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Sample records for striatal memory system

  1. Interaction between hippocampal and striatal systems predicts subsequent consolidation of motor sequence memory.

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    Geneviève Albouy

    Full Text Available The development of fast and reproducible motor behavior is a crucial human capacity. The aim of the present study was to address the relationship between the implementation of consistent behavior during initial training on a sequential motor task (the Finger Tapping Task and subsequent sleep-dependent motor sequence memory consolidation, using functional magnetic resonance imaging (fMRI and total sleep deprivation protocol. Our behavioral results indicated significant offline gains in performance speed after sleep whereas performance was only stabilized, but not enhanced, after sleep deprivation. At the cerebral level, we previously showed that responses in the caudate nucleus increase, in parallel to a decrease in its functional connectivity with frontal areas, as performance became more consistent. Here, the strength of the competitive interaction, assessed through functional connectivity analyses, between the caudate nucleus and hippocampo-frontal areas during initial training, predicted delayed gains in performance at retest in sleepers but not in sleep-deprived subjects. Moreover, during retest, responses increased in the hippocampus and medial prefrontal cortex in sleepers whereas in sleep-deprived subjects, responses increased in the putamen and cingulate cortex. Our results suggest that the strength of the competitive interplay between the striatum and the hippocampus, participating in the implementation of consistent motor behavior during initial training, conditions subsequent motor sequence memory consolidation. The latter process appears to be supported by a reorganisation of cerebral activity in hippocampo-neocortical networks after sleep.

  2. Episodic Memory Encoding Interferes with Reward Learning and Decreases Striatal Prediction Errors

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    Braun, Erin Kendall; Daw, Nathaniel D.

    2014-01-01

    Learning is essential for adaptive decision making. The striatum and its dopaminergic inputs are known to support incremental reward-based learning, while the hippocampus is known to support encoding of single events (episodic memory). Although traditionally studied separately, in even simple experiences, these two types of learning are likely to co-occur and may interact. Here we sought to understand the nature of this interaction by examining how incremental reward learning is related to concurrent episodic memory encoding. During the experiment, human participants made choices between two options (colored squares), each associated with a drifting probability of reward, with the goal of earning as much money as possible. Incidental, trial-unique object pictures, unrelated to the choice, were overlaid on each option. The next day, participants were given a surprise memory test for these pictures. We found that better episodic memory was related to a decreased influence of recent reward experience on choice, both within and across participants. fMRI analyses further revealed that during learning the canonical striatal reward prediction error signal was significantly weaker when episodic memory was stronger. This decrease in reward prediction error signals in the striatum was associated with enhanced functional connectivity between the hippocampus and striatum at the time of choice. Our results suggest a mechanism by which memory encoding may compete for striatal processing and provide insight into how interactions between different forms of learning guide reward-based decision making. PMID:25378157

  3. Episodic memory encoding interferes with reward learning and decreases striatal prediction errors.

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    Wimmer, G Elliott; Braun, Erin Kendall; Daw, Nathaniel D; Shohamy, Daphna

    2014-11-05

    Learning is essential for adaptive decision making. The striatum and its dopaminergic inputs are known to support incremental reward-based learning, while the hippocampus is known to support encoding of single events (episodic memory). Although traditionally studied separately, in even simple experiences, these two types of learning are likely to co-occur and may interact. Here we sought to understand the nature of this interaction by examining how incremental reward learning is related to concurrent episodic memory encoding. During the experiment, human participants made choices between two options (colored squares), each associated with a drifting probability of reward, with the goal of earning as much money as possible. Incidental, trial-unique object pictures, unrelated to the choice, were overlaid on each option. The next day, participants were given a surprise memory test for these pictures. We found that better episodic memory was related to a decreased influence of recent reward experience on choice, both within and across participants. fMRI analyses further revealed that during learning the canonical striatal reward prediction error signal was significantly weaker when episodic memory was stronger. This decrease in reward prediction error signals in the striatum was associated with enhanced functional connectivity between the hippocampus and striatum at the time of choice. Our results suggest a mechanism by which memory encoding may compete for striatal processing and provide insight into how interactions between different forms of learning guide reward-based decision making. Copyright © 2014 the authors 0270-6474/14/3414901-12$15.00/0.

