed habituation to the new environment in normal rats, and increased the exploratory behaviors of glucose-loaded rats. There were no significant differences observed for emotionality or fear-motivated learning and memory. Together, these results indicate that GEN treatment improved spatial learning and memory only in the early stages of testing in the normal state, but improved spatial learning and memory when glucose levels increased during memory consolidation. Copyright © 2014 Elsevier Inc. All rights reserved.

Symptom validity testing in memory clinics: Hippocampal-memory associations and relevance for diagnosing mild cognitive impairment.

PubMed

Rienstra, Anne; Groot, Paul F C; Spaan, Pauline E J; Majoie, Charles B L M; Nederveen, Aart J; Walstra, Gerard J M; de Jonghe, Jos F M; van Gool, Willem A; Olabarriaga, Silvia D; Korkhov, Vladimir V; Schmand, Ben

2013-01-01

Patients with mild cognitive impairment (MCI) do not always convert to dementia. In such cases, abnormal neuropsychological test results may not validly reflect cognitive symptoms due to brain disease, and the usual brain-behavior relationships may be absent. This study examined symptom validity in a memory clinic sample and its effect on the associations between hippocampal volume and memory performance. Eleven of 170 consecutive patients (6.5%; 13% of patients younger than 65 years) referred to memory clinics showed noncredible performance on symptom validity tests (SVTs, viz. Word Memory Test and Test of Memory Malingering). They were compared to a demographically matched group (n = 57) selected from the remaining patients. Hippocampal volume, measured by an automated volumetric method (Freesurfer), was correlated with scores on six verbal memory tests. The median correlation was r = .49 in the matched group. However, the relation was absent (median r = -.11) in patients who failed SVTs. Memory clinic samples may include patients who show noncredible performance, which invalidates their MCI diagnosis. This underscores the importance of applying SVTs in evaluating patients with cognitive complaints that may signify a predementia stage, especially when these patients are relatively young.

Fear reactivation prior to exposure therapy: does it facilitate the effects of VR exposure in a randomized clinical sample?

PubMed

Shiban, Youssef; Brütting, Johanna; Pauli, Paul; Mühlberger, Andreas

2015-03-01

The current study is the first to examine whether reactivation of fear memory prior to exposure therapy reduces relapse in a randomized clinical sample. In a standardized treatment protocol combining virtual reality and in-vivo exposure, patients underwent a fear reactivation procedure using a virtual spider 10 min prior to a virtual reality (VR) exposure (reactivation group: RG, n = 15). A control group (CG, n = 17) was exposed to a virtual plant 10 min prior to the VR exposure. Outcome measures were a VR spontaneous recovery test (SRT) and in-vivo a behavioral avoidance test assessed 24 h after VR exposure. One week later an in-vivo exposure session followed. Additionally, a follow-up using psychometric assessment was conducted six months after the first session. Both groups benefitted significantly and equally from the combined treatment, and importantly, the SRT revealed no return of fear in both groups. Furthermore, follow-up tests showed long-term treatment effects with no group differences. Due to different study components (VR treatment and in-vivo), we were not able to determine which treatment module was mainly responsible for the long-term treatment effect. Furthermore, no direct measure of memory destabilization was possible in this study. Our treatment package was highly effective in reducing phobic fear up to 6 months following treatment. Explicit fear reactivation prior to exposure was not beneficial in VR exposure treatment, possibly due to a failure to induce a memory destabilization or due to an implicit fear reactivation prior to treatment in both groups.

Colored noise and memory effects on formal spiking neuron models

NASA Astrophysics Data System (ADS)

da Silva, L. A.; Vilela, R. D.

2015-06-01

Simplified neuronal models capture the essence of the electrical activity of a generic neuron, besides being more interesting from the computational point of view when compared to higher-dimensional models such as the Hodgkin-Huxley one. In this work, we propose a generalized resonate-and-fire model described by a generalized Langevin equation that takes into account memory effects and colored noise. We perform a comprehensive numerical analysis to study the dynamics and the point process statistics of the proposed model, highlighting interesting new features such as (i) nonmonotonic behavior (emergence of peak structures, enhanced by the choice of colored noise characteristic time scale) of the coefficient of variation (CV) as a function of memory characteristic time scale, (ii) colored noise-induced shift in the CV, and (iii) emergence and suppression of multimodality in the interspike interval (ISI) distribution due to memory-induced subthreshold oscillations. Moreover, in the noise-induced spike regime, we study how memory and colored noise affect the coherence resonance (CR) phenomenon. We found that for sufficiently long memory, not only is CR suppressed but also the minimum of the CV-versus-noise intensity curve that characterizes the presence of CR may be replaced by a maximum. The aforementioned features allow to interpret the interplay between memory and colored noise as an effective control mechanism to neuronal variability. Since both variability and nontrivial temporal patterns in the ISI distribution are ubiquitous in biological cells, we hope the present model can be useful in modeling real aspects of neurons.

Effects of MDMA on olfactory memory and reversal learning in rats

PubMed Central

Hawkey, Andrew; April, L. Brooke; Galizio, Mark

2014-01-01

The effects of acute and sub-chronic MDMA were assessed using a procedure designed to test rodent working memory capacity: the odor span task (OST). Rats were trained to select an odor that they had not previously encountered within the current session, and the number of odors to remember was incremented up to 24 during the course of each session. In order to separate drug effects on the OST from more general performance impairment, a simple olfactory discrimination was also assessed in each session. In Experiment 1, acute doses of MDMA were administered prior to select sessions. MDMA impaired memory span in a dose-dependent fashion, but impairment was seen only at doses (1.8 and 3.0 mg/kg) that also increased response omissions on both the simple discrimination and the OST. In Experiment 2, a sub-chronic regimen of MDMA (10.0 mg/kg, twice daily over four days) was administered after OST training. There was no evidence of reduced memory span following sub-chronic MDMA, but a temporary increase in omission errors on the OST was observed. In addition, rats exposed to sub-chronic MDMA showed delayed learning when the simple discrimination was reversed. Overall, the disruptive effects of both acute and sub-chronic MDMA appeared to be due to non-mnemonic processes, rather than effects on specific memory functions. PMID:25017644

Preventing the return of fear memories with postretrieval extinction: A human study using a burst of white noise as an aversive stimulus.

PubMed

Fernandez-Rey, Jose; Gonzalez-Gonzalez, Daniel; Redondo, Jaime

2018-06-07

Standard extinction procedures seem to imply an inhibition of the fear response, but not a modification of the original fear-memory trace, which remains intact (Bouton, 2002, 2004). Typically, the behavioral procedure used to modify this trace is the so-called postretrieval extinction, consisting of fear-memory reactivation followed by extinction applied within the reconsolidation window. However, the application of this technique yields mixed results, probably due to a series of boundary conditions that limit the effectiveness of postretrieval-extinction effects. In this study a number of potential, and hitherto unexplored, moderators of such effects are considered. Using an interval of 48 hr between extinction and re-extinction, the findings show a spontaneous recovery similar to that found in studies that use a 24-hr interval. Also, the use of intervals of 10 and 20 min between reactivation and extinction led to a similar fear return. Finally, the burst of white noise used as an unconditioned stimulus (US) here was shown to be as effective as the electric shock normally used in the study of fear-memory reconsolidation. These findings suggest that postretrieval extinction is an effective behavioral technique for modifying the original fear memory and for the elimination of the fear return. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Working and reference memory across the estrous cycle of rat: a long-term study in gonadally intact females.

PubMed

Pompili, Assunta; Tomaz, Carlos; Arnone, Benedetto; Tavares, Maria Clotilde; Gasbarri, Antonella

2010-11-12

The results of many studies conducted over the past two decades suggested a role of estrogen on mammal's ability to learn and remember. In the present paper, we analyzed the influence that the endogenous fluctuation of estrogen, naturally present across the different phases of estrous cycle of female rats, can exert over the performance of tasks utilized to assess memory. In particular, we analyzed the performances in an eight arms radial maze task, dependent upon working memory, and in a water maze (WM) task, dependent upon spatial reference memory. The water maze is aversively motivated by the desire to escape onto a safe platform, whereas the radial arm maze (RAM) is motivated by food reward. The difference in reinforcement may affect the speed of learning, the strategy adopted and the necessity for accurate navigation. Therefore, coherent results obtained through the two different tasks can be due to mnemonic factors. The study was conducted during a long period of time, 14 months, utilizing gonadally intact females, without pharmacological and surgical treatments. In order to evaluate the post-acquisition phase we first trained the animals to reach the criterion in performing tasks, and then we submitted them to experimental phase. Our results show that estrogen can have an effect on memory processes, and that this effect may be different in relation to different kinds of memory. In fact, in our study, estrogen selectively improved working memory, but not reference memory, during post-acquisition performance of a RAM task with four baited and four un-baited arms. Moreover, WM performances showed that estrogen have a negative effect on spatial reference memory. (c) 2010 Elsevier B.V. All rights reserved.

Neutral details associated with emotional events are encoded: evidence from a cued recall paradigm.

PubMed

Mickley Steinmetz, Katherine R; Knight, Aubrey G; Kensinger, Elizabeth A

2016-11-01

Enhanced emotional memory often comes at the cost of memory for surrounding background information. Narrowed-encoding theories suggest that this is due to narrowed attention for emotional information at encoding, leading to impaired encoding of background information. Recent work has suggested that an encoding-based theory may be insufficient. Here, we examined whether cued recall-instead of previously used recognition memory tasks-would reveal evidence that non-emotional information associated with emotional information was effectively encoded. Participants encoded positive, negative, or neutral objects on neutral backgrounds. At retrieval, they were given either the item or the background as a memory cue and were asked to recall the associated scene element. Counter to narrowed-encoding theories, emotional items were more likely than neutral items to trigger recall of the associated background. This finding suggests that there is a memory trace of this contextual information and that emotional cues may facilitate retrieval of this information.

Visual short-term memory capacity for simple and complex objects.

PubMed

Luria, Roy; Sessa, Paola; Gotler, Alex; Jolicoeur, Pierre; Dell'Acqua, Roberto

2010-03-01

Does the capacity of visual short-term memory (VSTM) depend on the complexity of the objects represented in memory? Although some previous findings indicated lower capacity for more complex stimuli, other results suggest that complexity effects arise during retrieval (due to errors in the comparison process with what is in memory) that is not related to storage limitations of VSTM, per se. We used ERPs to track neuronal activity specifically related to retention in VSTM by measuring the sustained posterior contralateral negativity during a change detection task (which required detecting if an item was changed between a memory and a test array). The sustained posterior contralateral negativity, during the retention interval, was larger for complex objects than for simple objects, suggesting that neurons mediating VSTM needed to work harder to maintain more complex objects. This, in turn, is consistent with the view that VSTM capacity depends on complexity.

Nanoscale CuO solid-electrolyte-based conductive-bridging, random-access memory cell with a TiN liner

NASA Astrophysics Data System (ADS)

Lee, Jong-Sun; Kim, Dong-Won; Kim, Hea-Jee; Jin, Soo-Min; Song, Myung-Jin; Kwon, Ki-Hyun; Park, Jea-Gun; Jalalah, Mohammed; Al-Hajry, Ali

2018-01-01

The Conductive-bridge random-access memory (CBRAM) cell is a promising candidate for a terabit-level non-volatile memory due to its remarkable advantages. We present for the first time TiN as a diffusion barrier in CBRAM cells for enhancing their reliability. CuO solid-electrolyte-based CBRAM cells implemented with a 0.1-nm TiN liner demonstrated better non-volatile memory characteristics such as 106 AC write/erase endurance cycles with 100-μs AC pulse width and a long retention time of 7.4-years at 85 °C. In addition, the analysis of Ag diffusion in the CBRAM cell suggests that the morphology of the Ag filaments in the electrolyte can be effectively controlled by tuning the thickness of the TiN liner. These promising results pave the way for faster commercialization of terabit-level non-volatile memories.

Is there pre-attentive memory-based comparison of pitch?

PubMed

Jacobsen, T; Schröger, E

2001-07-01

The brain's responsiveness to changes in sound frequency has been demonstrated by an overwhelming number of studies. Change detection occurs unintentionally and automatically. It is generally assumed that this brain response, the so-called mismatch negativity (MMN) of the event-related brain potential or evoked magnetic field, is based on the outcome of a memory-comparison mechanism rather than being due to a differential state of refractoriness of tonotopically organized cortical neurons. To the authors' knowledge, however, there is no entirely compelling evidence for this belief. An experimental protocol controlling for refractoriness effects was developed and a true memory-comparison-based brain response to pitch change was demonstrated.

Computational modeling of the negative priming effect based on inhibition patterns and working memory

PubMed Central

Chung, Dongil; Raz, Amir; Lee, Jaewon; Jeong, Jaeseung

2013-01-01

Negative priming (NP), slowing down of the response for target stimuli that have been previously exposed, but ignored, has been reported in multiple psychological paradigms including the Stroop task. Although NP likely results from the interplay of selective attention, episodic memory retrieval, working memory, and inhibition mechanisms, a comprehensive theoretical account of NP is currently unavailable. This lacuna may result from the complexity of stimuli combinations in NP. Thus, we aimed to investigate the presence of different degrees of the NP effect according to prime-probe combinations within a classic Stroop task. We recorded reaction times (RTs) from 66 healthy participants during Stroop task performance and examined three different NP subtypes, defined according to the type of the Stroop probe in prime-probe pairs. Our findings show significant RT differences among NP subtypes that are putatively due to the presence of differential disinhibition, i.e., release from inhibition. Among the several potential origins for differential subtypes of NP, we investigated the involvement of selective attention and/or working memory using a parallel distributed processing (PDP) model (employing selective attention only) and a modified PDP model with working memory (PDP-WM, employing both selective attention and working memory). Our findings demonstrate that, unlike the conventional PDP model, the PDP-WM successfully simulates different levels of NP effects that closely follow the behavioral data. This outcome suggests that working memory engages in the re-accumulation of the evidence for target response and induces differential NP effects. Our computational model complements earlier efforts and may pave the road to further insights into an integrated theoretical account of complex NP effects. PMID:24312046

The effects of aging on emotion-induced modulations of source retrieval ERPs: evidence for valence biases.

PubMed

Newsome, Rachel N; Dulas, Michael R; Duarte, Audrey

2012-12-01

Many behavioral studies have shown that memory is enhanced for emotionally salient events across the lifespan. It has been suggested that this mnemonic boost may be observed for both age groups, particularly the old, in part because emotional information is retrieved with less effort than neutral information. Neuroimaging evidence suggests that inefficient retrieval processing (temporally delayed and attenuated) may contribute to age-related impairments in episodic memory for neutral events. It is not entirely clear whether emotional salience may reduce these age-related changes in neural activity associated with episodic retrieval for neutral events. Here, we investigated these ideas using event-related potentials (ERPs) to assess the neural correlates of successful source memory retrieval ("old-new effects") for neutral and emotional (negative and positive) images. Behavioral results showed that older adults demonstrated source memory impairments compared to the young but that both groups showed reduced source memory accuracy for negative compared to positive and neutral images; most likely due to an arousal-induced memory tradeoff for the negative images, which were subjectively more arousing than both positive and neutral images. ERP results showed that early onsetting old-new effects, between 100 and 300 ms, were observed for emotional but not neutral images in both age groups. Interestingly, these early effects were observed for negative items in the young and for positive items in the old. These ERP findings offer support for the idea that emotional events may be retrieved more automatically than neutral events across the lifespan. Furthermore, we suggest that very early retrieval mechanisms, possibly perceptual priming or familiarity, may underlie the negativity and positivity effects sometimes observed in the young and old, respectively, for various behavioral measures of attention and memory. Copyright © 2012 Elsevier Ltd. All rights reserved.

The interrelated effect of sleep and learning in dogs (Canis familiaris); an EEG and behavioural study

PubMed Central

Kis, Anna; Szakadát, Sára; Gácsi, Márta; Kovács, Enikő; Simor, Péter; Török, Csenge; Gombos, Ferenc; Bódizs, Róbert; Topál, József

2017-01-01

The active role of sleep in memory consolidation is still debated, and due to a large between-species variation, the investigation of a wide range of different animal species (besides humans and laboratory rodents) is necessary. The present study applied a fully non-invasive methodology to study sleep and memory in domestic dogs, a species proven to be a good model of human awake behaviours. Polysomnography recordings performed following a command learning task provide evidence that learning has an effect on dogs’ sleep EEG spectrum. Furthermore, spectral features of the EEG were related to post-sleep performance improvement. Testing an additional group of dogs in the command learning task revealed that sleep or awake activity during the retention interval has both short- and long-term effects. This is the first evidence to show that dogs’ human-analogue social learning skills might be related to sleep-dependent memory consolidation. PMID:28165489

Enhanced magnetic hysteresis in Ni-Mn-Ga single crystal and its influence on magnetic shape memory effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heczko, O., E-mail: heczko@fzu.cz; Drahokoupil, J.; Straka, L.

2015-05-07

Enhanced magnetic hysteresis due to boron doping in combination with magnetic shape memory effect in Ni-Mn-Ga single crystal results in new interesting functionality of magnetic shape memory (MSM) alloys such as mechanical demagnetization. In Ni{sub 50.0}Mn{sub 28.5}Ga{sub 21.5} single crystal, the boron doping increased magnetic coercivity from few Oe to 270 Oe while not affecting the transformation behavior and 10 M martensite structure. However, the magnetic field needed for MSM effect also increased in doped sample. The magnetic behavior is compared to undoped single crystal of similar composition. The evidence from the X-ray diffraction, magnetic domain structure, magnetization loops, and temperature evolutionmore » of the magnetic coercivity points out that the enhanced hysteresis is caused by stress-induced anisotropy.« less

Does attitude acquisition in evaluative conditioning without explicit CS-US memory reflect implicit misattribution of affect?

PubMed

Mierop, Adrien; Hütter, Mandy; Stahl, Christoph; Corneille, Olivier

2018-02-05

Research that dissociates different types of processes within a given task using a processing tree approach suggests that attitudes may be acquired through evaluative conditioning in the absence of explicit encoding of CS-US pairings in memory. This research distinguishes explicit memory for the CS-US pairings from CS-liking acquired without encoding of CS-US pairs in explicit memory. It has been suggested that the latter effect may be due to an implicit misattribution process that is assumed to operate when US evocativeness is low. In the present research, the latter assumption was supported neither by two high-powered experiments nor by complementary meta-analytic evidence, whereas evocativeness exerted an influence on explicit memory. This pattern of findings is inconsistent with the view that CS-liking acquired without encoding of CS-US pairs in explicit memory reflects an implicit misattribution process at learning. Hence, the underlying learning process is awaiting further empirical scrutiny.

Spatial serial order processing in schizophrenia.

PubMed

Fraser, David; Park, Sohee; Clark, Gina; Yohanna, Daniel; Houk, James C

2004-10-01

The aim of this study was to examine serial order processing deficits in 21 schizophrenia patients and 16 age- and education-matched healthy controls. In a spatial serial order working memory task, one to four spatial targets were presented in a randomized sequence. Subjects were required to remember the locations and the order in which the targets were presented. Patients showed a marked deficit in ability to remember the sequences compared with controls. Increasing the number of targets within a sequence resulted in poorer memory performance for both control and schizophrenia subjects, but the effect was much more pronounced in the patients. Targets presented at the end of a long sequence were more vulnerable to memory error in schizophrenia patients. Performance deficits were not attributable to motor errors, but to errors in target choice. The results support the idea that the memory errors seen in schizophrenia patients may be due to saturating the working memory network at relatively low levels of memory load.

Color appearance of familiar objects: effects of object shape, texture, and illumination changes.

PubMed

Olkkonen, Maria; Hansen, Thorsten; Gegenfurtner, Karl R

2008-05-26

People perceive roughly constant surface colors despite large changes in illumination. The familiarity of colors of some natural objects might help achieve this feat through direct modulation of the objects' color appearance. Research on memory colors and color appearance has yielded controversial results and due to the employed methods has often confounded perceptual with semantic effects. We studied the effect of memory colors on color appearance by presenting photographs of fruit on a monitor under various simulated illuminations and by asking observers to make either achromatic or typical color settings without placing demands on short-term memory or semantic processing. In a control condition, we presented photographs of 3D fruit shapes without texture and 2D outline shapes. We found that (1) achromatic settings for fruit were systematically biased away from the gray point toward the opposite direction of a fruit's memory color; (2) the strength of the effect depended on the degree of naturalness of the stimuli; and (3) the effect was evident under all tested illuminations, being strongest for illuminations whose chromaticity was closest to the stimulus chromaticity. We conclude that the visual identity of an object has a measurable effect on color perception, and that this effect is robust under illuminant changes, indicating its potential significance as an additional mechanism for color constancy.

The levels of processing effect under nitrogen narcosis.

PubMed

Kneller, Wendy; Hobbs, Malcolm

2013-01-01

Previous research has consistently demonstrated that inert gas (nitrogen) narcosis affects free recall but not recognition memory in the depth range of 30 to 50 meters of sea water (msw), possibly as a result of narcosis preventing processing when learned material is encoded. The aim of the current research was to test this hypothesis by applying a levels of processing approach to the measurement of free recall under narcosis. Experiment 1 investigated the effect of depth (0-2 msw vs. 37-39 msw) and level of processing (shallow vs. deep) on free recall memory performance in 67 divers. When age was included as a covariate, recall was significantly worse in deep water (i.e., under narcosis), compared to shallow water, and was significantly higher in the deep processing compared to shallow processing conditions in both depth conditions. Experiment 2 demonstrated that this effect was not simply due to the different underwater environments used for the depth conditions in Experiment 1. It was concluded memory performance can be altered by processing under narcosis and supports the contention that narcosis affects the encoding stage of memory as opposed to self-guided search (retrieval).

The effect of bacterial cellulose on the shape memory behavior of polyvinyl alcohol nanocomposite hydrogel

NASA Astrophysics Data System (ADS)

Pirahmadi, Pegah; Kokabi, Mehrdad

2018-01-01

Most research on shape memory polymers has been confined to neat polymers in their dry state, while, some hydrogel networks are known for their shape memory properties. Hydrogels have low glass transition temperatures which are below 100°C depend on the content of water. But they are usually weak and brittle, and not suitable for structural applications due to their low mechanical strengths because of these materials have large amount of water (>50%), so they could not remember original shape perfectly. Bacterial cellulose nanofibers with perfect properties such as high water holding capacity, high crystallinity, high tensile strength and good biocompatibility can dismiss all the drawbacks. In the present study, polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel prepared by repetitive freezing-thawing method. The bacterial cellulose was used as reinforcement to improve the mechanical properties and stimuli response. Differential scanning calorimetry was employed to obtain the glass transition temperature. Nanocomposite morphology was characterized by field-emission scanning electron microscopy and mechanical properties were investigated by standard tensile test. Finally, the effect of bacterial cellulose nanofiber on shape memory behavior of polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel was investigated. It is found that switching temperature of this system is the glass transition temperature of the nano domains formed within the system. The results also show increase of shape recovery, and shape recovery speed due to presence of bacterial cellulose.

Low-Pressure and Low-Temperature Hydriding-Pulverization-Dehydriding Method for Producing Shape Memory Alloy Powders

NASA Astrophysics Data System (ADS)

Murguia, Silvia Briseño; Clauser, Arielle; Dunn, Heather; Fisher, Wendy; Snir, Yoav; Brennan, Raymond E.; Young, Marcus L.

2018-04-01

Shape memory alloys (SMAs) are of high interest as active, adaptive "smart" materials for applications such as sensors and actuators due to their unique properties, including the shape memory effect and pseudoelasticity. Binary NiTi SMAs have shown the most desirable properties, and consequently have generated the most commercial success. A major challenge for SMAs, in particular, is their well-known compositional sensitivity. Therefore, it is critical to control the powder composition and morphology. In this study, a low-pressure, low-temperature hydriding-pulverization-dehydriding method for preparing well-controlled compositions, size, and size distributions of SMA powders from wires is presented. Starting with three different diameters of as-drawn martensitic NiTi SMA wires, pre-alloyed NiTi powders of various well-controlled sizes are produced by hydrogen charging the wires in a heated H3PO4 solution. After hydrogen charging for different charging times, the wires are pulverized and subsequently dehydrided. The wires and the resulting powders are characterized using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. The relationship between the wire diameter and powder size is investigated as a function of hydrogen charging time. The rate of diameter reduction after hydrogen charging of wire is also examined. Finally, the recovery behavior due to the shape memory effect is investigated after dehydriding.

The PKC-β selective inhibitor, Enzastaurin, impairs memory in middle-aged rats.

PubMed

Willeman, Mari N; Mennenga, Sarah E; Siniard, Ashley L; Corneveaux, Jason J; De Both, Matt; Hewitt, Lauren T; Tsang, Candy W S; Caselli, Jason; Braden, B Blair; Bimonte-Nelson, Heather A; Huentelman, Matthew J

2018-01-01

Enzastaurin is a Protein Kinase C-β selective inhibitor that was developed to treat cancers. Protein Kinase C-β is an important enzyme for a variety of neuronal functions; in particular, previous rodent studies have reported deficits in spatial and fear-conditioned learning and memory with lower levels of Protein Kinase C-β. Due to Enzastaurin's mechanism of action, the present study investigated the consequences of Enzastaurin exposure on learning and memory in 12-month-old Fischer-344 male rats. Rats were treated daily with subcutaneous injections of either vehicle or Enzastaurin, and behaviorally tested using the spatial reference memory Morris Water Maze. Rats treated with Enzastaurin exhibited decreased overnight retention and poorer performance on the latter testing day, indicating a mild, but significant, memory impairment. There were no differences during the probe trial indicating that all animals were able to spatially localize the platform to the proper quadrant by the end of testing. RNA isolated from the hippocampus was analyzed using Next Generation Sequencing (Illumina). No statistically significant transcriptional differences were noted. Our findings suggest that acute Enzastaurin treatment can impair hippocampal-based learning and memory performance, with no effects on transcription in the hippocampus. We propose that care should be taken in future clinical trials that utilize Protein Kinase C-ß inhibitors, to monitor for possible cognitive effects, future research should examine if these effects are fully reversible.

Differential effects of ADORA2A gene variations in pre-attentive visual sensory memory subprocesses.

PubMed

Beste, Christian; Stock, Ann-Kathrin; Ness, Vanessa; Epplen, Jörg T; Arning, Larissa

2012-08-01

The ADORA2A gene encodes the adenosine A(2A) receptor that is highly expressed in the striatum where it plays a role in modulating glutamatergic and dopaminergic transmission. Glutamatergic signaling has been suggested to play a pivotal role in cognitive functions related to the pre-attentive processing of external stimuli. Yet, the precise molecular mechanism of these processes is poorly understood. Therefore, we aimed to investigate whether ADORA2A gene variation has modulating effects on visual pre-attentive sensory memory processing. Studying two polymorphisms, rs5751876 and rs2298383, in 199 healthy control subjects who performed a partial-report paradigm, we find that ADORA2A variation is associated with differences in the efficiency of pre-attentive sensory memory sub-processes. We show that especially the initial visual availability of stimulus information is rendered more efficiently in the homozygous rare genotype groups. Processes related to the transfer of information into working memory and the duration of visual sensory (iconic) memory are compromised in the homozygous rare genotype groups. Our results show a differential genotype-dependent modulation of pre-attentive sensory memory sub-processes. Hence, we assume that this modulation may be due to differential effects of increased adenosine A(2A) receptor signaling on glutamatergic transmission and striatal medium spiny neuron (MSN) interaction. Copyright © 2011 Elsevier B.V. and ECNP. All rights reserved.

The neural correlates of age effects on verbal-spatial binding in working memory.

PubMed

Meier, Timothy B; Nair, Veena A; Meyerand, Mary E; Birn, Rasmus M; Prabhakaran, Vivek

2014-06-01

In this study, we investigated the neural correlates of age-related differences in the binding of verbal and spatial information utilizing event-related working memory tasks. Twenty-one right handed younger adults and twenty-one right handed older adults performed two versions of a dual task of verbal and spatial working memory. In the unbound dual task version letters and locations were presented simultaneously in separate locations, while in the bound dual task version each letter was paired with a specific location. In order to identify binding-specific differences, mixed-effects ANOVAs were run with the interaction of age and task as the effect of interest. Although older adults performed worse in the bound task than younger adults, there was no significant interaction between task and age on working memory performance. However, interactions of age and task were observed in brain activity analyses. Older adults did not display the greater unbound than bound task activity that younger adults did at the encoding phase in bilateral inferior parietal lobule, right putamen, and globus pallidus as well as at the maintenance phase in the cerebellum. We conclude that the binding of letters and locations in working memory is not as efficient in older adults as it is in younger adults, possibly due to the decline of cognitive control processes that are specific to working memory binding. Copyright © 2014 Elsevier B.V. All rights reserved.

Glucocorticoids mediate stress-induced impairment of retrieval of stimulus-response memory.

PubMed

Atsak, Piray; Guenzel, Friederike M; Kantar-Gok, Deniz; Zalachoras, Ioannis; Yargicoglu, Piraye; Meijer, Onno C; Quirarte, Gina L; Wolf, Oliver T; Schwabe, Lars; Roozendaal, Benno

2016-05-01

Acute stress and elevated glucocorticoid hormone levels are well known to impair the retrieval of hippocampus-dependent 'declarative' memory. Recent findings suggest that stress might also impair the retrieval of non-hippocampal memories. In particular, stress shortly before retention testing was shown to impair the retrieval of striatal stimulus-response associations in humans. However, the mechanism underlying this stress-induced retrieval impairment of non-hippocampal stimulus-response memory remains elusive. In the present study, we investigated whether an acute elevation in glucocorticoid levels mediates the impairing effects of stress on retrieval of stimulus-response memory. Male Sprague-Dawley rats were trained on a stimulus-response task in an eight-arm radial maze until they learned to associate a stimulus, i.e., cue, with a food reward in one of the arms. Twenty-four hours after successful acquisition, they received a systemic injection of vehicle, corticosterone (1mg/kg), the corticosterone-synthesis inhibitor metyrapone (35mg/kg) or were left untreated 1h before retention testing. We found that the corticosterone injection impaired the retrieval of stimulus-response memory. We further found that the systemic injection procedure per se was stressful as the vehicle administration also increased plasma corticosterone levels and impaired the retrieval of stimulus-response memory. However, memory retrieval was not impaired when rats were tested 2min after the systemic vehicle injection, before any stress-induced elevation in corticosterone levels had occurred. Moreover, metyrapone treatment blocked the effect of injection stress on both plasma corticosterone levels and memory retrieval impairment, indicating that the endogenous corticosterone response mediates the stress-induced memory retrieval impairment. None of the treatments affected rats' locomotor activity or motivation to search for the food reward within the maze. These findings show that stress may affect memory processes beyond the hippocampus and that these stress effects are due to the action of glucocorticoids. Copyright © 2016 Elsevier Ltd. All rights reserved.

The "One-Shot" Hypothesis for Context Storage

ERIC Educational Resources Information Center

Malmberg, Kenneth J.; Shiffrin, Richard M.

2005-01-01

In 3 experiments motivated by the implicit memory literature, the authors investigated the effects of different strengthening operations on the list strength effect (LSE) for explicit free recall, an effect posited by R. M. Shiffrin, R. Ratcliff, and S. E. Clark (1990) to be due to context cuing. According to the one-shot hypothesis, a fixed…

The (lack of) effect of dynamic visual noise on the concreteness effect in short-term memory.

PubMed

Castellà, Judit; Campoy, Guillermo

2018-05-17

It has been suggested that the concreteness effect in short-term memory (STM) is a consequence of concrete words having more distinctive and richer semantic representations. The generation and storage of visual codes in STM could also play a crucial role on the effect because concrete words are more imaginable than abstract words. If this were the case, the introduction of a visual interference task would be expected to disrupt recall of concrete words. A Dynamic Visual Noise (DVN) display, which has been proven to eliminate the concreteness effect on long-term memory (LTM), was presented along encoding of concrete and abstract words in a STM serial recall task. Results showed a main effect of word type, with more item errors in abstract words, a main effect of DVN, which impaired global performance due to more order errors, but no interaction, suggesting that DVN did not have any impact on the concreteness effect. These findings are discussed in terms of LTM participation through redintegration processes and in terms of the language-based models of verbal STM.

Re-presentation of Olfactory Exposure Therapy Success Cues during Non-Rapid Eye Movement Sleep did not Increase Therapy Outcome but Increased Sleep Spindles

PubMed Central

Rihm, Julia S.; Sollberger, Silja B.; Soravia, Leila M.; Rasch, Björn

2016-01-01

Exposure therapy induces extinction learning and is an effective treatment for specific phobias. Sleep after learning promotes extinction memory and benefits therapy success. As sleep-dependent memory-enhancing effects are based on memory reactivations during sleep, here we aimed at applying the beneficial effect of sleep on therapy success by cueing memories of subjective therapy success during non-rapid eye movement sleep after in vivo exposure-based group therapy for spider phobia. In addition, oscillatory correlates of re-presentation during sleep (i.e., sleep spindles and slow oscillations) were investigated. After exposure therapy, spider-phobic patients verbalized their subjectively experienced therapy success under presence of a contextual odor. Then, patients napped for 90 min recorded by polysomnography. Half of the sleep group received the odor during sleep while the other half was presented an odorless vehicle as control. A third group served as a wake control group without odor presentation. While exposure therapy significantly reduced spider-phobic symptoms in all subjects, these symptoms could not be further reduced by re-presenting the odor associated with therapy success, probably due to a ceiling effect of the highly effective exposure therapy. However, odor re-exposure during sleep increased left-lateralized frontal slow spindle (11.0–13.0 Hz) and right-lateralized parietal fast spindle (13.0–15.0 Hz) activity, suggesting the possibility of a successful re-presentation of therapy-related memories during sleep. Future studies need to further examine the possibility to enhance therapy success by targeted memory reactivation (TMR) during sleep. PMID:27445775

Value conditioning modulates visual working memory processes.

PubMed

Thomas, Paul M J; FitzGibbon, Lily; Raymond, Jane E

2016-01-01

Learning allows the value of motivationally salient events to become associated with stimuli that predict those events. Here, we asked whether value associations could facilitate visual working memory (WM), and whether such effects would be valence dependent. Our experiment was specifically designed to isolate value-based effects on WM from value-based effects on selective attention that might be expected to bias encoding. In a simple associative learning task, participants learned to associate the color of tinted faces with gaining or losing money or neither. Tinted faces then served as memoranda in a face identity WM task for which previously learned color associations were irrelevant and no monetary outcomes were forthcoming. Memory was best for faces with gain-associated tints, poorest for faces with loss-associated tints, and average for faces with no-outcome-associated tints. Value associated with 1 item in the WM array did not modulate memory for other items in the array. Eye movements when studying faces did not depend on the valence of previously learned color associations, arguing against value-based biases being due to differential encoding. This valence-sensitive value-conditioning effect on WM appears to result from modulation of WM maintenance processes. (c) 2015 APA, all rights reserved).

The positional-specificity effect reveals a passive-trace contribution to visual short-term memory.

PubMed

Postle, Bradley R; Awh, Edward; Serences, John T; Sutterer, David W; D'Esposito, Mark

2013-01-01

The positional-specificity effect refers to enhanced performance in visual short-term memory (VSTM) when the recognition probe is presented at the same location as had been the sample, even though location is irrelevant to the match/nonmatch decision. We investigated the mechanisms underlying this effect with behavioral and fMRI studies of object change-detection performance. To test whether the positional-specificity effect is a direct consequence of active storage in VSTM, we varied memory load, reasoning that it should be observed for all objects presented in a sub-span array of items. The results, however, indicated that although robust with a memory load of 1, the positional-specificity effect was restricted to the second of two sequentially presented sample stimuli in a load-of-2 experiment. An additional behavioral experiment showed that this disruption wasn't due to the increased load per se, because actively processing a second object--in the absence of a storage requirement--also eliminated the effect. These behavioral findings suggest that, during tests of object memory, position-related information is not actively stored in VSTM, but may be retained in a passive tag that marks the most recent site of selection. The fMRI data were consistent with this interpretation, failing to find location-specific bias in sustained delay-period activity, but revealing an enhanced response to recognition probes that matched the location of that trial's sample stimulus.

Retrieval of concrete words involves more contextual information than abstract words: multiple components for the concreteness effect.

PubMed

Xiao, Xin; Zhao, Di; Zhang, Qin; Guo, Chun-yan

2012-03-01

The current study used the directed forgetting paradigm in implicit and explicit memory to investigate the concreteness effect. Event-related potentials (ERPs) were recorded to explore the neural basis of this phenomenon. The behavioral results showed a clear concreteness effect in both implicit and explicit memory tests; participants responded significantly faster to concrete words than to abstract words. The ERP results revealed a concreteness effect (N400) in both the encoding and retrieval phases. In addition, behavioral and ERP results showed an interaction between word concreteness and memory instruction (to-be-forgotten vs. to-be-remembered) in the late epoch of the explicit retrieval phase, revealing a significant concreteness effect only under the to-be-remembered instruction condition. This concreteness effect was realized as an increased P600-like component in response to concrete words relative to abstract words, likely reflecting retrieval of contextual details. The time course of the concreteness effect suggests advantages of concrete words over abstract words due to greater contextual information. Copyright © 2011 Elsevier Inc. All rights reserved.

Selective transfer of visual working memory training on Chinese character learning.

PubMed

Opitz, Bertram; Schneiders, Julia A; Krick, Christoph M; Mecklinger, Axel

2014-01-01

Previous research has shown a systematic relationship between phonological working memory capacity and second language proficiency for alphabetic languages. However, little is known about the impact of working memory processes on second language learning in a non-alphabetic language such as Mandarin Chinese. Due to the greater complexity of the Chinese writing system we expect that visual working memory rather than phonological working memory exerts a unique influence on learning Chinese characters. This issue was explored in the present experiment by comparing visual working memory training with an active (auditory working memory training) control condition and a passive, no training control condition. Training induced modulations in language-related brain networks were additionally examined using functional magnetic resonance imaging in a pretest-training-posttest design. As revealed by pre- to posttest comparisons and analyses of individual differences in working memory training gains, visual working memory training led to positive transfer effects on visual Chinese vocabulary learning compared to both control conditions. In addition, we found sustained activation after visual working memory training in the (predominantly visual) left infero-temporal cortex that was associated with behavioral transfer. In the control conditions, activation either increased (active control condition) or decreased (passive control condition) without reliable behavioral transfer effects. This suggests that visual working memory training leads to more efficient processing and more refined responses in brain regions involved in visual processing. Furthermore, visual working memory training boosted additional activation in the precuneus, presumably reflecting mental image generation of the learned characters. We, therefore, suggest that the conjoint activity of the mid-fusiform gyrus and the precuneus after visual working memory training reflects an interaction of working memory and imagery processes with complex visual stimuli that fosters the coherent synthesis of a percept from a complex visual input in service of enhanced Chinese character learning. © 2013 Published by Elsevier Ltd.

On the transition from reconsolidation to extinction of contextual fear memories

PubMed Central

Flavell, Charlotte R.; Lee, Jonathan L.C.

2017-01-01

Retrieval of an associative memory can lead to different phenomena. Brief reexposure sessions tend to trigger reconsolidation, whereas more extended ones trigger extinction. In appetitive and fear cued Pavlovian memories, an intermediate “null point” period has been observed where neither process seems to be engaged. Here we investigated whether this phenomenon extends to contextual fear memory. Adult rats were subjected to a contextual fear conditioning paradigm, reexposed to the context 2 d later for 3, 5, 10, 20, or 30 min, with immediate injections of MK-801 or saline following reexposure, and tested on the following day. We observed a significant effect of MK-801 with the 3- and 30-min sessions, impairing reconsolidation and extinction, respectively. However, it did not have significant effects with 5-, 10-, or 20-min sessions, even though freezing decreased from reexposure to test. Further analyses indicated that this is not likely to be due to a variable transition point at the population level. In conclusion, the results show that in contextual fear memories there is a genuine “null point” between the parameters that induce reconsolidation and extinction, as defined by the effects of MK-801, although NMDA receptor-independent decreases in freezing can still occur in these conditions. PMID:28814464

MEMORY FOR POETRY: MORE THAN MEANING?

PubMed

Atchley, Rachel M; Hare, Mary L

The assumption has become that memory for words' sound patterns, or form, is rapidly lost in comparison to content. Memory for form is also assumed to be verbatim rather than schematic. Oral story-telling traditions suggest otherwise. The present experiment investigated if form can be remembered schematically in spoken poetry, a context in which form is important. We also explored if sleep could help preserve memory for form. We tested whether alliterative sound patterns could cue memory for poetry lines both immediately and after a delay of 12 hours that did or did not include sleep. Twelve alliterative poetry lines were modified into same alliteration, different alliteration, and no alliteration paraphrases. We predicted that memory for original poetry lines would be less accurate after 12 hours, same alliteration paraphrases would be falsely recognized as originals more often after 12 hours, and that the no-sleep group would make more errors. Different alliteration and no alliteration paraphrases were not expected to share this effect due to schematically different sound patterns. Our data support these hypotheses and provide evidence that memory for form is schematic in nature, retained in contexts in which form matters, and that sleep may help preserve memory for sound patterns.

MEMORY FOR POETRY: MORE THAN MEANING?

PubMed Central

Atchley, Rachel M.; Hare, Mary L.

2015-01-01

The assumption has become that memory for words’ sound patterns, or form, is rapidly lost in comparison to content. Memory for form is also assumed to be verbatim rather than schematic. Oral story-telling traditions suggest otherwise. The present experiment investigated if form can be remembered schematically in spoken poetry, a context in which form is important. We also explored if sleep could help preserve memory for form. We tested whether alliterative sound patterns could cue memory for poetry lines both immediately and after a delay of 12 hours that did or did not include sleep. Twelve alliterative poetry lines were modified into same alliteration, different alliteration, and no alliteration paraphrases. We predicted that memory for original poetry lines would be less accurate after 12 hours, same alliteration paraphrases would be falsely recognized as originals more often after 12 hours, and that the no-sleep group would make more errors. Different alliteration and no alliteration paraphrases were not expected to share this effect due to schematically different sound patterns. Our data support these hypotheses and provide evidence that memory for form is schematic in nature, retained in contexts in which form matters, and that sleep may help preserve memory for sound patterns. PMID:26401226

Aging affects the interaction between attentional control and source memory: an fMRI study.

PubMed

Dulas, Michael R; Duarte, Audrey

2014-12-01

Age-related source memory impairments may be due, at least in part, to deficits in executive processes mediated by the PFC at both study and test. Behavioral work suggests that providing environmental support at encoding, such as directing attention toward item-source associations, may improve source memory and reduce age-related deficits in the recruitment of these executive processes. The present fMRI study investigated the effects of directed attention and aging on source memory encoding and retrieval. At study, participants were shown pictures of objects. They were either asked to attend to the objects and their color (source) or to their size. At test, participants determined if objects were seen before, and if so, whether they were the same color as previously. Behavioral results showed that direction of attention improved source memory for both groups; however, age-related deficits persisted. fMRI results revealed that, across groups, direction of attention facilitated medial temporal lobe-mediated contextual binding processes during study and attenuated right PFC postretrieval monitoring effects at test. However, persistent age-related source memory deficits may be related to increased recruitment of medial anterior PFC during encoding, indicative of self-referential processing, as well as underrecruitment of lateral anterior PFC-mediated relational processes. Taken together, this study suggests that, even when supported, older adults may fail to selectively encode goal-relevant contextual details supporting source memory performance.

Increased plasma d-lactic acid associated with impaired memory in rats.

PubMed

Hanstock, T L; Mallet, P E; Clayton, E H

2010-12-02

d-Lactic acidosis is associated with memory impairment in humans. Recent research indicates that d-lactic acid may inhibit the supply of energy from astrocytes to neurons involved with memory formation. However, little is known about the effects of increased hind-gut fermentation due to changes in diet on circulating lactic acid concentrations and memory. Thirty-six male Wistar rats were fed three dietary treatments: a commercial rat and mouse chow, a soluble carbohydrate based diet or a fermentable carbohydrate based diet. The parameters estimating memory were examined by employing the object recognition test. Physical parameters of fermentation including hind-gut and plasma lactic acid concentrations were examined after sacrifice, either 3 or 21h after feeding. Increased fermentation in the hind-gut of rats, indicated by lower caecum pH, was associated with increased plasma l-lactic acid (r=-0.41, p=0.020) and d-lactic acid (r=-0.33, p=0.087). Memory, being able to discriminate between a familiar and a novel object during the object recognition test, was reduced with increasing plasma d-lactic acid (r=-0.51, p=0.021). Memory impairment was associated with alterations in plasma d-lactic acid following the fermentation of carbohydrate in the hind-gut. Further work is still required to determine whether these effects are mediated centrally or via direct connections through the enteric nervous system. Copyright © 2010 Elsevier Inc. All rights reserved.

Binding neutral information to emotional contexts: Brain dynamics of long-term recognition memory.

PubMed

Ventura-Bort, Carlos; Löw, Andreas; Wendt, Julia; Moltó, Javier; Poy, Rosario; Dolcos, Florin; Hamm, Alfons O; Weymar, Mathias

2016-04-01

There is abundant evidence in memory research that emotional stimuli are better remembered than neutral stimuli. However, effects of an emotionally charged context on memory for associated neutral elements is also important, particularly in trauma and stress-related disorders, where strong memories are often activated by neutral cues due to their emotional associations. In the present study, we used event-related potentials (ERPs) to investigate long-term recognition memory (1-week delay) for neutral objects that had been paired with emotionally arousing or neutral scenes during encoding. Context effects were clearly evident in the ERPs: An early frontal ERP old/new difference (300-500 ms) was enhanced for objects encoded in unpleasant compared to pleasant and neutral contexts; and a late central-parietal old/new difference (400-700 ms) was observed for objects paired with both pleasant and unpleasant contexts but not for items paired with neutral backgrounds. Interestingly, objects encoded in emotional contexts (and novel objects) also prompted an enhanced frontal early (180-220 ms) positivity compared to objects paired with neutral scenes indicating early perceptual significance. The present data suggest that emotional--particularly unpleasant--backgrounds strengthen memory for items encountered within these contexts and engage automatic and explicit recognition processes. These results could help in understanding binding mechanisms involved in the activation of trauma-related memories by neutral cues.

Effects of Short-Term Memory and Content Representation Type on Mobile Language Learning

ERIC Educational Resources Information Center

Chen, Nian-Shing; Hsieh, Sheng-Wen; Kinshuk

2008-01-01

Due to the rapid advancements in mobile communication and wireless technologies, many researchers and educators have started to believe that these emerging technologies can be leveraged to support formal and informal learning opportunities. Mobile language learning can be effectively implemented by delivering learning content through mobile…

Knowledge Of Memory Aging In Adulthood

ERIC Educational Resources Information Center

Hawley, Karri S.; Cherry, Katie E.; Su, L. Joseph; Chiu, Yu-Wen; Jazwinski, S. Michal

2006-01-01

The Knowledge of Memory Aging Questionnaire (KMAQ) measures laypersons' knowledge of memory changes in adulthood for research or educational purposes. Half of the questions pertain to normal memory aging and the other half cover pathological memory deficits due to non-normative factors, such as adult dementia. In this study, we compared memory…

Developmental amnesia: effect of age at injury.

PubMed

Vargha-Khadem, F; Salmond, C H; Watkins, K E; Friston, K J; Gadian, D G; Mishkin, M

2003-08-19

Hypoxic-ischemic events sustained within the first year of life can result in developmental amnesia, a disorder characterized by markedly impaired episodic memory and relatively preserved semantic memory, in association with medial temporal pathology that appears to be restricted to the hippocampus. Here we compared children who had hypoxic-ischemic events before 1 year of age (early group, n = 6) with others who showed memory problems after suffering hypoxic-ischemic events between the ages of 6 and 14 years (late group, n = 5). Morphometric analyses of the whole brain revealed that, compared with age-matched controls, both groups had bilateral abnormalities in the hippocampus, putamen, and posterior thalamus, as well as in the right retrosplenial cortex. The two groups also showed similar reductions (approximately 40%) in hippocampal volumes. Neuropsychologically, the only significant differences between the two were on a few tests of immediate memory, where the early group surpassed the late group. The latter measures provided the only clear indication that very early injury can lead to greater functional sparing than injury acquired later in childhood, due perhaps to the greater plasticity of the infant brain. On measures of long-term memory, by contrast, the two groups had highly similar profiles, both showing roughly equivalent preservation of semantic memory combined with marked impairment in episodic memory. It thus appears that, if this selective memory disorder is a special syndrome related to the early occurrence of hypoxia-induced damage, then the effective age at injury for this syndrome extends from birth to puberty.

EEG alpha power during maintenance of information in working memory in adults with ADHD and its plasticity due to working memory training: A randomized controlled trial.

PubMed

Liu, Zhong-Xu; Glizer, Daniel; Tannock, Rosemary; Woltering, Steven

2016-02-01

The present study examined whether neural indices of working memory maintenance differ between young adults with ADHD and their healthy peers (Study 1), and whether this neural index would change after working memory training (Study 2). Study 1 involved 136 college students with ADHD and 41 healthy peers (aged 18-35 years) and measured their posterior alpha activity during a visual delayed-match-to-sample task using electroencephalography (EEG). Study 2 involved 99 of the participants with ADHD who were randomized into a standard-length or shortened-length Cogmed working memory training program or a waitlist control group. The ADHD group tended to be less accurate than the peers. Similarly, the ADHD group exhibited lower posterior alpha power at a trend level compared to their healthy peers. There were no training effects on participants' performance and only marginal increases in posterior alpha power in training groups compared to the waitlist group. Considering that the training effects were small and there was no load and dose effect, we conclude that the current study provides no convincing evidence for specific effects of Cogmed. These findings provide unique insights into neuroplasticity, or lack thereof, with near-transfer tasks in individuals with ADHD. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Vertical bloch line memory

NASA Technical Reports Server (NTRS)

Katti, Romney R. (Inventor); Stadler, Henry L. (Inventor); Wu, Jiin-chuan (Inventor)

1995-01-01

A new read gate design for the vertical Bloch line (VBL) memory is disclosed which offers larger operating margin than the existing read gate designs. In the existing read gate designs, a current is applied to all the stripes. The stripes that contain a VBL pair are chopped, while the stripes that do not contain a VBL pair are not chopped. The information is then detected by inspecting the presence or absence of the bubble. The margin of the chopping current amplitude is very small, and sometimes non-existent. A new method of reading Vertical Bloch Line memory is also disclosed. Instead of using the wall chirality to separate the two binary states, the spatial deflection of the stripe head is used. Also disclosed herein is a compact memory which uses vertical Bloch line (VBL) memory technology for providing data storage. A three-dimensional arrangement in the form of stacks of VBL memory layers is used to achieve high volumetric storage density. High data transfer rate is achieved by operating all the layers in parallel. Using Hall effect sensing, and optical sensing via the Faraday effect to access the data from within the three-dimensional packages, an even higher data transfer rate can be achieved due to parallel operation within each layer.

Edible Bird's Nest Prevents Menopause-Related Memory and Cognitive Decline in Rats via Increased Hippocampal Sirtuin-1 Expression

PubMed Central

He, Peiyuan; Qi, Jiemen; Tang, Shiying; Song, Chengjun; Ismail, Maznah

2017-01-01

Menopause causes cognitive and memory dysfunction due to impaired neuronal plasticity in the hippocampus. Sirtuin-1 (SIRT1) downregulation in the hippocampus is implicated in the underlying molecular mechanism. Edible bird's nest (EBN) is traditionally used to improve general wellbeing, and in this study, we evaluated its effects on SIRT1 expression in the hippocampus and implications on ovariectomy-induced memory and cognitive decline in rats. Ovariectomized female Sprague-Dawley rats were fed with normal pellet alone or normal pellet + EBN (6, 3, or 1.5%), compared with estrogen therapy (0.2 mg/kg/day). After 12 weeks of intervention, Morris water maze (four-day trial and one probe trial) was conducted, and serum estrogen levels, toxicity markers (alanine transaminase, alkaline phosphatase, urea, and creatinine), and hippocampal SIRT1 immunohistochemistry were estimated after sacrifice. The results indicated that EBN and estrogen enhanced spatial learning and memory and increased serum estrogen and hippocampal SIRT1 expression. In addition, the EBN groups did not show as much toxicity to the liver as the estrogen group. The data suggested that EBN treatment for 12 weeks could improve cognition and memory in ovariectomized female rats and may be an effective alternative to estrogen therapy for menopause-induced aging-related memory loss. PMID:29104731

Resistive switching effect of N-doped MoS2-PVP nanocomposites films for nonvolatile memory devices

NASA Astrophysics Data System (ADS)

Wu, Zijin; Wang, Tongtong; Sun, Changqi; Liu, Peitao; Xia, Baorui; Zhang, Jingyan; Liu, Yonggang; Gao, Daqiang

2017-12-01

Resistive memory technology is very promising in the field of semiconductor memory devices. According to Liu et al, MoS2-PVP nanocomposite can be used as an active layer material for resistive memory devices due to its bipolar resistive switching behavior. Recent studies have also indicated that the doping of N element can reduce the band gap of MoS2 nanosheets, which is conducive to improving the conductivity of the material. Therefore, in this paper, we prepared N-doped MoS2 nanosheets and then fabricated N-doped MoS2-PVP nanocomposite films by spin coating. Finally, the resistive memory [C. Tan et al., Chem. Soc. Rev. 44, 2615 (2015)], device with ITO/N-doped MoS2-PVP/Pt structure was fabricated. Study on the I-V characteristics shows that the device has excellent resistance switching effect. It is worth mentioning that our device possesses a threshold voltage of 0.75 V, which is much better than 3.5 V reported previously for the undoped counterparts. The above research shows that N-doped MoS2-PVP nanocomposite films can be used as the active layer of resistive switching memory devices, and will make the devices have better performance.

Working memory load affects repetitive behaviour but not cognitive flexibility in adolescent autism spectrum disorder.

PubMed

Wolff, Nicole; Chmielewski, Witold X; Beste, Christian; Roessner, Veit

2017-03-16

Autism spectrum disorder (ASD) is associated with repetitive and stereotyped behaviour, suggesting that cognitive flexibility may be deficient in ASD. A central, yet not examined aspect to understand possible deficits in flexible behaviour in ASD relates (i) to the role of working memory and (ii) to neurophysiological mechanisms underlying behavioural modulations. We analysed behavioural and neurophysiological (EEG) correlates of cognitive flexibility using a task-switching paradigm with and without working memory load in adolescents with ASD and typically developing controls (TD). Adolescents with ASD versus TD show similar performance in task switching with no memory load, indicating that 'pure' cognitive flexibility is not in deficit in adolescent ASD. However performance during task repetition decreases with increasing memory load. Neurophysiological data reflect the pattern of behavioural effects, showing modulations in P2 and P3 event-related potentials. Working memory demands affect repetitive behaviour while processes of cognitive flexibility are unaffected. Effects emerge due to deficits in preparatory attentional processes and deficits in task rule activation, organisation and implementation of task sets when repetitive behaviour is concerned. It may be speculated that the habitual response mode in ASD (i.e. repetitive behaviour) is particularly vulnerable to additional demands on executive control processes.

Memory reactivation and consolidation during sleep

PubMed Central

Paller, Ken A.; Voss, Joel L.

2004-01-01

Do our memories remain static during sleep, or do they change? We argue here that memory change is not only a natural result of sleep cognition, but further, that such change constitutes a fundamental characteristic of declarative memories. In general, declarative memories change due to retrieval events at various times after initial learning and due to the formation and elaboration of associations with other memories, including memories formed after the initial learning episode. We propose that declarative memories change both during waking and during sleep, and that such change contributes to enhancing binding of the distinct representational components of some memories, and thus to a gradual process of cross-cortical consolidation. As a result of this special form of consolidation, declarative memories can become more cohesive and also more thoroughly integrated with other stored information. Further benefits of this memory reprocessing can include developing complex networks of interrelated memories, aligning memories with long-term strategies and goals, and generating insights based on novel combinations of memory fragments. A variety of research findings are consistent with the hypothesis that cross-cortical consolidation can progress during sleep, although further support is needed, and we suggest some potentially fruitful research directions. Determining how processing during sleep can facilitate memory storage will be an exciting focus of research in the coming years. PMID:15576883

The impact of marijuana use on memory in HIV-infected patients: a comprehensive review of the HIV and marijuana literatures

PubMed Central

Skalski, Linda M.; Towe, Sheri L.; Sikkema, Kathleen J.; Meade, Christina S.

2016-01-01

Background The most robust neurocognitive effect of marijuana use is memory impairment. Memory deficits are also high among persons living with HIV/AIDS, and marijuana is the most commonly used drug in this population. Yet research examining neurocognitive outcomes resulting from co-occurring marijuana and HIV is limited. Objective The primary objectives of this comprehensive review are to: (1) examine the literature on memory functioning in HIV-infected individuals; (2) examine the literature on memory functioning in marijuana users; (3) synthesize findings and propose a theoretical framework to guide future research. Method PubMed was searched for English publications 2000–2013. Twenty-two studies met inclusion criteria in the HIV literature, and 23 studies in the marijuana literature. Results Among HIV-infected individuals, memory deficits with medium to large effect sizes were observed. Marijuana users also demonstrated memory problems, but results were less consistent due to the diversity of samples. Conclusion A compensatory hypothesis, based on the cognitive aging literature, is proposed to provide a framework to explore the interaction between marijuana and HIV. There is some evidence that individuals infected with HIV recruit additional brain regions during memory tasks to compensate for HIV-related declines in neurocognitive functioning. Marijuana use causes impairment in similar brain systems, and thus it is hypothesized that the added neural strain of marijuana can exhaust neural resources, resulting in pronounced memory impairment. It will be important to test this hypothesis empirically, and future research priorities are discussed. PMID:27138170

Memory and mood during the night and in the morning after repeated evening doses of MDMA.

PubMed

Kuypers, K P C; Wingen, M; Ramaekers, J G

2008-11-01

Previously it has been shown that MDMA causes memory impairment during daytime testing. However, MDMA is usually taken in the evening or during the night. In addition, it is known that sleep deprivation also causes memory impairment. The present study aimed to assess whether evening doses of MDMA added to, or interacted with the memory impairment due to sleep deprivation. Fourteen healthy subjects participated in a double-blind, placebo-controlled, two-way cross-over study. Treatments consisted of MDMA 75 and 50 mg divided over the evening or double placebo. Memory tests and subjective measures of mood were conducted at baseline and three times post dosing that is at 6.30 pm, 9.30 pm, 1.30 am and 7 am, respectively -1.5, 1.5, 5.5 and 11 h relative to drug intake (first dose). Memory performance detoriated progessively over time as a function of sleep loss, independent of treatment. MDMA added to this impairment as indicated by a significant main effect of MDMA on verbal and spatial memory performance. Mood ratings and response speed revealed an MDMA by Time interaction. After administration of MDMA response speed improved and feelings of vigor, friendliness, elation, anxiety, confusion, arousal and positive mood increased in magnitude during the night, while all these parameters returned to placebo-like levels on the final morning session. It is concluded that evening doses of MDMA selectively impair memory performance, and that this impairment is additional to the effect of sleep deprivation on memory performance.

Memory retrieval by activating engram cells in mouse models of early Alzheimer's disease.

PubMed

Roy, Dheeraj S; Arons, Autumn; Mitchell, Teryn I; Pignatelli, Michele; Ryan, Tomás J; Tonegawa, Susumu

2016-03-24

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory decline and subsequent loss of broader cognitive functions. Memory decline in the early stages of AD is mostly limited to episodic memory, for which the hippocampus has a crucial role. However, it has been uncertain whether the observed amnesia in the early stages of AD is due to disrupted encoding and consolidation of episodic information, or an impairment in the retrieval of stored memory information. Here we show that in transgenic mouse models of early AD, direct optogenetic activation of hippocampal memory engram cells results in memory retrieval despite the fact that these mice are amnesic in long-term memory tests when natural recall cues are used, revealing a retrieval, rather than a storage impairment. Before amyloid plaque deposition, the amnesia in these mice is age-dependent, which correlates with a progressive reduction in spine density of hippocampal dentate gyrus engram cells. We show that optogenetic induction of long-term potentiation at perforant path synapses of dentate gyrus engram cells restores both spine density and long-term memory. We also demonstrate that an ablation of dentate gyrus engram cells containing restored spine density prevents the rescue of long-term memory. Thus, selective rescue of spine density in engram cells may lead to an effective strategy for treating memory loss in the early stages of AD.

Memory in children with epilepsy: a systematic review.

PubMed

Menlove, Leanne; Reilly, Colin

2015-02-01

Research suggests an increased risk for cognitive impairment in childhood epilepsy with memory being one area of cognition most likely to be affected. Understanding the prevalence and predictors of memory difficulties may help improve awareness of the difficulties and allow efficacious supports to be put in place. A systematic review was carried out using the search terms 'memory', 'children' and 'epilepsy' in the database PUBMED. Eighty-eight studies met inclusion criteria. The review focuses on comparisons of memory scores of children with epilepsy and controls, and comparison of memory scores of children with epilepsy to normative scores. Predictors of memory impairment and the effect of surgery on memory functioning are also reviewed. The majority (78%) of studies reviewed revealed that children with epilepsy scored lower than controls and normative scores on measures of memory. Post-surgery, memory scores were reported to improve in 50% of studies. Predictors of memory impairment included a greater number of AEDs used, younger age of onset, increased seizure frequency and longer duration of epilepsy. Children with epilepsy have a high frequency of memory impairments. However, the exact prevalence of difficulties is not clear due to the lack of population-based data. Most studies have not controlled for IQ and thus it is unclear if difficulties are always related to global cognitive difficulties. There is need for future population-based studies and studies focussing on the neurobiology of memory problems in children with epilepsy. Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Monkey׳s short-term auditory memory nearly abolished by combined removal of the rostral superior temporal gyrus and rhinal cortices.

PubMed

Fritz, Jonathan B; Malloy, Megan; Mishkin, Mortimer; Saunders, Richard C

2016-06-01

While monkeys easily acquire the rules for performing visual and tactile delayed matching-to-sample, a method for testing recognition memory, they have extraordinary difficulty acquiring a similar rule in audition. Another striking difference between the modalities is that whereas bilateral ablation of the rhinal cortex (RhC) leads to profound impairment in visual and tactile recognition, the same lesion has no detectable effect on auditory recognition memory (Fritz et al., 2005). In our previous study, a mild impairment in auditory memory was obtained following bilateral ablation of the entire medial temporal lobe (MTL), including the RhC, and an equally mild effect was observed after bilateral ablation of the auditory cortical areas in the rostral superior temporal gyrus (rSTG). In order to test the hypothesis that each of these mild impairments was due to partial disconnection of acoustic input to a common target (e.g., the ventromedial prefrontal cortex), in the current study we examined the effects of a more complete auditory disconnection of this common target by combining the removals of both the rSTG and the MTL. We found that the combined lesion led to forgetting thresholds (performance at 75% accuracy) that fell precipitously from the normal retention duration of ~30 to 40s to a duration of ~1 to 2s, thus nearly abolishing auditory recognition memory, and leaving behind only a residual echoic memory. This article is part of a Special Issue entitled SI: Auditory working memory. Published by Elsevier B.V.

Prefrontal Cortical GABA Modulation of Spatial Reference and Working Memory

PubMed Central

Auger, Meagan L.

2015-01-01

Background: Dysfunction in prefrontal cortex (PFC) GABA transmission has been proposed to contribute to cognitive dysfunction in schizophrenia, yet how this system regulates different cognitive and mnemonic functions remains unclear. Methods: We assessed the effects of pharmacological reduction of GABAA signaling in the medial PFC of rats on spatial reference/working memory using different versions of the radial-arm maze task. We used a massed-trials procedure to probe how PFC GABA regulates susceptibility to proactive interference. Male rats were well-trained to retrieve food from the same 4 arms of an 8-arm maze, receiving 5 trials/day (1–2min intervals). Results: Infusions of the GABAA receptor antagonist bicuculline (12.5–50ng) markedly increased working and reference memory errors and response latencies. Similar treatments also impaired short-term memory on an 8-baited arm task. These effects did not appear to be due to increased susceptibility to proactive interference. In contrast, PFC inactivation via infusion of GABA agonists baclofen/muscimol did not affect reference/working memory. In comparison to the pronounced effects on the 8-arm maze tasks, PFC GABAA antagonism only causes a slight and transient decrease in accuracy on a 2-arm spatial discrimination. Conclusions: These findings demonstrate that prefrontal GABA hypofunction severely disrupts spatial reference and short-term memory and that disinhibition of the PFC can, in some instances, perturb memory processes not normally dependent on the frontal lobes. Moreover, these impairments closely resemble those observed in schizophrenic patients, suggesting that perturbation in PFC GABA signaling may contribute to these types of cognitive deficits associated with the disorder. PMID:25552433

Chronic sleep deprivation differentially affects short and long-term operant memory in Aplysia.

PubMed

Krishnan, Harini C; Noakes, Eric J; Lyons, Lisa C

2016-10-01

The induction, formation and maintenance of memory represent dynamic processes modulated by multiple factors including the circadian clock and sleep. Chronic sleep restriction has become common in modern society due to occupational and social demands. Given the impact of cognitive impairments associated with sleep deprivation, there is a vital need for a simple animal model in which to study the interactions between chronic sleep deprivation and memory. We used the marine mollusk Aplysia californica, with its simple nervous system, nocturnal sleep pattern and well-characterized learning paradigms, to assess the effects of two chronic sleep restriction paradigms on short-term (STM) and long-term (LTM) associative memory. The effects of sleep deprivation on memory were evaluated using the operant learning paradigm, learning that food is inedible, in which the animal associates a specific netted seaweed with failed swallowing attempts. We found that two nights of 6h sleep deprivation occurring during the first or last half of the night inhibited both STM and LTM. Moreover, the impairment in STM persisted for more than 24h. A milder, prolonged sleep deprivation paradigm consisting of 3 consecutive nights of 4h sleep deprivation also blocked STM, but had no effect on LTM. These experiments highlight differences in the sensitivity of STM and LTM to chronic sleep deprivation. Moreover, these results establish Aplysia as a valid model for studying the interactions between chronic sleep deprivation and associative memory paving the way for future studies delineating the mechanisms through which sleep restriction affects memory formation. Copyright © 2016 Elsevier Inc. All rights reserved.

Chronic Sleep Deprivation Differentially Affects Short and Long-term Operant Memory in Aplysia

PubMed Central

Krishnan, Harini C.; Noakes, Eric J.; Lyons, Lisa C.

2016-01-01

The induction, formation and maintenance of memory represent dynamic processes modulated by multiple factors including the circadian clock and sleep. Chronic sleep restriction has become common in modern society due to occupational and social demands. Given the impact of cognitive impairments associated with sleep deprivation, there is a vital need for a simple animal model in which to study the interactions between chronic sleep deprivation and memory. We used the marine mollusk Aplysia californica, with its simple nervous system, nocturnal sleep pattern and well-characterized learning paradigms, to assess the effects of two chronic sleep restriction paradigms on short-term (STM) and long-term (LTM) associative memory. The effects of sleep deprivation on memory were evaluated using the operant learning paradigm, learning that food is inedible, in which the animal associates a specific netted seaweed with failed swallowing attempts. We found that two nights of 6 h sleep deprivation occurring during the first or last half of the night inhibited both STM and LTM. Moreover, the impairment in STM persisted for more than 24 hours. A milder, prolonged sleep deprivation paradigm consisting of 3 consecutive nights of 4 h sleep deprivation also blocked STM, but had no effect on LTM. These experiments highlight differences in the sensitivity of STM and LTM to chronic sleep deprivation. Moreover, these results establish Aplysia as a valid model for studying the interactions between chronic sleep deprivation and associative memory paving the way for future studies delineating the mechanisms through which sleep restriction affects memory formation. PMID:27555235

Fabrication and electrical characterization of a MOS memory device containing self-assembled metallic nanoparticles

NASA Astrophysics Data System (ADS)

Sargentis, Ch.; Giannakopoulos, K.; Travlos, A.; Tsamakis, D.

2007-04-01

Floating gate devices with nanoparticles embedded in dielectrics have recently attracted much attention due to the fact that these devices operate as non-volatile memories with high speed, high density and low power consumption. In this paper, memory devices containing gold (Au) nanoparticles have been fabricated using e-gun evaporation. The Au nanoparticles are deposited on a very thin SiO 2 layer and are then fully covered by a HfO 2 layer. The HfO 2 is a high- k dielectric and gives good scalability to the fabricated devices. We studied the effect of the deposition parameters to the size and the shape of the Au nanoparticles using capacitance-voltage and conductance-voltage measurements, we demonstrated that the fabricated device can indeed operate as a low-voltage memory device.

Explicit processing demands reveal language modality-specific organization of working memory.

PubMed

Rudner, Mary; Rönnberg, Jerker

2008-01-01

The working memory model for Ease of Language Understanding (ELU) predicts that processing differences between language modalities emerge when cognitive demands are explicit. This prediction was tested in three working memory experiments with participants who were Deaf Signers (DS), Hearing Signers (HS), or Hearing Nonsigners (HN). Easily nameable pictures were used as stimuli to avoid confounds relating to sensory modality. Performance was largely similar for DS, HS, and HN, suggesting that previously identified intermodal differences may be due to differences in retention of sensory information. When explicit processing demands were high, differences emerged between DS and HN, suggesting that although working memory storage in both groups is sensitive to temporal organization, retrieval is not sensitive to temporal organization in DS. A general effect of semantic similarity was also found. These findings are discussed in relation to the ELU model.

Recognition memory span in autopsy-confirmed Dementia with Lewy Bodies and Alzheimer's Disease.

PubMed

Salmon, David P; Heindel, William C; Hamilton, Joanne M; Vincent Filoteo, J; Cidambi, Varun; Hansen, Lawrence A; Masliah, Eliezer; Galasko, Douglas

2015-08-01

Evidence from patients with amnesia suggests that recognition memory span tasks engage both long-term memory (i.e., secondary memory) processes mediated by the diencephalic-medial temporal lobe memory system and working memory processes mediated by fronto-striatal systems. Thus, the recognition memory span task may be particularly effective for detecting memory deficits in disorders that disrupt both memory systems. The presence of unique pathology in fronto-striatal circuits in Dementia with Lewy Bodies (DLB) compared to AD suggests that performance on the recognition memory span task might be differentially affected in the two disorders even though they have quantitatively similar deficits in secondary memory. In the present study, patients with autopsy-confirmed DLB or AD, and Normal Control (NC) participants, were tested on separate recognition memory span tasks that required them to retain increasing amounts of verbal, spatial, or visual object (i.e., faces) information across trials. Results showed that recognition memory spans for verbal and spatial stimuli, but not face stimuli, were lower in patients with DLB than in those with AD, and more impaired relative to NC performance. This was despite similar deficits in the two patient groups on independent measures of secondary memory such as the total number of words recalled from long-term storage on the Buschke Selective Reminding Test. The disproportionate vulnerability of recognition memory span task performance in DLB compared to AD may be due to greater fronto-striatal involvement in DLB and a corresponding decrement in cooperative interaction between working memory and secondary memory processes. Assessment of recognition memory span may contribute to the ability to distinguish between DLB and AD relatively early in the course of disease. Copyright © 2015 Elsevier Ltd. All rights reserved.

Recognition Memory Span in Autopsy-Confirmed Dementia with Lewy Bodies and Alzheimer’s Disease

PubMed Central

Salmon, David P.; Heindel, William C.; Hamilton, Joanne M.; Filoteo, J. Vincent; Cidambi, Varun; Hansen, Lawrence A.; Masliah, Eliezer; Galasko, Douglas

2016-01-01

Evidence from patients with amnesia suggests that recognition memory span tasks engage both long-term memory (i.e., secondary memory) processes mediated by the diencephalic-medial temporal lobe memory system and working memory processes mediated by fronto-striatal systems. Thus, the recognition memory span task may be particularly effective for detecting memory deficits in disorders that disrupt both memory systems. The presence of unique pathology in fronto-striatal circuits in Dementia with Lewy Bodies (DLB) compared to AD suggests that performance on the recognition memory span task might be differentially affected in the two disorders even though they have quantitatively similar deficits in secondary memory. In the present study, patients with autopsy-confirmed DLB or AD, and normal control (NC) participants, were tested on separate recognition memory span tasks that required them to retain increasing amounts of verbal, spatial, or visual object (i.e., faces) information across trials. Results showed that recognition memory spans for verbal and spatial stimuli, but not face stimuli, were lower in patients with DLB than in those with AD, and more impaired relative to NC performance. This was despite similar deficits in the two patient groups on independent measures of secondary memory such as the total number of words recalled from Long-Term Storage on the Buschke Selective Reminding Test. The disproportionate vulnerability of recognition memory span task performance in DLB compared to AD may be due to greater fronto-striatal involvement in DLB and a corresponding decrement in cooperative interaction between working memory and secondary memory processes. Assessment of recognition memory span may contribute to the ability to distinguish between DLB and AD relatively early in the course of disease. PMID:26184443

Timing the state of light with anomalous dispersion and a gradient echo memory

NASA Astrophysics Data System (ADS)

Clark, Jeremy B.

We study the effects of anomalous dispersion on the continuous-variable entanglement of EPR states (generated using four-wave mixing in 85 Rb) by sending one part of the state through a fast-light medium and measuring the state's quantum mutual information. We observe an advance in the maximum of the quantum mutual information between modes. In contrast, due to uncorrelated noise added by a small phase-insensitive gain, we do not observe any statistically significant advance in the leading edge of the mutual information. We also study the storage and retrieval of multiplexed optical signals in a Gradient Echo Memory (GEM) at relevant four-wave mixing frequencies in 85Rb. Temporal multiplexing capabilities are demonstrated by storing multiple classical images in the memory simultaneously and observing the expected first-in last-out order of recall without obvious cross-talk. We also develop a technique wherein selected portions of an image written into the memory can be spatially targeted for readout and erasure on demand. The effect of diffusion on the quality of the recalled images is characterized. Our results indicate that Raman-based atomic memories may serve as a flexible platform for the storage and retrieval of multiplexed optical signals.

[Korsakoff amnesia syndrome].

PubMed

Verstichel, P

2000-10-14

PATHOLOGY CORRELATIONS: The Korsakoff syndrome results from cerebral lesions due to thiamine depletion, usually of alcoholic etiology. Other nutritional, or genetic factors, could be implicated. Exceptionally, it results from thalamic disease or a tumor of the third ventricle floor. Anterograde and retrograde aspects of episodic memory are principally impaired, contrasting with the preservation of semantic and procedural memory. Opposition between explicit (impaired) and implicit (unimpaired) memory is one of the main cognitive features of this syndrome. Several cerebral structures, components of various memory systems, are simultaneously damaged. Critical lesion sites for anterograde amnesia involve the memillary bodies, the mamillotalamic tract and the anterior thalamus. Retrograde amnesia is dependent on function abnormalities of a circuit between the dorso-median thalamus and the prefrontal cortex. Impairment of retrieval and chronological disorganization of memories contribute to this extensive retrograde amnesia, probably because of frontal dysfunction. Confabulations and false recognitions are produced in the initial stage of the disease. They are, in the same way, interpreted as the consequence of frontal desafferentation due to dorso-median thalamus damage. The impact of diencephalic destruction on the frontal lobes is evidenced clinically by behavioral changes and dysexecutive syndrome. Neuroimaging studies of the brain show a decreased regional metabolic ration in the frontal areas. Korsakoff syndrome is a serious disorder, responsible for cognitive handicap. There is no curative treatment. Preventive measures, consisting in systematic prescription of thiamine in alcoholics, is the main effective measure.

Reduced Consolidation, Reinstatement, and Renewal of Conditioned Fear Memory by Repetitive Treatment of Radix Polygalae in Mice

PubMed Central

Shin, Jung-Won; Park, Hyunwoo; Cho, Yoonju; Lee, Suck; Yoon, Jiwon; Maeng, Sungho

2017-01-01

The therapeutic goal for the treatment of posttraumatic stress disorder (PTSD) is to promote extinction and to prevent the relapse of fearful memories. Research has identified pharmacological treatments that may regulate the formation and extinction of fear memories, but not many reagents that block the relapse of extinguished fear are known. Radix Polygalae (RP) is an Asian herb used for sedation, and its ingredients have anxiolytic and antidepressant properties. As various neurological effects have been identified, we tested whether RP affects the relapse of fear. Freezing in response to a conditioned context and cues was used to measure the effects of RP in mice. In cohort 1 (n = 30), consolidation, extinction, and reinstatement were tested during the course of 18 days of treatment. In cohort 2 (n = 30), consolidation, extinction, and renewal were tested during 10 days of treatment. The consolidation, extinction, reinstatement, and possibly the renewal of context-induced freezing were inhibited due to the administration of RP in animal subjects. However, the effects of RP on the freezing responses of subjects elicited by conditioned auditory cues were less obvious. Because it effectively suppresses the consolidation of fear memories, RP may be used for primary and secondary prevention of symptoms in PTSD patients. Additionally, because it effectively suppresses the reinstatement and renewal of fear memories, RP may be applied for the prevention of fear relapse in PTSD patients who have undergone exposure therapy. PMID:28620325

Memory effects of Aronia melanocarpa fruit juice in a passive avoidance test in rats.

PubMed

Valcheva-Kuzmanova, Stefka V; Eftimov, Miroslav Tz; Tashev, Roman E; Belcheva, Iren P; Belcheva, Stiliana P

2014-01-01

To study the effect of Aronia melanocarpa fruit juice on memory in male Wistar rats. The juice was administered orally for 7, 14, 21 and 30 days at doses of 2.5 ml/kg, 5 ml/kg and 10 ml/kg. Memory was assessed in the one-way passive avoidance task (step through) which consisted of one training session and two retention tests (3 hours and 24 hours after training). The variables measured were the latency time to step into the dark compartment of the apparatus and the learning criterion (remaining in the illuminated compartment for at least 180 sec). Oral administration of Aronia melanocarpa fruit juice for 7 and 14 days resulted in a dose-dependent tendency to increase the latency time and the learning criterion compared to saline-treated controls but the effect failed to reach statistical significance. After 21 days of treatment, the juice dose-dependently prolonged the latency time at the retention tests, the effect being significant at doses of 5 ml/kg and 10 ml/kg. Applied for 30 days, the juice in all the tested doses increased significantly the latency time at the retention tests and the dose of 10 ml/kg significantly increased the percentage of rats reaching the learning criterion. These findings suggest that Aronia melanocarpa fruit juice could improve memory in rats. The effect is probably due to the polyphenolic ingredients of the juice which have been shown to be involved in learning and memory processes.

Knowledge of Normal versus Pathological Memory Aging among Police Officers

ERIC Educational Resources Information Center

Hawley, Karri S.; Garrity, April W.; Cherry, Katie E.

2005-01-01

The authors examined police officers' knowledge of memory changes in adulthood utilizing the Knowledge of Memory Aging Questionnaire (KMAQ). The KMAQ is a 28-item true/false questionnaire that covers a broad range of topics related to normal memory aging due to maturational processes and pathological memory aging, such as adult dementia. Results…

The relationship between eye movements and subsequent recognition: Evidence from individual differences and amnesia.

PubMed

Olsen, Rosanna K; Sebanayagam, Vinoja; Lee, Yunjo; Moscovitch, Morris; Grady, Cheryl L; Rosenbaum, R Shayna; Ryan, Jennifer D

2016-12-01

There is consistent agreement regarding the positive relationship between cumulative eye movement sampling and subsequent recognition, but the role of the hippocampus in this sampling behavior is currently unknown. It is also unclear whether the eye movement repetition effect, i.e., fewer fixations to repeated, compared to novel, stimuli, depends on explicit recognition and/or an intact hippocampal system. We investigated the relationship between cumulative sampling, the eye movement repetition effect, subsequent memory, and the hippocampal system. Eye movements were monitored in a developmental amnesic case (H.C.), whose hippocampal system is compromised, and in a group of typically developing participants while they studied single faces across multiple blocks. The faces were studied from the same viewpoint or different viewpoints and were subsequently tested with the same or different viewpoint. Our previous work suggested that hippocampal representations support explicit recognition for information that changes viewpoint across repetitions (Olsen et al., 2015). Here, examination of eye movements during encoding indicated that greater cumulative sampling was associated with better memory among controls. Increased sampling, however, was not associated with better explicit memory in H.C., suggesting that increased sampling only improves memory when the hippocampal system is intact. The magnitude of the repetition effect was not correlated with cumulative sampling, nor was it related reliably to subsequent recognition. These findings indicate that eye movements collect information that can be used to strengthen memory representations that are later available for conscious remembering, whereas eye movement repetition effects reflect a processing change due to experience that does not necessarily reflect a memory representation that is available for conscious appraisal. Lastly, H.C. demonstrated a repetition effect for fixed viewpoint faces but not for variable viewpoint faces, which suggests that repetition effects are differentially supported by neocortical and hippocampal systems, depending upon the representational nature of the underlying memory trace. Copyright © 2016 Elsevier Ltd. All rights reserved.

Delta-9-Tetrahydrocannabinol Potentiates Fear Memory Salience Through Functional Modulation of Mesolimbic Dopaminergic Activity States.

PubMed

Fitoussi, Aurelie; Zunder, Jordan; Tan, Huibing; Laviolette, Steven R

2018-05-18

Chronic or acute exposure to delta-9-tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, has been associated with numerous neuropsychiatric side-effects, including dysregulation of emotional processing and associative memory formation. Clinical and pre-clinical evidence suggests that the effects of THC are due to the ability to modulate mesolimbic dopamine (DA) activity states in the nucleus accumbens (NAc) and ventral tegmental area (VTA). Nevertheless, the mechanisms by which THC modulates mesolimbic DA function and emotional processing are not well understood. Using an olfactory associative fear memory procedure combined with in vivo neuronal electrophysiology, we examined the effects of direct THC microinfusions targeting the shell region of the NAc (NASh) and examined how THC may modulate the processing of fear-related emotional memory and concomitant activity states of the mesolimbic DA system. We report that intra-NASh THC dose-dependently potentiates the emotional salience of normally sub-threshold fear-conditioning cues. These effects were dependent upon intra-VTA transmission through GABAergic receptor mechanisms and intra-NASh DAergic transmission. Furthermore, doses of intra-NASh THC that potentiated fear memory salience were found to modulate intra-VTA neuronal network activity by increasing the spontaneous firing and bursting frequency of DAergic neurons whilst decreasing the activity levels of a subpopulation of putative GABAergic VTA neurons. These findings demonstrate that THC can act directly in the NASh to modulate mesolimbic activity states and induce disturbances in emotional salience and memory formation through modulation of VTA DAergic transmission. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Anomalous diffusion due to the non-Markovian process of the dust particle velocity in complex plasmas

NASA Astrophysics Data System (ADS)

Ghannad, Z.; Hakimi Pajouh, H.

2017-12-01

In this work, the motion of a dust particle under the influence of the random force due to dust charge fluctuations is considered as a non-Markovian stochastic process. Memory effects in the velocity process of the dust particle are studied. A model is developed based on the fractional Langevin equation for the motion of the dust grain. The fluctuation-dissipation theorem for the dust grain is derived from this equation. The mean-square displacement and the velocity autocorrelation function of the dust particle are obtained in terms of the Mittag-Leffler functions. Their asymptotic behavior and the dust particle temperature due to charge fluctuations are studied in the long-time limit. As an interesting result, it is found that the presence of memory effects in the velocity process of the dust particle as a non-Markovian process can cause an anomalous diffusion in dusty plasmas. In this case, the velocity autocorrelation function of the dust particle has a power-law decay like t - α - 2, where the exponent α take values 0 < α < 1.

Natural Memory Beyond the Storage Model: Repression, Trauma, and the Construction of a Personal Past

PubMed Central

Axmacher, Nikolai; Do Lam, Anne T. A.; Kessler, Henrik; Fell, Juergen

2010-01-01

Naturally occurring memory processes show features which are difficult to investigate by conventional cognitive neuroscience paradigms. Distortions of memory for problematic contents are described both by psychoanalysis (internal conflicts) and research on post-traumatic stress disorder (PTSD; external traumata). Typically, declarative memory for these contents is impaired – possibly due to repression in the case of internal conflicts or due to dissociation in the case of external traumata – but they continue to exert an unconscious pathological influence: neurotic symptoms or psychosomatic disorders after repression or flashbacks and intrusions in PTSD after dissociation. Several experimental paradigms aim at investigating repression in healthy control subjects. We argue that these paradigms do not adequately operationalize the clinical process of repression, because they rely on an intentional inhibition of random stimuli (suppression). Furthermore, these paradigms ignore that memory distortions due to repression or dissociation are most accurately characterized by a lack of self-referential processing, resulting in an impaired integration of these contents into the self. This aspect of repression and dissociation cannot be captured by the concept of memory as a storage device which is usually employed in the cognitive neurosciences. It can only be assessed within the framework of a constructivist memory concept, according to which successful memory involves a reconstruction of experiences such that they fit into a representation of the self. We suggest several experimental paradigms that allow for the investigation of the neural correlates of repressed memories and trauma-induced memory distortions based on a constructivist memory concept. PMID:21151366

The antioxidant activity of Beta vulgaris leaf extract in improving scopolamine-induced spatial memory disorders in rats.

PubMed

Hajihosseini, Shadieh; Setorki, Mahbubeh; Hooshmandi, Zahra

2017-01-01

Medicinal plants have attracted global attention due to their safety as well as their considerable antioxidant content that helps to prevent or ameliorate various disorders including memory impairments. This study was conducted to investigate the effect of beet root ( Beta vulgaris ) leaf extract on scopolamine-induced spatial memory impairments in male Wistar rats. Male Wistar rats were randomly divided into 5 groups (n=10): Control (C), scopolamine 1 mg/kg/day (S), scopolamine+50 mg/kg B. vulgaris leaf extract (S+B 50), scopolamine+100 mg/kg B. vulgaris leaf extract (S+B 100) and scopolamine+200 mg/kg B. vulgaris leaf extract (S+B 200). Morris water maze task was used to assess spatial memory. Serum antioxidant capacity and malondialdehyde (MDA) level were also measured. Group S spent significantly less time in the target quadrant compared to the control group, and the administration of B. vulgaris leaf extract (100 and 200 mg/kg) significantly increased this time (p<0.05). Scopolamine decreased serum antioxidant capacity and increased serum MDA level yet insignificantly. B. vulgaris extract (200 mg/kg) significantly increased the antioxidant capacity and decreased serum MDA level in scopolamine-treated rats (p<0.05). Our results suggested that B. vulgaris leaf extract could ameliorate the memory impairments and exhibited protective effects against scopolamine-induced oxidation. Further investigation is needed to isolate specific antioxidant compounds from B. vulgaris leaf extract with protective effect against brain and memory impairments.

Monkey’s short-term auditory memory nearly abolished by combined removal of the rostral superior temporal gyrus and rhinal cortices

PubMed Central

Fritz, Jonathan B.; Malloy, Megan; Mishkin, Mortimer; Saunders, Richard C.