  4. DAT genotype modulates striatal processing and long-term memory for items associated with reward and punishment.

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    Wittmann, Bianca C; Tan, Geoffrey C; Lisman, John E; Dolan, Raymond J; Düzel, Emrah

    2013-09-01

    Previous studies have shown that appetitive motivation enhances episodic memory formation via a network including the substantia nigra/ventral tegmental area (SN/VTA), striatum and hippocampus. This functional magnetic resonance imaging (fMRI) study now contrasted the impact of aversive and appetitive motivation on episodic long-term memory. Cue pictures predicted monetary reward or punishment in alternating experimental blocks. One day later, episodic memory for the cue pictures was tested. We also investigated how the neural processing of appetitive and aversive motivation and episodic memory were modulated by dopaminergic mechanisms. To that end, participants were selected on the basis of their genotype for a variable number of tandem repeat polymorphism of the dopamine transporter (DAT) gene. The resulting groups were carefully matched for the 5-HTTLPR polymorphism of the serotonin transporter gene. Recognition memory for cues from both motivational categories was enhanced in participants homozygous for the 10-repeat allele of the DAT, the functional effects of which are not known yet, but not in heterozygous subjects. In comparison with heterozygous participants, 10-repeat homozygous participants also showed increased striatal activity for anticipation of motivational outcomes compared to neutral outcomes. In a subsequent memory analysis, encoding activity in striatum and hippocampus was found to be higher for later recognized items in 10-repeat homozygotes compared to 9/10-repeat heterozygotes. These findings suggest that processing of appetitive and aversive motivation in the human striatum involve the dopaminergic system and that dopamine plays a role in memory for both types of motivational information. In accordance with animal studies, these data support the idea that encoding of motivational events depends on dopaminergic processes in the hippocampus. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

  5. Altered cortico-striatal-thalamic connectivity in relation to spatial working memory capacity in children with ADHD

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    Kathryn L. Mills

    2012-01-01

    Full Text Available Introduction: Attention deficit hyperactivity disorder (ADHD captures a heterogeneous group of children, who are characterized by a range of cognitive and behavioral symptoms. Previous resting state functional connectivity (rs-fcMRI studies have sought to understand the neural correlates of ADHD by comparing connectivity measurements between those with and without the disorder, focusing primarily on cortical-striatal circuits mediated by the thalamus. To integrate the multiple phenotypic features associated with ADHD and help resolve its heterogeneity, it is helpful to determine how specific circuits relate to unique cognitive domains of the ADHD syndrome. Spatial working memory has been proposed as a key mechanism in the pathophysiology of ADHD.Methods: We correlated the rs-fcMRI of five thalamic regions of interest with spatial span working memory scores in a sample of 67 children aged 7-11 years (ADHD and typically developing children; TDC. In an independent dataset, we then examined group differences in thalamo-striatal functional connectivity between 70 ADHD and 89 TDC (7-11 years from the ADHD-200 dataset. Thalamic regions of interest were created based on previous methods that utilize known thalamo-cortical loops and rs-fcMRI to identify functional boundaries in the thalamus.Results/Conclusions: Using these thalamic regions, we found atypical rs-fcMRI between specific thalamic groupings with the basal ganglia. To identify the thalamic connections that relate to spatial working memory in ADHD, only connections identified in both the correlational and comparative analyses were considered. Multiple connections between the thalamus and basal ganglia, particularly between medial and anterior dorsal thalamus and the putamen, were related to spatial working memory and also altered in ADHD. These thalamo-striatal disruptions may be one of multiple atypical neural and cognitive mechanisms that relate to the ADHD clinical phenotype.

  6. Factors that influence the relative use of multiple memory systems.

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    Packard, Mark G; Goodman, Jarid

    2013-11-01

    Neurobehavioral evidence supports the existence of at least two anatomically distinct "memory systems" in the mammalian brain that mediate dissociable types of learning and memory; a "cognitive" memory system dependent upon the hippocampus and a "stimulus-response/habit" memory system dependent upon the dorsolateral striatum. Several findings indicate that despite their anatomical and functional distinctiveness, hippocampal- and dorsolateral striatal-dependent memory systems may potentially interact and that, depending on the learning situation, this interaction may be cooperative or competitive. One approach to examining the neural mechanisms underlying these interactions is to consider how various factors influence the relative use of multiple memory systems. The present review examines several such factors, including information compatibility, temporal sequence of training, the visual sensory environment, reinforcement parameters, emotional arousal, and memory modulatory systems. Altering these parameters can lead to selective enhancements of either hippocampal-dependent or dorsolateral striatal-dependent memory, and bias animals toward the use of either cognitive or habit memory in dual-solution tasks that may be solved adequately with either memory system. In many learning situations, the influence of such experimental factors on the relative use of memory systems likely reflects a competitive interaction between the systems. Research examining how various factors influence the relative use of multiple memory systems may be a useful method for investigating how these systems interact with one another. Copyright © 2013 Wiley Periodicals, Inc.