2016-01-01

While monkeys easily acquire the rules for performing visual and tactile delayed matching-to-sample, a method for testing recognition memory, they have extraordinary difficulty acquiring a similar rule in audition. Another striking difference between the modalities is that whereas bilateral ablation of the rhinal cortex (RhC) leads to profound impairment in visual and tactile recognition, the same lesion has no detectable effect on auditory recognition memory (Fritz et al., 2005). In our previous study, a mild impairment in auditory memory was obtained following bilateral ablation of the entire medial temporal lobe (MTL), including the RhC, and an equally mild effect was observed after bilateral ablation of the auditory cortical areas in the rostral superior temporal gyrus (rSTG). In order to test the hypothesis that each of these mild impairments was due to partial disconnection of acoustic input to a common target (e.g., the ventromedial prefrontal cortex), in the current study we examined the effects of a more complete auditory disconnection of this common target by combining the removals of both the rSTG and the MTL. We found that the combined lesion led to forgetting thresholds (performance at 75% accuracy) that fell precipitously from the normal retention duration of ~30–40 seconds to a duration of ~1–2 seconds, thus nearly abolishing auditory recognition memory, and leaving behind only a residual echoic memory. PMID:26707975

Functional Drink Containing the Extracts of Purple Corn Cob and Pandan Leaves, the Novel Cognitive Enhancer, Increases Spatial Memory and Hippocampal Neuron Density Through the Improvement of Extracellular Signal Regulated Protein Kinase Expression, Cholinergic Function, and Oxidative Status in Ovariectomized Rats.

PubMed

Wattanathorn, Jintanaporn; Kirisattayakul, Woranan; Suriharn, Bhalang; Lertrat, Kamol

2018-05-30

Due to requirement of novel memory enhancer for menopausal women, this study aimed to determine safety and effect of the functional drink containing the extracts of purple corn cob and pandan leaves (PCP) on memory and brain changes in experimental menopause induced by bilateral ovariectomy (OVX). Acute toxicity of PCP was carried out in female Wistar rats. The results showed that LD50 was more than 2000 mg/kg BW. To determine the cognitive enhancing effect of PCP, OVX rats were orally treated with PCP at the doses of 20, 40, and 80 mg/kg BW for 28 days. The spatial memory was assessed every 7 days throughout the study period. At the end of the study, oxidative stress status, acetylcholinesterase (AChE) activity, monoamine oxidase (MAO) activity, neuronal density, and extracellular signal regulated protein kinase 1 and 2 (ERK1/2) signaling in hippocampus were measured. The improved spatial memory, ERK1/2 expression, and neuron density in dentate gyrus of hippocampus were observed in PCP-treated rats. In addition, a reduction of AChE activity was also observed. Unfortunately, no improved oxidative stress status was observed. Taken altogether, PCP exerts the memory-enhancing effect partly through the suppression of AChE and the increase in ERK signaling in the hippocampus.

Asymmetric effects of emotion on mnemonic interference

PubMed Central

Leal, Stephanie L.; Tighe, Sarah K.; Yassa, Michael A.

2014-01-01

Emotional experiences can strengthen memories so that they can be used to guide future behavior. Emotional arousal, mediated by the amygdala, is thought to modulate storage by the hippocampus, which may encode unique episodic memories via pattern separation – the process by which similar memories are stored using non-overlapping representations. While prior work has examined mnemonic interference due to similarity and emotional modulation of memory independently, examining the mechanisms by which emotion influences mnemonic interference has not been previously accomplished in humans. To this end, we developed an emotional memory task where emotional content and stimulus similarity were varied to examine the effect of emotion on fine mnemonic discrimination (a putative behavioral correlate of hippocampal pattern separation). When tested immediately after encoding, discrimination was reduced for similar emotional items compared to similar neutral items, consistent with a reduced bias towards pattern separation. After 24 h, recognition of emotional target items was preserved compared to neutral items, whereas similar emotional item discrimination was further diminished. This suggests a potential mechanism for the emotional modulation of memory with a selective remembering of gist, as well as a selective forgetting of detail, indicating an emotion-induced reduction in pattern separation. This can potentially increase the effective signal-to-noise ratio in any given situation to promote survival. Furthermore, we found that individuals with depressive symptoms hyper-discriminate negative items, which correlated with their symptom severity. This suggests that utilizing mnemonic discrimination paradigms allows us to tease apart the nuances of disorders with aberrant emotional mnemonic processing. PMID:24607286

The effects of GABAA and NMDA receptors in the shell-accumbens on spatial memory of METH-treated rats.

PubMed

Heysieattalab, Soomaayeh; Naghdi, Nasser; Zarrindast, Mohammad-Reza; Haghparast, Abbas; Mehr, Shahram Ejtemaei; Khoshbouei, Habibeh

2016-03-01

Methamphetamine (METH) is a highly addictive and neurotoxic psychostimulant. Its use in humans is often associated with neurocognitive impairment and deficits in hippocampal plasticity. Striatal dopamine system is one of the main targets of METH. The dopamine neurons in the striatum directly or indirectly regulate the GABA and glutamatergic signaling in this region and thus their outputs. This is consistent with previous reports showing modification of neuronal activity in the striatum modulates the expression of hippocampal LTP and hippocampal-dependent memory tasks such as Morris water maze (MWM). Therefore, reversing or preventing METH-induced synaptic modifications via pharmacological manipulations of the shell-nucleus accumbens (shell-NAc) may introduce a viable therapeutic target to attenuate the METH-induced memory deficits. This study is designed to investigate the role of intra-shell NAc manipulation of GABAA and NMDA receptors and their interaction with METH on memory performance in MWM task. Pharmacological manipulations were performed in rats received METH or saline. We found systemic saline plus intra-shell NAc infusions of muscimol dose-dependently impaired performance, while bicuculline had no effect. Surprisingly, the intra-NAc infusions of 0.005μg/rat muscimol that has no effect on memory performance (ineffective dose) prevented METH-induced memory impairment. In the contrary, the intra-NAc infusions of bicuculline (0.2μg/rat) increased METH-induced memory impairment. However, pre-training intra-NAc infusions of D-AP5 dose-dependently impaired performance, while NMDA had no effect in rats received systemic saline (control group). The intra-NAc infusions with an ineffective dose of NMDA (0.1μg/rat) increased METH-induced memory impairment. Furthermore, intra-NAc infusions of D-AP5 with an ineffective dose (0.1μg/rat) prevented METH-induced memory impairment. Our result is consistent with the interpretation that METH-mediated learning deficit might be due to modification of hippocampus-VTA loop and that augmentation of GABAA receptor function in the shell-NAc may provide a new therapeutic target for alleviating METH-induced memory deficits. Copyright © 2015. Published by Elsevier Inc.

Effects of cue frequency and repetition on prospective memory: an ERP investigation.

PubMed

Wilson, Jennifer; Cutmore, Tim R H; Wang, Ya; Chan, Raymond C K; Shum, David H K

2013-11-01

Prospective memory involves the formation and completion of delayed intentions and is essential for independent living. In this study (n = 33), event-related potentials (ERPs) were used to systematically evaluate the effects of PM cue frequency (10% versus 30%) and PM cue repetition (high versus low) on ERP modulations. PM cues elicited prospective positivity and frontal positivity but not N300, perhaps due to the semantic nature of the task. Results of this study revealed an interesting interaction between PM cue frequency and PM cue repetition for prospective positivity and frontal positivity, highlighting the importance of taking both factors into account when designing future studies. © 2013.

Interlaboratory study of the ion source memory effect in 36Cl accelerator mass spectrometry

NASA Astrophysics Data System (ADS)

Pavetich, Stefan; Akhmadaliev, Shavkat; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Buchriegler, Josef; Golser, Robin; Keddadouche, Karim; Martschini, Martin; Merchel, Silke; Rugel, Georg; Steier, Peter

2014-06-01

Understanding and minimization of contaminations in the ion source due to cross-contamination and long-term memory effect is one of the key issues for accurate accelerator mass spectrometry (AMS) measurements of volatile elements. The focus of this work is on the investigation of the long-term memory effect for the volatile element chlorine, and the minimization of this effect in the ion source of the Dresden accelerator mass spectrometry facility (DREAMS). For this purpose, one of the two original HVE ion sources at the DREAMS facility was modified, allowing the use of larger sample holders having individual target apertures. Additionally, a more open geometry was used to improve the vacuum level. To evaluate this improvement in comparison to other up-to-date ion sources, an interlaboratory comparison had been initiated. The long-term memory effect of the four Cs sputter ion sources at DREAMS (two sources: original and modified), ASTER (Accélérateur pour les Sciences de la Terre, Environnement, Risques) and VERA (Vienna Environmental Research Accelerator) had been investigated by measuring samples of natural 35Cl/37Cl-ratio and samples highly-enriched in 35Cl (35Cl/37Cl ∼ 999). Besides investigating and comparing the individual levels of long-term memory, recovery time constants could be calculated. The tests show that all four sources suffer from long-term memory, but the modified DREAMS ion source showed the lowest level of contamination. The recovery times of the four ion sources were widely spread between 61 and 1390 s, where the modified DREAMS ion source with values between 156 and 262 s showed the fastest recovery in 80% of the measurements.

Auditory memory function in expert chess players.

PubMed

Fattahi, Fariba; Geshani, Ahmad; Jafari, Zahra; Jalaie, Shohreh; Salman Mahini, Mona

2015-01-01

Chess is a game that involves many aspects of high level cognition such as memory, attention, focus and problem solving. Long term practice of chess can improve cognition performances and behavioral skills. Auditory memory, as a kind of memory, can be influenced by strengthening processes following long term chess playing like other behavioral skills because of common processing pathways in the brain. The purpose of this study was to evaluate the auditory memory function of expert chess players using the Persian version of dichotic auditory-verbal memory test. The Persian version of dichotic auditory-verbal memory test was performed for 30 expert chess players aged 20-35 years and 30 non chess players who were matched by different conditions; the participants in both groups were randomly selected. The performance of the two groups was compared by independent samples t-test using SPSS version 21. The mean score of dichotic auditory-verbal memory test between the two groups, expert chess players and non-chess players, revealed a significant difference (p≤ 0.001). The difference between the ears scores for expert chess players (p= 0.023) and non-chess players (p= 0.013) was significant. Gender had no effect on the test results. Auditory memory function in expert chess players was significantly better compared to non-chess players. It seems that increased auditory memory function is related to strengthening cognitive performances due to playing chess for a long time.

When memory is not enough: Electrophysiological evidence for goal-dependent use of working memory representations in guiding visual attention

PubMed Central

Carlisle, Nancy B.; Woodman, Geoffrey F.

2014-01-01

Biased competition theory proposes that representations in working memory drive visual attention to select similar inputs. However, behavioral tests of this hypothesis have led to mixed results. These inconsistent findings could be due to the inability of behavioral measures to reliably detect the early, automatic effects on attentional deployment that the memory representations exert. Alternatively, executive mechanisms may govern how working memory representations influence attention based on higher-level goals. In the present study, we tested these hypotheses using the N2pc component of participants’ event-related potentials (ERPs) to directly measure the early deployments of covert attention. Participants searched for a target in an array that sometimes contained a memory-matching distractor. In Experiments 1–3, we manipulated the difficulty of the target discrimination and the proximity of distractors, but consistently observed that covert attention was deployed to the search targets and not the memory-matching distractors. In Experiment 4, we showed that when participants’ goal involved attending to memory-matching items that these items elicited a large and early N2pc. Our findings demonstrate that working memory representations alone are not sufficient to guide early deployments of visual attention to matching inputs and that goal-dependent executive control mediates the interactions between working memory representations and visual attention. PMID:21254796

Soft-error tolerance and energy consumption evaluation of embedded computer with magnetic random access memory in practical systems using computer simulations

NASA Astrophysics Data System (ADS)

Nebashi, Ryusuke; Sakimura, Noboru; Sugibayashi, Tadahiko

2017-08-01

We evaluated the soft-error tolerance and energy consumption of an embedded computer with magnetic random access memory (MRAM) using two computer simulators. One is a central processing unit (CPU) simulator of a typical embedded computer system. We simulated the radiation-induced single-event-upset (SEU) probability in a spin-transfer-torque MRAM cell and also the failure rate of a typical embedded computer due to its main memory SEU error. The other is a delay tolerant network (DTN) system simulator. It simulates the power dissipation of wireless sensor network nodes of the system using a revised CPU simulator and a network simulator. We demonstrated that the SEU effect on the embedded computer with 1 Gbit MRAM-based working memory is less than 1 failure in time (FIT). We also demonstrated that the energy consumption of the DTN sensor node with MRAM-based working memory can be reduced to 1/11. These results indicate that MRAM-based working memory enhances the disaster tolerance of embedded computers.

Investigating the Modality and Redundancy Effects for Learners with Persistent Pain

ERIC Educational Resources Information Center

Smith, Alexander; Ayres, Paul

2016-01-01

Two experiments were conducted to investigate how individuals with persistent pain would respond to instructional materials designed to promote the modality and redundancy effects. It was predicted that persistent pain would reduce the positive impact of narrated text due to reduced working memory capacity. One hundred thirty-seven full-time…

Neutral Details Associated with Emotional Events are Encoded: Evidence from a Cued Recall Paradigm

PubMed Central

Steinmetz, Katherine R. Mickley; Knight, Aubrey G.; Kensinger, Elizabeth A.

2015-01-01

Enhanced emotional memory often comes at the cost of memory for surrounding background information. Narrowed-encoding theories suggest that this is due to narrowed attention for emotional information at encoding, leading to impaired encoding of background information. Recent work has suggested that an encoding-based theory may be insufficient. Here, we examined whether cued recall – instead of previously used recognition memory tasks - would reveal evidence that non-emotional information associated with emotional information was effectively encoded. Participants encoded positive, negative, or neutral objects on neutral backgrounds. At retrieval, they were given either the item or the background as a memory cue and were asked to recall the associated scene element. Counter to narrowed-encoding theories, emotional items were more likely than neutral items to trigger recall of the associated background. This finding suggests that there is a memory trace of this contextual information and that emotional cues may facilitate retrieval of this information. PMID:26220708

Neural networks engaged in short-term memory rehearsal are disrupted by irrelevant speech in human subjects.

PubMed

Kopp, Franziska; Schröger, Erich; Lipka, Sigrid

2004-01-02

Rehearsal mechanisms in human short-term memory are increasingly understood in the light of both behavioural and neuroanatomical findings. However, little is known about the cooperation of participating brain structures and how such cooperations are affected when memory performance is disrupted. In this paper we use EEG coherence as a measure of synchronization to investigate rehearsal processes and their disruption by irrelevant speech in a delayed serial recall paradigm. Fronto-central and fronto-parietal theta (4-7.5 Hz), beta (13-20 Hz), and gamma (35-47 Hz) synchronizations are shown to be involved in our short-term memory task. Moreover, the impairment in serial recall due to irrelevant speech was preceded by a reduction of gamma band coherence. Results suggest that the irrelevant speech effect has its neural basis in the disruption of left-lateralized fronto-central networks. This stresses the importance of gamma band activity for short-term memory operations.

The effects of angry and happy expressions on recognition memory for unfamiliar faces in delusion-prone individuals.

PubMed

Larøi, Frank; D'Argembeau, Arnaud; Van der Linden, Martial

2006-12-01

Numerous studies suggest a cognitive bias for threat-related material in delusional ideation. However, few studies have examined this bias using a memory task. We investigated the influence of delusion-proneness on identity and expression memory for angry and happy faces. Participants high and low in delusion-proneness were presented with happy and angry faces and were later asked to recognise the same faces displaying a neutral expression. They also had to remember what the initial expressions of the faces had been. Remember/know/guess judgments were asked for both identity and expression memory. Results showed that delusion-prone participants better recognised the identity of angry faces compared to non-delusional participants. Also, this difference between the two groups was mainly due to a greater number of remember responses in delusion-prone participants. These findings extend previous studies by showing that delusions are associated with a memory bias for threat-related stimuli.

An Implicit Algorithm for the Numerical Simulation of Shape-Memory Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, R; Stolken, J; Jannetti, C

Shape-memory alloys (SMA) have the potential to be used in a variety of interesting applications due to their unique properties of pseudoelasticity and the shape-memory effect. However, in order to design SMA devices efficiently, a physics-based constitutive model is required to accurately simulate the behavior of shape-memory alloys. The scope of this work is to extend the numerical capabilities of the SMA constitutive model developed by Jannetti et. al. (2003), to handle large-scale polycrystalline simulations. The constitutive model is implemented within the finite-element software ABAQUS/Standard using a user defined material subroutine, or UMAT. To improve the efficiency of the numericalmore » simulations, so that polycrystalline specimens of shape-memory alloys can be modeled, a fully implicit algorithm has been implemented to integrate the constitutive equations. Using an implicit integration scheme increases the efficiency of the UMAT over the previously implemented explicit integration method by a factor of more than 100 for single crystal simulations.« less

Skyrmion-skyrmion and skyrmion-edge repulsions in skyrmion-based racetrack memory

NASA Astrophysics Data System (ADS)

Zhang, Xichao; Zhao, G. P.; Fangohr, Hans; Liu, J. Ping; Xia, W. X.; Xia, J.; Morvan, F. J.

2015-01-01

Magnetic skyrmions are promising for building next-generation magnetic memories and spintronic devices due to their stability, small size and the extremely low currents needed to move them. In particular, skyrmion-based racetrack memory is attractive for information technology, where skyrmions are used to store information as data bits instead of traditional domain walls. Here we numerically demonstrate the impacts of skyrmion-skyrmion and skyrmion-edge repulsions on the feasibility of skyrmion-based racetrack memory. The reliable and practicable spacing between consecutive skyrmionic bits on the racetrack as well as the ability to adjust it are investigated. Clogging of skyrmionic bits is found at the end of the racetrack, leading to the reduction of skyrmion size. Further, we demonstrate an effective and simple method to avoid the clogging of skyrmionic bits, which ensures the elimination of skyrmionic bits beyond the reading element. Our results give guidance for the design and development of future skyrmion-based racetrack memory.

Effects of aging and divided attention on episodic feeling-of-knowing accuracy.

PubMed

Sacher, Mathilde; Isingrini, Michel; Taconnat, Laurence

2013-10-01

This research investigated the effect of aging on episodic feeling-of-knowing (FOK) using a divided attention (DA) paradigm in order to examine whether DA in younger adults mimics the effects of aging when decreasing either memory encoding or monitoring processes. To that end, four groups of participants were tested on the FOK task: young adults (control group), young adults under DA at encoding, young adults under DA when making FOK judgments, and older adults. Our results showed that DA at encoding in young adults mimicked the effect of aging on memory performance, and also on FOK magnitude and accuracy, supporting the memory-constraint hypothesis (Hertzog et al., 2010). However, our results do not completely contradict the monitoring-deficit hypothesis, as DA during FOK judgments also affected FOK accuracy, but to a lesser extent than the aging effect or DA during encoding. We suggest that the age-related FOK deficit may be due to a lower level of deep encoding, leading to difficulty retrieving target-related contextual details enabling accurate prediction of subsequent recognition. © 2013.

Acute memory deficits in chemotherapy-treated adults.

PubMed

Lindner, Oana C; Mayes, Andrew; McCabe, Martin G; Talmi, Deborah

2017-11-01

Data from research on amnesia and epilepsy are equivocal with regards to the dissociation, shown in animal models, between rapid and slow long-term memory consolidation. Cancer treatments have lasting disruptive effects on memory and on brain structures associated with memory, but their acute effects on synaptic consolidation are unknown. We investigated the hypothesis that cancer treatment selectively impairs slow synaptic consolidation. Cancer patients and their matched controls were administered a novel list-learning task modelled on the Rey Auditory Verbal Learning Test. Learning, forgetting, and retrieval were tested before, and one day after patients' first chemotherapy treatment. Due to difficulties recruiting cancer patients at that sensitive time, we were only able to study 10 patients and their matched controls. Patients exhibited treatment-dependent accelerated forgetting over 24 hours compared to their own pre-treatment performance and to the performance of control participants, in agreement with our hypothesis. The number of intrusions increased after treatment, suggesting retrieval deficits. Future research with larger samples should adapt our methods to distinguish between consolidation and retrieval causes for treatment-dependent accelerated forgetting. The presence of significant accelerated forgetting in our small sample is indicative of a potentially large acute effect of chemotherapy treatment on forgetting, with potentially clinically relevant implications.

Enhancing Cognition with Video Games: A Multiple Game Training Study

PubMed Central

Oei, Adam C.; Patterson, Michael D.

2013-01-01

Background Previous evidence points to a causal link between playing action video games and enhanced cognition and perception. However, benefits of playing other video games are under-investigated. We examined whether playing non-action games also improves cognition. Hence, we compared transfer effects of an action and other non-action types that required different cognitive demands. Methodology/Principal Findings We instructed 5 groups of non-gamer participants to play one game each on a mobile device (iPhone/iPod Touch) for one hour a day/five days a week over four weeks (20 hours). Games included action, spatial memory, match-3, hidden- object, and an agent-based life simulation. Participants performed four behavioral tasks before and after video game training to assess for transfer effects. Tasks included an attentional blink task, a spatial memory and visual search dual task, a visual filter memory task to assess for multiple object tracking and cognitive control, as well as a complex verbal span task. Action game playing eliminated attentional blink and improved cognitive control and multiple-object tracking. Match-3, spatial memory and hidden object games improved visual search performance while the latter two also improved spatial working memory. Complex verbal span improved after match-3 and action game training. Conclusion/Significance Cognitive improvements were not limited to action game training alone and different games enhanced different aspects of cognition. We conclude that training specific cognitive abilities frequently in a video game improves performance in tasks that share common underlying demands. Overall, these results suggest that many video game-related cognitive improvements may not be due to training of general broad cognitive systems such as executive attentional control, but instead due to frequent utilization of specific cognitive processes during game play. Thus, many video game training related improvements to cognition may be attributed to near-transfer effects. PMID:23516504

High Performance Transparent Transistor Memory Devices Using Nano-Floating Gate of Polymer/ZnO Nanocomposites

NASA Astrophysics Data System (ADS)

Shih, Chien-Chung; Lee, Wen-Ya; Chiu, Yu-Cheng; Hsu, Han-Wen; Chang, Hsuan-Chun; Liu, Cheng-Liang; Chen, Wen-Chang

2016-02-01

Nano-floating gate memory devices (NFGM) using metal nanoparticles (NPs) covered with an insulating polymer have been considered as a promising electronic device for the next-generation nonvolatile organic memory applications NPs. However, the transparency of the device with metal NPs is restricted to 60~70% due to the light absorption in the visible region caused by the surface plasmon resonance effects of metal NPs. To address this issue, we demonstrate a novel NFGM using the blends of hole-trapping poly (9-(4-vinylphenyl) carbazole) (PVPK) and electron-trapping ZnO NPs as the charge storage element. The memory devices exhibited a remarkably programmable memory window up to 60 V during the program/erase operations, which was attributed to the trapping/detrapping of charge carriers in ZnO NPs/PVPK composite. Furthermore, the devices showed the long-term retention time (>105 s) and WRER test (>200 cycles), indicating excellent electrical reliability and stability. Additionally, the fabricated transistor memory devices exhibited a relatively high transparency of 90% at the wavelength of 500 nm based on the spray-coated PEDOT:PSS as electrode, suggesting high potential for transparent organic electronic memory devices.

The role of the BDNF Val66Met polymorphism in individual differences in long-term memory capacity.

PubMed

Montag, Christian; Felten, Andrea; Markett, Sebastian; Fischer, Luise; Winkel, Katja; Cooper, Andrew; Reuter, Martin

2014-12-01

The protein brain-derived neurotrophic factor (BDNF) plays an important role in diverse memory processes and is strongly expressed in the hippocampus. The hippocampus itself is a key structure involved in the processing of information from short-term to long-term memory. Due to the putative role of BDNF in memory consolidation, a prominent single nucleotide polymorphism (SNP) on the BDNF gene (BDNF Val66Met) was investigated in the context of long-term memory performance. N=138 students were presented with 40 words from 10 categories, each consisting of eight words such as 'fruits' or 'vehicles' in a memory recognition task (specifically the Deese-Roediger-McDermott Paradigm). Recognition performance was analyzed 25 min after the initial presentation of the word list and subsequently 1 week after the initial presentation. Overall, individual long-term memory performance immediately after learning the word list (T1) and performance 1 week later (T2) did not differ on the basis of the BDNF SNP, but an interaction effect of BDNF Val66Met by time-of-recall was found: Carriers of the Met66+ variant showed the strongest decline in hit rate performance over time.

Repeated retrieval practice and item difficulty: does criterion learning eliminate item difficulty effects?

PubMed

Vaughn, Kalif E; Rawson, Katherine A; Pyc, Mary A

2013-12-01

A wealth of previous research has established that retrieval practice promotes memory, particularly when retrieval is successful. Although successful retrieval promotes memory, it remains unclear whether successful retrieval promotes memory equally well for items of varying difficulty. Will easy items still outperform difficult items on a final test if all items have been correctly recalled equal numbers of times during practice? In two experiments, normatively difficult and easy Lithuanian-English word pairs were learned via test-restudy practice until each item had been correctly recalled a preassigned number of times (from 1 to 11 correct recalls). Despite equating the numbers of successful recalls during practice, performance on a delayed final cued-recall test was lower for difficult than for easy items. Experiment 2 was designed to diagnose whether the disadvantage for difficult items was due to deficits in cue memory, target memory, and/or associative memory. The results revealed a disadvantage for the difficult versus the easy items only on the associative recognition test, with no differences on cue recognition, and even an advantage on target recognition. Although successful retrieval enhanced memory for both difficult and easy items, equating retrieval success during practice did not eliminate normative item difficulty differences.

Does virtual reality have a future for the study of episodic memory in aging?

PubMed

Abichou, Kouloud; La Corte, Valentina; Piolino, Pascale

2017-03-01

Episodic memory is the memory of personally lived events located in time and space, it shapes our identity and allows us to project ourselves into the past and the future. This form of memory is vulnerable to the effects of age and its alteration, hindering the autonomy of the subjects, can predict the evolution towards neurodegenerative disorders. Hence, a better understanding of this type of memory is a priority in the field of public health. Actually, traditional neuropsychological tools are often decontextualized, using simplistic situations that did not require the mobilization of all the characteristics of episodic memory, thus they just offer a partial measure of this complex mnemonic capacity. Nowadays, the virtual reality (VR) is a tool allowing the immersion of subjects in simulations of real situations, rich in spatial and temporal naturalistic contexts. Due to its many characteristics, the VR allows to solve several limitations of the traditional tests. The purpose of this review is to expose studies that investigated episodic memory in normal and Alzheimer's disease using VR in order to address its relevance as a new tool in the future practice of neuropsychology of aging.

Bright-light effects on cognitive performance in elderly persons working simulated night shifts: psychological well-being as a mediator?

PubMed

Kretschmer, Veronika; Schmidt, Klaus-Helmut; Griefahn, Barbara

2013-11-01

The present study examined whether the relationship between light exposure and cognitive functioning is mediated by psychological well-being in elderly persons working night shifts. The role of psychological well-being has been neglected so far in the relationship between bright light and cognitive performance. Sleepiness and mood were applied as indicators of psychological well-being. Cognitive functioning was examined in terms of concentration, working memory, and divided attention. A total of thirty-two test persons worked in three consecutive simulated night shifts, 16 under bright light (3,000 lux) and 16 under room light (300 lux). Concentration, working memory, and divided attention were measured by computerised tasks. The hypothesised mediators were recorded by questionnaires. Mediation analyses were conducted for estimating direct, total, and indirect effects in simple mediation models. Results indicate that sleepiness and mood did not function as mediators in the prediction of concentration, working memory, and/or divided attention by light exposure. Sleepiness led to an underestimation of the positive bright-light effect on concentration performance. Mood showed only a random effect due to the positive bright-light effect on working memory. Sleepiness and mood could completely be excluded as mediators in the relationship between light exposure and cognitive functioning. This study underlines that psychological well-being of elderly persons is not a critical component in the treatment of bright light on cognitive performance in the night shift workplace. In summary, it becomes evident that bright light has a strong direct and independent effect on cognitive performance, particularly on working memory and concentration.

Entanglement distillation for quantum communication network with atomic-ensemble memories.

PubMed

Li, Tao; Yang, Guo-Jian; Deng, Fu-Guo

2014-10-06

Atomic ensembles are effective memory nodes for quantum communication network due to the long coherence time and the collective enhancement effect for the nonlinear interaction between an ensemble and a photon. Here we investigate the possibility of achieving the entanglement distillation for nonlocal atomic ensembles by the input-output process of a single photon as a result of cavity quantum electrodynamics. We give an optimal entanglement concentration protocol (ECP) for two-atomic-ensemble systems in a partially entangled pure state with known parameters and an efficient ECP for the systems in an unknown partially entangled pure state with a nondestructive parity-check detector (PCD). For the systems in a mixed entangled state, we introduce an entanglement purification protocol with PCDs. These entanglement distillation protocols have high fidelity and efficiency with current experimental techniques, and they are useful for quantum communication network with atomic-ensemble memories.

Micromirror structure actuated by TiNi shape memory thin films

NASA Astrophysics Data System (ADS)

Fu, Y. Q.; Luo, J. K.; Hu, M.; Du, H. J.; Flewitt, A. J.; Milne, W. I.

2005-10-01

TiNi films were deposited by co-sputtering TiNi and Ti targets. Results from differential scanning calorimetry and curvature measurement revealed martensitic transformation and shape memory effect upon heating and cooling. Two types of TiNi/Si micromirror structures with a Si mirror cap (40 µm thick) and TiNi/Si actuation beams were designed and fabricated. For the first design, a V-shaped cantilever based on the TiNi/Si bimorph structure was used as the actuation mechanism for the micromirror. In the second design, three elbow-shaped Si beams with TiNi electrodes were used as the arms to actuate the mirror. The TiNi/Si microbeams were flat at room temperature and bent up by applying voltage in the TiNi electrodes (due to phase transformation and shape memory effect), thus causing changes in angles of the micromirror.

Presentation format effects in a levels-of-processing task.

PubMed

Foos, Paul W; Goolkasian, Paula

2008-01-01

Three experiments were conducted to examine better performance in long-term memory when stimulus items are pictures or spoken words compared to printed words. Hypotheses regarding the allocation of attention to printed words, the semantic link between pictures and processing, and a rich long-term representation for pictures were tested. Using levels-of-processing tasks eliminated format effects when no memory test was expected and processing was deep (El), and when study and test formats did not match (E3). Pictures produced superior performance when a memory test was expected (El & 2) and when study and test formats were the same (E3). Results of all experiments support the attenuation of attention model and that picture superiority is due to a more direct access to semantic processing and a richer visual code. General principles to guide the processing of stimulus information are discussed.

Single-Event Effect Response of a Commercial ReRAM

NASA Technical Reports Server (NTRS)

Chen, Dakai; Label, Kenneth A.; Kim, Hak; Phan, Anthony; Wilcox, Edward; Buchner, Stephen; Khachatrian, Ani; Roche, Nicolas

2014-01-01

We show heavy ion test results of a commercial production-level ReRAM. The memory array is robust to bit upsets. However the ReRAM system is vulnerable to SEFIs due to upsets in peripheral circuits, including the sense amplifier.

Hippocampus-dependent spatial memory impairment due to molar tooth loss is ameliorated by an enriched environment.

PubMed

Kondo, Hiroko; Kurahashi, Minori; Mori, Daisuke; Iinuma, Mitsuo; Tamura, Yasuo; Mizutani, Kenmei; Shimpo, Kan; Sonoda, Shigeru; Azuma, Kagaku; Kubo, Kin-ya

2016-01-01

Teeth are crucial, not only for mastication, but for overall nutrition and general health, including cognitive function. Aged mice with chronic stress due to tooth loss exhibit impaired hippocampus-dependent learning and memory. Exposure to an enriched environment restores the reduced hippocampal function. Here, we explored the effects of an enriched environment on learning deficits and hippocampal morphologic changes in aged senescence-accelerated mouse strain P8 (SAMP8) mice with tooth loss. Eight-month-old male aged SAMP8 mice with molar intact or with molars removed were housed in either a standard environment or enriched environment for 3 weeks. The Morris water maze was performed for spatial memory test. The newborn cell proliferation, survival, and differentiation in the hippocampus were analyzed using 5-Bromodeoxyuridine (BrdU) immunohistochemical method. The hippocampal brain-derived neurotrophic factor (BDNF) levels were also measured. Mice with upper molars removed (molarless) exhibited a significant decline in the proliferation and survival of newborn cells in the dentate gyrus (DG) as well as in hippocampal BDNF levels. In addition, neuronal differentiation of newly generated cells was suppressed and hippocampus-dependent spatial memory was impaired. Exposure of molarless mice to an enriched environment attenuated the reductions in the hippocampal BDNF levels and neuronal differentiation, and partially improved the proliferation and survival of newborn cells, as well as the spatial memory ability. These findings indicated that an enriched environment could ameliorate the hippocampus-dependent spatial memory impairment induced by molar tooth loss. Copyright © 2015 Elsevier Ltd. All rights reserved.

The stability of working memory: do previous tasks influence complex span?

PubMed

Healey, M Karl; Hasher, Lynn; Danilova, Elena

2011-11-01

Schmeichel (2007) reported that performing an initial task before completing a working memory span task can lower span scores and suggested that the effect was due to depleted cognitive resources. We showed that the detrimental effect of prior tasks depends on a match between the stimuli used in the span task and the preceding task. A task requiring participants to ignore words reduced performance on a subsequent word-based verbal span task but not on an arrow-based spatial span task. Ignoring arrows had the opposite pattern of effects: reducing performance on the spatial span task but not on the word-based span task. Finally, we showed that antisaccade, a nonverbal task that taxes domain-general processes implicated in working memory, did not influence subsequent performance of either a verbal or a spatial span task. Together these results suggest that while span is sensitive to prior tasks, that sensitivity does not stem from depleted resources. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

Role of glucose in chewing gum-related facilitation of cognitive function.

PubMed

Stephens, Richard; Tunney, Richard J

2004-10-01

This study tests the hypothesis that chewing gum leads to cognitive benefits through improved delivery of glucose to the brain, by comparing the cognitive performance effects of gum and glucose administered separately and together. Participants completed a battery of cognitive tests in a fully related 2 x 2 design, where one factor was Chewing Gum (gum vs. mint sweet) and the other factor was Glucose Co-administration (consuming a 25 g glucose drink vs. consuming water). For four tests (AVLT Immediate Recall, Digit Span, Spatial Span and Grammatical Transformation), beneficial effects of chewing and glucose were found, supporting the study hypothesis. However, on AVLT Delayed Recall, enhancement due to chewing gum was not paralleled by glucose enhancement, suggesting an alternative mechanism. The glucose delivery model is supported with respect to the cognitive domains: working memory, immediate episodic long-term memory and language-based attention and processing speed. However, some other mechanism is more likely to underlie the facilitatory effect of chewing gum on delayed episodic long-term memory.

Effect of cutting parameters on strain hardening of nickel–titanium shape memory alloy

NASA Astrophysics Data System (ADS)

Wang, Guijie; Liu, Zhanqiang; Ai, Xing; Huang, Weimin; Niu, Jintao

2018-07-01

Nickel–titanium shape memory alloy (SMA) has been widely used as implant materials due to its good biocompatibility, shape memory property and super-elasticity. However, the severe strain hardening is a main challenge due to cutting force and temperature caused by machining. An orthogonal experiment of nickel–titanium SMA with different milling parameters conditions was conducted in this paper. On the one hand, the effect of cutting parameters on work hardening is obtained. It is found that the cutting speed has the most important effect on work hardening. The depth of machining induced layer and the degree of hardening become smaller with the increase of cutting speed when the cutting speed is less than 200 m min‑1 and then get larger with further increase of cutting speed. The relative intensity of diffraction peak increases as the cutting speed increase. In addition, all of the depth of machining induced layer, the degree of hardening and the relative intensity of diffraction peak increase when the feed rate increases. On the other hand, it is found that the depth of machining induced layer is closely related with the degree of hardening and phase transition. The higher the content of austenite in the machined surface is, the higher the degree of hardening will be. The depth of the machining induced layer increases with the degree of hardening increasing.

Memory reorganization following anterior temporal lobe resection: a longitudinal functional MRI study

PubMed Central

Bonelli, Silvia B.; Thompson, Pamela J.; Yogarajah, Mahinda; Powell, Robert H. W.; Samson, Rebecca S.; McEvoy, Andrew W.; Symms, Mark R.; Koepp, Matthias J.

2013-01-01

Anterior temporal lobe resection controls seizures in 50–60% of patients with intractable temporal lobe epilepsy but may impair memory function, typically verbal memory following left, and visual memory following right anterior temporal lobe resection. Functional reorganization can occur within the ipsilateral and contralateral hemispheres. We investigated the reorganization of memory function in patients with temporal lobe epilepsy before and after left or right anterior temporal lobe resection and the efficiency of postoperative memory networks. We studied 46 patients with unilateral medial temporal lobe epilepsy (25/26 left hippocampal sclerosis, 16/20 right hippocampal sclerosis) before and after anterior temporal lobe resection on a 3 T General Electric magnetic resonance imaging scanner. All subjects had neuropsychological testing and performed a functional magnetic resonance imaging memory encoding paradigm for words, pictures and faces, testing verbal and visual memory in a single scanning session, preoperatively and again 4 months after surgery. Event-related analysis revealed that patients with left temporal lobe epilepsy had greater activation in the left posterior medial temporal lobe when successfully encoding words postoperatively than preoperatively. Greater pre- than postoperative activation in the ipsilateral posterior medial temporal lobe for encoding words correlated with better verbal memory outcome after left anterior temporal lobe resection. In contrast, greater postoperative than preoperative activation in the ipsilateral posterior medial temporal lobe correlated with worse postoperative verbal memory performance. These postoperative effects were not observed for visual memory function after right anterior temporal lobe resection. Our findings provide evidence for effective preoperative reorganization of verbal memory function to the ipsilateral posterior medial temporal lobe due to the underlying disease, suggesting that it is the capacity of the posterior remnant of the ipsilateral hippocampus rather than the functional reserve of the contralateral hippocampus that is important for maintaining verbal memory function after anterior temporal lobe resection. Early postoperative reorganization to ipsilateral posterior or contralateral medial temporal lobe structures does not underpin better performance. Additionally our results suggest that visual memory function in right temporal lobe epilepsy is affected differently by right anterior temporal lobe resection than verbal memory in left temporal lobe epilepsy. PMID:23715092

Examining object recognition and object-in-Place memory in plateau zokors, Eospalax baileyi.

PubMed

Hegab, Ibrahim M; Tan, Yuchen; Wang, Chan; Yao, Baohui; Wang, Haifang; Ji, Weihong; Su, Junhu

2018-01-01

Recognition memory is important for the survival and fitness of subterranean rodents due to the barren underground conditions that require avoiding the burden of higher energy costs or possible conflict with conspecifics. Our study aims to examine the object and object/place recognition memories in plateau zokors (Eospalax baileyi) and test whether their underground life exerts sex-specific differences in memory functions using Novel Object Recognition (NOR) and Object-in-Place (OiP) paradigms. Animals were tested in the NOR with short (10min) and long-term (24h) inter-trial intervals (ITI) and in the OiP for a 30-min ITI between the familiarization and testing sessions. Plateau zokors showed a strong preference for novel objects manifested by a longer exploration time for the novel object after 10min ITI but failed to remember the familiar object when tested after 24h, suggesting a lack of long-term memory. In the OiP test, zokors effectively formed an association between the objects and the place where they were formerly encountered, resulting in a higher duration of exploration to the switched objects. However, both sexes showed equivalent results in exploration time during the NOR and OiP tests, which eliminates the possibility of discovering sex-specific variations in memory performance. Taken together, our study illustrates robust novelty preference and an effective short-term recognition memory without marked sex-specific differences, which might elucidate the dynamics of recognition memory formation and retrieval in plateau zokors. Copyright © 2017 Elsevier B.V. All rights reserved.

Associations between speech understanding and auditory and visual tests of verbal working memory: effects of linguistic complexity, task, age, and hearing loss

PubMed Central

Smith, Sherri L.; Pichora-Fuller, M. Kathleen

2015-01-01

Listeners with hearing loss commonly report having difficulty understanding speech, particularly in noisy environments. Their difficulties could be due to auditory and cognitive processing problems. Performance on speech-in-noise tests has been correlated with reading working memory span (RWMS), a measure often chosen to avoid the effects of hearing loss. If the goal is to assess the cognitive consequences of listeners’ auditory processing abilities, however, then listening working memory span (LWMS) could be a more informative measure. Some studies have examined the effects of different degrees and types of masking on working memory, but less is known about the demands placed on working memory depending on the linguistic complexity of the target speech or the task used to measure speech understanding in listeners with hearing loss. Compared to RWMS, LWMS measures using different speech targets and maskers may provide a more ecologically valid approach. To examine the contributions of RWMS and LWMS to speech understanding, we administered two working memory measures (a traditional RWMS measure and a new LWMS measure), and a battery of tests varying in the linguistic complexity of the speech materials, the presence of babble masking, and the task. Participants were a group of younger listeners with normal hearing and two groups of older listeners with hearing loss (n = 24 per group). There was a significant group difference and a wider range in performance on LWMS than on RWMS. There was a significant correlation between both working memory measures only for the oldest listeners with hearing loss. Notably, there were only few significant correlations among the working memory and speech understanding measures. These findings suggest that working memory measures reflect individual differences that are distinct from those tapped by these measures of speech understanding. PMID:26441769

Exploring laterality and memory effects in the haptic discrimination of verbal and non-verbal shapes.

PubMed

Stoycheva, Polina; Tiippana, Kaisa

2018-03-14

The brain's left hemisphere often displays advantages in processing verbal information, while the right hemisphere favours processing non-verbal information. In the haptic domain due to contra-lateral innervations, this functional lateralization is reflected in a hand advantage during certain functions. Findings regarding the hand-hemisphere advantage for haptic information remain contradictory, however. This study addressed these laterality effects and their interaction with memory retention times in the haptic modality. Participants performed haptic discrimination of letters, geometric shapes and nonsense shapes at memory retention times of 5, 15 and 30 s with the left and right hand separately, and we measured the discriminability index d'. The d' values were significantly higher for letters and geometric shapes than for nonsense shapes. This might result from dual coding (naming + spatial) or/and from a low stimulus complexity. There was no stimulus-specific laterality effect. However, we found a time-dependent laterality effect, which revealed that the performance of the left hand-right hemisphere was sustained up to 15 s, while the performance of the right-hand-left hemisphere decreased progressively throughout all retention times. This suggests that haptic memory traces are more robust to decay when they are processed by the left hand-right hemisphere.

WAY 267,464, a non-peptide oxytocin receptor agonist, impairs social recognition memory in rats through a vasopressin 1A receptor antagonist action.

PubMed

Hicks, Callum; Ramos, Linnet; Reekie, Tristan A; Narlawar, Rajeshwar; Kassiou, Michael; McGregor, Iain S

2015-08-01

Recent in vitro studies suggest that the oxytocin receptor (OTR) agonist WAY 267,464 has vasopressin 1A receptor (V1AR) antagonist effects. This might limit its therapeutic potential due to the positive involvement of the V1AR in social behavior. The objective of this study was to assess functional V1AR antagonist-like effects of WAY 267,464 in vivo using a test of social recognition memory. Adult experimental rats were tested for their recognition of a juvenile conspecific rat that they had briefly met 30 or 120 min previously. The modulatory effects of vasopressin (AVP), the selective V1AR antagonist SR49059, and WAY 267,464 were examined together with those of the selective OTR antagonist Compound 25 (C25). Drugs were administered immediately after the first meeting. Control rats showed recognition of juveniles at a 30 min, but not a 120 min retention interval. AVP (0.005, but not 0.001 mg/kg intraperitoneal (i.p.)) improved memory such that recognition was evident after 120 min. This was prevented by pretreatment with SR49059 (1 mg/kg) and WAY 267,464 (10, 30, and 100 mg/kg). Given alone, SR49059 (1 mg/kg) and WAY 267,464 (30 and 100 mg/kg) impaired memory at a 30 min retention interval. The impairment with WAY 267,464 was not prevented by C25 (5 mg/kg), suggesting V1AR rather than OTR mediation of the effect. Given alone, C25 also impaired memory. These results highlight a tonic role for endogenous AVP (and oxytocin) in social recognition memory and indicate that WAY 267,464 functions in vivo as a V1AR antagonist to prevent the memory-enhancing effects of AVP.

A mega-analysis of memory reports from eight peer-reviewed false memory implantation studies.

PubMed

Scoboria, Alan; Wade, Kimberley A; Lindsay, D Stephen; Azad, Tanjeem; Strange, Deryn; Ost, James; Hyman, Ira E

2017-02-01

Understanding that suggestive practices can promote false beliefs and false memories for childhood events is important in many settings (e.g., psychotherapeutic, medical, and legal). The generalisability of findings from memory implantation studies has been questioned due to variability in estimates across studies. Such variability is partly due to false memories having been operationalised differently across studies and to differences in memory induction techniques. We explored ways of defining false memory based on memory science and developed a reliable coding system that we applied to reports from eight published implantation studies (N = 423). Independent raters coded transcripts using seven criteria: accepting the suggestion, elaboration beyond the suggestion, imagery, coherence, emotion, memory statements, and not rejecting the suggestion. Using this scheme, 30.4% of cases were classified as false memories and another 23% were classified as having accepted the event to some degree. When the suggestion included self-relevant information, an imagination procedure, and was not accompanied by a photo depicting the event, the memory formation rate was 46.1%. Our research demonstrates a useful procedure for systematically combining data that are not amenable to meta-analysis, and provides the most valid estimate of false memory formation and associated moderating factors within the implantation literature to date.

Identifying the appropriate time for deep brain stimulation to achieve spatial memory improvement on the Morris water maze.

PubMed

Jeong, Da Un; Lee, Jihyeon; Chang, Won Seok; Chang, Jin Woo

2017-03-07

The possibility of using deep brain stimulation (DBS) for memory enhancement has recently been reported, but the precise underlying mechanisms of its effects remain unknown. Our previous study suggested that spatial memory improvement by medial septum (MS)-DBS may be associated with cholinergic regulation and neurogenesis. However, the affected stage of memory could not be distinguished because the stimulation was delivered during the execution of all memory processes. Therefore, this study was performed to determine the stage of memory affected by MS-DBS. Rats were administered 192 IgG-saporin to lesion cholinergic neurons. Stimulation was delivered at different times in different groups of rats: 5 days before the Morris water maze test (pre-stimulation), 5 days during the training phase of the Morris water maze test (training-stimulation), and 2 h before the Morris water maze probe test (probe-stimulation). A fourth group of rats was lesioned but received no stimulation. These four groups were compared with a normal (control) group. The most effective memory restoration occurred in the pre-stimulation group. Moreover, the pre-stimulation group exhibited better recall of the platform position than the other stimulation groups. An increase in the level of brain derived neurotrophic factor (BDNF) was observed in the pre-stimulation group; this increase was maintained for 1 week. However, acetylcholinesterase activity in the pre-stimulation group was not significantly different from the lesion group. Memory impairment due to cholinergic denervation can be improved by DBS. The improvement is significantly correlated with the up-regulation of BDNF expression and neurogenesis. Based on the results of this study, the use of MS-DBS during the early stage of disease may restore spatial memory impairment.

ABA signaling is necessary but not sufficient for RD29B transcriptional memory during successive dehydration stresses in Arabidopsis thaliana.

PubMed

Virlouvet, Laetitia; Ding, Yong; Fujii, Hiroaki; Avramova, Zoya; Fromm, Michael

2014-07-01

Plants subjected to a prior dehydration stress were seen to have altered transcriptional responses during a subsequent dehydration stress for up to 5 days after the initial stress. The abscisic acid (ABA) inducible RD29B gene of Arabidopsis thaliana was strongly induced after the first stress and displayed transcriptional memory with transcript levels nine-fold higher during the second dehydration stress. These increased transcript levels were due to an increased rate of transcription and are associated with an altered chromatin template during the recovery interval between the dehydration stresses. Here we use a combination of promoter deletion/substitutions, mutants in the trans-acting transcription factors and their upstream protein kinases, and treatments with exogenous ABA or dehydration stress to advance our understanding of the features required for transcriptional memory of RD29B. ABA Response Elements (ABREs) are sufficient to confer transcriptional memory on a minimal promoter, although there is a context effect from flanking sequences. Different mutations in Snf1 Related Protein Kinase 2 (SnRK2) genes positively and negatively affected the response, suggesting that this effect is important for transcriptional memory. Although exogenous ABA treatments could prime transcriptional memory, a second ABA treatment was not sufficient to activate transcriptional memory. Therefore, we concluded that transcriptional memory requires ABA and an ABA-independent factor that is induced or activated by a subsequent dehydration stress and directly or indirectly results in a more active RD29B chromatin template. These results advance our knowledge of the cis- and trans-acting factors that are required for transcriptional memory of RD29B. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

To hear or not to hear: Voice processing under visual load.

PubMed

Zäske, Romi; Perlich, Marie-Christin; Schweinberger, Stefan R

2016-07-01

Adaptation to female voices causes subsequent voices to be perceived as more male, and vice versa. This contrastive aftereffect disappears under spatial inattention to adaptors, suggesting that voices are not encoded automatically. According to Lavie, Hirst, de Fockert, and Viding (2004), the processing of task-irrelevant stimuli during selective attention depends on perceptual resources and working memory. Possibly due to their social significance, faces may be an exceptional domain: That is, task-irrelevant faces can escape perceptual load effects. Here we tested voice processing, to study whether voice gender aftereffects (VGAEs) depend on low or high perceptual (Exp. 1) or working memory (Exp. 2) load in a relevant visual task. Participants adapted to irrelevant voices while either searching digit displays for a target (Exp. 1) or recognizing studied digits (Exp. 2). We found that the VGAE was unaffected by perceptual load, indicating that task-irrelevant voices, like faces, can also escape perceptual-load effects. Intriguingly, the VGAE was increased under high memory load. Therefore, visual working memory load, but not general perceptual load, determines the processing of task-irrelevant voices.

Acute cannabinoids impair working memory through astroglial CB1 receptor modulation of hippocampal LTD.

PubMed

Han, Jing; Kesner, Philip; Metna-Laurent, Mathilde; Duan, Tingting; Xu, Lin; Georges, Francois; Koehl, Muriel; Abrous, Djoher Nora; Mendizabal-Zubiaga, Juan; Grandes, Pedro; Liu, Qingsong; Bai, Guang; Wang, Wei; Xiong, Lize; Ren, Wei; Marsicano, Giovanni; Zhang, Xia

2012-03-02

Impairment of working memory is one of the most important deleterious effects of marijuana intoxication in humans, but its underlying mechanisms are presently unknown. Here, we demonstrate that the impairment of spatial working memory (SWM) and in vivo long-term depression (LTD) of synaptic strength at hippocampal CA3-CA1 synapses, induced by an acute exposure of exogenous cannabinoids, is fully abolished in conditional mutant mice lacking type-1 cannabinoid receptors (CB(1)R) in brain astroglial cells but is conserved in mice lacking CB(1)R in glutamatergic or GABAergic neurons. Blockade of neuronal glutamate N-methyl-D-aspartate receptors (NMDAR) and of synaptic trafficking of glutamate α-amino-3-hydroxy-5-methyl-isoxazole propionic acid receptors (AMPAR) also abolishes cannabinoid effects on SWM and LTD induction and expression. We conclude that the impairment of working memory by marijuana and cannabinoids is due to the activation of astroglial CB(1)R and is associated with astroglia-dependent hippocampal LTD in vivo. Copyright © 2012 Elsevier Inc. All rights reserved.

Odor-induced recall of emotional memories in PTSD-Review and new paradigm for research.

PubMed

Daniels, Judith K; Vermetten, Eric

2016-10-01

It is clinically well known that olfactory intrusions in PTSD can be a disabling phenomena due to the involuntary recall of odor memories. Odorants can trigger involuntary recall of emotional memories as well have the potential to help diminishing emotional arousal as grounding stimuli. Despite major advances in our understanding of the function of olfactory system, the study of the relation of olfaction and emotional memory is still relatively scarce. Odor memory is long thought to be different than other types of memories such as verbal or visual memories, being more strongly engraved and more closely related to strong emotions. Brain areas mediating smell memory including orbitofrontal cortex and other parts of medial prefrontal cortex, hippocampus and amygdala, have been implicated in learning and memory and are part of a neural circuitry that is involved in PTSD. The olfactory cortex itself also plays an important role in emotional processing. Clinical observations support the notion that odor-evoked memories can play a role in the symptomatology of PTSD. This paper reviews a re-emerging body of science linking odor processing to emotional processing in PTSD using the calming and grounding effect of odors as well as the use of odors in augmented exposure therapy. This results in converging evidence that olfaction is an excellent model for studying many questions germane to the field of human emotional memory processing. Copyright © 2016 Elsevier Inc. All rights reserved.

Memory retrieval by activating engram cells in mouse models of early Alzheimer’s disease

PubMed Central

Roy, Dheeraj S.; Arons, Autumn; Mitchell, Teryn I.; Pignatelli, Michele; Ryan, Tomás J.; Tonegawa, Susumu

2016-01-01

Summary Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by progressive memory decline and subsequent loss of broader cognitive functions1. Memory decline in early stages of Alzheimer’s is mostly limited to episodic memory, for which the hippocampus (HPC) plays a crucial role2. However, it has been uncertain whether the observed amnesia in early stages of Alzheimer’s is due to disrupted encoding and consolidation of episodic information, or an impairment in the retrieval of stored memory information. Here we show that in transgenic mouse models of early Alzheimer’s, direct optogenetic activation of hippocampal memory engram cells results in memory retrieval despite the fact that these mice are amnesic in long-term memory tests when natural recall cues are utilized, revealing a retrieval, rather than a storage impairment. Prior to amyloid plaque deposition, the amnesia in these mice is age-dependent3–5, which correlates with a progressive reduction of spine density of hippocampal dentate gyrus (DG) engram cells. We show that optogenetic induction of long-term potentiation (LTP) at perforant path (PP) synapses of DG engram cells restores both spine density and long-term memory. We also demonstrate that an ablation of DG engram cells containing restored spine density prevents the rescue of long-term memory. Thus, selective rescue of spine density in engram cells may lead to an effective strategy for treating memory loss in early stages of Alzheimer’s disease. PMID:26982728

Valenced cues and contexts have different effects on event-based prospective memory.

PubMed

Graf, Peter; Yu, Martin

2015-01-01

This study examined the separate influence and joint influences on event-based prospective memory task performance due to the valence of cues and the valence of contexts. We manipulated the valence of cues and contexts with pictures from the International Affective Picture System. The participants, undergraduate students, showed higher performance when neutral compared to valenced pictures were used for cueing prospective memory. In addition, neutral pictures were more effective as cues when they occurred in a valenced context than in the context of neutral pictures, but the effectiveness of valenced cues did not vary across contexts that differed in valence. The finding of an interaction between cue and context valence indicates that their respective influence on event-based prospective memory task performance cannot be understood in isolation from each other. Our findings are not consistent with by the prevailing view which holds that the scope of attention is broadened and narrowed, respectively, by positively and negatively valenced stimuli. Instead, our findings are more supportive of the recent proposal that the scope of attention is determined by the motivational intensity associated with valenced stimuli. Consistent with this proposal, we speculate that the motivational intensity associated with different retrieval cues determines the scope of attention, that contexts with different valence values determine participants' task engagement, and that prospective memory task performance is determined jointly by attention scope and task engagement.

Valenced Cues and Contexts Have Different Effects on Event-Based Prospective Memory

PubMed Central

Graf, Peter; Yu, Martin

2015-01-01

This study examined the separate influence and joint influences on event-based prospective memory task performance due to the valence of cues and the valence of contexts. We manipulated the valence of cues and contexts with pictures from the International Affective Picture System. The participants, undergraduate students, showed higher performance when neutral compared to valenced pictures were used for cueing prospective memory. In addition, neutral pictures were more effective as cues when they occurred in a valenced context than in the context of neutral pictures, but the effectiveness of valenced cues did not vary across contexts that differed in valence. The finding of an interaction between cue and context valence indicates that their respective influence on event-based prospective memory task performance cannot be understood in isolation from each other. Our findings are not consistent with by the prevailing view which holds that the scope of attention is broadened and narrowed, respectively, by positively and negatively valenced stimuli. Instead, our findings are more supportive of the recent proposal that the scope of attention is determined by the motivational intensity associated with valenced stimuli. Consistent with this proposal, we speculate that the motivational intensity associated with different retrieval cues determines the scope of attention, that contexts with different valence values determine participants’ task engagement, and that prospective memory task performance is determined jointly by attention scope and task engagement. PMID:25647484

Predicting memory benefits in the production effect: the use and misuse of self-generated distinctive cues when making judgments of learning.

PubMed

Castel, Alan D; Rhodes, Matthew G; Friedman, Michael C

2013-01-01

The production effect occurs when reading a word aloud leads to better memory for the item, relative to words that are read silently. In the present study, we assessed the degree to which judgments of learning (JOLs) are sensitive to the production effect, to determine whether people are aware of how distinctive cues can enhance memory. If the act of saying a word aloud is used as a cue for later memorability, then JOLs should be sensitive to production. Experiment 1 demonstrated that this was the case, as participants provided higher JOLs for produced items than for those read silently. This pattern of JOLs was also evident when participants silently mouthed words (Exp. 2). In Experiment 3, participants instead made a nonunique response as the production component (saying "yes" instead of the word itself). JOLs were still higher under production, although memory performance did not differ from that in a silent condition. The results suggest that the presence of both specific and nonspecific self-generated cues is used to make metacognitive judgments, likely due to the high accessibility of this information, but that participants are not precisely aware of how distinctiveness enhances encoding and retrieval. Such findings have implications for how distinctiveness is perceived by learners and for what cues would appropriately be incorporated when predicting future memory performance.

Effects of immediate feedback and errorless learning on recognition memory processing in young and older adults.

PubMed

da Silva, Luisa; Sunderland, Alan

2010-01-01

Age-related memory decline appears to be due to impaired recollection whereas familiarity may be intact. An intervention was therefore designed with the aim of optimising use of this intact sense of familiarity. A continuous face recognition paradigm was used which required detection of repeats in a long series. The experimental intervention consisted of immediate feedback on response accuracy and avoidance of errors by discouraging guessing. Experimental and control interventions were compared by recruiting 40 people aged under 30 years or over 60 years for six 45-minute training sessions. The elderly participants initially showed a more lax response criterion than young people but the experimental intervention reversed this effect so that by the end of training the elderly participants were less prone to false alarms than the younger participants. However, there was only limited evidence of generalisation of this training effect to other memory tasks and no effect on recognition sensitivity. This study demonstrates that combined feedback and errorless learning allow elderly people to adjust their response criterion during recognition memory tasks. Taken together with previous encouraging studies, it seems that this training approach might have potential as a therapy for age-related memory impairment. However this would require development of additional methods to enhance generalisation beyond trained tasks and to elicit improvements in sensitivity as well as reduction of false alarms. The separate contributions of feedback and errorless learning also need to be investigated.

Butane dihedral angle dynamics in water is dominated by internal friction

PubMed Central

Daldrop, Jan O.; Kappler, Julian; Brünig, Florian N.; Netz, Roland R.

2018-01-01

The dihedral dynamics of butane in water is known to be rather insensitive to the water viscosity; possible explanations for this involve inertial effects or Kramers’ turnover, the finite memory time of friction, and the presence of so-called internal friction. To disentangle these factors, we introduce a method to directly extract the friction memory function from unconstrained simulations in the presence of an arbitrary free-energy landscape. By analysis of the dihedral friction in butane for varying water viscosity, we demonstrate the existence of an internal friction contribution that does not scale linearly with water viscosity. At normal water viscosity, the internal friction turns out to be eight times larger than the solvent friction and thus completely dominates the effective friction. By comparison with simulations of a constrained butane molecule that has the dihedral as the only degree of freedom, we show that internal friction comes from the six additional degrees of freedom in unconstrained butane that are orthogonal to the dihedral angle reaction coordinate. While the insensitivity of butane’s dihedral dynamics to water viscosity is solely due to the presence of internal friction, inertial effects nevertheless crucially influence the resultant transition rates. In contrast, non-Markovian effects due to the finite memory time are present but do not significantly influence the dihedral barrier-crossing rate of butane. These results not only settle the character of dihedral dynamics in small solvated molecular systems such as butane, they also have important implications for the folding of polymers and proteins. PMID:29712838

Electrical and ferroelectric properties of RF sputtered PZT/SBN on silicon for non-volatile memory applications

NASA Astrophysics Data System (ADS)

Singh, Prashant; Jha, Rajesh Kumar; Singh, Rajat Kumar; Singh, B. R.

2018-02-01

We report the integration of multilayer ferroelectric film deposited by RF magnetron sputtering and explore the electrical characteristics for its application as the gate of ferroelectric field effect transistor for non-volatile memories. PZT (Pb[Zr0.35Ti0.65]O3) and SBN (SrBi2Nb2O9) ferroelectric materials were selected for the stack fabrication due to their large polarization and fatigue free properties respectively. Electrical characterization has been carried out to obtain memory window, leakage current density, PUND and endurance characteristics. Fabricated multilayer ferroelectric film capacitor structure shows large memory window of 17.73 V and leakage current density of the order 10-6 A cm-2 for the voltage sweep of -30 to +30 V. This multilayer gate stack of PZT/SBN shows promising endurance property with no degradation in the remnant polarization for the read/write iteration cycles upto 108.

High Storage Efficiency and Large Fractional Delay of EIT-Based Memory

NASA Astrophysics Data System (ADS)

Chen, Yi-Hsin; Lee, Meng-Jung; Wang, I.-Chung; Du, Shengwang; Chen, Yong-Fan; Chen, Ying-Cheng; Yu, Ite

2013-05-01

In long-distance quantum communication and optical quantum computation, an efficient and long-lived quantum memory is an important component. We first experimentally demonstrated that a time-space-reversing method plus the optimum pulse shape can improve the storage efficiency (SE) of light pulses to 78% in cold media based on the effect of electromagnetically induced transparency (EIT). We obtain a large fractional delay of 74 at 50% SE, which is the best record so far. The measured classical fidelity of the recalled pulse is higher than 90% and nearly independent of the storage time, implying that the optical memory maintains excellent phase coherence. Our results suggest the current result may be readily applied to single-photon quantum states due to quantum nature of the EIT light-matter inference. This study advances the EIT-based quantum memory in practical quantum information applications.

Automatic Generation of Directive-Based Parallel Programs for Shared Memory Parallel Systems

NASA Technical Reports Server (NTRS)

Jin, Hao-Qiang; Yan, Jerry; Frumkin, Michael

2000-01-01

The shared-memory programming model is a very effective way to achieve parallelism on shared memory parallel computers. As great progress was made in hardware and software technologies, performance of parallel programs with compiler directives has demonstrated large improvement. The introduction of OpenMP directives, the industrial standard for shared-memory programming, has minimized the issue of portability. Due to its ease of programming and its good performance, the technique has become very popular. In this study, we have extended CAPTools, a computer-aided parallelization toolkit, to automatically generate directive-based, OpenMP, parallel programs. We outline techniques used in the implementation of the tool and present test results on the NAS parallel benchmarks and ARC3D, a CFD application. This work demonstrates the great potential of using computer-aided tools to quickly port parallel programs and also achieve good performance.

ERP C250 Shows the Elderly (Cognitively Normal, Alzheimer’s Disease) Store More Stimuli in Short-Term Memory than Young Adults Do

PubMed Central

Chapman, Robert M.; Gardner, Margaret N.; Mapstone, Mark; Klorman, Rafael; Porsteinsson, Anton P.; Dupree, Haley M.; Antonsdottir, Inga M.; Kamalyan, Lily

2016-01-01

Objective To determine how aging and dementia affect the brain’s initial storing of task-relevant and irrelevant information in short-term memory. Methods We used brain Event-Related Potentials (ERPs) to measure short-term memory storage (ERP component C250) in 36 Young Adults, 36 Normal Elderly, and 36 early-stage AD subjects. Participants performed the Number-Letter task, a cognitive paradigm requiring memory storage of a first relevant stimulus to compare it with a second stimulus. Results In Young Adults, C250 was more positive for the first task-relevant stimulus compared to all other stimuli. C250 in Normal Elderly and AD subjects was roughly the same to relevant and irrelevant stimuli in intratrial parts 1–3 but not 4. The AD group had lower C250 to relevant stimuli in part 1. Conclusions Both normal aging and dementia cause less differentiation of relevant from irrelevant information in initial storage. There was a large aging effect involving differences in the pattern of C250 responses of the Young Adult versus the Normal Elderly/AD groups. Also, a potential dementia effect was obtained. Significance C250 is a candidate tool for measuring short-term memory performance on a biological level, as well as a potential marker for memory changes due to normal aging and dementia. PMID:27178862

The effect of vertical and horizontal symmetry on memory for tactile patterns in late blind individuals.

PubMed

Cattaneo, Zaira; Vecchi, Tomaso; Fantino, Micaela; Herbert, Andrew M; Merabet, Lotfi B

2013-02-01

Visual stimuli that exhibit vertical symmetry are easier to remember than stimuli symmetric along other axes, an advantage that extends to the haptic modality as well. Critically, the vertical symmetry memory advantage has not been found in early blind individuals, despite their overall superior memory, as compared with sighted individuals, and the presence of an overall advantage for identifying symmetric over asymmetric patterns. The absence of the vertical axis memory advantage in the early blind may depend on their total lack of visual experience or on the effect of prolonged visual deprivation. To disentangle this issue, in this study, we measured the ability of late blind individuals to remember tactile spatial patterns that were either vertically or horizontally symmetric or asymmetric. Late blind participants showed better memory performance for symmetric patterns. An additional advantage for the vertical axis of symmetry over the horizontal one was reported, but only for patterns presented in the frontal plane. In the horizontal plane, no difference was observed between vertical and horizontal symmetric patterns, due to the latter being recalled particularly well. These results are discussed in terms of the influence of the spatial reference frame adopted during exploration. Overall, our data suggest that prior visual experience is sufficient to drive the vertical symmetry memory advantage, at least when an external reference frame based on geocentric cues (i.e., gravity) is adopted.

Increased attention and memory for beloved-related information during infatuation: behavioral and electrophysiological data.

PubMed

Langeslag, Sandra J E; Olivier, Jamie R; Köhlen, Martine E; Nijs, Ilse M; Van Strien, Jan W

2015-01-01

Emotionally salient information is well attended and remembered. It has been shown that infatuated individuals have increased attention for their beloved. It is unknown whether this attention bias generalizes to information related to the beloved. Moreover, infatuated individuals report to remember trivial things about their beloved, but this has not yet been tested empirically. In two studies, we tested whether infatuated individuals have increased attention and memory for beloved-related information. In a passive viewing task (Study 1), the late positive potential, an event-related potential (ERP) component reflecting motivated attention, was enhanced for beloved-related vs friend-related words/phrases. In a recognition task (Study 2), memory performance and the frontal and parietal ERP old/new effects, reflecting familiarity and recollection, respectively, were not enhanced for beloved-related compared with friend-related words/phrases. In free recall tasks in both studies, memory was better for beloved-related than friend-related words/phrases. This research reveals that attention and memory are enhanced for beloved-related information. These attention and memory biases for beloved-related information were not due to valence, semantic relatedness, or experience, but to arousal. To conclude, romantic love has profound effects on cognition that play a clear role in daily life. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Knowledge of Memory Aging in Students, Caregivers, and Senior Service Providers

ERIC Educational Resources Information Center

Cherry, Katie E.; Allen, Priscilla D.; Boudreaux, Emily O.; Robichaux, Mary L.; Hawley, Karri S.

2009-01-01

The Knowledge of Memory Aging Questionnaire (KMAQ) (Cherry, Brigman, Hawley, & Reese, 2003) measures laypersons' knowledge of normal memory changes in late life and pathological deficits due to nonnormative factors such as adult dementia. In this study, we examined memory knowledge in community college and university students, caregivers, and…

Prefrontal cortical GABA modulation of spatial reference and working memory.

PubMed

Auger, Meagan L; Floresco, Stan B

2014-10-31

Dysfunction in prefrontal cortex (PFC) GABA transmission has been proposed to contribute to cognitive dysfunction in schizophrenia, yet how this system regulates different cognitive and mnemonic functions remains unclear. We assessed the effects of pharmacological reduction of GABAA signaling in the medial PFC of rats on spatial reference/working memory using different versions of the radial-arm maze task. We used a massed-trials procedure to probe how PFC GABA regulates susceptibility to proactive interference. Male rats were well-trained to retrieve food from the same 4 arms of an 8-arm maze, receiving 5 trials/day (1-2 min intervals). Infusions of the GABAA receptor antagonist bicuculline (12.5-50 ng) markedly increased working and reference memory errors and response latencies. Similar treatments also impaired short-term memory on an 8-baited arm task. These effects did not appear to be due to increased susceptibility to proactive interference. In contrast, PFC inactivation via infusion of GABA agonists baclofen/muscimol did not affect reference/working memory. In comparison to the pronounced effects on the 8-arm maze tasks, PFC GABAA antagonism only causes a slight and transient decrease in accuracy on a 2-arm spatial discrimination. These findings demonstrate that prefrontal GABA hypofunction severely disrupts spatial reference and short-term memory and that disinhibition of the PFC can, in some instances, perturb memory processes not normally dependent on the frontal lobes. Moreover, these impairments closely resemble those observed in schizophrenic patients, suggesting that perturbation in PFC GABA signaling may contribute to these types of cognitive deficits associated with the disorder. © The Author 2014. Published by Oxford University Press on behalf of CINP.

Clomp

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gylenhaal, J.; Bronevetsky, G.

2007-05-25

CLOMP is the C version of the Livermore OpenMP benchmark deeloped to measure OpenMP overheads and other performance impacts due to threading (like NUMA memory layouts, memory contention, cache effects, etc.) in order to influence future system design. Current best-in-class implementations of OpenMP have overheads at least ten times larger than is required by many of our applications for effective use of OpenMP. This benchmark shows the significant negative performance impact of these relatively large overheads and of other thread effects. The CLOMP benchmark highly configurable to allow a variety of problem sizes and threading effects to be studied andmore » it carefully checks its results to catch many common threading errors. This benchmark is expected to be included as part of the Sequoia Benchmark suite for the Sequoia procurement.« less

Study of self-compliance behaviors and internal filament characteristics in intrinsic SiO{sub x}-based resistive switching memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Yao-Feng, E-mail: yfchang@utexas.edu; Zhou, Fei; Chen, Ying-Chen

2016-01-18

Self-compliance characteristics and reliability optimization are investigated in intrinsic unipolar silicon oxide (SiO{sub x})-based resistive switching (RS) memory using TiW/SiO{sub x}/TiW device structures. The program window (difference between SET voltage and RESET voltage) is dependent on external series resistance, demonstrating that the SET process is due to a voltage-triggered mechanism. The program window has been optimized for program/erase disturbance immunity and reliability for circuit-level applications. The SET and RESET transitions have also been characterized using a dynamic conductivity method, which distinguishes the self-compliance behavior due to an internal series resistance effect (filament) in SiO{sub x}-based RS memory. By using amore » conceptual “filament/resistive gap (GAP)” model of the conductive filament and a proton exchange model with appropriate assumptions, the internal filament resistance and GAP resistance can be estimated for high- and low-resistance states (HRS and LRS), and are found to be independent of external series resistance. Our experimental results not only provide insights into potential reliability issues but also help to clarify the switching mechanisms and device operating characteristics of SiO{sub x}-based RS memory.« less

Mild cognitive impairment: Profile of a cohort from a private sector memory clinic.

PubMed

Srinivasan, Srikanth

2014-07-01

Private hospital memory clinics might see a different clientele than university or academic institutes due to referral biases. To characterize the profile of patients with mild cognitive impairment (MCI) from a private sector memory clinic. MCI was diagnosed according to revised clinical criteria of Petersen et al. For a subset of patients with MCI medial temporal atrophy and cerebral small vessel disease (white matter lesions and lacunes) were rated on magnetic resonance imaging (MRI) scans and analyzed for their contribution towards cognitive impairment. Subjects with MCI formed one-third (113/371) of this memory clinic sample from a private hospital. MCI could be effectively diagnosed and subtyped using a brief cognitive scale (Concise Cognitive Test (CONCOG)). The amnestic MCI (single and multiple domains) subtype comprised the majority of cases with MCI. In a subsample of 33 patients, lacunar infarcts were more common than white matter lesions and hippocampal atrophy and were inversely associated with verbal fluency. MCI may be more commonly encountered in private hospital settings probably due to early referrals. It is possible to diagnose and subtype MCI using a brief cognitive instrument such as the CONCOG. In this sample, lacunar infarcts were more commonly encountered than medial temporal atrophy in such patients.

Minimal effects of visual memory training on the auditory performance of adult cochlear implant users

PubMed Central

Oba, Sandra I.; Galvin, John J.; Fu, Qian-Jie

2014-01-01

Auditory training has been shown to significantly improve cochlear implant (CI) users’ speech and music perception. However, it is unclear whether post-training gains in performance were due to improved auditory perception or to generally improved attention, memory and/or cognitive processing. In this study, speech and music perception, as well as auditory and visual memory were assessed in ten CI users before, during, and after training with a non-auditory task. A visual digit span (VDS) task was used for training, in which subjects recalled sequences of digits presented visually. After the VDS training, VDS performance significantly improved. However, there were no significant improvements for most auditory outcome measures (auditory digit span, phoneme recognition, sentence recognition in noise, digit recognition in noise), except for small (but significant) improvements in vocal emotion recognition and melodic contour identification. Post-training gains were much smaller with the non-auditory VDS training than observed in previous auditory training studies with CI users. The results suggest that post-training gains observed in previous studies were not solely attributable to improved attention or memory, and were more likely due to improved auditory perception. The results also suggest that CI users may require targeted auditory training to improve speech and music perception. PMID:23516087

Visual short-term memory load strengthens selective attention.

PubMed

Roper, Zachary J J; Vecera, Shaun P

2014-04-01

Perceptual load theory accounts for many attentional phenomena; however, its mechanism remains elusive because it invokes underspecified attentional resources. Recent dual-task evidence has revealed that a concurrent visual short-term memory (VSTM) load slows visual search and reduces contrast sensitivity, but it is unknown whether a VSTM load also constricts attention in a canonical perceptual load task. If attentional selection draws upon VSTM resources, then distraction effects-which measure attentional "spill-over"-will be reduced as competition for resources increases. Observers performed a low perceptual load flanker task during the delay period of a VSTM change detection task. We observed a reduction of the flanker effect in the perceptual load task as a function of increasing concurrent VSTM load. These findings were not due to perceptual-level interactions between the physical displays of the two tasks. Our findings suggest that perceptual representations of distractor stimuli compete with the maintenance of visual representations held in memory. We conclude that access to VSTM determines the degree of attentional selectivity; when VSTM is not completely taxed, it is more likely for task-irrelevant items to be consolidated and, consequently, affect responses. The "resources" hypothesized by load theory are at least partly mnemonic in nature, due to the strong correspondence they share with VSTM capacity.

The Difference between Anxiolytic and Anxiogenic Effects Induced by Acute and Chronic Alcohol Exposure and Changes in Associative Learning and Memory Based on Color Preference and the Cause of Parkinson-Like Behaviors in Zebrafish.

PubMed

Li, Xiang; Li, Xu; Li, Yi-Xiang; Zhang, Yuan; Chen, Di; Sun, Ming-Zhu; Zhao, Xin; Chen, Dong-Yan; Feng, Xi-Zeng

2015-01-01

We describe an interdisciplinary comparison of the effects of acute and chronic alcohol exposure in terms of their disturbance of light, dark and color preferences and the occurrence of Parkinson-like behavior in zebrafish through computer visual tracking, data mining, and behavioral and physiological analyses. We found that zebrafish in anxiolytic and anxious states, which are induced by acute and chronic repeated alcohol exposure, respectively, display distinct emotional reactions in light/dark preference tests as well as distinct learning and memory abilities in color-enhanced conditional place preference (CPP) tests. Additionally, compared with the chronic alcohol (1.0%) treatment, acute alcohol exposure had a significant, dose-dependent effect on anxiety, learning and memory (color preference) as well as locomotive activities. Acute exposure doses (0.5%, 1.0%, and 1.5%) generated an "inverted V" dose-dependent pattern in all of the behavioral parameters, with 1.0% having the greatest effect, while the chronic treatment had a moderate effect. Furthermore, by measuring locomotive activity, learning and memory performance, the number of dopaminergic neurons, tyrosine hydroxylase expression, and the change in the photoreceptors in the retina, we found that acute and chronic alcohol exposure induced varying degrees of Parkinson-like symptoms in zebrafish. Taken together, these results illuminated the behavioral and physiological mechanisms underlying the changes associated with learning and memory and the cause of potential Parkinson-like behaviors in zebrafish due to acute and chronic alcohol exposure.

The Difference between Anxiolytic and Anxiogenic Effects Induced by Acute and Chronic Alcohol Exposure and Changes in Associative Learning and Memory Based on Color Preference and the Cause of Parkinson-Like Behaviors in Zebrafish

PubMed Central

Zhang, Yuan; Chen, Di; Sun, Ming-Zhu; Zhao, Xin; Chen, Dong-Yan; Feng, Xi-Zeng

2015-01-01

We describe an interdisciplinary comparison of the effects of acute and chronic alcohol exposure in terms of their disturbance of light, dark and color preferences and the occurrence of Parkinson-like behavior in zebrafish through computer visual tracking, data mining, and behavioral and physiological analyses. We found that zebrafish in anxiolytic and anxious states, which are induced by acute and chronic repeated alcohol exposure, respectively, display distinct emotional reactions in light/dark preference tests as well as distinct learning and memory abilities in color-enhanced conditional place preference (CPP) tests. Additionally, compared with the chronic alcohol (1.0%) treatment, acute alcohol exposure had a significant, dose-dependent effect on anxiety, learning and memory (color preference) as well as locomotive activities. Acute exposure doses (0.5%, 1.0%, and 1.5%) generated an “inverted V” dose-dependent pattern in all of the behavioral parameters, with 1.0% having the greatest effect, while the chronic treatment had a moderate effect. Furthermore, by measuring locomotive activity, learning and memory performance, the number of dopaminergic neurons, tyrosine hydroxylase expression, and the change in the photoreceptors in the retina, we found that acute and chronic alcohol exposure induced varying degrees of Parkinson-like symptoms in zebrafish. Taken together, these results illuminated the behavioral and physiological mechanisms underlying the changes associated with learning and memory and the cause of potential Parkinson-like behaviors in zebrafish due to acute and chronic alcohol exposure. PMID:26558894

Potential roles of cholinergic modulation in the neural coding of location and movement speed

PubMed Central

Dannenberg, Holger; Hinman, James R.; Hasselmo, Michael E.

2016-01-01

Behavioral data suggest that cholinergic modulation may play a role in certain aspects of spatial memory, and neurophysiological data demonstrate neurons that fire in response to spatial dimensions, including grid cells and place cells that respond on the basis of location and running speed. These neurons show firing responses that depend upon the visual configuration of the environment, due to coding in visually-responsive regions of the neocortex. This review focuses on the physiological effects of acetylcholine that may influence the sensory coding of spatial dimensions relevant to behavior. In particular, the local circuit effects of acetylcholine within the cortex regulate the influence of sensory input relative to internal memory representations, via presynaptic inhibition of excitatory and inhibitory synaptic transmission, and the modulation of intrinsic currents in cortical excitatory and inhibitory neurons. In addition, circuit effects of acetylcholine regulate the dynamics of cortical circuits including oscillations at theta and gamma frequencies. These effects of acetylcholine on local circuits and network dynamics could underlie the role of acetylcholine in coding of spatial information for the performance of spatial memory tasks. PMID:27677935

Differential effects of white noise in cognitive and perceptual tasks

PubMed Central

Herweg, Nora A.; Bunzeck, Nico

2015-01-01

Beneficial effects of noise on higher cognition have recently attracted attention. Hypothesizing an involvement of the mesolimbic dopamine system and its functional interactions with cortical areas, the current study aimed to demonstrate a facilitation of dopamine-dependent attentional and mnemonic functions by externally applying white noise in five behavioral experiments including a total sample of 167 healthy human subjects. During working memory, acoustic white noise impaired accuracy when presented during the maintenance period (Experiments 1–3). In a reward based long-term memory task, white noise accelerated perceptual judgments for scene images during encoding but left subsequent recognition memory unaffected (Experiment 4). In a modified Posner task (Experiment 5), the benefit due to white noise in attentional orienting correlated weakly with reward dependence, a personality trait that has been associated with the dopaminergic system. These results suggest that white noise has no general effect on cognitive functions. Instead, they indicate differential effects on perception and cognition depending on a variety of factors such as task demands and timing of white noise presentation. PMID:26579024

The Memory Aid study: protocol for a randomized controlled clinical trial evaluating the effect of computer-based working memory training in elderly patients with mild cognitive impairment (MCI)

PubMed Central

2014-01-01

Background Mild cognitive impairment (MCI) is a condition characterized by memory problems that are more severe than the normal cognitive changes due to aging, but less severe than dementia. Reduced working memory (WM) is regarded as one of the core symptoms of an MCI condition. Recent studies have indicated that WM can be improved through computer-based training. The objective of this study is to evaluate if WM training is effective in improving cognitive function in elderly patients with MCI, and if cognitive training induces structural changes in the white and gray matter of the brain, as assessed by structural MRI. Methods/Designs The proposed study is a blinded, randomized, controlled trail that will include 90 elderly patients diagnosed with MCI at a hospital-based memory clinic. The participants will be randomized to either a training program or a placebo version of the program. The intervention is computerized WM training performed for 45 minutes of 25 sessions over 5 weeks. The placebo version is identical in duration but is non-adaptive in the difficulty level of the tasks. Neuropsychological assessment and structural MRI will be performed before and 1 month after training, and at a 5-month folllow-up. Discussion If computer-based training results in positive changes to memory functions in patients with MCI this may represent a new, cost-effective treatment for MCI. Secondly, evaluation of any training-induced structural changes to gray or white matter will improve the current understanding of the mechanisms behind effective cognitive interventions in patients with MCI. Trial registration ClinicalTrials.gov NCT01991405. November 18, 2013. PMID:24886034

The Memory Aid study: protocol for a randomized controlled clinical trial evaluating the effect of computer-based working memory training in elderly patients with mild cognitive impairment (MCI).

PubMed

Flak, Marianne M; Hernes, Susanne S; Chang, Linda; Ernst, Thomas; Douet, Vanessa; Skranes, Jon; Løhaugen, Gro C C

2014-05-03

Mild cognitive impairment (MCI) is a condition characterized by memory problems that are more severe than the normal cognitive changes due to aging, but less severe than dementia. Reduced working memory (WM) is regarded as one of the core symptoms of an MCI condition. Recent studies have indicated that WM can be improved through computer-based training. The objective of this study is to evaluate if WM training is effective in improving cognitive function in elderly patients with MCI, and if cognitive training induces structural changes in the white and gray matter of the brain, as assessed by structural MRI. The proposed study is a blinded, randomized, controlled trail that will include 90 elderly patients diagnosed with MCI at a hospital-based memory clinic. The participants will be randomized to either a training program or a placebo version of the program. The intervention is computerized WM training performed for 45 minutes of 25 sessions over 5 weeks. The placebo version is identical in duration but is non-adaptive in the difficulty level of the tasks. Neuropsychological assessment and structural MRI will be performed before and 1 month after training, and at a 5-month folllow-up. If computer-based training results in positive changes to memory functions in patients with MCI this may represent a new, cost-effective treatment for MCI. Secondly, evaluation of any training-induced structural changes to gray or white matter will improve the current understanding of the mechanisms behind effective cognitive interventions in patients with MCI. ClinicalTrials.gov NCT01991405. November 18, 2013.

Effects of gender and executive function on visuospatial working memory in adult obsessive-compulsive disorder.

PubMed

Martoni, Riccardo Maria; Salgari, Giulia; Galimberti, Elisa; Cavallini, Maria Cristina; O'Neill, Joseph

2015-12-01

Visuospatial working memory (VSWM) is the ability of the brain to transiently store and manipulate visual information. VSWM deficiencies have been reported in obsessive-compulsive disorder (OCD), but not consistently, perhaps due to variability in task design and clinical patient factors. To explore this variability, this study assessed effects of the design factors task difficulty and executive organizational strategy and of the clinical factors gender, OCD symptom dimension, and duration of illness on VSWM in OCD. The CANTAB spatial working memory, spatial recognition memory, delayed matching to sample, and stop signal tasks were administered to 42 adult OCD patients and 42 age- and sex-matched healthy controls. Aims were to detect a possible VSWM deficit in the OCD sample, to evaluate influences of the above task and patient factors, to determine the specificity of the deficit to the visuospatial subdomain, and to examine effects of sustained attention as potential neurocognitive confound. We confirmed previous findings of a VSWM deficit in OCD that was more severe for greater memory load (task difficulty) and that was affected by task strategy (executive function). We failed to demonstrate significant deficits in neighboring or confounding neurocognitive subdomains (visual object recognition or visual object short-term memory, sustained attention). Notably, the VSWM deficit was only significant for female patients, adding to evidence for sexual dimorphism in OCD. Again as in prior work, more severe OCD symptoms in the symmetry dimension (but no other dimension) significantly negatively impacted VSWM. Duration of illness had no significant effect on VSWM. VSWM deficits in OCD appear more severe with higher task load and may be mediated through poor task strategy. Such deficits may present mainly in female patients and in (male and female) patients with symmetry symptoms.

Early effects of modern electroconvulsive therapy on subjective memory in patients with mania or depression

PubMed Central

Bag, Sevda; Canbek, Ozge; Atagun, Ilhan Murat; Kutlar, Tarik Mehmet

2016-01-01

Context: Although electroconvulsive therapy (ECT) is considered a very effective tool for the treatment of psychiatric diseases, memory disturbances are among the most important adverse effects. Aims: This study aimed to assess prospectively early subjective memory complaints in depressive and manic patients due to bilateral, brief-pulse ECT, at different stages of the treatment, compare the associations between psychiatric diagnosis, sociodemographic characteristics, and ECT characteristics. Settings and Design: This prospective study was done with patients undergoing ECT between November 2008 and April 2009 at a tertiary care psychiatry hospital of 2000 beds. Materials and Methods: A total of 140 patients, scheduled for ECT with a diagnosis of bipolar disorder (depressive or manic episode) or unipolar depression according to Diagnostic and Statistical Manual of Mental Disorders IV diagnostic criteria, were included in the study and invited to complete the Squire Subjective Memory Questionnaire (SSMQ) before ECT, after the first and third sessions and end of ECT treatment. Statistical Analysis: Mean values were compared with the Kruskal–Wallis test and comparison of the longitudinal data was performed with a nonparametric longitudinal data analysis method, F1_LD_F1 design. Results: SSMQ scores of the patients before ECT were zero. SSMQ scores showed a decrease after the first and third ECT sessions and before discharge, showing a memory disturbance after ECT and were significantly less severe in patients with mania in comparison to those with depression. Conclusions: These findings suggest an increasing degree of subjective memory complaints with bilateral brief-pulse ECT parallel to the increasing number of ECT sessions. PMID:27385854

Competitive short-term and long-term memory processes in spatial habituation.

PubMed

Sanderson, David J; Bannerman, David M

2011-04-01

Exposure to a spatial location leads to habituation of exploration such that, in a novelty preference test, rodents subsequently prefer exploring a novel location to the familiar location. According to Wagner's (1981) theory of memory, short-term and long-term habituation are caused by separate and sometimes opponent processes. In the present study, this dual-process account of memory was tested. Mice received a series of exposure training trials to a location before receiving a novelty preference test. The novelty preference was greater when tested after a short, rather than a long, interval. In contrast, the novelty preference was weaker when exposure training trials were separated by a short, rather than a long interval. Furthermore, it was found that long-term habituation was determined by the independent effects of the amount of exposure training and the number of exposure training trials when factors such as the intertrial interval and the cumulative intertrial interval were controlled. A final experiment demonstrated that a long-term reduction of exploration could be caused by a negative priming effect due to associations formed during exploration. These results provide evidence against a single-process account of habituation and suggest that spatial habituation is determined by both short-term, recency-based memory and long-term, incrementally strengthened memory.

FAST TRACK COMMUNICATION: Eight-logic memory cell based on multiferroic junctions

NASA Astrophysics Data System (ADS)

Yang, Feng; Zhou, Y. C.; Tang, M. H.; Liu, Fen; Ma, Ying; Zheng, X. J.; Zhao, W. F.; Xu, H. Y.; Sun, Z. H.

2009-04-01

A model is proposed for a device combining a multiferroic tunnel junction with a magnetoelectric (ME) film in which the magnetic configuration is controlled by the electric field. Calculations embodying the Green's function approach show that the magnetic polarization can be switched on and off by an electric field in the ME film due to the effect of elastic coupling interaction. Using a model including the spin-filter effect and screening of polarization charges, we have produced eight logic states of tunnelling resistance in the tunnel junction and have obtained corresponding laws that control them. The results provide some insights into the realization of an eight-logic memory cell.

Experimental study on Response Parameters of Ni-rich NiTi Shape Memory Alloy during Wire Electric Discharge Machining

NASA Astrophysics Data System (ADS)

Bisaria, Himanshu; Shandilya, Pragya

2018-03-01

Nowadays NiTi SMAs are gaining more prominence due to their unique properties such as superelasticity, shape memory effect, high fatigue strength and many other enriched physical and mechanical properties. The current studies explore the effect of machining parameters namely, peak current (Ip), pulse off time (TOFF), and pulse on time (TON) on wire wear ratio (WWR), and dimensional deviation (DD) in WEDM. It was found that high discharge energy was mainly ascribed to high WWR and DD. The WWR and DD increased with the increase in pulse on time and peak current whereas high pulse off time was favourable for low WWR and DD.

Eye Movements and Visual Memory for Scenes

DTIC Science & Technology

2005-01-01

Scene memory research has demonstrated that the memory representation of a semantically inconsistent object in a scene is more detailed and/or complete... memory during scene viewing, then changes to semantically inconsistent objects (which should be represented more com- pletely) should be detected more... semantic description. Due to the surprise nature of the visual memory test, any learning that occurred during the search portion of the experiment was

Auditory memory function in expert chess players

PubMed Central

Fattahi, Fariba; Geshani, Ahmad; Jafari, Zahra; Jalaie, Shohreh; Salman Mahini, Mona

2015-01-01

Background: Chess is a game that involves many aspects of high level cognition such as memory, attention, focus and problem solving. Long term practice of chess can improve cognition performances and behavioral skills. Auditory memory, as a kind of memory, can be influenced by strengthening processes following long term chess playing like other behavioral skills because of common processing pathways in the brain. The purpose of this study was to evaluate the auditory memory function of expert chess players using the Persian version of dichotic auditory-verbal memory test. Methods: The Persian version of dichotic auditory-verbal memory test was performed for 30 expert chess players aged 20-35 years and 30 non chess players who were matched by different conditions; the participants in both groups were randomly selected. The performance of the two groups was compared by independent samples t-test using SPSS version 21. Results: The mean score of dichotic auditory-verbal memory test between the two groups, expert chess players and non-chess players, revealed a significant difference (p≤ 0.001). The difference between the ears scores for expert chess players (p= 0.023) and non-chess players (p= 0.013) was significant. Gender had no effect on the test results. Conclusion: Auditory memory function in expert chess players was significantly better compared to non-chess players. It seems that increased auditory memory function is related to strengthening cognitive performances due to playing chess for a long time. PMID:26793666

False Memories Seconds Later: The Rapid and Compelling Onset of Illusory Recognition

ERIC Educational Resources Information Center

Flegal, Kristin E.; Atkins, Alexandra S.; Reuter-Lorenz, Patricia A.

2010-01-01

Distortions of long-term memory (LTM) in the converging associates task are thought to arise from semantic associative processes and monitoring failures due to degraded verbatim and/or contextual memory. Sensory-based coding is traditionally considered more prevalent than meaning-based coding in short-term memory (STM), whereas the converse is…

[Episodic autobiographical memory in depression: a review].

PubMed

Lemogne, C; Piolino, P; Jouvent, R; Allilaire, J-F; Fossati, P

2006-10-01

Autobiographical memory and personal identity (self) are linked by a reciprocal relationship. Autobiographical memory is critical for both grounding and changing the self. Individuals' current self-views, beliefs, and goals influence their recollections of the past. According to Tulving, episodic memory is characterized by autonoetic consciousness, which is associated with a sense of the self in the past (emotions and goals) and mental reliving of an experience. Its close relationship with self and emotion strongly involves episodic autobiographical memory in the psychopathology of depression. However, due to methodological and conceptual issues, little attention has been paid to episodic autobiographical memory in depression. Since the seminal work of Williams et al. 15 years ago, there is now growing interest around this issue. We reviewed the evidence for three major features of autobiographical memory functioning in depression: an increase in general memory retrieval (overgenerality), a mood-congruent memory effect and the high occurrence of intrusive memories of stressful events. Although it was first observed among suicidal patients, overgenerality is actually associated with both depression and post-traumatic stress disorder. Overgenerality is not associated with anxious disorders other than post-traumatic stress disorder, obsessive-compulsive disorder, or borderline personality disorder. Most of controlled studies carried out on autobiographical memory in depression rely on the Williams' Autobiographical Memory Test (AMT). When presented with positive and negative cue words and asked to retrieve specific personal events, depressed patients (unlike matched controls) are less specific in their memories. They tend to recall repeated events (categorical overgeneral memories) rather than single episodes (specific memories). Overgenerality in depression is: 1) more evident with positive than with negative events (mood-congruent memory effect); 2) related to avoidance of intrusive memories; 3) quite stable over time, ie, remaining after remission; and 4) related to short-term prognosis in depression. Although it is not clear whether overgenerality is a cause or an effect of depression, there is some evidence to suggest that overgenerality is a trait marker indicating vulnerability to persistent depression. Mood-congruent effect, a well-known effect in depression, has been addressed in both autobio-graphical and non-autobiographical memory. Depressed patients spontaneously recall more negative than positive memories. With the AMT, depressed patients take longer to respond to positive than to negative cues, whereas controls do the opposite. Depression is also associated with a high occurrence of spontaneous intrusive memories of stressful life events. Studies found intrusions and related avoidance, as measured by the Impact of Event Scale, to be positively correlated with overgenerality, whereas there was no direct link between performance on the Autobiographical Memory Test and stressful life events per se. Both Williams' mnemonic interlock model and Conway's self-memory system are useful models to address the complexity of findings regarding autobiographical memory and depression. According to Williams, repeated avoidance of stressful memories leads depressed patients to have an autobiographical memory functioning characterized by iterative retrievals of categorical overgeneral memories, producing an enduring overgeneral retrieval style. According to Conway, the recollection of autobiographical memories requires a retrieval process that provides access to sensory/perceptual event-specific knowledge (ie perceptions and feelings) via a personal semantic knowledge base (ie lifetime periods and generic events). This retrieval process (generative retrieval mode) relies on both executive functioning and current self-view, namely the working-self. Spontaneous memories, usually vivid, result from a direct retrieval mode in which event-specific knowledge is directly triggered. In line with this model, episodic autobiographical memory impairment in state depression may arise from the working self rather than from autobiographical knowledge. The mood-congruent effect may be explained by the current (depressed) self. The high occurrence of intrusive memories may be explained by lack of executive control during direct retrieval. Overgenerality may rely on the interaction of both executive dysfunction and current (depressed) self, within the working-self, during generative retrieval. Our review suggests that further evidence is needed to address the relationship between executive functioning, self and autobiographical memory in depression.

Multi-floor cascading ferroelectric nanostructures: multiple data writing-based multi-level non-volatile memory devices

NASA Astrophysics Data System (ADS)

Hyun, Seung; Kwon, Owoong; Lee, Bom-Yi; Seol, Daehee; Park, Beomjin; Lee, Jae Yong; Lee, Ju Hyun; Kim, Yunseok; Kim, Jin Kon

2016-01-01

Multiple data writing-based multi-level non-volatile memory has gained strong attention for next-generation memory devices to quickly accommodate an extremely large number of data bits because it is capable of storing multiple data bits in a single memory cell at once. However, all previously reported devices have failed to store a large number of data bits due to the macroscale cell size and have not allowed fast access to the stored data due to slow single data writing. Here, we introduce a novel three-dimensional multi-floor cascading polymeric ferroelectric nanostructure, successfully operating as an individual cell. In one cell, each floor has its own piezoresponse and the piezoresponse of one floor can be modulated by the bias voltage applied to the other floor, which means simultaneously written data bits in both floors can be identified. This could achieve multi-level memory through a multiple data writing process.Multiple data writing-based multi-level non-volatile memory has gained strong attention for next-generation memory devices to quickly accommodate an extremely large number of data bits because it is capable of storing multiple data bits in a single memory cell at once. However, all previously reported devices have failed to store a large number of data bits due to the macroscale cell size and have not allowed fast access to the stored data due to slow single data writing. Here, we introduce a novel three-dimensional multi-floor cascading polymeric ferroelectric nanostructure, successfully operating as an individual cell. In one cell, each floor has its own piezoresponse and the piezoresponse of one floor can be modulated by the bias voltage applied to the other floor, which means simultaneously written data bits in both floors can be identified. This could achieve multi-level memory through a multiple data writing process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07377d

Drinking hydrogen water ameliorated cognitive impairment in senescence-accelerated mice.

PubMed

Gu, Yeunhwa; Huang, Chien-Sheng; Inoue, Tota; Yamashita, Takenori; Ishida, Torao; Kang, Ki-Mun; Nakao, Atsunori

2010-05-01

Hydrogen has been reported to have neuron protective effects due to its antioxidant properties, but the effects of hydrogen on cognitive impairment due to senescence-related brain alterations and the underlying mechanisms have not been characterized. In this study, we investigated the efficacies of drinking hydrogen water for prevention of spatial memory decline and age-related brain alterations using senescence-accelerated prone mouse 8 (SAMP8), which exhibits early aging syndromes including declining learning ability and memory. However, treatment with hydrogen water for 30 days prevented age-related declines in cognitive ability seen in SAMP8 as assessed by a water maze test and was associated with increased brain serotonin levels and elevated serum antioxidant activity. In addition, drinking hydrogen water for 18 weeks inhibited neurodegeneration in hippocampus, while marked loss of neurons was noted in control, aged brains of mice receiving regular water. On the basis of our results, hydrogen water merits further investigation for possible therapeutic/preventative use for age-related cognitive disorders.

Does the generation effect occur for pictures?

PubMed

Kinjo, H; Snodgrass, J G

2000-01-01

The generation effect is the finding that self-generated stimuli are recalled and recognized better than read stimuli. The effect has been demonstrated primarily with words. This article examines the effect for pictures in two experiments: Subjects named complete pictures (name condition) and fragmented pictures (generation condition). In Experiment 1, memory was tested in 3 explicit tasks: free recall, yes/no recognition, and a source-monitoring task on whether each picture was complete or fragmented (the complete/incomplete task). The generation effect was found for all 3 tasks. However, in the recognition and source-monitoring tasks, the generation effect was observed only in the generation condition. We hypothesized that absence of the effect in the name condition was due to the sensory or process match effect between study and test pictures and the superior identification of pictures in the name condition. Therefore, stimuli were changed from pictures to their names in Experiment 2. Memory was tested in the recognition task, complete/incomplete task, and second source-monitoring task (success/failure) on whether each picture had been identified successfully. The generation effect was observed for all 3 tasks. These results suggest that memory of structural and semantic characteristics and of success in identification of generated pictures may contribute to the generation effect.

Semantic and Syntactic Interference in Sentence Comprehension: A Comparison of Working Memory Models

PubMed Central

Tan, Yingying; Martin, Randi C.; Van Dyke, Julie A.

2017-01-01

This study investigated the nature of the underlying working memory system supporting sentence processing through examining individual differences in sensitivity to retrieval interference effects during sentence comprehension. Interference effects occur when readers incorrectly retrieve sentence constituents which are similar to those required during integrative processes. We examined interference arising from a partial match between distracting constituents and syntactic and semantic cues, and related these interference effects to performance on working memory, short-term memory (STM), vocabulary, and executive function tasks. For online sentence comprehension, as measured by self-paced reading, the magnitude of individuals' syntactic interference effects was predicted by general WM capacity and the relation remained significant when partialling out vocabulary, indicating that the effects were not due to verbal knowledge. For offline sentence comprehension, as measured by responses to comprehension questions, both general WM capacity and vocabulary knowledge interacted with semantic interference for comprehension accuracy, suggesting that both general WM capacity and the quality of semantic representations played a role in determining how well interference was resolved offline. For comprehension question reaction times, a measure of semantic STM capacity interacted with semantic but not syntactic interference. However, a measure of phonological capacity (digit span) and a general measure of resistance to response interference (Stroop effect) did not predict individuals' interference resolution abilities in either online or offline sentence comprehension. The results are discussed in relation to the multiple capacities account of working memory (e.g., Martin and Romani, 1994; Martin and He, 2004), and the cue-based retrieval parsing approach (e.g., Lewis et al., 2006; Van Dyke et al., 2014). While neither approach was fully supported, a possible means of reconciling the two approaches and directions for future research are proposed. PMID:28261133

Memory Before and After Sleep in Patients with Moderate Obstructive Sleep Apnea

PubMed Central

Kloepfer, Corinna; Riemann, Dieter; Nofzinger, Eric A.; Feige, Bernd; Unterrainer, Josef; O'Hara, Ruth; Sorichter, Stephan; Nissen, Christoph

2009-01-01

Objective: The aim of this study was to investigate the effects of obstructive sleep apnea (OSA) on procedural and declarative memory encoding in the evening prior to sleep, on memory consolidation during subsequent sleep, and on retrieval in the morning after sleep. Methods: Memory performance (procedural mirror-tracing task, declarative visual and verbal memory task) and general neuropsychological performance were assessed before and after one night of polysomnographic monitoring in 15 patients with moderate OSA and 20 age-, sex-, and IQ-matched healthy subjects. Results: Encoding levels prior to sleep were similar across groups for all tasks. Conventional analyses of averaged mirror tracing performance suggested a significantly reduced overnight improvement in OSA patients. Single trial analyses, however, revealed that this effect was due to significantly flattened learning curves in the evening and morning session in OSA patients. OSA patients showed a significantly lower verbal retention rate and a non-significantly reduced visual retention rate after sleep compared to healthy subjects. Polysomnography revealed a significantly reduced REM density, increased frequency of micro-arousals, elevated apnea-hypopnea index, and subjectively disturbed sleep quality in OSA patients compared to healthy subjects. Conclusions: The results suggest that moderate OSA is associated with a significant impairment of procedural and verbal declarative memory. Future work is needed to further determine the contribution of structural or functional alterations in brain circuits relevant for memory, and to test whether OSA treatment improves or normalizes the observed deficits in learning. Citation: Kloepfer C; Riemann D; Nofzinger EA; Feige B; Unterrainer J; O'Hara R; Sorichter S; Nissen C. Memory before and after sleep in patients with moderate obstructive sleep apnea. J Clin Sleep Med 2009;5(6):540-548. PMID:20465021

Effects of 5-HT and insulin on learning and memory formation in food-deprived snails.

PubMed

Aonuma, Hitoshi; Totani, Yuki; Kaneda, Mugiho; Nakamura, Ryota; Watanabe, Takayuki; Hatakeyama, Dai; Dyakonova, Varvara E; Lukowiak, Ken; Ito, Etsuro

2018-02-01

The pond snail Lymnaea stagnalis learns conditioned taste aversion (CTA) and consolidates it into long-term memory (LTM). How well they learn and form memory depends on the degree of food deprivation. Serotonin (5-HT) plays an important role in mediating feeding, and insulin enhances the memory consolidation process following CTA training. However, the relationship between these two signaling pathways has not been addressed. We measured the 5-HT content in the central nervous system (CNS) of snails subjected to different durations of food deprivation. One-day food-deprived snails, which exhibit the best learning and memory, had the lowest 5-HT content in the CNS, whereas 5-day food-deprived snails, which do not learn, had a high 5-HT content. Immersing 1-day food-deprived snails in 5-HT impaired learning and memory by causing an increase in 5-HT content, and that the injection of insulin into these snails reversed this impairment. We conclude that insulin rescues the CTA deficit and this may be due to a decrease in the 5-HT content in the CNS of Lymnaea. Copyright © 2018 Elsevier Inc. All rights reserved.

Inhibition of transcription and translation in the striatum after memory reactivation: Lack of evidence of reconsolidation.

PubMed

Prado-Alcalá, Roberto A; Medina, Andrea Cristina; Bello-Medina, Paola C; Quirarte, Gina L

2017-07-01

It has been found that interference with neural activity after a consolidated memory is retrieved produces an amnestic state; this has been taken has indicative of destabilization of the memory trace that would have been produced by a process of reconsolidation (allowing for maintenance of the original trace). However, a growing body of evidence shows that this is not a reliable effect, and that it is dependent upon some experimental conditions, such as the age of the memory, memory reactivation procedures, the predictability of the reactivation stimulus, and strength of training. In some instances, where post-retrieval treatments induce a retention deficit (which would be suggestive of interference with reconsolidation), memory is rescued by simple passing of time or by repeated retention tests. We now report that post-training and post-retrieval inhibition of transcription and translation in dorsal striatum, a structure where both of these manipulations have not been studied, produce interference with consolidation and a transitory retention deficit, respectively. These results do not give support to the reconsolidation hypothesis and lead to the conclusion that the post-activation deficiencies are due to interference with retrieval of information. Copyright © 2016 Elsevier Inc. All rights reserved.

Pre-dementia memory impairment is associated with white matter tract affection.

PubMed

Grambaite, Ramune; Reinvang, Ivar; Selnes, Per; Fjell, Anders M; Walhovd, Kristine B; Stenset, Vidar; Fladby, Tormod

2011-01-01

Mild cognitive impairment (MCI), especially amnestic, often represents pre-dementia Alzheimer's disease, characterized by medial temporal lobe atrophy, while white matter (WM) alterations are insufficiently described. We analyze both cortical morphometric and WM diffusivity differences in amnestic versus non-amnestic subtypes and ask if memory and WM tract affection are related independently of cortical atrophy. Forty-nine patients from a university-hospital based memory clinic with a score of 3 on the Global Deterioration Scale aged 43-77 years (45% female) were included. Two neuropsychologists have classified cases as amnestic (aMCI), non-amnestic (naMCI), or less advanced (laMCI), not satisfying criteria for aMCI/naMCI. Diffusion tensor imaging (DTI) WM tract and morphometric data of the temporal-parietal memory network were compared among patient subtypes and related to story, word list, and visual memory. WM radial and mean diffusivity (DR and MD), underlying the entorhinal cortex, were higher in aMCI compared with laMCI. WM DR and MD, underlying the entorhinal, parahippocampal, and middle temporal cortex, explained unique variance in word list and story memory, and this was not due to secondary effects of cortical thinning. DTI may thus potentially aid diagnosis in early disease stages. ).

Thickness effect of nickel oxide thin films on associated solution-processed write-once-read-many-times memory devices

NASA Astrophysics Data System (ADS)

Wang, Xiao Lin; Liu, Zhen; Wen, Chao; Liu, Yang; Wang, Hong Zhe; Chen, T. P.; Zhang, Hai Yan

2018-06-01

With self-prepared nickel acetate based solution, NiO thin films with different thicknesses have been fabricated by spin coating followed by thermal annealing. By forming a two-terminal Ag/NiO/ITO structure on glass, write-once-read-many-times (WORM) memory devices are realized. The WORM memory behavior is based on a permanent switching from an initial high-resistance state (HRS) to an irreversible low-resistance state (LRS) under the application of a writing voltage, due to the formation of a solid bridge across Ag and ITO electrodes by conductive filaments (CFs). The memory performance is investigated as a function of the NiO film thickness, which is determined by the number of spin-coated NiO layers. For devices with 4 and 6 NiO layers, data retention up to 104 s and endurance of 103 reading operations in the measurement range have been obtained with memory window maintained above four orders for both HRS and LRS. Before and after writing, the devices show the hopping and ohmic conduction behaviors, respectively, confirming that the CF formation could be the mechanism responsible for writing in the WORM memory devices.

Circulating Estradiol Regulates Brain-Derived Estradiol via Actions at GnRH Receptors to Impact Memory in Ovariectomized Rats.

PubMed

Nelson, Britta S; Black, Katelyn L; Daniel, Jill M

2016-01-01

Systemic estradiol treatment enhances hippocampus-dependent memory in ovariectomized rats. Although these enhancements are traditionally thought to be due to circulating estradiol, recent data suggest these changes are brought on by hippocampus-derived estradiol, the synthesis of which depends on gonadotropin-releasing hormone (GnRH) activity. The goal of the current work is to test the hypothesis that peripheral estradiol affects hippocampus-dependent memory through brain-derived estradiol regulated via hippocampal GnRH receptor activity. In the first experiment, intracerebroventricular infusion of letrozole, which prevents the synthesis of estradiol, blocked the ability of peripheral estradiol administration in ovariectomized rats to enhance hippocampus-dependent memory in a radial-maze task. In the second experiment, hippocampal infusion of antide, a long-lasting GnRH receptor antagonist, blocked the ability of peripheral estradiol administration in ovariectomized rats to enhance hippocampus-dependent memory. In the third experiment, hippocampal infusion of GnRH enhanced hippocampus-dependent memory, the effects of which were blocked by letrozole infusion. Results indicate that peripheral estradiol-induced enhancement of cognition is mediated by brain-derived estradiol via hippocampal GnRH receptor activity.

NPY2-receptor variation modulates iconic memory processes.

PubMed

Arning, Larissa; Stock, Ann-Kathrin; Kloster, Eugen; Epplen, Jörg T; Beste, Christian

2014-08-01

Sensory memory systems are modality-specific buffers that comprise information about external stimuli, which represent the earliest stage of information processing. While these systems have been the subject of cognitive neuroscience research for decades, little is known about the neurobiological basis of sensory memory. However, accumulating evidence suggests that the glutamatergic system and systems influencing glutamatergic neural transmission are important. In the current study we examine if functional promoter variations in neuropeptide Y (NPY) and its receptor gene NPY2R affect iconic memory processes using a partial report paradigm. We found that iconic memory decayed much faster in individuals carrying the rare promoter NPY2R G allele which is associated with increased expression of the Y2 receptor. Possibly this effect is due to altered presynaptic inhibition of glutamate release, known to be modulated by Y2 receptors. Altogether, our results provide evidence that the functionally relevant single nucleotide polymorphism (SNP) in the NPY2R promoter gene affect circumscribed processes of early sensory processing, i.e. only the stability of information in sensory memory buffers. This leads us to suggest that especially the stability of information in sensory memory buffers depends on glutamatergic neural transmission and factors modulating glutamatergic turnover. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

Fabrication of InGaZnO Nonvolatile Memory Devices at Low Temperature of 150 degrees C for Applications in Flexible Memory Displays and Transparency Coating on Plastic Substrates.

PubMed

Hanh, Nguyen Hong; Jang, Kyungsoo; Yi, Junsin

2016-05-01

We directly deposited amorphous InGaZnO (a-IGZO) nonvolatile memory (NVM) devices with oxynitride-oxide-dioxide (OOO) stack structures on plastic substrate by a DC pulsed magnetron sputtering and inductively coupled plasma chemical vapor deposition (ICPCVD) system, using a low-temperature of 150 degrees C. The fabricated bottom gate a-IGZO NVM devices have a wide memory window with a low operating voltage during programming and erasing, due to an effective control of the gate dielectrics. In addition, after ten years, the memory device retains a memory window of over 73%, with a programming duration of only 1 ms. Moreover, the a-IGZO films show high optical transmittance of over 85%, and good uniformity with a root mean square (RMS) roughness of 0.26 nm. This film is a promising candidate to achieve flexible displays and transparency on plastic substrates because of the possibility of low-temperature deposition, and the high transparent properties of a-IGZO films. These results demonstrate that the a-IGZO NVM devices obtained at low-temperature have a suitable programming and erasing efficiency for data storage under low-voltage conditions, in combination with excellent charge retention characteristics, and thus show great potential application in flexible memory displays.

Tualang Honey Attenuates Noise Stress-Induced Memory Deficits in Aged Rats

PubMed Central

Azman, Khairunnuur Fairuz; Abdul Aziz, Che Badariah; Othman, Zahiruddin

2016-01-01

Ageing and stress exposure may lead to memory impairment while oxidative stress is thought to be one of the underlying mechanisms involved. This study aimed to investigate the potential protective effects of Tualang honey supplementation on memory performance in aged rats exposed to noise stress. Tualang honey supplementation was given orally, 200 mg/kg body weight for 28 days. Rats in the stress group were subjected to loud noise, 100 dB(A), 4 hours daily for 14 days. All rats were subjected to novel object recognition test for evaluation of memory performance. It was observed that the rats subjected to noise stress exhibited significantly lower memory performance and higher oxidative stress as evident by elevated malondialdehyde and protein carbonyl levels and reduction of antioxidant enzymes activities compared to the nonstressed rats. Tualang honey supplementation was able to improve memory performance, decrease oxidative stress levels, increase brain-derived neurotrophic factor (BDNF) concentration, decrease acetylcholinesterase activity, and enhance neuronal proliferation in the medial prefrontal cortex (mPFC) and hippocampus. In conclusion, Tualang honey protects against memory decline due to stress exposure and/or ageing via enhancement of mPFC and hippocampal morphology possibly secondary to reduction in brain oxidative stress and/or upregulation of BDNF concentration and cholinergic system. PMID:27119005

Do working memory-driven attention shifts speed up visual awareness?

PubMed

Pan, Yi; Cheng, Qiu-Ping

2011-11-01

Previous research has shown that content representations in working memory (WM) can bias attention in favor of matching stimuli in the scene. Using a visual prior-entry procedure, we here investigate whether such WM-driven attention shifts can speed up the conscious awareness of memory-matching relative to memory-mismatching stimuli. Participants were asked to hold a color cue in WM and to subsequently perform a temporal order judgment (TOJ) task by reporting either of two different-colored circles (presented to the left and right of fixation with a variable temporal interval) as having the first onset. One of the two TOJ circles could match the memory cue in color. We found that awareness of the temporal order of the circle onsets was not affected by the contents of WM, even when participants were explicitly informed that one of the TOJ circles would always match the WM contents. The null effect of WM on TOJs was not due to an inability of the memory-matching item to capture attention, since response times to the target in a follow-up experiment were improved when it appeared at the location of the memory-matching item. The present findings suggest that WM-driven attention shifts cannot accelerate phenomenal awareness of matching stimuli in the visual field.

Functionalized Graphitic Carbon Nitride for Metal-free, Flexible and Rewritable Nonvolatile Memory Device via Direct Laser-Writing

NASA Astrophysics Data System (ADS)

Zhao, Fei; Cheng, Huhu; Hu, Yue; Song, Long; Zhang, Zhipan; Jiang, Lan; Qu, Liangti

2014-07-01

Graphitic carbon nitride nanosheet (g-C3N4-NS) has layered structure similar with graphene nanosheet and presents unusual physicochemical properties due to the s-triazine fragments. But their electronic and electrochemical applications are limited by the relatively poor conductivity. The current work provides the first example that atomically thick g-C3N4-NSs are the ideal candidate as the active insulator layer with tunable conductivity for achieving the high performance memory devices with electrical bistability. Unlike in conventional memory diodes, the g-C3N4-NSs based devices combined with graphene layer electrodes are flexible, metal-free and low cost. The functionalized g-C3N4-NSs exhibit desirable dispersibility and dielectricity which support the all-solution fabrication and high performance of the memory diodes. Moreover, the flexible memory diodes are conveniently fabricated through the fast laser writing process on graphene oxide/g-C3N4-NSs/graphene oxide thin film. The obtained devices not only have the nonvolatile electrical bistability with great retention and endurance, but also show the rewritable memory effect with a reliable ON/OFF ratio of up to 105, which is the highest among all the metal-free flexible memory diodes reported so far, and even higher than those of metal-containing devices.

Depressive Mood and Testosterone Related to Declarative Verbal Memory Decline in Middle-Aged Caregivers of Children with Eating Disorders.

PubMed

Romero-Martínez, Ángel; Ruiz-Robledillo, Nicolás; Moya-Albiol, Luis

2016-03-04

Caring for children diagnosed with a chronic psychological disorder such as an eating disorder (ED) can be used as a model of chronic stress. This kind of stress has been reported to have deleterious effects on caregivers' cognition, particularly in verbal declarative memory of women caregivers. Moreover, high depressive mood and variations in testosterone (T) levels moderate this cognitive decline. The purpose of this study was to characterize whether caregivers of individuals with EDs (n = 27) show declarative memory impairments compared to non-caregivers caregivers (n = 27), using for this purpose a standardized memory test (Rey's Auditory Verbal Learning Test). Its purpose was also to examine the role of depressive mood and T in memory decline. Results showed that ED caregivers presented high depressive mood, which was associated to worse verbal memory performance, especially in the case of women. In addition, all caregivers showed high T levels. Nonetheless, only in the case of women caregivers did T show a curvilinear relationship with verbal memory performance, meaning that the increases of T were associated to the improvement in verbal memory performance, but only up to a certain point, as after such point T continued to increase and memory performance decreased. Thus, chronic stress due to caregiving was associated to disturbances in mood and T levels, which in turn was associated to verbal memory decline. These findings should be taken into account in the implementation of intervention programs for helping ED caregivers cope with caregiving situations and to prevent the risk of a pronounced verbal memory decline.

Why Narrating Changes Memory: A Contribution to an Integrative Model of Memory and Narrative Processes.

PubMed

Smorti, Andrea; Fioretti, Chiara

2016-06-01

This paper aims to reflect on the relation between autobiographical memory (ME) and autobiographical narrative (NA), examining studies on the effects of narrating on the narrator and showing how studying these relations can make more comprehensible both memory's and narrating's way of working. Studies that address explicitly on ME and NA are scarce and touch this issue indirectly. Authors consider different trends of studies of ME and NA: congruency vs incongruency hypotheses on retrieving, the way of organizing memories according to gist or verbatim format and their role in organizing positive and negative emotional experiences, the social roots of ME and NA, the rules of conversation based on narrating. Analysis of investigations leads the Authors to point out three basic results of their research. Firstly, NA transforms ME because it narrativizes memories according to a narrative format. This means that memories, when are narrated, are transformed in stories (verbal language) and socialised. Secondly, the narrativization process is determined by the act of telling something within a communicative situation. Thus, relational situation of narrating act, by modifying the story, modifies also memories. The Authors propose the RE.NA.ME model (RElation, NArration, MEmory) to understand and study ME and NA. Finally, this study claims that ME and NA refer to two different types of processes having a wide area of overlapping. This is due to common social, developmental and cultural roots that make NA to include part of ME (narrative of memory) and ME to include part of NA (memory of personal events that have been narrated).

Does recall after sleep-dependent memory consolidation reinstate sensitivity to retroactive interference?

PubMed

Deliens, Gaétane; Schmitz, Rémy; Caudron, Isaline; Mary, Alison; Leproult, Rachel; Peigneux, Philippe

2013-01-01

Previous studies have shown that newly encoded memories are more resistant to retroactive interference when participants are allowed to sleep after learning the original material, suggesting a sleep-related strengthening of memories. In the present study, we investigated delayed, long-term effects of sleep vs. sleep deprivation (SD) on the first post-training night on memory consolidation and resistance to interference. On day 1, participants learned a list of unrelated word pairs (AB), either in the morning or in the evening, then spent the post-training night in a sleep or sleep deprivation condition, in a within-subject paradigm. On day 4, at the same time of day, they learned a novel list of word pairs (AC) in which 50% of the word pairs stemmed with the same word than in the AB list, resulting in retroactive interference. Participants had then to recall items from the AB list upon presentation of the "A" stem. Recall was marginally improved in the evening, as compared to the morning learning group. Most importantly, retroactive interference effects were found in the sleep evening group only, contrary to the hypothesis that sleep exerts a protective role against intrusion by novel but similar learning. We tentatively suggest that these results can be explained in the framework of the memory reconsolidation theory, stating that exposure to similar information sets back consolidated items in a labile form again sensitive to retroactive interference. In this context, sleep might not protect against interference but would promote an update of existing episodic memories while preventing saturation of the memory network due to the accumulation of dual traces.

Enhanced recognition memory following glycine transporter 1 deletion in forebrain neurons.

PubMed

Singer, Philipp; Boison, Detlev; Möhler, Hanns; Feldon, Joram; Yee, Benjamin K

2007-10-01

Selective deletion of glycine transporter 1 (GlyT1) in forebrain neurons enhances N-methyl-D-aspartate receptor (NMDAR)-dependent neurotransmission and facilitates associative learning. These effects are attributable to increases in extracellular glycine availability in forebrain neurons due to reduced glycine re-uptake. Using a forebrain- and neuron-specific GlyT1-knockout mouse line (CamKIIalphaCre; GlyT1tm1.2fl/fI), the authors investigated whether this molecular intervention can affect recognition memory. In a spontaneous object recognition memory test, enhanced preference for a novel object was demonstrated in mutant mice relative to littermate control subjects at a retention interval of 2 hr, but not at 2 min. Furthermore, mutants were responsive to a switch in the relative spatial positions of objects, whereas control subjects were not. These potential procognitive effects were demonstrated against a lack of difference in contextual novelty detection: Mutant and control subjects showed equivalent preference for a novel over a familiar context. Results therefore extend the possible range of potential promnesic effects of specific forebrain neuronal GlyT1 deletion from associative learning to recognition memory and further support the possibility that mnemonic functions can be enhanced by reducing GlyT1 function. (PsycINFO Database Record (c) 2007 APA, all rights reserved).

Beneficial effects of garlic on learning and memory deficits and brain tissue damages induced by lead exposure during juvenile rat growth is comparable to the effect of ascorbic acid.

PubMed

Ghasemi, Simagol; Hosseini, Mahmoud; Feizpour, Azadeh; Alipour, Fatemeh; Sadeghi, Akram; Vafaee, Farzaneh; Mohammadpour, Toktam; Soukhtanloo, Mohammad; Ebrahimzadeh Bideskan, Alireza; Beheshti, Farimah

2017-04-01

The neuroprotective effects of both garlic and ascorbic acid (AA) have been documented. In this study the effects of garlic and ascorbic acid on memory deficits and brain tissue oxidative damages induced by lead exposure was investigated. The juvenile rats were divided and treated: (1) Control, (2) Lead (lead acetate in drinking water, 8 weeks), (3) Lead - Ascorbic Acid (Lead-AA), (4)  Lead - Garlic (100 mg/kg, daily, gavage) (Lead-Gar). In Morris water maze (MWM), the escape latency and traveled path in the Lead group were significantly higher while, the time spent in the target quadrant (Q1) was lower than Control. Both Lead-Gar and Lead-AA groups spent more times in Q1than to lead group. There were no significant differences in swimming speed between the groups. In passive avoidance (PA) test, the time latency for entering the dark compartment by Lead group was lower than Control. Treatment of the animals by AA and garlic significantly increased the time latency. In Lead group, the total thiol concentration in brain tissues was significantly lower while, MDA was higher than Control. Treatment by both garlic and AA increased total thiol concentrations and decreased MDA. Both garlic and AA decreased the lead content of brain tissues. It is suggested that treatment with garlic attenuates the learning and memory impairments due to lead exposure during juvenile rat growth which is comparable to AA. The possible mechanism may be due to its protective effects against brain tissues oxidative damage as well the lowering effects of brain lead content.

The Differential Relations between Verbal, Numerical and Spatial Working Memory Abilities and Children's Reading Comprehension

ERIC Educational Resources Information Center

Oakhill, Jane; Yuill, Nicola; Garnham, Alan

2011-01-01

Working memory predicts children's reading comprehension but it is not clear whether this relation is due to a modality-specific or general working memory. This study, which investigated the relations between children's reading skills and working memory (WM) abilities in 3 modalities, extends previous work by including measures of both reading…

"Brain-specific" nutrients: a memory cure?

PubMed

McDaniel, Mark A; Maier, Steven F; Einstein, Gilles O

2003-01-01

We review the experimental evaluations of several widely marketed nonprescription compounds claimed to be memory enhancers and treatments for age-related memory decline. We generally limit our review to double-blind placebo-controlled studies. The compounds examined are phosphatidylserine (PS), phosphatidylcholine (PC), citicoline, piracetam, vinpocetine, acetyl-L-carnitine (ALC), and antioxidants (particularly vitamin E). In animals, PS has been shown to attenuate many neuronal effects of aging, and to restore normal memory on a variety of tasks. Preliminary findings with humans, though, are limited. For older adults with probable Alzheimer's disease, a single study failed to demonstrate positive effects of PS on memory performance. For older adults with moderate cognitive impairment, PS has produced consistently modest increases in recall of word lists. Positive effects have not been as consistently reported for other memory tests. There is one report of consistent benefits across a number of memory tests for a subset of normal adults who performed more poorly than their peers at baseline. The choline compounds PC and citicoline are thought to promote synthesis and transmission of neurotransmitters important to memory. PC has not proven effective for improving memory in patients with probable Alzheimer's disease. The issue remains open for older adults without serious degenerative neural disease. Research on citicoline is practically nonexistent, but one study reported a robust improvement in story recall for a small sample of normally aging older adults who scored lower than their peers in baseline testing. Animal studies suggest that piracetam may improve neuronal efficiency, facilitate activity in neurotransmitter systems, and combat the age-related decrease in receptors on the neuronal membrane. However, for patients with probable Alzheimer's disease, as well as for adults with age-associated memory impairment, there is no clear-cut support for a mnemonic benefit of piracetam. Vinpocetine increases blood circulation and metabolism in the brain. Animal studies have shown that vinpocetine can reduce the loss of neurons due to decreased blood flow. In three studies of older adults with memory problems associated with poor brain circulation or dementia-related disease, vinpocetine produced significantly more improvement than a placebo in performance on global cognitive tests reflecting attention, concentration, and memory. Effects on episodic memory per se have been tested minimally, if at all. ALC participates in cellular energy production, a process especially important in neurons, and in removal of toxic accumulation of fatty acids. Animal studies show that ALC reverses the age-related decline in the number of neuron membrane receptors. Studies of patients with probable Alzheimer's disease have reported nominal advantages over a range of memory tests for ALC-treated patients relative to placebo groups. Significant differences have been reported rarely, however. Whether ALC would have mnemonic benefits for aging adults without brain disease is untested as far as we know. Antioxidants help neutralize tissue-damaging free radicals, which become more prevalent as organisms age. It is hypothesized that increasing antioxidant levels in the organism might retard or reverse the damaging effects of free radicals on neurons. Thus far, however, studies have found that vitamin E does not significantly slow down memory decline for Alzheimer's patients and does not produce significant memory benefits among early Parkinson's patients. Neither did a combination of vitamins E and C significantly improve college students' performance on several cognitive tasks. In sum, for most of the "brain-specific" nutrients we review, some mildly suggestive effects have been found in preliminary controlled studies using standard psychometric memory assessments or more general tests designed to reveal cognitive impairment. We suggest that future evaluations of the possible memory benefits of these supplements might fruitfully focus on memory processes rather than on memory tests per se.

The effect of working memory capacity limitations on the intuitive assessment of correlation: amplification, attenuation, or both?

PubMed

Cahan, Sorel; Mor, Yaniv

2007-03-01

This article challenges Yaakov Kareev's (1995a, 2000) argument regarding the positive bias of intuitive correlation estimates due to working memory capacity limitations and its adaptive value. The authors show that, under narrow window theory's primacy effect assumption, there is a considerable between-individual variability of the effects of capacity limitations on the intuitive assessment of correlation, in terms of both sign and magnitude: Limited capacity acts as an amplifier for some individuals and as a silencer for others. Furthermore, the average amount of attenuation exceeds the average amount of amplification, and the more so, the smaller the capacity. Implications regarding the applicability and contribution of the bias notion in this context and the evaluation of the adaptive value of capacity limitations are discussed.

Does music training facilitate the mnemonic effect of song? An exploration of musicians and nonmusicians with and without Alzheimer's dementia.

PubMed

Baird, Amee; Samson, Séverine; Miller, Laurie; Chalmers, Kerry

2017-02-01

The efficacy of using sung words as a mnemonic device for verbal memory has been documented in persons with probable Alzheimer's dementia (AD), but it is not yet known whether this effect is related to music training. Given that music training can enhance cognitive functioning, we explored the effects of music training and modality (sung vs. spoken) on verbal memory in persons with and without AD. We used a mixed factorial design to compare learning (5 trials), delayed recall (30-min and, 24-hour), and recognition of sung versus spoken information in 22 healthy elderly (15 musicians), and 11 people with AD (5 musicians). Musicians with AD showed better total learning (over 5 trials) of sung information than nonmusicians with AD. There were no significant differences in delayed recall and recognition accuracy (of either modality) between musicians with and without AD, suggesting that music training may facilitate memory function in AD. Analysis of individual performances showed that two of the five musicians with AD were able to recall some information on delayed recall, whereas the nonmusicians with AD recalled no information on delay. The only significant finding in regard to modality (sung vs. spoken) was that total learning was significantly worse for sung than spoken information for nonmusicians with AD. This may be due to the need to recode information presented in song into spoken recall, which may be more cognitively demanding for this group. This is the first study to demonstrate that music training modulates memory of sung and spoken information in AD. The mechanism underlying these results is unclear, but may be due to music training, higher cognitive abilities, or both. Our findings highlight the need for further research into the potentially protective effect of music training on cognitive abilities in our aging population.

Multilevel resistance switching effect in Au/La2/3Ba1/3MnO3/Pt heterostructure manipulated by external fields

NASA Astrophysics Data System (ADS)

Wen, Jiahong; Zhao, Xiaoyu; Li, Qian; Zhang, Sheng; Wang, Dunhui; Du, Youwei

2018-04-01

Multilevel resistance switching (RS) effect has attracted more and more attention due to its promising potential for the increase of storage density in memory devices. In this work, the transport properties are investigated in an Au/La2/3Ba1/3MnO3 (LBMO)/Pt heterostructure. Taking advantage of the strong interplay among the spin, charge, orbital and lattice of LBMO, the Au/LBMO/Pt device can exhibit bipolar RS effect and magnetoresistance effect simultaneously. Under the coaction of electric field and magnetic field, four different resistance states are achieved in this device. These resistance states show excellent repeatability and retentivity and can be switched between any two states, which suggest the potential applications in the multilevel RS memory devices with enhanced storage density.

Unconstrained Recovery Characterization of Shape-Memory Polymer Networks for Cardiovascular Applications

PubMed Central

Yakacki, Christopher M.; Shandas, Robin; Lanning, Craig; Rech, Bryan; Eckstein, Alex; Gall, Ken

2009-01-01

Shape-memory materials have been proposed in biomedical device design due to their ability to facilitate minimally invasive surgery and recover to a predetermined shape in-vivo. Use of the shape-memory effect in polymers is proposed for cardiovascular stent interventions to reduce the catheter size for delivery and offer highly controlled and tailored deployment at body temperature. Shape-memory polymer networks were synthesized via photopolymerization of tert-butyl acrylate and poly (ethylene glycol) dimethacrylate to provide precise control over the thermomechanical response of the system. The free recovery response of the polymer stents at body temperature was studied as a function of glass transition temperature (Tg), crosslink density, geometrical perforation, and deformation temperature, all of which can be independently controlled. Room temperature storage of the stents was shown to be highly dependent on Tg and crosslink density. The pressurized response of the stents is also demonstrated to depend on crosslink density. This polymer system exhibits a wide range of shape-memory and thermomechanical responses to adapt and meet specific needs of minimally invasive cardiovascular devices. PMID:17296222

Time limits during visual foraging reveal flexible working memory templates.

PubMed

Kristjánsson, Tómas; Thornton, Ian M; Kristjánsson, Árni

2018-06-01

During difficult foraging tasks, humans rarely switch between target categories, but switch frequently during easier foraging. Does this reflect fundamental limits on visual working memory (VWM) capacity or simply strategic choice due to effort? Our participants performed time-limited or unlimited foraging tasks where they tapped stimuli from 2 target categories while avoiding items from 2 distractor categories. These time limits should have no effect if capacity imposes limits on VWM representations but more flexible VWM could allow observers to use VWM according to task demands in each case. We found that with time limits, participants switched more frequently and switch-costs became much smaller than during unlimited foraging. Observers can therefore switch between complex (conjunction) target categories when needed. We propose that while maintaining many complex templates in working memory is effortful and observers avoid this, they can do so if this fits task demands, showing the flexibility of working memory representations used for visual exploration. This is in contrast with recent proposals, and we discuss the implications of these findings for theoretical accounts of working memory. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Thermomechanical Analysis of Shape-Memory Composite Tape Spring

NASA Astrophysics Data System (ADS)

Yang, H.; Wang, L. Y.

2013-06-01

Intelligent materials and structures have been extensively applied for satellite designs in order to minimize the mass and reduce the cost in the launch of the spacecraft. Elastic memory composites (EMCs) have the ability of high-strain packaging and shape-memory effect, but increase the parts and total weight due to the additional heating system. Shape-memory sandwich structures Li and Wang (J. Intell. Mater. Syst. Struct. 22(14), 1605-1612, 2011) can overcome such disadvantage by using the metal skin acting as the heating element. However, the high strain in the micro-buckled metal skin decreases the deployment efficiency. This paper aims to present an insight into the folding and deployment behaviors of shape-memory composite (SMC) tape springs. A thermomechanical process was analyzed, including the packaging deformation at an elevated temperature, shape frozen at the low temperature and shape recovery after reheating. The result shows that SMC tape springs can significantly decrease the strain concentration in the metal skin, as well as exhibiting excellent shape frozen and recovery behaviors. Additionally, possible failure modes of SMC tape springs were also analyzed.

Damage evolution during actuation fatigue in shape memory alloys (SPIE Best Student Paper Award)

NASA Astrophysics Data System (ADS)

Phillips, Francis R.; Wheeler, Robert; Lagoudas, Dimitris C.

2018-03-01

Shape Memory Alloys (SMAs) are unique materials able to undergo a thermomechanically induced, reversible phase transformation. Additionally, SMA are subject to two types of fatigue, that is structural fatigue due to cyclic loading as experienced by most materials, as well as actuation fatigue due to repeated thermally induced phase transformation. The evolution of multiple material characteristics is presented over the actuation fatigue lifetime of NiTiHf actuators, including the accumulation of irrecoverable strain, the evolution of internal voids, and the evolution of the effective modulus of the actuator. The results indicate that all three of these material characteristics are clearly interconnected and careful analysis of each of these characteristics can help to understand the evolution of the others, as well as help to understand how actuation fatigue leads to ultimate failure of the actuator.

Effect of Calendula officinalis hydroalcoholic extract on passive avoidance learning and memory in streptozotocin-induced diabetic rats

PubMed Central

Moradkhani, Shirin; Salehi, Iraj; Abdolmaleki, Somayeh; Komaki, Alireza

2015-01-01

Background: Medicinal plants, owing to their different mechanisms such as antioxidants effects, may improve learning and memory impairments in diabetic rats. Calendula officinalis (CO), has a significant antioxidant activity. Aims: To examine the effect of hydroalcoholic extract of CO on passive avoidance learning (PAL) and memory in streptozotocin (STZ)-induced diabetic male rats. Settings and Design: A total of 32 adult male Wistar rats were randomly allocated to four groups: Control, diabetic, control + extract of CO and diabetic control + extract of CO groups with free access to regular rat diet. Subjects and Methods: Diabetes in diabetic rats was induced by single intraperitoneal injection of 60 mg/kg STZ. After confirmation of diabetes, oral administration of 300 mg/kg CO extract to extract-treated groups have been done. PAL was tested 8 weeks after onset of treatment, and blood glucose and body weight were measured in all groups at the beginning and end of the experiment. Statistical Analysis Used: The statistical analysis of data was performed by ANOVA followed by least significant difference post-hoc analysis. Results: Diabetes decreased learning and memory. Effect of CO extract in retention test (after 24 and 48 h) has been shown a significant decrease in step-through latency and increase in time spent in the dark compartment part. Also the extract partially improved hyperglycemia and reduced body weight. Conclusion: Taken together, CO extract can improve PAL and memory impairments in STZ-diabetic rats. This improvement may be due to its antioxidant, anticholinergic activities or its power to reduce hyperglycemia. PMID:26120230

Voluntary eyeblinks disrupt iconic memory.

PubMed

Thomas, Laura E; Irwin, David E

2006-04-01

In the present research, we investigated whether eyeblinks interfere with cognitive processing. In Experiment 1, the participants performed a partial-report iconic memory task in which a letter array was presented for 106 msec, followed 50, 150, or 750 msec later by a tone that cued recall of onerow of the array. At a cue delay of 50 msec between array offset and cue onset, letter report accuracy was lower when the participants blinked following array presentation than under no-blink conditions; the participants made more mislocation errors under blink conditions. This result suggests that blinking interferes with the binding of object identity and object position in iconic memory. Experiment 2 demonstrated that interference due to blinks was not due merely to changes in light intensity. Experiments 3 and 4 demonstrated that other motor responses did not interfere with iconic memory. We propose a new phenomenon, cognitive blink suppression, in which blinking inhibits cognitive processing. This phenomenon may be due to neural interference. Blinks reduce activation in area V1, which may interfere with the representation of information in iconic memory.

N-acetyl-L-tryptophan, a substance-P receptor antagonist attenuates aluminum-induced spatial memory deficit in rats.

PubMed

Fernandes, Joylee; Mudgal, Jayesh; Rao, Chamallamudi Mallikarjuna; Arora, Devinder; Basu Mallik, Sanchari; Pai, K S R; Nampoothiri, Madhavan

2018-06-01

Neuroinflammation plays an important role in the pathophysiology of Alzheimer's disease. Neurokinin substance P is a key mediator which modulates neuroinflammation through neurokinin receptor. Involvement of substance P in Alzheimer's disease is still plausible and various controversies exist in this hypothesis. Preventing the deleterious effects of substance P using N-acetyl-L-tryptophan, a substance P antagonist could be a promising therapeutic strategy. This study was aimed to evaluate the effect of N-acetyl-L-tryptophan on aluminum induced spatial memory alterations in rats. Memory impairment was induced using aluminum chloride (AlCl 3 ) at a dose of 10 mg/kg for 42 d. After induction of dementia, rats were exposed to 30 and 50 mg/kg of N-acetyl-L-tryptophan for 28 d. Spatial memory alterations were measured using Morris water maze. Acetylcholinesterase activity and antioxidant enzyme glutathione level were assessed in hippocampus, frontal cortex and striatum. The higher dose of N-acetyl-L-tryptophan (50 mg/kg) significantly improved the aluminum induced memory alterations. N-acetyl-L-tryptophan exposure resulted in significant increase in acetylcholinesterase activity and glutathione level in hippocampus. The neuroprotective effect of N-acetyl-L-tryptophan could be due to its ability to block substance P mediated neuroinflammation, reduction in oxidative stress and anti-apoptotic properties. To conclude, N-acetyl-L-tryptophan may be considered as a novel neuroprotective therapy in Alzheimer's disease.

High altitude memory impairment is due to neuronal apoptosis in hippocampus, cortex and striatum.

PubMed

Maiti, Panchanan; Singh, Shashi B; Mallick, Birendranath; Muthuraju, Sangu; Ilavazhagan, Govindasami

2008-12-01

Cognitive and neuropsychological functions have been impaired at high altitude and the effects depend on altitude and duration of stay. However, the neurobiological mechanism of this impairment is poorly understood especially exposure to different duration. Aim of the present study was to investigate the changes of behavior, biochemistry and morphology after exposure to different duration of hypobaric hypoxia. The rats were exposed continuously to a simulated high altitude of 6100m for 3, 7, 14 and 21 days in an animal decompression chamber. Spatial reference memory was tested by Morris water maze. The oxidative stress markers like free radicals, NO, lipid peroxidation, LDH activity and antioxidant systems like GSH, GSSG, GPx, GR, SOD were estimated from cortex, hippocampus and striatum. The morphological changes, neurodegeneration, DNA fragmentation and mode of cell death have also been studied. It was observed that the spatial reference memory was significantly affected after exposure to hypobaric hypoxia. Increased oxidative stress markers along with decreased effectiveness of antioxidant system were also observed in hypoxia-exposed animals. Further pyknotic, shrunken, tangle-like neurons were observed in all these regions after hypoxia and neurodegeneration, DNA fragmentation and apoptosis were also observed in all the three regions. But after 21 days of exposure, the spatial memory was improved along with improvement of antioxidant activities. Our result suggests that the apoptotic death may be involved in HA-induced memory impairment and after 7 days of exposure the effect was more pronounced but after 21 days of exposure recovery was observed.

Cognitive Load Does Not Affect the Behavioral and Cognitive Foundations of Social Cooperation.

PubMed

Mieth, Laura; Bell, Raoul; Buchner, Axel

2016-01-01

The present study serves to test whether the cognitive mechanisms underlying social cooperation are affected by cognitive load. Participants interacted with trustworthy-looking and untrustworthy-looking partners in a sequential Prisoner's Dilemma Game. Facial trustworthiness was manipulated to stimulate expectations about the future behavior of the partners which were either violated or confirmed by the partners' cheating or cooperation during the game. In a source memory test, participants were required to recognize the partners and to classify them as cheaters or cooperators. A multinomial model was used to disentangle item memory, source memory and guessing processes. We found an expectancy-congruent bias toward guessing that trustworthy-looking partners were more likely to be associated with cooperation than untrustworthy-looking partners. Source memory was enhanced for cheating that violated the participants' positive expectations about trustworthy-looking partners. We were interested in whether or not this expectancy-violation effect-that helps to revise unjustified expectations about trustworthy-looking partners-depends on cognitive load induced via a secondary continuous reaction time task. Although this secondary task interfered with working memory processes in a validation study, both the expectancy-congruent guessing bias as well as the expectancy-violation effect were obtained with and without cognitive load. These findings support the hypothesis that the expectancy-violation effect is due to a simple mechanism that does not rely on demanding elaborative processes. We conclude that most cognitive mechanisms underlying social cooperation presumably operate automatically so that they remain unaffected by cognitive load.

Effects of postnatal malnutrition and senescence on learning, long-term memory, and extinction in the rat.

PubMed

Martínez, Yvonne; Díaz-Cintra, Sofía; León-Jacinto, Uriel; Aguilar-Vázquez, Azucena; Medina, Andrea C; Quirarte, Gina L; Prado-Alcalá, Roberto A

2009-10-12

There is a wealth of information indicating that the hippocampal formation is important for learning and memory consolidation. The hippocampus is very sensitive to ageing and developmentally stressful factors such as prenatal malnutrition, which produces anatomical alterations of hippocampal pyramidal cells as well as impaired spatial learning. On the other hand, there are no reports about differential effects of postnatal malnutrition, installed at birth and maintained all through life in young and aged rats, on learning and memory of active avoidance, a task with an important procedural component. We now report that learning and long-term retention of this task were impaired in young malnourished animals, but not in young control, senile control, and senile malnourished Sprague-Dawley rats; young and senile rats were 90 and 660 days of age, respectively. Extinction tests showed, however, that long-term memory of the malnourished groups and senile control animals is impaired as compared with the young control animals. These data strongly suggest that the learning and long-term retention impairments seen in the young animals were due to postnatal malnutrition; in the senile groups, this cognitive alteration did not occur, probably because ageing itself is an important factor that enables the brain to engage in compensatory mechanisms that reduce the effects of malnutrition. Nonetheless, ageing and malnutrition, conditions known to produce anatomic and functional hippocampal alterations, impede the maintenance of long-term memory, as seen during the extinction test.

The endocannabinoid system and Post Traumatic Stress Disorder (PTSD): From preclinical findings to innovative therapeutic approaches in clinical settings.

PubMed

Berardi, Andrea; Schelling, Gustav; Campolongo, Patrizia

2016-09-01

Post-Traumatic Stress Disorder (PTSD) is a psychiatric chronic disease developing in individuals after the experience of an intense and life-threatening traumatic event. The post-traumatic symptomatology encompasses alterations in memory processes, mood, anxiety and arousal. There is now consensus in considering the disease as an aberrant adaptation to traumatic stress. Pharmacological research, aimed at the discovery of new potential effective treatments, has lately directed its attention towards the "so-called" cognitive enhancers. This class of substances, by modulating cognitive processes involved in the development and/or persistence of the post-traumatic symptomatology, could be of great help in improving the outcome of psychotherapies and patients' prognosis. In this perspective, drugs acting on the endocannabinoid system are receiving great attention due to their dual ability to modulate memory processes on one hand, and to reduce anxiety and depression on the other. The purpose of the present review is to offer a thorough overview of both animal and human studies investigating the effects of cannabinoids on memory processes. First, we will briefly describe the characteristics of the endocannabinoid system and the most commonly used animal models of learning and memory. Then, studies investigating cannabinoid modulatory influences on memory consolidation, retrieval and extinction will be separately presented, and the potential benefits associated with each approach will be discussed. In the final section, we will review literature data reporting beneficial effects of cannabinoid drugs in PTSD patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

The impact of napping on memory for future-relevant stimuli: Prioritization among multiple salience cues.

PubMed

Bennion, Kelly A; Payne, Jessica D; Kensinger, Elizabeth A

2016-06-01

Prior research has demonstrated that sleep enhances memory for future-relevant information, including memory for information that is salient due to emotion, reward, or knowledge of a later memory test. Although sleep has been shown to prioritize information with any of these characteristics, the present study investigates the novel question of how sleep prioritizes information when multiple salience cues exist. Participants encoded scenes that were future-relevant based on emotion (emotional vs. neutral), reward (rewarded vs. unrewarded), and instructed learning (intentionally vs. incidentally encoded), preceding a delay consisting of a nap, an equivalent time period spent awake, or a nap followed by wakefulness (to control for effects of interference). Recognition testing revealed that when multiple dimensions of future relevance co-occur, sleep prioritizes top-down, goal-directed cues (instructed learning, and to a lesser degree, reward) over bottom-up, stimulus-driven characteristics (emotion). Further, results showed that these factors interact; the effect of a nap on intentionally encoded information was especially strong for neutral (relative to emotional) information, suggesting that once one cue for future relevance is present, there are diminishing returns with additional cues. Sleep may binarize information based on whether it is future-relevant or not, preferentially consolidating memory for the former category. Potential neural mechanisms underlying these selective effects and the implications of this research for educational and vocational domains are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Restricted sedation and absence of cognitive impairments after administration of intranasal scopolamine.

PubMed

Weerts, Aurélie P; Pattyn, Nathalie; Putcha, Lakshmi; Hoag, Stephen W; Van Ombergen, Angelique; Hallgren, Emma; Van de Heyning, Paul H; Wuyts, Floris L

2015-12-01

Space motion sickness in astronauts during spaceflight causes significant discomfort, which might impede their functionality. Pharmacological treatment has been mainly restricted to promethazine. Transdermal and oral scopolamine have also been used in space; however, their use was reduced due to unpredictable effectiveness and side effects. Recently, intranasal scopolamine administration has gained much interest, since this route ensures fast and reliable absorption with a decreased incidence of undesirable side effects. The aim of this study was to evaluate the effect of intranasal scopolamine on cognitive performance and to determine its side effects. This double-blind, placebo controlled, repeated measures study evaluated vigilant attention, short-term memory, implicit memory and working memory. Side effects were reported on a 22-item questionnaire and sleepiness was assessed by the Karolinska, Stanford and Epworth Sleepiness Scales. Scopolamine had no effect on cognitive function. Only the Karolinska score was significantly increased for scopolamine compared to placebo. Participants reported a dry mouth and dizziness after receiving scopolamine. Results show that intranasal scopolamine did not impair cognitive performance. Intranasal scopolamine might be a good alternative to promethazine for the alleviation of space motion sickness, since the agent has minimal sedative effects and does not hamper cognitive performance. © The Author(s) 2015.

ERP C250 shows the elderly (cognitively normal, Alzheimer's disease) store more stimuli in short-term memory than Young Adults do.

PubMed

Chapman, Robert M; Gardner, Margaret N; Mapstone, Mark; Klorman, Rafael; Porsteinsson, Anton P; Dupree, Haley M; Antonsdottir, Inga M; Kamalyan, Lily

2016-06-01

To determine how aging and dementia affect the brain's initial storing of task-relevant and irrelevant information in short-term memory. We used brain Event-Related Potentials (ERPs) to measure short-term memory storage (ERP component C250) in 36 Young Adults, 36 Normal Elderly, and 36 early-stage AD subjects. Participants performed the Number-Letter task, a cognitive paradigm requiring memory storage of a first relevant stimulus to compare it with a second stimulus. In Young Adults, C250 was more positive for the first task-relevant stimulus compared to all other stimuli. C250 in Normal Elderly and AD subjects was roughly the same to relevant and irrelevant stimuli in Intratrial Parts 1-3 but not 4. The AD group had lower C250 to relevant stimuli in part 1. Both normal aging and dementia cause less differentiation of relevant from irrelevant information in initial storage. There was a large aging effect involving differences in the pattern of C250 responses of the Young Adult versus the Normal Elderly/AD groups. Also, a potential dementia effect was obtained. C250 is a candidate tool for measuring short-term memory performance on a biological level, as well as a potential marker for memory changes due to normal aging and dementia. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Intrusion errors in visuospatial working memory performance.

PubMed

Cornoldi, Cesare; Mammarella, Nicola

2006-02-01

This study tested the hypothesis that failure in active visuospatial working memory tasks involves a difficulty in avoiding intrusions due to information that is already activated. Two experiments are described, in which participants were required to process several series of locations on a 4 x 4 matrix and then to produce only the final location of each series. Results revealed a higher number of errors due to already activated locations (intrusions) compared with errors due to new locations (inventions). Moreover, when participants were required to pay extra attention to some irrelevant (non-final) locations by tapping on the table, intrusion errors increased. Results are discussed in terms of current models of working memory functioning.

Synchronized brain activity during rehearsal and short-term memory disruption by irrelevant speech is affected by recall mode.

PubMed

Kopp, Franziska; Schröger, Erich; Lipka, Sigrid

2006-08-01

EEG coherence as a measure of synchronization of brain activity was used to investigate effects of irrelevant speech. In a delayed serial recall paradigm 21 healthy participants retained verbal items over a 10-s delay with and without interfering irrelevant speech. Recall after the delay was varied in two modes (spoken vs. written). Behavioral data showed the classic irrelevant speech effect and a superiority of written over spoken recall mode. Coherence, however, was more sensitive to processing characteristics and showed interactions between the irrelevant speech effect and recall mode during the rehearsal delay in theta (4-7.5 Hz), alpha (8-12 Hz), beta (13-20 Hz), and gamma (35-47 Hz) frequency bands. For gamma, a rehearsal-related decrease of the duration of high coherence due to presentation of irrelevant speech was found in a left-lateralized fronto-central and centro-temporal network only in spoken but not in written recall. In theta, coherence at predominantly fronto-parietal electrode combinations was indicative for memory demands and varied with individual working memory capacity assessed by digit span. Alpha coherence revealed similar results and patterns as theta coherence. In beta, a left-hemispheric network showed longer high synchronizations due to irrelevant speech only in written recall mode. EEG results suggest that mode of recall is critical for processing already during the retention period of a delayed serial recall task. Moreover, the finding that different networks are engaged with different recall modes shows that the disrupting effect of irrelevant speech is not a unitary mechanism.

Effect of methamphetamine exposure and cross-fostering on cognitive function in adult male rats.

PubMed

Hrubá, Lenka; Schutová, Barbora; Pometlová, Marie; Rokyta, Richard; Slamberová, Romana

2010-03-17

The aim of our study was to examine the effect of prenatal methamphetamine (MA) exposure and cross-fostering on cognitive functions of adult male rats tested in Morris water maze (MWM). Rat mothers were exposed daily to injection of MA (5mg/kg) or saline for 9 weeks: prior to impregnation, throughout gestation and lactation periods. Females without any injections were used as an absolute control. On postnatal day 1, pups were cross-fostered so that each mother raised 4 pups of her own and 8 pups from the mothers with the other two treatments. Four types of tests were used: (1) Place navigation test (Learning), (2) Probe test (Probe), (3) Retention memory test (Memory) and (4) Visible platform task. Our results demonstrate that the prenatal exposure to MA does not impact learning and memory, while postnatal exposure to MA shows impairments in cognition. In the test of learning, all animals fostered to MA-treated dams had longer latencies, bigger search error and used lower spatial strategies than the animals fostered to control or saline-treated mother, regardless of prenatal exposure. Regardless of postnatal exposure, the animals prenatally exposed to saline swam faster in all the tests than the animals prenatally exposed to MA and controls, respectively. This study indicates that postnatal but not prenatal exposure to MA affects learning in adult male rats. However, it is still not clear whether these impairments are due to a direct effect of MA on neuronal structure or due to an indirect effect of MA mediated by impaired maternal care. Copyright 2009 Elsevier B.V. All rights reserved.

Butane dihedral angle dynamics in water is dominated by internal friction.

PubMed

Daldrop, Jan O; Kappler, Julian; Brünig, Florian N; Netz, Roland R

2018-05-15

The dihedral dynamics of butane in water is known to be rather insensitive to the water viscosity; possible explanations for this involve inertial effects or Kramers' turnover, the finite memory time of friction, and the presence of so-called internal friction. To disentangle these factors, we introduce a method to directly extract the friction memory function from unconstrained simulations in the presence of an arbitrary free-energy landscape. By analysis of the dihedral friction in butane for varying water viscosity, we demonstrate the existence of an internal friction contribution that does not scale linearly with water viscosity. At normal water viscosity, the internal friction turns out to be eight times larger than the solvent friction and thus completely dominates the effective friction. By comparison with simulations of a constrained butane molecule that has the dihedral as the only degree of freedom, we show that internal friction comes from the six additional degrees of freedom in unconstrained butane that are orthogonal to the dihedral angle reaction coordinate. While the insensitivity of butane's dihedral dynamics to water viscosity is solely due to the presence of internal friction, inertial effects nevertheless crucially influence the resultant transition rates. In contrast, non-Markovian effects due to the finite memory time are present but do not significantly influence the dihedral barrier-crossing rate of butane. These results not only settle the character of dihedral dynamics in small solvated molecular systems such as butane, they also have important implications for the folding of polymers and proteins. Copyright © 2018 the Author(s). Published by PNAS.

Fractionation of the component processes underlying successful episodic encoding: a combined fMRI and divided-attention study.

PubMed

Uncapher, Melina R; Rugg, Michael D

2008-02-01

Considerable evidence suggests that attentional resources are necessary for the encoding of episodic memories, but the nature of the relationship between attention and neural correlates of encoding is unclear. Here we address this question using functional magnetic resonance imaging and a divided-attention paradigm in which competition for different types of attentional resources was manipulated. Fifteen volunteers were scanned while making animacy judgments to visually presented words and concurrently performing one of three tasks on auditorily presented words: male/female voice discrimination (control task), 1-back voice comparison (1-back task), or indoor/outdoor judgment (semantic task). The 1-back and semantic tasks were designed to compete for task-generic and task-specific attentional resources, respectively. Using the "remember/know" procedure, memory for the study words was assessed after 15 min. In the control condition, subsequent memory effects associated with later recollection were identified in the left dorsal inferior frontal gyrus and in the left hippocampus. These effects were differentially attenuated in the two more difficult divided-attention conditions. The effects of divided attention seem, therefore, to reflect impairments due to limitations at both task-generic and task-specific levels. Additionally, each of the two more difficult divided-attention conditions was associated with subsequent memory effects in regions distinct from those showing effects in the control condition. These findings suggest the engagement of alternative encoding processes to those engaged in the control task. The overall pattern of findings suggests that divided attention can impact later memory in different ways, and accordingly, that different attentional resources, including task-generic and task-specific resources, make distinct contributions to successful episodic encoding.

Optimal proximity correction: application for flash memory design

NASA Astrophysics Data System (ADS)

Chen, Y. O.; Huang, D. L.; Sung, K. T.; Chiang, J. J.; Yu, M.; Teng, F.; Chu, Lung; Rey, Juan C.; Bernard, Douglas A.; Li, Jiangwei; Li, Junling; Moroz, V.; Boksha, Victor V.

1998-06-01

Proximity Correction is the technology for which the most of IC manufacturers are committed already. The final intended result of correction is affected by many factors other than the optical characteristics of the mask-stepper system, such as photoresist exposure, post-exposure bake and development parameters, etch selectivity and anisotropy, and underlying topography. The most advanced industry and research groups already reported immediate need to consider wafer topography as one of the major components during a Proximity Correction procedure. In the present work we are discussing the corners rounding effect (which eventually cause electrical leakage) observed for the elements of Poly2 layer for a Flash Memory Design. It was found that the rounding originated by three- dimensional effects due to variation of photoresist thickness resulting from the non-planar substrate. Our major goal was to understand the reasons and correct corner rounding. As a result of this work highly effective layout correction methodology was demonstrated and manufacturable Depth Of Focus was achieved. Another purpose of the work was to demonstrate complete integration flow for a Flash Memory Design based on photolithography; deposition/etch; ion implantation/oxidation/diffusion; and device simulators.

Senile dementia: treatment with deanol.

PubMed

Ferris, S H; Sathananthan, G; Gershon, S; Clark, C

1977-06-01

Recent research indicates a possible cholinergic involvement in memory processes and thus the possibility that acetylcholine deficiency may underlie memory impairment in senile dementia. Deanol (2-dimethylaminoethanol), which is assumed to increase brain acetylcholine, was given openly for 4 weeks to 14 senile outpatients, to determine the safety of the drug and whether or not it reduces cognitive impairment. The dosage was gradually increased to 600 mg three times daily during the first two weeks, with no adverse effects. Ten patients improved globally and 4 were unchanged (p less than .01). The total score on the Sandoz Clinical Assessment-Geriatric (SCAG) was lowered by the third week (p less than .01), primarily as a result of reduced depression, irritability and anxiety, and increased motivation-initiative. However, neither the clinical ratings nor an extensive pre- versus post-treatment series of cognitive tests revealed changes in memory or other cognitive functions. Since a similar separate study with a different compound produced no behavioral changes, it is unlikely that the improvement with deanol was due entirely to placebo effects. The results thus suggest that although deanol may not improve memory, it may produce positive behavioral changes in some senile patients.

Self-healing bolted joint employing a shape memory actuator

NASA Astrophysics Data System (ADS)

Muntges, Daniel E.; Park, Gyuhae; Inman, Daniel J.

2001-08-01

This paper is a report of an initial investigation into the active control of preload in the joint using a shape memory actuator around the axis of the bolt shaft. Specifically, the actuator is a cylindrical Nitinol washer that expands axially when heated, according to the shape memory effect. The washer is actuated in response to an artificial decrease in torque. Upon actuation, the stress generated by its axial strain compresses the bolted members and creates a frictional force that has the effect of generating a preload and restoring lost torque. In addition to torque wrenches, the system in question was monitored in all stages of testing using piezoelectric impedance analysis. Impedance analysis drew upon research techniques developed at Center for Intelligent Material Systems and Structures, in which phase changes in the impedance of a self-sensing piezoceramic actuator correspond to changes in joint stiffness. Through experimentation, we have documented a successful actuation of the shape memory element. Due to complexity of constitutive modeling, qualitative analysis by the impedance method is used to illustrate the success. Additional considerations encountered in this initial investigation are made to guide further thorough research required for the successful commercial application of this promising technique.

The role of nitrogen doping in ALD Ta2O5 and its influence on multilevel cell switching in RRAM

NASA Astrophysics Data System (ADS)

Sedghi, N.; Li, H.; Brunell, I. F.; Dawson, K.; Potter, R. J.; Guo, Y.; Gibbon, J. T.; Dhanak, V. R.; Zhang, W. D.; Zhang, J. F.; Robertson, J.; Hall, S.; Chalker, P. R.

2017-03-01

The role of nitrogen doping on the stability and memory window of resistive state switching in N-doped Ta2O5 deposited by atomic layer deposition is elucidated. Nitrogen incorporation increases the stability of resistive memory states which is attributed to neutralization of electronic defect levels associated with oxygen vacancies. The density functional simulations with the screened exchange hybrid functional approximation show that the incorporation of nitrogen dopant atoms in the oxide network removes the O vacancy midgap defect states, thus nullifying excess defects and eliminating alternative conductive paths. By effectively reducing the density of vacancy-induced defect states through N doping, 3-bit multilevel cell switching is demonstrated, consisting of eight distinctive resistive memory states achieved by either controlling the set current compliance or the maximum voltage during reset. Nitrogen doping has a threefold effect: widening the switching memory window to accommodate the more intermediate states, improving the stability of states, and providing a gradual reset for multi-level cell switching during reset. The N-doped Ta2O5 devices have relatively small set and reset voltages (< 1 V) with reduced variability due to doping.

Shared processing in multiple object tracking and visual working memory in the absence of response order and task order confounds

PubMed Central

Howe, Piers D. L.

2017-01-01

To understand how the visual system represents multiple moving objects and how those representations contribute to tracking, it is essential that we understand how the processes of attention and working memory interact. In the work described here we present an investigation of that interaction via a series of tracking and working memory dual-task experiments. Previously, it has been argued that tracking is resistant to disruption by a concurrent working memory task and that any apparent disruption is in fact due to observers making a response to the working memory task, rather than due to competition for shared resources. Contrary to this, in our experiments we find that when task order and response order confounds are avoided, all participants show a similar decrease in both tracking and working memory performance. However, if task and response order confounds are not adequately controlled for we find substantial individual differences, which could explain the previous conflicting reports on this topic. Our results provide clear evidence that tracking and working memory tasks share processing resources. PMID:28410383

Shared processing in multiple object tracking and visual working memory in the absence of response order and task order confounds.

PubMed

Lapierre, Mark D; Cropper, Simon J; Howe, Piers D L

2017-01-01

To understand how the visual system represents multiple moving objects and how those representations contribute to tracking, it is essential that we understand how the processes of attention and working memory interact. In the work described here we present an investigation of that interaction via a series of tracking and working memory dual-task experiments. Previously, it has been argued that tracking is resistant to disruption by a concurrent working memory task and that any apparent disruption is in fact due to observers making a response to the working memory task, rather than due to competition for shared resources. Contrary to this, in our experiments we find that when task order and response order confounds are avoided, all participants show a similar decrease in both tracking and working memory performance. However, if task and response order confounds are not adequately controlled for we find substantial individual differences, which could explain the previous conflicting reports on this topic. Our results provide clear evidence that tracking and working memory tasks share processing resources.

75 FR 29891 - Special Local Regulation; Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-28

...-AA08 Special Local Regulation; Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay... Lighthouse Dock, Fire Island, NY due to the annual Maggie Fischer Memorial Great South Bay Cross Bay Swim..., Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, NY, in the Federal Register (74...

A comparison of the Cray-2 performance before and after the installation of memory pseudo-banking

NASA Technical Reports Server (NTRS)

Schmickley, Ronald D.; Bailey, David H.

1987-01-01

A suite of 13 large Fortran benchmark codes were run on a Cray-2 configured with memory pseudo-banking circuits, and floating point operation rates were measured for each under a variety of system load configurations. These were compared with similar flop measurements taken on the same system before installation of the pseudo-banking. A useful memory access efficiency parameter was defined and calculated for both sets of performance rates, allowing a crude quantitative measure of the improvement in efficiency due to pseudo-banking. Programs were categorized as either highly scalar (S) or highly vectorized (V) and either memory-intensive or register-intensive, giving 4 categories: S-memory, S-register, V-memory, and V-register. Using flop rates as a simple quantifier of these 4 categories, a scatter plot of efficiency gain vs Mflops roughly illustrates the improvement in floating point processing speed due to pseudo-banking. On the Cray-2 system tested this improvement ranged from 1 percent for S-memory codes to about 12 percent for V-memory codes. No significant gains were made for V-register codes, which was to be expected.

Daily supplementation with mushroom (Agaricus bisporus) improves balance and working memory in aged rats

USDA-ARS?s Scientific Manuscript database

Animals and humans show decrements in motor control, cognition, and brain function during normal aging, partly due to the long-term effects of oxidative stress and inflammation. Recent studies have identified a number of fruits and vegetables, whose phytochemical make-up contains potent antioxidant ...

Sleep-dependent memory consolidation and accelerated forgetting

PubMed Central

Atherton, Kathryn E.; Nobre, Anna C.; Zeman, Adam Z.; Butler, Christopher R.

2014-01-01

Accelerated long-term forgetting (ALF) is a form of memory impairment in which learning and initial retention of information appear normal but subsequent forgetting is excessively rapid. ALF is most commonly associated with epilepsy and, in particular, a form of late-onset epilepsy called transient epileptic amnesia (TEA). ALF provides a novel opportunity to investigate post-encoding memory processes, such as consolidation. Sleep is implicated in the consolidation of memory in healthy people and a deficit in sleep-dependent memory consolidation has been proposed as an explanation for ALF. If this proposal were correct, then sleep would not benefit memory retention in people with ALF as much as in healthy people, and ALF might only be apparent when the retention interval contains sleep. To test this theory, we compared performance on a sleep-sensitive memory task over a night of sleep and a day of wakefulness. We found, contrary to the hypothesis, that sleep benefits memory retention in TEA patients with ALF and that this benefit is no smaller in magnitude than that seen in healthy controls. Indeed, the patients performed significantly more poorly than the controls only in the wake condition and not the sleep condition. Patients were matched to controls on learning rate, initial retention, and the effect of time of day on cognitive performance. These results indicate that ALF is not caused by a disruption of sleep-dependent memory consolidation. Instead, ALF may be due to an encoding abnormality that goes undetected on behavioural assessments of learning, or by a deficit in memory consolidation processes that are not sleep-dependent. PMID:24657478

The effect of magnetic field on shape memory behavior in Heusler-type nickel(,2)manganese-gallium-based compounds

NASA Astrophysics Data System (ADS)

Jeong, Soon-Jong

2000-08-01

Shape memory alloys (SMAs) have excellent mechanical properties showing large stroke and high power density when used as actuators. In terms of response speed, however, conventional SMAs have a drawback due to the isothermal nature of the associated phase transformation. A new type of SMA, called ferromagnetic SMA, is considered to replace conventional SMAs and is hoped to overcome such a slow response drawback by changing driving mode of shape memory behaviors from thermal to magnetic. The new type of ferromagnetic SMAs is expected to exhibit not only a large displacement but also rapid response when magnetic field is applied and removed. There are three kinds of ferromagnetic SMAs and among them, Ni2MnGa-based compounds exhibit prominent shape memory effects and superelasticity. In this study, Ni2MnGa-based alloys were chosen and studied to characterize shape memory behavior upon the application and removal of magnetic field. The relevance of the magnetic field-induced shape memory behavior to the magnetization process was investigated by using transformation and/or the movement of martensite variant interfaces. Two mechanisms have been proposed for controlling magnetic field-induced shape memory behaviors. One mechanism is related to shape memory behavior associated with magnetic field-induced martensitic transformation. The other is related to the rearrangement of martensite variants by magnetic field application. Magnetic field-induced martensitic transformation and shape memory effects for single- and poly-crystalline Ni2MnGa alloys were investigated under various conditions. In single crystalline specimens, it was observed that considerable strain changes are a function of magnetic field at temperatures below Mf (martensite finish temperature). Such strain changes, by application and subsequent removal of magnetic field, may be attributed to the martensite variant motion at lower temperatures than Mf. Magnetic field application made a significant contribution to the martensite transformation and related strain changes (0.3%--0.82%) at temperatures above Af (austenite finish temperature) in some polycrystalline Ni2MnGa alloys, where austenite and martensite phases possess paramagnetic and ferromagnetic properties, respectively.

Long-Term Recency in Anterograde Amnesia

PubMed Central

Talmi, Deborah; Caplan, Jeremy B.; Richards, Brian; Moscovitch, Morris

2015-01-01

Amnesia is usually described as an impairment of a long-term memory (LTM) despite an intact short-term memory (STM). The intact recency effect in amnesia had supported this view. Although dual-store models of memory have been challenged by single-store models based on interference theory, this had relatively little influence on our understanding and treatment of amnesia, perhaps because the debate has centred on experiments in the neurologically intact population. Here we tested a key prediction of single-store models for free recall in amnesia: that people with amnesia will exhibit a memory advantage for the most recent items even when all items are stored in and retrieved from LTM, an effect called long-term recency. People with amnesia and matched controls studied, and then free-recalled, word lists with a distractor task following each word, including the last (continual distractor task, CDFR). This condition was compared to an Immediate Free Recall (IFR, no distractors) and a Delayed Free Recall (DFR, end-of-list distractor only) condition. People with amnesia demonstrated the full long-term recency pattern: the recency effect was attenuated in DFR and returned in CDFR. The advantage of recency over midlist items in CDFR was comparable to that of controls, confirming a key prediction of single-store models. Memory deficits appeared only after the first word recalled in each list, suggesting the impairment in amnesia may emerge only as the participant’s recall sequence develops, perhaps due to increased susceptibility to output interference. Our findings suggest that interference mechanisms are preserved in amnesia despite the overall impairment to LTM, and challenge strict dual-store models of memory and their dominance in explaining amnesia. We discuss the implication of our findings for rehabilitation. PMID:26046770

Activity-based prospective memory in schizophrenia.

PubMed

Kumar, Devvarta; Nizamie, S Haque; Jahan, Masroor

2008-05-01

The study reports activity-based prospective memory as well as its clinical and neuropsychological correlates in schizophrenia. A total of 42 persons diagnosed with schizophrenia and 42 healthy controls were administered prospective memory, set-shifting, and verbal working memory tasks. The schizophrenia group was additionally administered various psychopathology rating scales. Group differences, with poorer performances of the schizophrenia group, were observed on the measures of prospective memory, working memory, and set shifting. The performance on prospective memory tasks correlated with the performance levels on verbal working memory and set-shifting tasks but not with the clinical measures. This study demonstrated impaired activity-based prospective memory in schizophrenia. The impairment can be due to deficits in various neuropsychological domains.

Microtraps for neutral atoms using superconducting structures in the critical state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emmert, A.; Brune, M.; Raimond, J.-M.

Recently demonstrated superconducting atom chips provide a platform for trapping atoms and coupling them to solid-state quantum systems. Controlling these devices requires a full understanding of the supercurrent distribution in the trapping structures. For type-II superconductors, this distribution is hysteretic in the critical state due to the partial penetration of the magnetic field in the thin superconducting film through pinned vortices. We report here an experimental observation of this memory effect. Our results are in good agreement with the predictions of the Bean model of the critical state without adjustable parameters. The memory effect allows to write and store permanentmore » currents in micron-sized superconducting structures and paves the way toward engineered trapping potentials.« less

Age Differences in the Effects of Domain Knowledge on Reading Efficiency

PubMed Central

Miller, Lisa M. Soederberg

2009-01-01

The present study investigated age differences in the effects of knowledge on the efficiency with which information is processed while reading. Individuals between 18 and 85 years of age, with varying levels of cooking knowledge, read and recalled a series of short passages within the domain of cooking. Reading efficiency was operationalized as time spent reading divided by the amount recalled for each passage. Results showed that reading efficiency increased with increasing levels of knowledge among older but not younger adults. Similarly, those with smaller working memory capacities showed increasing efficiency with increasing knowledge. These findings suggest that knowledge promotes a more efficient allocation policy which is particularly helpful in later life, perhaps due to age-related declines in working memory capacity. PMID:19290738

The neuropsychology of emerging psychosis and the role of working memory in episodic memory encoding.

PubMed

Pflueger, Marlon O; Calabrese, Pasquale; Studerus, Erich; Zimmermann, Ronan; Gschwandtner, Ute; Borgwardt, Stefan; Aston, Jacqueline; Stieglitz, Rolf-Dieter; Riecher-Rössler, Anita

2018-01-01

Episodic memory encoding and working memory (WM) deficits are among the first cognitive signs and symptoms in the course of schizophrenia spectrum disorders. However, it is not clear whether the deficit pattern is generalized or specific in nature. We hypothesized that encoding deficits at an early stage of the disease might be due to the more fundamental WM deficits. We examined episodic memory encoding and WM by administering the California Verbal Learning Test, a 2-back task, and the Wisconsin Card Sorting Test in 90 first-episode psychosis (FE) patients and 116 individuals with an at-risk mental state for psychosis (ARMS) compared to 57 healthy subjects. Learning progress, but not span of apprehension, was diminished to a similar extent in both the ARMS and the FE. We showed that this was due to WM impairment by applying a structural equation approach. Thus, we conclude that verbal memory encoding deficits are secondary to primary WM impairment in emerging psychosis.

Switching kinetics of SiC resistive memory for harsh environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, K. A., E-mail: kam2g11@soton.ac.uk; Huang, R.; Groot, C. H. de

2015-07-15

Cu/a-SiC/Au resistive memory cells are measured using voltage pulses and exhibit the highest R{sub OFF}/R{sub ON} ratio recorded for any resistive memory. The switching kinetics are investigated and fitted to a numerical model, using thermal conductivity and resistivity properties of the dielectric. The SET mechanism of the Cu/a-SiC/Au memory cells is found to be due to ionic motion without joule heating contributions, whereas the RESET mechanism is found to be due to thermally assisted ionic motion. The conductive filament diameter is extracted to be around 4nm. The high thermal conductivity and resistivity for the Cu/a-SiC/Au memory cells result in slowmore » switching but with high thermal reliability and stability, showing potential for use in harsh environments. Radiation properties of SiC memory cells are investigated. No change was seen in DC sweep or pulsed switching nor in conductive mechanisms, up to 2Mrad(Si) using {sup 60}Co gamma irradiation.« less

Spatial sequences, but not verbal sequences, are vulnerable to general interference during retention in working memory.

PubMed

Morey, Candice C; Miron, Monica D

2016-12-01

Among models of working memory, there is not yet a consensus about how to describe functions specific to storing verbal or visual-spatial memories. We presented aural-verbal and visual-spatial lists simultaneously and sometimes cued one type of information after presentation, comparing accuracy in conditions with and without informative retro-cues. This design isolates interference due specifically to maintenance, which appears most clearly in the uncued trials, from interference due to encoding, which occurs in all dual-task trials. When recall accuracy was comparable between tasks, we found that spatial memory was worse in uncued than in retro-cued trials, whereas verbal memory was not. Our findings bolster proposals that maintenance of spatial serial order, like maintenance of visual materials more broadly, relies on general rather than specialized resources, while maintenance of verbal sequences may rely on domain-specific resources. We argue that this asymmetry should be explicitly incorporated into models of working memory. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Nootropic activity of Celastrus paniculatus seed.

PubMed

Bhanumathy, M; Harish, M S; Shivaprasad, H N; Sushma, G

2010-03-01

The effect of Celastrus paniculatus Willd. (Celastraceae) seed aqueous extract on learning and memory was studied using elevated plus maze and passive avoidance test (sodium nitrite induced amnesia rodent model). The aqueous seed extract was administered orally in two different doses to rats (350 and 1050 mg/kg) and to mice (500 and 1500 mg/kg). The results were compared to piracetam (100 mg/kg, p.o.) used as a standard drug. Chemical hypoxia was induced by subcutaneous administration of sodium nitrite (35 mg/kg), immediately after acquisition training. In elevated plus maze and sodium nitrite-induced amnesia model, Celastrus paniculatus extract has showed statistically significant improvement in memory process when compared to control. The estimation of acetylcholinesterase enzyme in rat brain supports the plus maze and passive avoidance test by reducing acetylcholinesterase activity which helps in memory performance. The study reveals that the aqueous extract of Celastrus paniculatus seed has dose-dependent cholinergic activity, thereby improving memory performance. The mechanism by which Celastrus paniculatus enhances cognition may be due to increased acetylcholine level in rat brain.

Shape memory behavior of single crystal and polycrystalline Ni-rich NiTiHf high temperature shape memory alloys

NASA Astrophysics Data System (ADS)

Saghaian, Sayed M.

NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing. Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti 29.3Hf20, Ni51.2Ti28.8Hf20, and Ni52Ti28Hf20 (at. %)) were systematically characterized in the furnace cooled condition. H-phase precipitates were formed during furnace cooling in compositions with greater than 50.3Ni and the driving force for nucleation increased with Ni content. Alloy strength increased while recoverable strain decreased with increasing Ni content due to changes in precipitate characteristics. The effects of the heat treatments on the transformation characteristics and microstructure of the Ni-rich NiTiHf shape memory alloys have been investigated. Transformation temperatures are found to be highly annealing temperature dependent. Generation of nanosize precipitates (˜20 nm in size) after three hours aging at 450 °C and 550 °C improved the strength of the material, resulting in a near perfect dimensional stability under high stress levels (> 1500 MPa) with a work output of 20-30 J cm- 3. Superelastic behavior with 4% recoverable strain was demonstrated at low and high temperatures where stress could reach to a maximum value of more than 2 GPa after three hours aging at 450 and 550 °C for alloys with Ni great than 50.3 at. %. Shape memory properties of polycrystalline Ni50.3Ti29.7 Hf20 alloys were studied via thermal cycling under stress and isothermal stress cycling experiments in tension. Recoverable strain of ˜5% was observed for the as-extruded samples while it was decreased to ˜4% after aging due to the formation of precipitates. The aged alloys demonstrated near perfect shape memory effect under high tensile stress level of 700 MPa and perfect superelasticity at high temperatures up to 230 °C. Finally, the tension-compression asymmetry observed in NiTiHf where recoverable tensile strain was higher than compressive strain. The shape memory properties of solutionized and aged Ni-rich Ni50.3Ti29.7Hf20 single crystals were investigated along the [001], [011], and [111] orientations in compression. [001]-oriented single crystals showed high dimensional stability under stress levels as high as 1500 MPa in both the solutionized and aged conditions, but with transformation strains of less than 2%. Perfect superelasticity with recoverable strain of more than 4% was observed for solutionized and 550 °C-3h aged single crystals along the [011] and [111] orientations, and general superelastic behavior was observed over a wide temperature range. The calculated transformation strains were higher than the experimentally observed strains since the calculated strains could not capture the formation of martensite plates with (001) compound twins. KEYWORDS: NiTiHf, High Temperature Shape memory alloys, Mechanical Characterization, High Strength Shape Memory Alloy, Orientation Dependence of NiTiHf Sayed.

PMMA interlayer-modulated memory effects by space charge polarization in resistive switching based on CuSCN-nanopyramids/ZnO-nanorods p-n heterojunction

PubMed Central

Cheng, Baochang; Zhao, Jie; Xiao, Li; Cai, Qiangsheng; Guo, Rui; Xiao, Yanhe; Lei, Shuijin

2015-01-01

Resistive switching (RS) devices are commonly believed as a promising candidate for next generation nonvolatile resistance random access memory. Here, polymethylmethacrylate (PMMA) interlayer was introduced at the heterointerface of p-CuSCN hollow nanopyramid arrays and n-ZnO nanorod arrays, resulting in a typical bipolar RS behavior. We propose the mechanism of nanostructure trap-induced space charge polarization modulated by PMMA interlayer. At low reverse bias, PMMA insulator can block charges through the heterointerface, and and trapped states are respectively created on both sides of PMMA, resulting in a high resistance state (HRS) due to wider depletion region. At high reverse bias, however, electrons and holes can cross PMMA interlayer by Fowler-Nordeim tunneling due to a massive tilt of energy band, and then inject into the traps of ZnO and CuSCN, respectively. and trapped states are created, resulting in the formation of degenerate semiconductors on both sides of PMMA. Therefore, quantum tunneling and space charge polarization lead to a low resistance state (LRS). At relatively high forward bias, subsequently, the trapped states of and are recreated due to the opposite injection of charges, resulting in a recovery of HRS. The introduction of insulating interlayer at heterointerface, point a way to develop next-generation nonvolatile memories. PMID:26648249

Implementation of Ferroelectric Memories for Space Applications

NASA Technical Reports Server (NTRS)

Philpy, Stephen C.; Derbenwick, Gary F.; Kamp, David A.; Isaacson, Alan F.

2000-01-01

Ferroelectric random access semiconductor memories (FeRAMs) are an ideal nonvolatile solution for space applications. These memories have low power performance, high endurance and fast write times. By combining commercial ferroelectric memory technology with radiation hardened CMOS technology, nonvolatile semiconductor memories for space applications can be attained. Of the few radiation hardened semiconductor manufacturers, none have embraced the development of radiation hardened FeRAMs, due a limited commercial space market and funding limitations. Government funding may be necessary to assure the development of radiation hardened ferroelectric memories for space applications.

Chronic restraint stress promotes learning and memory impairment due to enhanced neuronal endoplasmic reticulum stress in the frontal cortex and hippocampus in male mice.

PubMed

Huang, Rong-Rong; Hu, Wen; Yin, Yan-Yan; Wang, Yu-Chan; Li, Wei-Ping; Li, Wei-Zu

2015-02-01

Chronic stress has been implicated in many types of neurodegenerative diseases, such as Alzheimer's disease (AD). In our previous study, we demonstrated that chronic restraint stress (CRS) induced reactive oxygen species (ROS) overproduction and oxidative damage in the frontal cortex and hippocampus in mice. In the present study, we investigated the effects of CRS (over a period of 8 weeks) on learning and memory impairment and endoplasmic reticulum (ER) stress in the frontal cortex and hippocampus in male mice. The Morris water maze was used to investigate the effects of CRS on learning and memory impairment. Immunohistochemistry and immunoblot analysis were also used to determine the expression levels of protein kinase C α (PKCα), 78 kDa glucose-regulated protein (GRP78), C/EBP-homologous protein (CHOP) and mesencephalic astrocyte-derived neurotrophic factor (MANF). The results revealed that CRS significantly accelerated learning and memory impairment, and induced neuronal damage in the frontal cortex and hippocampus CA1 region. Moreover, CRS significantly increased the expression of PKCα, CHOP and MANF, and decreased that of GRP78 in the frontal cortex and hippocampus. Our data suggest that exposure to CRS (for 8 weeks) significantly accelerates learning and memory impairment, and the mechanisms involved may be related to ER stress in the frontal cortex and hippocampus.

Multi-floor cascading ferroelectric nanostructures: multiple data writing-based multi-level non-volatile memory devices.

PubMed

Hyun, Seung; Kwon, Owoong; Lee, Bom-Yi; Seol, Daehee; Park, Beomjin; Lee, Jae Yong; Lee, Ju Hyun; Kim, Yunseok; Kim, Jin Kon

2016-01-21

Multiple data writing-based multi-level non-volatile memory has gained strong attention for next-generation memory devices to quickly accommodate an extremely large number of data bits because it is capable of storing multiple data bits in a single memory cell at once. However, all previously reported devices have failed to store a large number of data bits due to the macroscale cell size and have not allowed fast access to the stored data due to slow single data writing. Here, we introduce a novel three-dimensional multi-floor cascading polymeric ferroelectric nanostructure, successfully operating as an individual cell. In one cell, each floor has its own piezoresponse and the piezoresponse of one floor can be modulated by the bias voltage applied to the other floor, which means simultaneously written data bits in both floors can be identified. This could achieve multi-level memory through a multiple data writing process.

Study of in-situ formation of Fe-Mn-Si shape memory alloy welding seam by laser welding with filler powder

NASA Astrophysics Data System (ADS)

Ju, Heng; Lin, Chengxin; Liu, Zhijie; Zhang, Jiaqi

2018-08-01

To reduce the residual stresses and improve the mechanical properties of laser weldments, produced with the restrained mixing uniform design method, a Fe-Mn-Si shape memory alloy (SMA) welding seam was formed inside the 304 stainless steel by laser welding with powder filling. The mass fraction, shape memory effect, and phase composition of the welding seam was measured by SEM-EDS (photometric analyser), bending recovery method, and XRD, respectively. An optical microscope was used to observe the microstructure of the Fe-Mn-Si SMA welding seam by solid solution and pre-deformation treatment. Meanwhile, the mechanical properties (residual stress distribution, tensile strength, microhardness and fatigue strength) of the laser welded specimen with an Fe-Mn-Si SMA welding seam (experimental material) and a 304 stainless steel welding seam (contrast material) were measured by a tensile testing machine hole drilling method and full cycle bending fatigue test. The results show that Fe15Mn5Si12Cr6Ni SMA welding seam was formed in situ with shape memory effect and stress-induced γ → ε martensite phase transformation characteristic. The residual stress of the experimental material is lower than that of the contrast material. The former has larger tensile strength, longer elongation and higher microhardness than the latter has. The experimental material and contrast material possess 249 and 136 bending fatigue cycles at the strain of 6%, respectively. The mechanisms by which mechanical properties of the experimental material are strengthened includes (1) release of the residual stress inside the Fe-Mn-Si SMA welding seam due to the stress-induced γ → ε martensite phase transformation and (2) energy absorption and plastic slip restraint due to the deformations in martensite and reverse phase transformation.

FinFET memory cell improvements for higher immunity against single event upsets

NASA Astrophysics Data System (ADS)

Sajit, Ahmed Sattar

The 21st century is witnessing a tremendous demand for transistors. Life amenities have incorporated the transistor in every aspect of daily life, ranging from toys to rocket science. Day by day, scaling down the transistor is becoming an imperious necessity. However, it is not a straightforward process; instead, it faces overwhelming challenges. Due to these scaling changes, new technologies, such as FinFETs for example, have emerged as alternatives to the conventional bulk-CMOS technology. FinFET has more control over the channel, therefore, leakage current is reduced. FinFET could bridge the gap between silicon devices and non-silicon devices. The semiconductor industry is now incorporating FinFETs in systems and subsystems. For example, Intel has been using them in their newest processors, delivering potential saving powers and increased speeds to memory circuits. Memory sub-systems are considered a vital component in the digital era. In memory, few rows are read or written at a time, while the most rows are static; hence, reducing leakage current increases the performance. However, as a transistor shrinks, it becomes more vulnerable to the effects from radioactive particle strikes. If a particle hits a node in a memory cell, the content might flip; consequently, leading to corrupting stored data. Critical fields, such as medical and aerospace, where there are no second chances and cannot even afford to operate at 99.99% accuracy, has induced me to find a rigid circuit in a radiated working environment. This research focuses on a wide spectrum of memories such as 6T SRAM, 8T SRAM, and DICE memory cells using FinFET technology and finding the best platform in terms of Read and Write delay, susceptibility level of SNM, RSNM, leakage current, energy consumption, and Single Event Upsets (SEUs). This research has shown that the SEU tolerance that 6T and 8T FinFET SRAMs provide may not be acceptable in medical and aerospace applications where there is a very high likelihood of SEUs. Consequently, FinFET DICE memory can be a good candidate due to its high ability to tolerate SEUs of different amplitudes and long periods for both read and hold operations.

Cholinesterase inhibitors, donepezil and rivastigmine, attenuate spatial memory and cognitive flexibility impairment induced by acute ethanol in the Barnes maze task in rats.

PubMed

Gawel, Kinga; Labuz, Krzysztof; Gibula-Bruzda, Ewa; Jenda, Malgorzata; Marszalek-Grabska, Marta; Filarowska, Joanna; Silberring, Jerzy; Kotlinska, Jolanta H

2016-10-01

Central cholinergic dysfunction contributes to acute spatial memory deficits produced by ethanol administration. Donepezil and rivastigmine elevate acetylcholine levels in the synaptic cleft through the inhibition of cholinesterases-enzymes involved in acetylcholine degradation. The aim of our study was to reveal whether donepezil (acetylcholinesterase inhibitor) and rivastigmine (also butyrylcholinesterase inhibitor) attenuate spatial memory impairment as induced by acute ethanol administration in the Barnes maze task (primary latency and number of errors in finding the escape box) in rats. Additionally, we compared the influence of these drugs on ethanol-disturbed memory. In the first experiment, the dose of ethanol (1.75 g/kg, i.p.) was selected that impaired spatial memory, but did not induce motor impairment. Next, we studied the influence of donepezil (1 and 3 mg/kg, i.p.), as well as rivastigmine (0.5 and 1 mg/kg, i.p.), given either before the probe trial or the reversal learning on ethanol-induced memory impairment. Our study demonstrated that these drugs, when given before the probe trial, were equally effective in attenuating ethanol-induced impairment in both test situations, whereas rivastigmine, at both doses (0.5 and 1 mg/kg, i.p.), and donepezil only at a higher dose (3 mg/kg, i.p.) given prior the reversal learning, attenuated the ethanol-induced impairment in cognitive flexibility. Thus, rivastigmine appears to exert more beneficial effect than donepezil in reversing ethanol-induced cognitive impairments-probably due to its wider spectrum of activity. In conclusion, the ethanol-induced spatial memory impairment may be attenuated by pharmacological manipulation of central cholinergic neurotransmission.

Does Recall after Sleep-Dependent Memory Consolidation Reinstate Sensitivity to Retroactive Interference?

PubMed Central

Deliens, Gaétane; Schmitz, Rémy; Caudron, Isaline; Mary, Alison; Leproult, Rachel; Peigneux, Philippe

2013-01-01

Previous studies have shown that newly encoded memories are more resistant to retroactive interference when participants are allowed to sleep after learning the original material, suggesting a sleep-related strengthening of memories. In the present study, we investigated delayed, long-term effects of sleep vs. sleep deprivation (SD) on the first post-training night on memory consolidation and resistance to interference. On day 1, participants learned a list of unrelated word pairs (AB), either in the morning or in the evening, then spent the post-training night in a sleep or sleep deprivation condition, in a within-subject paradigm. On day 4, at the same time of day, they learned a novel list of word pairs (AC) in which 50% of the word pairs stemmed with the same word than in the AB list, resulting in retroactive interference. Participants had then to recall items from the AB list upon presentation of the “A” stem. Recall was marginally improved in the evening, as compared to the morning learning group. Most importantly, retroactive interference effects were found in the sleep evening group only, contrary to the hypothesis that sleep exerts a protective role against intrusion by novel but similar learning. We tentatively suggest that these results can be explained in the framework of the memory reconsolidation theory, stating that exposure to similar information sets back consolidated items in a labile form again sensitive to retroactive interference. In this context, sleep might not protect against interference but would promote an update of existing episodic memories while preventing saturation of the memory network due to the accumulation of dual traces. PMID:23874738

Slow Wave Sleep Induced by GABA Agonist Tiagabine Fails to Benefit Memory Consolidation

PubMed Central

Feld, Gordon B.; Wilhelm, Ines; Ma, Ying; Groch, Sabine; Binkofski, Ferdinand; Mölle, Matthias; Born, Jan

2013-01-01

Study Objectives: Slow wave sleep (SWS) plays a pivotal role in consolidating memories. Tiagabine has been shown to increase SWS in favor of REM sleep without impacting subjective sleep. However, it is unknown whether this effect is paralleled by an improved sleep-dependent consolidation of memory. Design: This double-blind within-subject crossover study tested sensitivity of overnight retention of declarative neutral and emotional materials (word pairs, pictures) as well as a procedural memory task (sequence finger tapping) to oral administration of placebo or 10 mg tiagabine (at 22:30). Participants: Fourteen healthy young men aged 21.9 years (range 18-28 years). Measurements and Results: Tiagabine significantly increased the time spent in SWS and decreased REM sleep compared to placebo. Tiagabine also enhanced slow wave activity (0.5-4.0 Hz) and density of < 1 Hz slow oscillations during NREM sleep. Fast (12-15 Hz) and slow (9-12 Hz) spindle activity, in particular that occurring phase-locked to the slow oscillation cycle, was decreased following tiagabine. Despite signs of deeper and more SWS, overnight retention of memory tested after sleep the next evening (19:30) was generally not improved after tiagabine, but on average even lower than after placebo, with this impairing effect reaching significance for procedural sequence finger tapping. Conclusions: Our data show that increasing slow wave sleep with tiagabine does not improve memory consolidation. Possibly this is due to functional differences from normal slow wave sleep, i.e., the concurrent suppressive influence of tiagabine on phase-locked spindle activity. Citation: Feld GB; Wilhelm I; Ma Y; Groch S; Binkofski F; Mölle M; Born J. Slow wave sleep induced by GABA agonist tiagabine fails to benefit memory consolidation. SLEEP 2013;36(9):1317-1326. PMID:23997364

Effect of W Contents on Martensitic Transformation and Shape Memory Effect in Co-Al-W Alloys

NASA Astrophysics Data System (ADS)

Yang, X.; Qian, B. N.; Peng, H. B.; Wu, B. J.; Wen, Y. H.

2018-04-01

To clarify the effect of W contents on the shape memory effect (SME) in the Co-Al alloys and its influencing mechanism, the SME, martensitic transformation, and deformation behavior were studied in the Co-7Al-xW ( x = 0, 4, 6, 9 wt pct) alloys. The results showed that the additions of W all deteriorated the SME in Co-7Al alloy when deformed at room temperature. However, when deformed in liquid nitrogen, the SME in Co-7Al alloy could be remarkably improved from 43 to 78 pct after the addition of 4 pct W, above which the SME decreased rapidly with the increase of W content although the yield strength of the parent phase rose due to the solution strengthening of W. The deterioration in SME induced by the excessive addition of W could be ascribed to its resulting significant drop of the start temperature of martensitic transformation.

Adiabatic passage in photon-echo quantum memories

NASA Astrophysics Data System (ADS)

Demeter, Gabor

2013-11-01

Photon-echo-based quantum memories use inhomogeneously broadened, optically thick ensembles of absorbers to store a weak optical signal and employ various protocols to rephase the atomic coherences for information retrieval. We study the application of two consecutive, frequency-chirped control pulses for coherence rephasing in an ensemble with a “natural” inhomogeneous broadening. Although propagation effects distort the two control pulses differently, chirped pulses that drive adiabatic passage can rephase atomic coherences in an optically thick storage medium. Combined with spatial phase-mismatching techniques to prevent primary echo emission, coherences can be rephased around the ground state to achieve secondary echo emission with close to unit efficiency. Potential advantages over similar schemes working with π pulses include greater potential signal fidelity, reduced noise due to spontaneous emission, and better capability for the storage of multiple memory channels.

Melatonin attenuates memory impairment induced by Klotho gene deficiency via interactive signaling between MT2 receptor, ERK, and Nrf2-related antioxidant potential.

PubMed

Shin, Eun-Joo; Chung, Yoon Hee; Le, Hoang-Lan Thi; Jeong, Ji Hoon; Dang, Duy-Khanh; Nam, Yunsung; Wie, Myung Bok; Nah, Seung-Yeol; Nabeshima, Yo-Ichi; Nabeshima, Toshitaka; Kim, Hyoung-Chun

2014-12-30

We demonstrated that oxidative stress plays a crucial role in cognitive impairment in klotho mutant mice, a genetic model of aging. Since down-regulation of melatonin due to aging is well documented, we used this genetic model to determine whether the antioxidant property of melatonin affects memory impairment. First, we examined the effects of melatonin on hippocampal oxidative parameters and the glutathione/oxidized glutathione (GSH/GSSG) ratio and memory dysfunction of klotho mutant mice. Second, we investigated whether a specific melatonin receptor is involved in the melatonin-mediated pharmacological response by application with melatonin receptor antagonists. Third, we examined phospho-extracellular-signal-regulated kinase (ERK) expression, nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, Nrf2 DNA binding activity, and glutamate-cysteine ligase (GCL) mRNA expression. Finally, we examined effects of the ERK inhibitor SL327 in response to antioxidant efficacy and memory enhancement mediated by melatonin. Treatment with melatonin resulted in significant attenuations of oxidative damage, a decrease in the GSH/GSSG ratio, and a significant amelioration of memory impairment in this aging model. These effects of melatonin were significantly counteracted by the selective MT2 receptor antagonist 4-P-PDOT. Importantly, 4-P-PDOT or SL327 also counteracted melatonin-mediated attenuation in response to the decreases in phospho-ERK expression, Nrf2 nuclear translocation, Nrf2 DNA-binding activity, and GCL mRNA expression in the hippocampi of klotho mutant mice. SL327 also counteracted the up-regulation of the GSH/GSSG ratio and the memory enhancement mediated by melatonin in klotho mutant mice. Melatonin attenuates oxidative stress and the associated memory impairment induced by klotho deficiency via signaling interaction between the MT2 receptor and ERK- and Nrf2-related antioxidant potential. © The Author 2015. Published by Oxford University Press on behalf of CINP.

Melatonin Attenuates Memory Impairment Induced by Klotho Gene Deficiency Via Interactive Signaling Between MT2 Receptor, ERK, and Nrf2-Related Antioxidant Potential

PubMed Central

Shin, Eun-Joo; Chung, Yoon Hee; Le, Hoang-Lan Thi; Jeong, Ji Hoon; Dang, Duy-Khanh; Nam, Yunsung; Wie, Myung Bok; Nah, Seung-Yeol; Nabeshima, Yo-Ichi; Nabeshima, Toshitaka; Kim, Hyoung-Chun

2015-01-01

Background: We demonstrated that oxidative stress plays a crucial role in cognitive impairment in klotho mutant mice, a genetic model of aging. Since down-regulation of melatonin due to aging is well documented, we used this genetic model to determine whether the antioxidant property of melatonin affects memory impairment. Methods: First, we examined the effects of melatonin on hippocampal oxidative parameters and the glutathione/oxidized glutathione (GSH/GSSG) ratio and memory dysfunction of klotho mutant mice. Second, we investigated whether a specific melatonin receptor is involved in the melatonin-mediated pharmacological response by application with melatonin receptor antagonists. Third, we examined phospho-extracellular-signal-regulated kinase (ERK) expression, nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, Nrf2 DNA binding activity, and glutamate-cysteine ligase (GCL) mRNA expression. Finally, we examined effects of the ERK inhibitor SL327 in response to antioxidant efficacy and memory enhancement mediated by melatonin. Results: Treatment with melatonin resulted in significant attenuations of oxidative damage, a decrease in the GSH/GSSG ratio, and a significant amelioration of memory impairment in this aging model. These effects of melatonin were significantly counteracted by the selective MT2 receptor antagonist 4-P-PDOT. Importantly, 4-P-PDOT or SL327 also counteracted melatonin-mediated attenuation in response to the decreases in phospho-ERK expression, Nrf2 nuclear translocation, Nrf2 DNA-binding activity, and GCL mRNA expression in the hippocampi of klotho mutant mice. SL327 also counteracted the up-regulation of the GSH/GSSG ratio and the memory enhancement mediated by melatonin in klotho mutant mice. Conclusions: Melatonin attenuates oxidative stress and the associated memory impairment induced by klotho deficiency via signaling interaction between the MT2 receptor and ERK- and Nrf2-related antioxidant potential. PMID:25550330

The role of nitric oxide in the PKA inhibitor induced spatial memory deficits in rat: involvement of choline acetyltransferase.

PubMed

Najafi, Sheyda; Payandemehr, Borna; Tabrizian, Kaveh; Shariatpanahi, Marjan; Nassireslami, Ehsan; Azami, Kian; Mohammadi, Mojdeh; Asadi, Farideh; Roghani, Ali; Sharifzadeh, Mohammad

2013-08-15

Several lines of evidence show that cAMP-PKA signaling pathway plays critical role in memory functions and suggest nitric oxide as an important modulator in learning and memory. In this study, we assessed the effects of intra-hippocampal infusion of H-89, a selective PKAII inhibitor, and 1400 W, a selective inducible nitric oxide synthase (iNOS) inhibitor, on spatial memory in rats. By using the Morris water maze, spatial memory retention parameters were examined 48 h after the infusions through measuring escape latency, traveled distance, and swimming speed. The rats receiving intra-hippocampal infusions of 1400 W (100 µM/side) showed a significant reduction (*P<0.05) in escape latency and traveled distance in comparison with the control saline group. In contrast, a significant increase (**P<0.01) in escape latency and traveled distance was observed after infusion of 10 µM H-89. Moreover, among combination groups, co-administration of 1400 W (400 µM/side) with 10 µM/side of H-89 caused a significant reduction (*P<0.05) in escape latency and traveled distance in comparison with the H-89 group. Also, we evaluated the molecular effects of 1400 W on the expression of choline acetyltransferase (ChAT), a cholinergic marker, in the CA1 region of the hippocampus and medial septal area (MSA). Immunohistochemical analysis of post-training bilateral intra-hippocampal infusion of 1400 W revealed a significant increase in ChAT immunoreactivity levels in both the CA1 and the MSA regions. Overall, the results suggest that 1400 W has protective effect against H89-induced spatial memory impairment. Moreover, the observed memory improvements caused by 1400 W infusions, might be due to interaction of iNOS with the cholinergic system. © 2013 Elsevier B.V. All rights reserved.

Effect of Co Addition on the Microstructure, Martensitic Transformation and Shape Memory Behavior of Fe-Mn-Si Alloys

NASA Astrophysics Data System (ADS)

Maji, Bikas C.; Krishnan, Madangopal; Sujata, M.; Gouthama; Ray, Ranjit K.

2013-01-01

The effect of Co addition has been studied in Fe-30Mn-6Si- xCo ( x = 0 to 9 wt pct) shape memory alloys in terms of their microstructure, martensitic transformation and shape recovery. Microstructural investigations reveal that in Fe-Mn-Si-Co alloys, the microstructure remains single-phase austenite (γ) up to 5 pct Co and beyond that becomes two-phase comprising γ and off-stoichiometric (Fe,Co)5Mn3Si2 intermetallic π-phases. The forward γ-ɛ martensite transformation start temperature ( M S) decreases with the addition of Co up to 5 pct, and alloys containing more than 5 pct Co, show slightly higher M S possibly on account of two-phase microstructure. Unlike M S, the ɛ-γ reverse transformation start temperature ( A S) has been found to remain almost unaltered by Co addition. In general, addition of Co to Fe-Mn-Si alloys deteriorates shape recovery due to decreasing resistance to plastic yielding concomitant with the formation of stress induced ɛ martensite. However, there is an improvement in shape recovery beyond 5 pct Co addition, possibly due to the strengthening effect arising from the presence of (Fe,Co)5Mn3Si2 precipitates within the two-phase microstructure and due to higher amount of stress induced ɛ martensite.

Enhanced switching stability in Ta2O5 resistive RAM by fluorine doping

NASA Astrophysics Data System (ADS)

Sedghi, N.; Li, H.; Brunell, I. F.; Dawson, K.; Guo, Y.; Potter, R. J.; Gibbon, J. T.; Dhanak, V. R.; Zhang, W. D.; Zhang, J. F.; Hall, S.; Robertson, J.; Chalker, P. R.

2017-08-01

The effect of fluorine doping on the switching stability of Ta2O5 resistive random access memory devices is investigated. It shows that the dopant serves to increase the memory window and improve the stability of the resistive states due to the neutralization of oxygen vacancies. The ability to alter the current in the low resistance state with set current compliance coupled with large memory window makes multilevel cell switching more favorable. The devices have set and reset voltages of <1 V with improved stability due to the fluorine doping. Density functional modeling shows that the incorporation of fluorine dopant atoms at the two-fold O vacancy site in the oxide network removes the defect state in the mid bandgap, lowering the overall density of defects capable of forming conductive filaments. This reduces the probability of forming alternative conducting paths and hence improves the current stability in the low resistance states. The doped devices exhibit more stable resistive states in both dc and pulsed set and reset cycles. The retention failure time is estimated to be a minimum of 2 years for F-doped devices measured by temperature accelerated and stress voltage accelerated retention failure methods.

Durability of carbon fiber reinforced shape memory polymer composites in space

NASA Astrophysics Data System (ADS)

Jang, Joon Hyeok; Hong, Seok Bin; Ahn, Yong San; Kim, Jin-Gyun; Nam, Yong-Youn; Lee, Geun Ho; Yu, Woong-Ryeol

2016-04-01

Shape memory polymer (SMP) is one of smart polymers which exhibit shape memory effect upon external stimuli. Recently, shape memory polymer composites (SMPCs) have been considered for space structure instead of shape memory alloys due to their deformability, lightweight and large recovery ratio, requiring characterization of their mechanical properties against harsh space environment and further prediction of the durability of SMPCs in space. As such, the durability of carbon fiber reinforced shape memory polymer composites (CF-SMPCs) was investigated using accelerated testing method based on short-term testing of CF-SMPCs in harsh condition. CF-SMPCs were prepared using woven carbon fabrics and a thermoset SMP via vacuum assisted resin transfer molding process. Bending tests with constant strain rate of CF-SMPCs were conducted using universal tensile machine (UTM) and Storage modulus test were conducted using dynamic mechanical thermal analysis (DMTA). Using the results, a master curve based on time-temperature superposition principle was then constructed, through which the mechanical properties of CF-SMPCs at harsh temperature were predicted. CF-SMPCs would be exposed to simulated space environments under ultra-violet radiations at various temperatures. The mechanical properties including flexural and tensile strength and shape memory properties of SMPCs would be measured using UTM before and after such exposures for comparison. Finally, the durability of SMPCs in space would be assessed by developing a degradation model of SMPC.

Functionalized Graphitic Carbon Nitride for Metal-free, Flexible and Rewritable Nonvolatile Memory Device via Direct Laser-Writing

PubMed Central

Zhao, Fei; Cheng, Huhu; Hu, Yue; Song, Long; Zhang, Zhipan; Jiang, Lan; Qu, Liangti

2014-01-01

Graphitic carbon nitride nanosheet (g-C3N4-NS) has layered structure similar with graphene nanosheet and presents unusual physicochemical properties due to the s-triazine fragments. But their electronic and electrochemical applications are limited by the relatively poor conductivity. The current work provides the first example that atomically thick g-C3N4-NSs are the ideal candidate as the active insulator layer with tunable conductivity for achieving the high performance memory devices with electrical bistability. Unlike in conventional memory diodes, the g-C3N4-NSs based devices combined with graphene layer electrodes are flexible, metal-free and low cost. The functionalized g-C3N4-NSs exhibit desirable dispersibility and dielectricity which support the all-solution fabrication and high performance of the memory diodes. Moreover, the flexible memory diodes are conveniently fabricated through the fast laser writing process on graphene oxide/g-C3N4-NSs/graphene oxide thin film. The obtained devices not only have the nonvolatile electrical bistability with great retention and endurance, but also show the rewritable memory effect with a reliable ON/OFF ratio of up to 105, which is the highest among all the metal-free flexible memory diodes reported so far, and even higher than those of metal-containing devices. PMID:25073687

Discrepancy of performance among working memory-related tasks in autism spectrum disorders was caused by task characteristics, apart from working memory, which could interfere with task execution.

PubMed

Nakahachi, Takayuki; Iwase, Masao; Takahashi, Hidetoshi; Honaga, Eiko; Sekiyama, Ryuji; Ukai, Satoshi; Ishii, Ryouhei; Ishigami, Wataru; Kajimoto, Osami; Yamashita, Ko; Hashimoto, Ryota; Tanii, Hisashi; Shimizu, Akira; Takeda, Masatoshi

2006-06-01

Working memory performance has been inconsistently reported in autism spectrum disorders (ASD). Several studies in ASD have found normal performance in digit span and poor performance in digit symbol task although these are closely related with working memory. It is assumed that poor performance in digit symbol could be explained by confirmatory behavior, which is induced due to the vague memory representation of number-symbol association. Therefore it was hypothesized that the performance of working memory task, in which vagueness did not cause confirmatory behavior, would be normal in ASD. For this purpose, the Advanced Trail Making Test (ATMT) was used. The performance of digit span, digit symbol and ATMT was compared between ASD and normal control. The digit span, digit symbol and ATMT was given to 16 ASD subjects and 28 IQ-, age- and sex-matched control subjects. The scores of these tasks were compared. A significantly lower score for ASD was found only in digit symbol compared with control subjects. There were no significant difference in digit span and working memory estimated by ATMT. Discrepancy of scores among working memory-related tasks was demonstrated in ASD. Poor digit symbol performance, normal digit span and normal working memory in ATMT implied that ASD subjects would be intact in working memory itself, and that superficial working memory dysfunction might be observed due to confirmatory behavior in digit symbol. Therefore, to evaluate working memory in ASD, tasks that could stimulate psychopathology specific to ASD should be avoided.

Appetitive Pavlovian Goal-Tracking Memories Reconsolidate Only under Specific Conditions

ERIC Educational Resources Information Center

Reichelt, Amy C.; Lee, Jonathan L. C.

2013-01-01

Despite extensive evidence that appetitive memories undergo reconsolidation, two notable failures to observe reconsolidation have been reported: instrumental responding and goal-tracking. However, these studies do not provide conclusive evidence for a lack of memory reconsolidation due to the numerous boundary conditions that dictate whether a…

Is the Survival-Processing Memory Advantage Due to Richness of Encoding?

ERIC Educational Resources Information Center

Röer, Jan P.; Bell, Raoul; Buchner, Axel

2013-01-01

Memory for words rated according to their relevance in a grassland survival context is exceptionally good. According to Nairne, Thompson, and Pandeirada's (2007) evolutionary-based explanation, natural selection processes have tuned the human memory system to prioritize the processing of fitness-relevant information. The survival-processing memory…

Verapamil enhances acute stress or glucocorticoid-induced deficits in retrieval of long-term memory in rats.

PubMed

Rashidy-Pour, Ali; Vafaei, Abbas Ali; Taherian, Abbas Ali; Miladi-Gorji, Hossein; Sadeghi, Hassan; Fathollahi, Yaghoub; Bandegi, Ahmad Reza

2009-10-12

This study was designed to investigate an interaction between acute restraint stress and corticosterone with verapamil, a blocker of L-type voltage-dependent calcium (VDC) channels on retrieval of long-term memory. Young adult male rats were trained in one trial inhibitory avoidance task (0.5 mA, 3 s footshock). On retention test given 48 h after training, the latency to re-enter dark compartment of the apparatus was recorded. In Experiment 1, verapamil pretreatment (5, 10, or 20 mg/kg) enhanced the impairing effects of acute stress (which was applied for 10 min in a Plexiglass tube 30 min before the retention test) on memory retrieval. The applied stress increased circulating corticosterone levels as assessed immediately after the retention test, indicating that stress-induced impairment of memory retrieval is mediated, in part, by increased plasma levels of glucocorticoids. Verapamil did not change this response. In Experiment 2, pretreatment of an intermediate dose of verapamil also enhanced corticosterone-induced impairment of memory retrieval. In Experiments 3 and 4, acute stress or corticosterone did not change motor activity with or without prior treatment of verapamil, suggesting that stress or glucocorticoid-induced impairment of memory retrieval is not due to any gross disturbances in motor performance of animals. These findings indicate that blockade of L-type VDC channels enhances stress or glucocorticoid-induced impairment of memory retrieval, and provide evidence for the existence of an interaction between glucocorticoids and L-type VDC channels on memory retrieval.

Directed Forgetting and Directed Remembering in Visual Working Memory

PubMed Central

Williams, Melonie; Woodman, Geoffrey F.

2013-01-01

A defining characteristic of visual working memory is its limited capacity. This means that it is crucial to maintain only the most relevant information in visual working memory. However, empirical research is mixed as to whether it is possible to selectively maintain a subset of the information previously encoded into visual working memory. Here we examined the ability of subjects to use cues to either forget or remember a subset of the information already stored in visual working memory. In Experiment 1, participants were cued to either forget or remember one of two groups of colored squares during a change-detection task. We found that both types of cues aided performance in the visual working memory task, but that observers benefited more from a cue to remember than a cue to forget a subset of the objects. In Experiment 2, we show that the previous findings, which indicated that directed-forgetting cues are ineffective, were likely due to the presence of invalid cues that appear to cause observers to disregard such cues as unreliable. In Experiment 3, we recorded event-related potentials (ERPs) and show that an electrophysiological index of focused maintenance is elicited by cues that indicate which subset of information in visual working memory needs to be remembered, ruling out alternative explanations of the behavioral effects of retention-interval cues. The present findings demonstrate that observers can focus maintenance mechanisms on specific objects in visual working memory based on cues indicating future task relevance. PMID:22409182

Evaluating Non-In-Place Update Techniques for Flash-Based Transaction Processing Systems

NASA Astrophysics Data System (ADS)

Wang, Yongkun; Goda, Kazuo; Kitsuregawa, Masaru

Recently, flash memory is emerging as the storage device. With price sliding fast, the cost per capacity is approaching to that of SATA disk drives. So far flash memory has been widely deployed in consumer electronics even partly in mobile computing environments. For enterprise systems, the deployment has been studied by many researchers and developers. In terms of the access performance characteristics, flash memory is quite different from disk drives. Without the mechanical components, flash memory has very high random read performance, whereas it has a limited random write performance because of the erase-before-write design. The random write performance of flash memory is comparable with or even worse than that of disk drives. Due to such a performance asymmetry, naive deployment to enterprise systems may not exploit the potential performance of flash memory at full blast. This paper studies the effectiveness of using non-in-place-update (NIPU) techniques through the IO path of flash-based transaction processing systems. Our deliberate experiments using both open-source DBMS and commercial DBMS validated the potential benefits; x3.0 to x6.6 performance improvement was confirmed by incorporating non-in-place-update techniques into file system without any modification of applications or storage devices.

Dietary self-control influences top-down guidance of attention to food cues.

PubMed

Higgs, Suzanne; Dolmans, Dirk; Humphreys, Glyn W; Rutters, Femke

2015-01-01

Motivational objects attract attention due to their rewarding properties, but less is known about the role that top-down cognitive processes play in the attention paid to motivationally relevant objects and how this is affected by relevant behavioral traits. Here we assess how thinking about food affects attentional guidance to food items and how this is modulated by traits relating to dietary self-control. Participants completed two tasks in which they were presented with an initial cue (food or non-food) to either hold in working memory (memory task) or to merely attend to (priming task). Holding food items in working memory strongly affected attention when the memorized cue re-appeared in the search display. Tendency towards disinhibited eating was associated with greater attention to food versus non-food pictures in both the priming and working memory tasks, consistent with greater attention to food cues per se. Successful dieters, defined as those high in dietary restraint and low in tendency to disinhibition, showed reduced attention to food when holding food-related information in working memory. These data suggest a strong top-down effect of thinking about food on attention to food items and indicate that the suppression of food items in working memory could be a marker of dieting success.

Neuroprotective effect of ipriflavone against scopolamine-induced memory impairment in rats.

PubMed

Hafez, Hani S; Ghareeb, Doaa A; Saleh, Samar R; Abady, Mariam M; El Demellawy, Maha A; Hussien, Hend; Abdel-Monem, Nihad

2017-10-01

Alzheimer's disease is an age-related neurodegenerative disorder characterized clinically by a progressive loss of memory and cognitive functions resulting in severe dementia. Ipriflavone (IPRI) is a non-hormonal, semi-synthetic isoflavone, clinically used in some countries for the treatment and prevention of postmenopausal osteoporosis. Moreover, ipriflavone is a non-peptidomimetic small molecule AChE inhibitor with an improved bioavailability after systemic administration, due to its efficient blood-brain barrier permeability in comparison with peptidomimetic inhibitors. The present study aimed to evaluate the possible enhancing effects of IPRI on memory impairments caused by scopolamine administration. Male rats were administered IPRI (50 mg/kg, oral) 2 h before scopolamine injection (2 mg/kg, intraperitoneally injected) daily for 4 weeks. Effects of IPRI on acetylcholinesterase activity, amyloid-β precursor processing, and neuroplasticity in the rats' hippocampus were investigated. Daily administration of IPRI reverted memory impairment caused by scopolamine as measured by the reduction of the escape latency. IPRI significantly alleviated the oxidative stress and restored the mRNA expression of both cAMP-response element-binding protein and brain-derived neurotrophic factor in the hippocampus. Furthermore, it significantly increased the expression of ADAM10 and ADAM17 (two putative α-secretase enzymes) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) that associated with decreased expression of β-secretase (BACE) in the hippocampus. Finally, both the amyloid-β (Aβ) and Tau pathologies were reduced. IPRI showed promising neuroprotective effects against scopolamine-induced memory dysfunction in rats. These findings contributed to the stimulation of α-secretase enzymes, the activation of MAPK/ERK1/2, and the alleviation of oxidative stress.

Protection against brain tissues oxidative damage as a possible mechanism for the beneficial effects of Rosa damascena hydroalcoholic extract on scopolamine induced memory impairment in rats.

PubMed

Mohammadpour, Toktam; Hosseini, Mahmoud; Naderi, Asieh; Karami, Reza; Sadeghnia, Hamid Reza; Soukhtanloo, Mohammad; Vafaee, Farzaneh

2015-10-01

Hypnotic, analgesic, anticonvulsant, and antioxidant effects of Rosa damascena have been reported. This study, investigated the effect of R. damascena hydroalcoholic extract on memory performance in a scopolamine-induced memory impairment model. The rats were divided into control group received just saline; scopolamine group was treated by saline for 2 weeks, but was injected by scopolamine 30 minutes before each trial in Morris water maze test; treatment groups (scopolamine + extract 50; Sco + Ext 50) and (scopolamine + extract 250; Sco + Ext 250) were daily treated by 50 and 250 mg/kg of R. damascena extract (2 weeks) and were finally injected by scopolamine before each trial in Morris water maze. The brains were removed for biochemical measurements. Time latency and path length in the scopolamine group were higher than control (P < 0.01 to <0.001). Both treatment groups showed shorter traveled distance and time latency compared with scopolamine group (P < 0.05 to <0.001). Time spent in target quadrant by scopolamine group was lower than control (P < 0.05), while Sco + Ext 250 group spent longer time in target quadrant than scopolamine group (P < 0.05). Malondialdehyde concentrations in hippocampal and cortical tissues of scopolamine group were higher, while thiol concentrations were lower than control ones (P < 0.001). Treatment by both doses of the extract decreased the malondialdehyde concentration, while increased the thiol concentration (P < 0.05 to <0.001). The results of this study showed that the hydroalcoholic extract of R. damascena prevents scopolamine-induced memory deficits. This finding suggests that memory improvement may be in part due to the antioxidant effects.

Effects of ginseol k-g3, an Rg3-enriched fraction, on scopolamine-induced memory impairment and learning deficit in mice

PubMed Central

Peña, Ike dela; Yoon, Seo Young; Kim, Hee Jin; Park, Sejin; Hong, Eun Young; Ryu, Jong Hoon; Park, Il Ho; Cheong, Jae Hoon

2013-01-01

Background Although ginsenosides such as Rg1, Rb1 and Rg3 have shown promise as potential nutraceuticals for cognitive impairment, their use has been limited due to high production cost and low potency. In particular, the process of extracting pure Rg3 from ginseng is laborious and expensive. Methods We described the methods in preparing ginseol k-g3, an Rg3-enriched fraction, and evaluated its effects on scopolamine-induced memory impairment in mice. Results Ginseol k-g3 (25–200 mg/kg) significantly reversed scopolamine-induced cognitive impairment in the passive avoidance, but not in Y-maze testing. Ginseol k-g3 (50 and 200 mg/kg) improved escape latency in training trials and increased swimming times within the target zone of the Morris water maze. The effect of ginseol k-g3 on the water maze task was more potent than that of Rg3 or Red ginseng. Acute or subchronic (6 d) treatment of ginseol k-g3 did not alter normal locomotor activity of mice in an open field. Ginseol k-g3 did not inhibit acetylcholinesterase activity, unlike donezepil, an acetylcholinesterase inhibitor. Rg3 enrichment through the ginseol k-g3 fraction enhanced the efficacy of Rg3 in scopolamine-induced memory impairment in mice as demonstrated in the Morris water maze task. Conclusion The effects of ginseol k-g3 in ameliorating scopolamine-induced memory impairment in the passive avoidance and Morris water maze tests indicate its specific influence on reference or long-term memory. The mechanism underlying the reversal of scopolamine-induced amnesia by ginseol k-g3 is not yet known, but is not related to anticholinesterase-like activity. PMID:24558303

Scopolamine-Induced Memory Impairment Is Alleviated by Xanthotoxin: Role of Acetylcholinesterase and Oxidative Stress Processes.

PubMed

Skalicka-Wozniak, Krystyna; Budzynska, Barbara; Biala, Grazyna; Boguszewska-Czubara, Anna

2018-05-16

Xanthotoxin, popularly occurring furanocoumarin, which can be found in plants from the Apiaceae family, was isolated from fruits of Pastinaca sativa L. by mean of high-performance countercurrent chromatography, and its effects on the scopolamine-induced cognitive deficits in male Swiss mice using the passive avoidance (PA) test were evaluated. To measure the acquisition of memory processes, xanthotoxin (1, 2.5, 5 mg/kg) was administered 30 min before PA test and scopolamine was administered 10 min after xanthotoxin. To measure the consolidation of memory processes, xanthotoxin (1 and 2.5 mg/kg) was injected immediately after removing the mouse from the apparatus and 10 min after scopolamine was administered. In subchronic experiments, mice were injected with xanthotoxin (1 mg/kg) or saline, 6 days, twice daily. At 24 h after the last injection of the drugs, the hippocampus and the prefrontal cortex were removed for biochemical assays. The results demonstrated that either single (2.5 and 5 mg/kg) or repeatable (1 mg/kg) administration of xanthotoxin significantly increased index of latency (IL) in both acquisition and consolidation of memory processes, showing some procognitive effects. The behavioral tests also showed that an acute (2.5 mg/kg) and subchronic (1 mg/kg) administration of xanthotoxin prevent memory impairment induced by injection of scopolamine (1 mg/kg). Observed effects could be due to the inhibition of acetylcholinesterase activities and amelioration of oxidative stress processes in the hippocampus and the prefrontal cortex. It was suggested that xanthotoxin could show neuroprotective effect in scopolamine-induced cognitive impairment connected to cholinergic neurotransmission and oxidative stress in the brain structures.

Providing Extrinsic Reward for Test Performance Undermines Long-Term Memory Acquisition.

PubMed

Kuhbandner, Christof; Aslan, Alp; Emmerdinger, Kathrin; Murayama, Kou

2016-01-01

Based on numerous studies showing that testing studied material can improve long-term retention more than restudying the same material, it is often suggested that the number of tests in education should be increased to enhance knowledge acquisition. However, testing in real-life educational settings often entails a high degree of extrinsic motivation of learners due to the common practice of placing important consequences on the outcome of a test. Such an effect on the motivation of learners may undermine the beneficial effects of testing on long-term memory because it has been shown that extrinsic motivation can reduce the quality of learning. To examine this issue, participants learned foreign language vocabulary words, followed by an immediate test in which one-third of the words were tested and one-third restudied. To manipulate extrinsic motivation during immediate testing, participants received either monetary reward contingent on test performance or no reward. After 1 week, memory for all words was tested. In the immediate test, reward reduced correct recall and increased commission errors, indicating that reward reduced the number of items that can benefit from successful retrieval. The results in the delayed test revealed that reward additionally reduced the gain received from successful retrieval because memory for initially successfully retrieved words was lower in the reward condition. However, testing was still more effective than restudying under reward conditions because reward undermined long-term memory for concurrently restudied material as well. These findings indicate that providing performance-contingent reward in a test can undermine long-term knowledge acquisition.

Providing Extrinsic Reward for Test Performance Undermines Long-Term Memory Acquisition

PubMed Central

Kuhbandner, Christof; Aslan, Alp; Emmerdinger, Kathrin; Murayama, Kou

2016-01-01

Based on numerous studies showing that testing studied material can improve long-term retention more than restudying the same material, it is often suggested that the number of tests in education should be increased to enhance knowledge acquisition. However, testing in real-life educational settings often entails a high degree of extrinsic motivation of learners due to the common practice of placing important consequences on the outcome of a test. Such an effect on the motivation of learners may undermine the beneficial effects of testing on long-term memory because it has been shown that extrinsic motivation can reduce the quality of learning. To examine this issue, participants learned foreign language vocabulary words, followed by an immediate test in which one-third of the words were tested and one-third restudied. To manipulate extrinsic motivation during immediate testing, participants received either monetary reward contingent on test performance or no reward. After 1 week, memory for all words was tested. In the immediate test, reward reduced correct recall and increased commission errors, indicating that reward reduced the number of items that can benefit from successful retrieval. The results in the delayed test revealed that reward additionally reduced the gain received from successful retrieval because memory for initially successfully retrieved words was lower in the reward condition. However, testing was still more effective than restudying under reward conditions because reward undermined long-term memory for concurrently restudied material as well. These findings indicate that providing performance–contingent reward in a test can undermine long-term knowledge acquisition. PMID:26869978

The role of pregnenolone sulphate in spatial orientation-acquisition and retention: an interplay between cognitive potentiation and mood regulation.

PubMed

Plescia, Fulvio; Marino, Rosa A M; Cannizzaro, Emanuele; Brancato, Anna; Cannizzaro, Carla

2013-10-01

Neurosteroids can alter neuronal excitability interacting with specific neurotransmitter receptors, thus affecting several functions such as cognition and emotionality. In this study, we investigated, in adult male rats, the effects of the acute administration of pregnenolone-sulfate (PREGS) (10 mg/Kg, s.c.) on cognitive processes using the Can test, a non aversive spatial/visual task which allows the assessment of spatial information-acquisition during the baseline training, and of memory retention in the longitudinal study. Furthermore, on the basis of PREGS pharmacological profile, the modulation of depressive-like behaviour was also evaluated in the forced swim test (FST). Our results indicate that acute PREGS induces: an improvement in spatial orientation-acquisition and in reference memory, during the baseline training; a strengthening effect on reference and working memory during the longitudinal study. A decrease in immobility time in the FST has also been recorded. In conclusion, PREGS exerts enhancing properties on acquisition, consolidation and retrieval of spatial information, probably due of improved hippocampal-dependent memory processes. The additional antidepressant effect observed in the FST can provide further evidence in support of the potential of PREGS as a therapeutic tool for the treatment of cognitive deficits associated with mood disorders. This article is part of a Special Issue entitled: insert SI title. Copyright © 2013 Elsevier B.V. All rights reserved.

Behavioral and neural bases of extinction learning in Hermissenda

PubMed Central

Cavallo, Joel S.; Hamilton, Brittany N.; Farley, Joseph

2014-01-01

Extinction of classical conditioning is thought to produce new learning that masks or interferes with the original memory. However, research in the nudibranch Hermissenda crassicornis (H.c.) has challenged this view, and instead suggested that extinction erased the original associative memory. We have re-examined extinction in H.c. to test whether extinguished associative memories can be detected on the behavioral and cellular levels, and to characterize the temporal variables involved. Associative conditioning using pairings of light (CS) and rotation (US) produced characteristic suppression of H.c. phototactic behavior. A single session of extinction training (repeated light-alone presentations) reversed suppressed behavior back to pre-training levels when administered 15 min after associative conditioning. This effect was abolished if extinction was delayed by 23 h, and yet was recovered using extended extinction training (three consecutive daily extinction sessions). Extinguished phototactic suppression did not spontaneously recover at any retention interval (RI) tested (2-, 24-, 48-, 72-h), or after additional US presentations (no observed reinstatement). Extinction training (single session, 15 min interval) also reversed the pairing-produced increases in light-evoked spike frequencies of Type B photoreceptors, an identified site of associative memory storage that is causally related to phototactic suppression. These results suggest that the behavioral effects of extinction training are not due to temporary suppression of associative memories, but instead represent a reversal of the underlying cellular changes necessary for the expression of learning. In the companion article, we further elucidate mechanisms responsible for extinction-produced reversal of memory-related neural plasticity in Type B photoreceptors. PMID:25191236

Towards Low-Cost Effective and Homogeneous Thermal Activation of Shape Memory Polymers

PubMed Central

Lantada, Andrés Díaz; Rebollo, María Ángeles Santamaría

2013-01-01

A typical limitation of intelligent devices based on the use of shape-memory polymers as actuators is linked to the widespread use of distributed heating resistors, via Joule effect, as activation method, which involves several relevant issues needing attention, such as: (a) Final device size is importantly increased due to the additional space required for the resistances; (b) the use of resistances limits materials’ strength and the obtained devices are normally weaker; (c) the activation process through heating resistances is not homogeneous, thus leading to important temperature differences among the polymeric structure and to undesirable thermal gradients and stresses, also limiting the application fields of shape-memory polymers. In our present work we describe interesting activation alternatives, based on coating shape-memory polymers with different kinds of conductive materials, including textiles, conductive threads and conductive paint, which stand out for their easy, rapid and very cheap implementation. Distributed heating and homogeneous activation can be achieved in several of the alternatives studied and the technical results are comparable to those obtained by using advanced shape-memory nanocomposites, which have to deal with complex synthesis, processing and security aspects. Different combinations of shape memory epoxy resin with several coating electrotextiles, conductive films and paints are prepared, simulated with the help of thermal finite element method based resources and characterized using infrared thermography for validating the simulations and overall design process. A final application linked to an active catheter pincer is detailed and the advantages of using distributed heating instead of conventional resistors are discussed. PMID:28788401

Remembering Makes Evidence Compelling: Retrieval from Memory Can Give Rise to the Illusion of Truth

ERIC Educational Resources Information Center

Ozubko, Jason D.; Fugelsang, Jonathan

2011-01-01

The "illusion of truth" is traditionally described as the increase in perceived validity of statements when they are repeated (Hasher, Goldstein, & Toppino, 1977). However, subsequent work has demonstrated that the effect can arise due to the increased familiarity or fluency afforded by repetition and not necessarily to repetition…

EPA Biofuels Research: Effects of Inhaled Ethanol on Cortical Functions in the Offspring of Rats Exposed During Gestation.**

EPA Science Inventory

Due to the increased interest in ethanol blends as an alternative fuel source, there is a need to assess their possible health risks to sensitive populations. Specifically, ethanol is known to alter cortical functions such as attention, processing speed, movement, working memory,...

The Effect of Configuration on VSWM Performance of Down Syndrome Individuals

ERIC Educational Resources Information Center

Carretti, B.; Lanfranchi, S.

2010-01-01

Background: Recent studies have demonstrated that individuals with Down syndrome (DS) are poorer than controls in spatial-simultaneous tasks, but not in spatial-sequential tasks. To explain this finding, it has been suggested that the simultaneous visuo-spatial working memory deficit of individuals with DS could be due to the request for…

Self-Regulatory Strategies in Daily Life: Selection, Optimization, and Compensation and Everyday Memory Problems

ERIC Educational Resources Information Center

Robinson, Stephanie A.; Rickenbach, Elizabeth H.; Lachman, Margie E.

2016-01-01

The effective use of self-regulatory strategies, such as selection, optimization, and compensation (SOC) requires resources. However, it is theorized that SOC use is most advantageous for those experiencing losses and diminishing resources. The present study explored this seeming paradox within the context of limitations or constraints due to…

Application of Local Discretization Methods in the NASA Finite-Volume General Circulation Model

NASA Technical Reports Server (NTRS)

Yeh, Kao-San; Lin, Shian-Jiann; Rood, Richard B.

2002-01-01

We present the basic ideas of the dynamics system of the finite-volume General Circulation Model developed at NASA Goddard Space Flight Center for climate simulations and other applications in meteorology. The dynamics of this model is designed with emphases on conservative and monotonic transport, where the property of Lagrangian conservation is used to maintain the physical consistency of the computational fluid for long-term simulations. As the model benefits from the noise-free solutions of monotonic finite-volume transport schemes, the property of Lagrangian conservation also partly compensates the accuracy of transport for the diffusion effects due to the treatment of monotonicity. By faithfully maintaining the fundamental laws of physics during the computation, this model is able to achieve sufficient accuracy for the global consistency of climate processes. Because the computing algorithms are based on local memory, this model has the advantage of efficiency in parallel computation with distributed memory. Further research is yet desirable to reduce the diffusion effects of monotonic transport for better accuracy, and to mitigate the limitation due to fast-moving gravity waves for better efficiency.

Neuroprotective effect of antioxidants on ischaemia and reperfusion-induced cerebral injury.

PubMed

Gupta, Ram; Singh, Manjeet; Sharma, Ajay

2003-08-01

The present study is designed to investigate the effect of dietary flavanoid rutin, micronutrient selenium and garlic oil on ischaemia and reperfusion-induced cerebral injury. Global cerebral ischaemia was induced by occluding right and left common carotid arteries for 10min followed by reperfusion for 24h. Cerebral infarct size was estimated using triphenyltetrazolium chloride staining. Elevated plus maze was employed to estimate short-term memory. Degree of motor incoordination was evaluated using inclined beam-walking test and lateral push test. Mitochondrial thiobarbituric acid reactive substances (TBARS) assay was employed as an index of oxidative stress. Global cerebral ischaemia followed by reperfusion produced a significant impairment in short-term memory and motor coordination and produced a notable increase in mitochondrial TBARS. Administration of rutin and garlic oil before global cerebral ischaemia markedly reduced cerebral infarct size and attenuated impairment in short-term memory and motor coordination. Administration of sodium selenite either before or after global cerebral ischaemia markedly reduced cerebral infarct size and attenuated impairment in short-term memory and motor coordination. The protective effect of rutin, sodium selenite and garlic oil was accompanied by a marked decrease in mitochondrial TBARS. On the basis of these results, it may be suggested that rutin and garlic oil administrated before cerebral ischaemia may scavenge reactive oxygen species and consequently attenuate global cerebral ischaemia and reperfusion-induced cerebral injury. Sodium selenite administrated before and after cerebral ischaemia may be neuroprotective due to its antioxidant effect.

RBANS memory percentage retention: No evidence of incremental validity beyond RBANS scores for diagnostic classification of mild cognitive impairment and dementia and for prediction of daily function.

PubMed

Jodouin, Kara A; O'Connell, Megan E; Morgan, Debra G

2017-01-01

RBANS percentage retention scores may be useful for diagnosis, but their incremental validity is unclear. Percentage retention versus RBANS immediate and delayed memory subtests and delayed index scores were compared for diagnostic classification and for prediction of function. Data from 173 memory clinic patients with an interdisciplinary diagnosis (no cognitive impairment, amnestic mild cognitive impairment [aMCI], and dementia due to Alzheimer's disease [AD]) and complete RBANS data were analyzed. Across diagnostic contrasts, list percentage retention classification accuracy was similar to List Learning delayed recall, but below the Delayed Memory Index (DMI). Similarly, for classifying no cognitive impairment versus aMCI or dementia due to AD, story percentage retention was similar to Story Memory subtests and below the DMI. For classifying aMCI versus AD; however, Story Memory exceeded the DMI, but was similar to Story Memory subtest scores. Similarly, for prediction of function percentage retention measures did not predict variance beyond that predicted by the RBANS subtest or index scores. In sum, there is no evidence that calculation of percentage retention for RBANS adds clinical utility beyond those provided by the standard RBANS scores.

Effects of age on a real-world What-Where-When memory task

PubMed Central

Mazurek, Adèle; Bhoopathy, Raja Meenakshi; Read, Jenny C. A.; Gallagher, Peter; Smulders, Tom V.

2015-01-01

Many cognitive abilities decline with aging, making it difficult to detect pathological changes against a background of natural changes in cognition. Most of the tests to assess cognitive decline are artificial tasks that have little resemblance to the problems faced by people in everyday life. This means both that people may have little practice doing such tasks (potentially contributing to the decline in performance) and that the tasks may not be good predictors of real-world cognitive problems. In this study, we test the performance of young people (18–25 years) and older people (60+-year-olds) on a novel, more ecologically valid test of episodic memory: the real-world What-Where-When (WWW) memory test. We also compare them on a battery of other cognitive tests, including working memory, psychomotor speed, executive function, and episodic memory. Older people show the expected age-related declines on the test battery. In the WWW memory task, older people were more likely to fail to remember any WWW combination than younger people were, although they did not significantly differ in their overall WWW score due to some older people performing as well as or better than most younger people. WWW memory performance was significantly predicted by other measures of episodic memory, such as the single-trial learning and long-term retention in the Rey Auditory Verbal Learning task and Combined Object Location Memory in the Object Relocation task. Self-reported memory complaints also predicted performance on the WWW task. These findings confirm that our real-world WWW memory task is a valid measure of episodic memory, with high ecological validity, which may be useful as a predictor of everyday memory abilities. The task will require a bit more development to improve its sensitivity to cognitive declines in aging and to potentially distinguish between mentally healthy older adults and those with early signs of cognitive pathologies. PMID:26042030

Neurocognitive Effect of Nootropic Drug Brahmi (Bacopa monnieri) in Alzheimer's Disease

PubMed Central

Chaudhari, Kaustubh S.; Tiwari, Nishant R.; Tiwari, Rakesh R.; Sharma, Rohan S.

2017-01-01

Alzheimer's disease (AD) is a progressive neurodegenerative disease of the elderly. The rapid increase in its incidence has necessitated development of newer drugs. Ayurvedic herbal medications are increasingly researched due to their biosafety profile and usefulness in cognitive impairment. In this article, we critically reviewed one such Medhya Rasayana (nootropic drug) Brahmi-derived from extract of Bacopa monnieri (EBm). Studies have shown that EBm promotes free radical scavenger mechanisms and protects cells in prefrontal cortex, hippocampus, and striatum against cytotoxicity and DNA damage implicated in AD. It also reduces lipoxygenase activity reducing lipid peroxidation, increases glutathione peroxidase and chelates iron. Administration of EBm was seen to protect the cholinergic neurons and reduce anticholinesterase activity comparable to donepezil, rivastigmine, and galantamine. It also reduces hippocampal β-amyloid deposition and stress-induced hippocampal damage. The neuroprotective effect of EBm is also due to nitric oxide-mediated cerebral vasodilation. EBm improved the total memory score and maximum improvement was seen in logical memory and paired associate learning in humans and reversed phenytoin-induced memory impairment in experimental model. EBm has not shown any serious clinical, neurological, hematological complications, or vital organs damage in experimental studies. Rats showed marked reduction in fertility; however, libido was unaffected. There is no experimental evidence of genotoxicity or teratogenesis by use of EBm. Mild nausea and gastrointestinal upset are seen in humans. Brahmi promises to be a novel agent in AD; however, further human trials are recommended to verify the efficacy and rule out any side effects as evidenced by the experimental models. PMID:28588366

Electrophysiological Correlates of Familiarity and Recollection in Associative Recognition: Contributions of Perceptual and Conceptual Processing to Unitization

PubMed Central

Li, Bingcan; Mao, Xinrui; Wang, Yujuan; Guo, Chunyan

2017-01-01

It is generally accepted that associative recognition memory is supported by recollection. In addition, recent research indicates that familiarity can support associative memory, especially when two items are unitized into a single item. Both perceptual and conceptual manipulations can be used to unitize items, but few studies have compared these two methods of unitization directly. In the present study, we investigated the effects of familiarity and recollection on successful retrieval of items that were unitized perceptually or conceptually. Participants were instructed to remember either a Chinese two-character compound or unrelated word-pairs, which were presented simultaneously or sequentially. Participants were then asked to recognize whether word-pairs were intact or rearranged. Event-related potential (ERP) recordings were performed during the recognition phase of the study. Two-character compounds were better discriminated than unrelated word-pairs and simultaneous presentation was found to elicit better discrimination than sequential presentation for unrelated word-pairs only. ERP recordings indicated that the early intact/rearranged effects (FN400), typically associated with familiarity, were elicited in compound word-pairs with both simultaneous and sequential presentation, and in simultaneously presented unrelated word-pairs, but not in sequentially presented unrelated word-pairs. In contrast, the late positive complex (LPC) effects associated with recollection were elicited in all four conditions. Together, these results indicate that while the engagement of familiarity in associative recognition is affected by both perceptual and conceptual unitization, conceptual unitization promotes a higher level of unitization (LOU). In addition, the engagement of recollection was not affected by unitized manipulations. It should be noted, however, that due to experimental design, the effects presented here may be due to semantic rather than episodic memory and future studies should take this into consideration when manipulating rearranged pairs. PMID:28400723

Study on advanced information processing system

NASA Technical Reports Server (NTRS)

Shin, Kang G.; Liu, Jyh-Charn

1992-01-01

Issues related to the reliability of a redundant system with large main memory are addressed. In particular, the Fault-Tolerant Processor (FTP) for Advanced Launch System (ALS) is used as a basis for our presentation. When the system is free of latent faults, the probability of system crash due to nearly-coincident channel faults is shown to be insignificant even when the outputs of computing channels are infrequently voted on. In particular, using channel error maskers (CEMs) is shown to improve reliability more effectively than increasing the number of channels for applications with long mission times. Even without using a voter, most memory errors can be immediately corrected by CEMs implemented with conventional coding techniques. In addition to their ability to enhance system reliability, CEMs--with a low hardware overhead--can be used to reduce not only the need of memory realignment, but also the time required to realign channel memories in case, albeit rare, such a need arises. Using CEMs, we have developed two schemes, called Scheme 1 and Scheme 2, to solve the memory realignment problem. In both schemes, most errors are corrected by CEMs, and the remaining errors are masked by a voter.

Study on fault-tolerant processors for advanced launch system

NASA Technical Reports Server (NTRS)

Shin, Kang G.; Liu, Jyh-Charn

1990-01-01

Issues related to the reliability of a redundant system with large main memory are addressed. The Fault-Tolerant Processor (FTP) for the Advanced Launch System (ALS) is used as a basis for the presentation. When the system is free of latent faults, the probability of system crash due to multiple channel faults is shown to be insignificant even when voting on the outputs of computing channels is infrequent. Using channel error maskers (CEMs) is shown to improve reliability more effectively than increasing redundancy or the number of channels for applications with long mission times. Even without using a voter, most memory errors can be immediately corrected by those CEMs implemented with conventional coding techniques. In addition to their ability to enhance system reliability, CEMs (with a very low hardware overhead) can be used to dramatically reduce not only the need of memory realignment, but also the time required to realign channel memories in case, albeit rare, such a need arises. Using CEMs, two different schemes were developed to solve the memory realignment problem. In both schemes, most errors are corrected by CEMs, and the remaining errors are masked by a voter.

Shape-memory surfaces for cell mechanobiology

PubMed Central

Ebara, Mitsuhiro

2015-01-01

Shape-memory polymers (SMPs) are a new class of smart materials, which have the capability to change from a temporary shape ‘A’ to a memorized permanent shape ‘B’ upon application of an external stimulus. In recent years, SMPs have attracted much attention from basic and fundamental research to industrial and practical applications due to the cheap and efficient alternative to well-known metallic shape-memory alloys. Since the shape-memory effect in SMPs is not related to a specific material property of single polymers, the control of nanoarchitecture of polymer networks is particularly important for the smart functions of SMPs. Such nanoarchitectonic approaches have enabled us to further create shape-memory surfaces (SMSs) with tunable surface topography at nano scale. The present review aims to bring together the exciting design of SMSs and the ever-expanding range of their uses as tools to control cell functions. The goal for these endeavors is to mimic the surrounding mechanical cues of extracellular environments which have been considered as critical parameters in cell fate determination. The untapped potential of SMSs makes them one of the most exciting interfaces of materials science and cell mechanobiology. PMID:27877747

Early Adolescent Sexual Debut: The Mediating Role of Working Memory Ability, Sensation Seeking, and Impulsivity

PubMed Central

Khurana, Atika; Romer, Daniel; Betancourt, Laura M.; Brodsky, Nancy L.; Giannetta, Joan M.; Hurt, Hallam

2013-01-01

Although deficits in working memory ability have been implicated in suboptimal decision making and risk taking among adolescents, its influence on early sexual initiation has so far not been examined. Analyzing 2 waves of panel data from a community sample of adolescents (N = 347; Mean age[baseline] = 13.4 years), assessed 1 year apart, the present study tested the hypothesis that weak working memory ability predicts early sexual initiation and explored whether this relationship is mediated by sensation seeking and 2 forms of impulsivity, namely acting-without-thinking and temporal discounting. The 2 forms of impulsivity were expected to be positively associated with early sexual initiation, whereas sensation seeking was hypothesized to be unrelated or to have a protective influence, due to its positive association with working memory. Results obtained from structural equation modeling procedures supported these predictions and in addition showed that the effects of 3 prominent risk factors (Black racial identity, low socioeconomic background, and early pubertal maturation) on early sexual initiation were entirely mediated by working memory and impulsivity. The findings are discussed in regard to their implications for preventing early sexual onset among adolescents. PMID:22369334

Retrograde and anterograde memory following selective damage to the dorsolateral entorhinal cortex.

PubMed

Gervais, Nicole J; Barrett-Bernstein, Meagan; Sutherland, Robert J; Mumby, Dave G

2014-12-01

Anatomical and electrophysiological evidence suggest the dorsolateral entorhinal cortex (DLEC) is involved in processing spatial information, but there is currently no consensus on whether its functions are necessary for normal spatial learning and memory. The present study examined the effects of excitotoxic lesions of the DLEC on retrograde and anterograde memory on two tests of allocentric spatial learning: a hidden fixed-platform watermaze task, and a novelty-preference-based dry-maze test. Deficits were observed on both tests when training occurred prior to but not following n-methyl d-aspartate (NMDA) lesions of DLEC, suggesting retrograde memory impairment in the absence of anterograde impairments for the same information. The retrograde memory impairments were temporally-graded; rats that received DLEC lesions 1-3 days following training displayed deficits, while those that received lesions 7-10 days following training performed like a control group that received sham surgery. The deficits were not attenuated by co-infusion of tetrodotoxin, suggesting they are not due to disruption of neural processing in structures efferent to the DLEC, such as the hippocampus. The present findings provide evidence that the DLEC is involved in the consolidation of allocentric spatial information. Copyright © 2014 Elsevier Inc. All rights reserved.

Transsylvian selective amygdalohippocampectomy in children with hippocampal sclerosis: seizure, intellectual and memory outcome.

PubMed

Beaton, Anne E; Durnford, Andrew; Heffer-Rahn, Phillip E; Kirkham, Fenella; Griffin, Angela; Gray, William P; Gray, W L S

2012-11-01

This study investigates the efficacy of transylvian selective amygdalohippocampectomy (TS SAH) in children with medically intractable epilepsy due to unilateral hippocampal sclerosis. Post-surgical seizure control, intellectual and memory outcomes are examined. This study reports on pre- and post-surgical clinical data from 10 patients who underwent TS SAH between 2002 and 2010 after 24 months follow-up. Pre- and post-operative change in seizure frequency, AED use, intellect and memory are compared. At 12 months and 24 months post-surgery, 9/10 (90%) and 7/8 (87.5%) patients respectively, were seizure free (Engel I). No patients were classed as Engel III or IV. No significant improvement or decline at a group level was found on measures of intellect or verbal or visual memory. One hundred per cent improved or remained within 1 SD of their pre-operatives score on verbal and perceptual reasoning learning and reasoning measures. Significant improvement was found post-operatively for both immediate and delayed facial memory. Our findings of good post-surgical seizure control and favourable cognitive outcome provides evidence against previous findings that SAH in children may not be effective. Copyright © 2012 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Pre- and long-term postoperative courses of hippocampus-associated memory impairment in epilepsy patients with antibody-associated limbic encephalitis and selective amygdalohippocampectomy.

PubMed

Hansen, Niels; Ernst, Leon; Rüber, Theodor; Widman, Guido; Becker, Albert J; Elger, Christian E; Helmstaedter, Christoph

2018-02-01

Limbic encephalitis (LE) is defined by mesiotemporal lobe structure abnormalities, seizures, memory, and psychiatric disturbances. This study aimed to identify the long-term clinical and neuropsychological outcome of selective amygdalohippocampectomy (sAH) in drug-resistant patients with temporal lobe epilepsy due to known or later diagnosed subacute LE not responding to immunotherapy associated with neuronal autoantibodies. In seven patients with temporal lobe epilepsy due to antibody positive LE (glutamic acid decarboxylase (GAD65): n=5; voltage-gated potassium channel complex (VGKC), N-methyl d-aspartate receptor (NMDAR): n=1; Ma-2/Ta: n=1) sAH (6 left, 1 right) was performed. Those patients underwent repeated electroencephalography (EEG) recordings, magnetic resonance imaging (MRI) volumetry of the amygdala and hippocampus, and neuropsychological examinations and were followed up for 6-7years on average. Verbal memory and figural memory were affected in 57% of patients at baseline and 71% at the last follow-up. At the last follow-up, 14% of the patients had declined in verbal memory and figural memory. We observed improved memory in 43% of patients regarding figural memory, but not in a single patient regarding verbal memory. Repeated evaluations across the individual courses reveal cognitive and MRI dynamics that appear to be unrelated to surgery and drug treatment. Three of the seven patients with LE with different antibodies (NMDAR: n=1, Ma-2/Ta: n=1 and GAD65: n=1) achieved persistent seizure freedom along with no accelerated memory decline after surgery. Two of the five GAD65-antibody patients positive with LE showed progressive memory decline and a long-term tendency to contralateral hippocampus atrophy. While memory demonstrated some decline in the long run, what is most important is that a progressive decline in memory is seldom found after sAH in patients with LE. Moreover, the dynamics in performance and MRI before and after surgery reveal disease dynamics independent of surgery. Selective amygdalohippocampectomy can lead to seizure freedom, but should be considered as a last resort treatment option for drug-resistant patients with temporal lobe epilepsy due to LE. Particular caution is recommended in patients with GAD65-LE. Copyright © 2017 Elsevier Inc. All rights reserved.

Inhibition of γ-secretase worsens memory deficits in a genetically congruous mouse model of Danish dementia

PubMed Central

2012-01-01

Background A mutation in the BRI2/ITM2b gene causes familial Danish dementia (FDD). BRI2 is an inhibitor of amyloid-β precursor protein (APP) processing, which is genetically linked to Alzheimer’s disease (AD) pathogenesis. The FDD mutation leads to a loss of BRI2 protein and to increased APP processing. APP haplodeficiency and inhibition of APP cleavage by β-secretase rescue synaptic/memory deficits of a genetically congruous mouse model of FDD (FDDKI). β-cleavage of APP yields the β-carboxyl-terminal (β-CTF) and the amino-terminal-soluble APPβ (sAPPβ) fragments. γ-secretase processing of β-CTF generates Aβ, which is considered the main cause of AD. However, inhibiting Aβ production did not rescue the deficits of FDDKI mice, suggesting that sAPPβ/β-CTF, and not Aβ, are the toxic species causing memory loss. Results Here, we have further analyzed the effect of γ-secretase inhibition. We show that treatment with a γ-secretase inhibitor (GSI) results in a worsening of the memory deficits of FDDKI mice. This deleterious effect on memory correlates with increased levels of the β/α-CTFs APP fragments in synaptic fractions isolated from hippocampi of FDDKI mice, which is consistent with inhibition of γ-secretase activity. Conclusion This harmful effect of the GSI is in sharp contrast with a pathogenic role for Aβ, and suggests that the worsening of memory deficits may be due to accumulation of synaptic-toxic β/α-CTFs caused by GSI treatment. However, γ-secretase cleaves more than 40 proteins; thus, the noxious effect of GSI on memory may be dependent on inhibition of cleavage of one or more of these other γ-secretase substrates. These two possibilities do not need to be mutually exclusive. Our results are consistent with the outcome of a clinical trial with the GSI Semagacestat, which caused a worsening of cognition, and advise against targeting γ-secretase in the therapy of AD. Overall, the data also indicate that FDDKI is a valuable mouse model to study AD pathogenesis and predict the clinical outcome of therapeutic agents for AD. PMID:22537414

Inhibition of γ-secretase worsens memory deficits in a genetically congruous mouse model of Danish dementia.

PubMed

Tamayev, Robert; D'Adamio, Luciano

2012-04-26

A mutation in the BRI2/ITM2b gene causes familial Danish dementia (FDD). BRI2 is an inhibitor of amyloid-β precursor protein (APP) processing, which is genetically linked to Alzheimer's disease (AD) pathogenesis. The FDD mutation leads to a loss of BRI2 protein and to increased APP processing. APP haplodeficiency and inhibition of APP cleavage by β-secretase rescue synaptic/memory deficits of a genetically congruous mouse model of FDD (FDDKI). β-cleavage of APP yields the β-carboxyl-terminal (β-CTF) and the amino-terminal-soluble APPβ (sAPPβ) fragments. γ-secretase processing of β-CTF generates Aβ, which is considered the main cause of AD. However, inhibiting Aβ production did not rescue the deficits of FDDKI mice, suggesting that sAPPβ/β-CTF, and not Aβ, are the toxic species causing memory loss. Here, we have further analyzed the effect of γ-secretase inhibition. We show that treatment with a γ-secretase inhibitor (GSI) results in a worsening of the memory deficits of FDDKI mice. This deleterious effect on memory correlates with increased levels of the β/α-CTFs APP fragments in synaptic fractions isolated from hippocampi of FDDKI mice, which is consistent with inhibition of γ-secretase activity. This harmful effect of the GSI is in sharp contrast with a pathogenic role for Aβ, and suggests that the worsening of memory deficits may be due to accumulation of synaptic-toxic β/α-CTFs caused by GSI treatment. However, γ-secretase cleaves more than 40 proteins; thus, the noxious effect of GSI on memory may be dependent on inhibition of cleavage of one or more of these other γ-secretase substrates. These two possibilities do not need to be mutually exclusive. Our results are consistent with the outcome of a clinical trial with the GSI Semagacestat, which caused a worsening of cognition, and advise against targeting γ-secretase in the therapy of AD. Overall, the data also indicate that FDDKI is a valuable mouse model to study AD pathogenesis and predict the clinical outcome of therapeutic agents for AD.

The unified mechanism of aging effects in both martensite and parent phase for shape-memory alloys: atomic-level simulations

NASA Astrophysics Data System (ADS)

Deng, J.; Ding, X.; Suzuki, T.; Otsuka, K.; Lookman, T.; Saxena, A.; Sun, J.; Ren, X.

2011-03-01

Most shape-memory alloys (SMAs) subject to the aging effects not only in the martensite phase but also in the parent phase. These aging effects have been attracted much attention as they strongly affect the practical applications of SMAs. So far, the intrinsic mechanism of them has remained controversial due to the difficulty in visualization of what happens in atomic scale. In the present study, by using a combination of molecular dynamics method and Monte-Carlo method [1], we investigate the aging effects in both martensite and parent phase. We successfully reproduced the thermal behaviors of aging effects for SMAs, i.e., the Af temperature increase with aging time in martensite and the Ms temperature decrease with aging time in parent phase, which keep good agreement with the experimental observations [2]. In addition, quantitative analysis of the atomic configurations during aging reveals that the aging effects are not associated with a change in the average structure.

Short-Term Memory Limitations in Children: Capacity or Processing Deficits?

ERIC Educational Resources Information Center

Chi, Michelene T. H.

1976-01-01

Evaluates the assertion that short-term memory (STM) capacity increases with age and concludes that the STM capacity limitation in children is due to the deficits in the processing strategies and speeds, which presumably improve with age through cumulative learning. (JM) Available from: Memory and Cognition, Psychonomic Society, 1018 West 34…

3 CFR 8507 - Proclamation 8507 of April 28, 2010. Workers Memorial Day, 2010

Code of Federal Regulations, 2011 CFR

2011-01-01

... and activities in memory of those who have been killed due to unsafe working conditions. IN WITNESS... done, and my Administration is dedicated to renewing our Nation’s commitment to achieve safe working... their memory, we rededicate ourselves to preventing such tragedies, and to securing a safer workplace...

MK-801 Impairs Cognitive Coordination on a Rotating Arena (Carousel) and Contextual Specificity of Hippocampal Immediate-Early Gene Expression in a Rat Model of Psychosis

PubMed Central

Kubík, Štěpán; Buchtová, Helena; Valeš, Karel; Stuchlík, Aleš

2014-01-01

Flexible behavior in dynamic, real-world environments requires more than static spatial learning and memory. Discordant and unstable cues must be organized in coherent subsets to give rise to meaningful spatial representations. We model this form of cognitive coordination on a rotating arena – Carousel where arena- and room-bound spatial cues are dissociated. Hippocampal neuronal ensemble activity can repeatedly switch between multiple representations of such an environment. Injection of tetrodotoxin into one hippocampus prevents cognitive coordination during avoidance of a stationary room-defined place on the Carousel and increases coactivity of previously unrelated neurons in the uninjected hippocampus. Place avoidance on the Carousel is impaired after systemic administration of non-competitive NMDAr blockers (MK-801) used to model schizophrenia in animals and people. We tested if this effect is due to cognitive disorganization or other effect of NMDAr antagonism such as hyperlocomotion, spatial memory impairment, or general learning deficit. We also examined if the same dose of MK-801 alters patterns of immediate-early gene (IEG) expression in the hippocampus. IEG expression is triggered in neuronal nuclei in a context-specific manner after behavioral exploration and it is used to map activity in neuronal populations. IEG expression is critical for maintenance of synaptic plasticity and memory consolidation. We show that the same dose of MK-801 that impairs spatial coordination of rats on the Carousel also eliminates contextual specificity of IEG expression in hippocampal CA1 ensembles. This effect is due to increased similarity between ensembles activated in different environments, consistent with the idea that it is caused by increased coactivity between neurons, which did not previously fire together. Our data support the proposition of the Hypersynchrony theory that cognitive disorganization in psychosis is due to increased coactivity between unrelated neurons. PMID:24659959

Effects of validating communication on recall during a pain-task in healthy participants.

PubMed

Carstens, Johan K P; Boersma, Katja; Schrooten, Martien G S; Linton, Steven J

2017-10-01

Increasing recall of instructions and advice in a pain consultation is important, since it is a prerequisite for adherence to treatment recommendations. However, interference due to pain-related distress may result in poor recall. Whereas there are some indications that recall can be increased by empathic communication that reduces interference, this interesting possibility remains largely untested experimentally. The current experiment aimed at studying effects of empathic communication, and more specifically validation, on recall during a pain test and possible mediators and moderators of this effect. Participants received either validating (N=25) or invalidating responses (N=25) from the experimenter during a pain provoking task, followed by self-report measures of interference (affect, situational pain catastrophizing) and recall (accurate and false memories of words). As expected, the validated group exhibited higher accurate recall and less false memories following the pain test as compared to the invalidated group. This was partly due to the effect of interference being counteracted by moderating the relationship between pain catastrophizing and recall. These novel results suggest that validating communication can counteract interference due to pain catastrophizing on recall, at least in a controlled experimental setting. Good communication by health professionals is of utmost importance for adherence to pain management. The current results expand our knowledge on the effects of pain communication by establishing and explaining a clear link between empathic communication and recall, highlighting the role of pain catastrophizing. Copyright © 2017 Scandinavian Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Patterns of effective connectivity during memory encoding and retrieval differ between patients with mild cognitive impairment and healthy older adults.

PubMed

Hampstead, B M; Khoshnoodi, M; Yan, W; Deshpande, G; Sathian, K

2016-01-01

Previous research has shown that there is considerable overlap in the neural networks mediating successful memory encoding and retrieval. However, little is known about how the relevant human brain regions interact during these distinct phases of memory or how such interactions are affected by memory deficits that characterize mild cognitive impairment (MCI), a condition that often precedes dementia due to Alzheimer's disease. Here we employed multivariate Granger causality analysis using autoregressive modeling of inferred neuronal time series obtained by deconvolving the hemodynamic response function from measured blood oxygenation level-dependent (BOLD) time series data, in order to examine the effective connectivity between brain regions during successful encoding and/or retrieval of object location associations in MCI patients and comparable healthy older adults. During encoding, healthy older adults demonstrated a left hemisphere dominant pattern where the inferior frontal junction, anterior intraparietal sulcus (likely involving the parietal eye fields), and posterior cingulate cortex drove activation in most left hemisphere regions and virtually every right hemisphere region tested. These regions are part of a frontoparietal network that mediates top-down cognitive control and is implicated in successful memory formation. In contrast, in the MCI patients, the right frontal eye field drove activation in every left hemisphere region examined, suggesting reliance on more basic visual search processes. Retrieval in the healthy older adults was primarily driven by the right hippocampus with lesser contributions of the right anterior thalamic nuclei and right inferior frontal sulcus, consistent with theoretical models holding the hippocampus as critical for the successful retrieval of memories. The pattern differed in MCI patients, in whom the right inferior frontal junction and right anterior thalamus drove successful memory retrieval, reflecting the characteristic hippocampal dysfunction of these patients. These findings demonstrate that neural network interactions differ markedly between MCI patients and healthy older adults. Future efforts will investigate the impact of cognitive rehabilitation of memory on these connectivity patterns. Published by Elsevier Inc.

Drug-, dose- and sex-dependent effects of chronic fluoxetine, reboxetine and venlafaxine on open-field behavior and spatial memory in rats.

PubMed

Gray, Vanessa C; Hughes, Robert N

2015-03-15

In an effort to address the need to include both sexes in studies of effects of the SSRI fluoxetine, the NRI reboxetine and the SNRI venlafaxine on anxiety-related behavior and memory along with the use of chronic drug administration, male and female PVG/c rats were fed diets containing two doses of each drug for 21 days. The rats' anxiety level was then assessed in an open field. Short-term spatial memory for a brightness change in a Y maze was also measured. While there was little evidence of anxiolytic effects of any of the drugs, both fluoxetine and, to a lesser extent, venlafaxine appeared to be mainly anxiogenic in their action depending on both dose and sex. Reboxetine was relatively ineffective in this respect. Ability to locate the Y-maze arm that had changed (from white to black) seemed to be impaired for male (but not female) rats by both fluoxetine and venlafaxine and, to a much lesser extent, by reboxetine. Given the relative ineffectiveness of reboxetine in either test, it is possible that the effects of the other two drugs on both anxiety and memory were mainly due to their serotonin reuptake inhibiting properties. The differences that occurred between males and females in responsiveness to all three drugs supported the long-held view that both sexes should be investigated in studies of this sort, especially in view of reports of sex differences in effects of clinically prescribed antidepressants. Copyright © 2014 Elsevier B.V. All rights reserved.

Generation and the subjective feeling of "aha!" are independently related to learning from insight.

PubMed

Kizilirmak, Jasmin M; Galvao Gomes da Silva, Joana; Imamoglu, Fatma; Richardson-Klavehn, Alan

2016-11-01

It has been proposed that sudden insight into the solutions of problems can enhance long-term memory for those solutions. However, the nature of insight has been operationalized differently across studies. Here, we examined two main aspects of insight problem-solving-the generation of a solution and the subjective "aha!" experience-and experimentally evaluated their respective relationships to long-term memory formation (encoding). Our results suggest that generation (generated solution vs. presented solution) and the "aha!" experience ("aha!" vs. no "aha!") are independently related to learning from insight, as well as to the emotional response towards understanding the solution during encoding. Moreover, we analyzed the relationship between generation and the "aha!" experience and two different kinds of later memory tests, direct (intentional) and indirect (incidental). Here, we found that the generation effect was larger for indirect testing, reflecting more automatic retrieval processes, while the relationship with the occurrence of an "aha!" experience was somewhat larger for direct testing. Our results suggest that both the generation of a solution and the subjective experience of "aha!" indicate processes that benefit long-term memory formation, though differently. This beneficial effect is possibly due to the intrinsic reward associated with sudden comprehension and the detection of schema-consistency, i.e., that novel information can be easily integrated into existing knowledge.