  7. Modeling pharmacological clock and memory patterns of interval timing in a striatal beat-frequency model with realistic, noisy neurons

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    Sorinel A. Oprisan

    2011-09-01

    Full Text Available In most species, the capability of perceiving and using the passage of time in the seconds-to-minutes range (interval timing is not only accurate but also scalar: errors in time estimation are linearly related to the estimated duration. The ubiquity of scalar timing extends over behavioral, lesion, and pharmacological manipulations. For example, in mammals, dopaminergic drugs induce an immediate, scalar change in the perceived time (clock pattern, whereas cholinergic drugs induce a gradual, scalar change in perceived time (memory pattern. How do these properties emerge from unreliable, noisy neurons firing in the milliseconds range? Neurobiological information relative to the brain circuits involved in interval timing provide support for an Striatal Beat Frequency (SBF model, in which time is coded by the coincidental activation of striatal spiny neurons by cortical neural oscillators. While biologically plausible, the impracticality of perfect oscillators, or their lack thereof, questions this mechanism in a brain with noisy neurons. We explored the computational mechanisms required for the clock and memory patterns in an SBF model with biophysically realistic and noisy Morris-Lecar neurons (SBF-ML. Under the assumption that dopaminergic drugs modulate the firing frequency of cortical oscillators, and that cholinergic drugs modulate the memory representation of the criterion time, we show that our SBF-ML model can reproduce the pharmacological clock and memory patterns observed in the literature. Numerical results also indicate that parameter variability (noise – which is ubiquitous in the form of small fluctuations in the intrinsic frequencies of neural oscillators within and between trails, and in the errors in recording/retrieving stored information related to criterion time – seems to be critical for the time-scale invariance of the clock and memory patterns.

  8. Increased cortico-striatal connectivity during motor practice contributes to the consolidation of motor memory in writer's cramp patients

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    C. Gallea

    2015-01-01

    Full Text Available Sensorimotor representations of movements are created in the sensorimotor network through repeated practice to support successful and effortless performance. Writer's cramp (WC is a disorder acquired through extensive practice of finger movements, and it is likely associated with the abnormal acquisition of sensorimotor representations. We investigated (i the activation and connectivity changes in the brain network supporting the acquisition of sensorimotor representations of finger sequences in patients with WC and (ii the link between these changes and consolidation of motor performance 24 h after the initial practice. Twenty-two patients with WC and 22 age-matched healthy volunteers practiced a complex sequence with the right (pathological hand during functional MRI recording. Speed and accuracy were measured immediately before and after practice (day 1 and 24 h after practice (day 2. The two groups reached equivalent motor performance on day 1 and day 2. During motor practice, patients with WC had (i reduced hippocampal activation and hippocampal–striatal functional connectivity; and (ii overactivation of premotor–striatal areas, whose connectivity correlated with motor performance after consolidation. These results suggest that patients with WC use alternative networks to reach equiperformance in the acquisition of new motor memories.

  9. Dopamine release in dissociable striatal subregions predicts the different effects of oral methylphenidate on reversal learning and spatial working memory.

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    Clatworthy, Philip L; Lewis, Simon J G; Brichard, Laurent; Hong, Young T; Izquierdo, David; Clark, Luke; Cools, Roshan; Aigbirhio, Franklin I; Baron, Jean-Claude; Fryer, Timothy D; Robbins, Trevor W

    2009-04-15

    Previous data suggest that methylphenidate can have variable effects on different cognitive tasks both within and between individuals. This is thought to be underpinned by inverted U-shaped relationships between cognitive performance and dopaminergic activity in relatively separate fronto-striatal circuits and reflected by individual differences in trait impulsivity. Direct evidence for this is currently lacking. In this study, we demonstrate for the first time that therapeutic doses of oral methylphenidate administered to young healthy subjects result in different sized changes in D(2)/D(3) receptor availability in different regions of the human striatum and that the change in receptor availability within an individual subregion predicts cognitive performance on a particular task. Methylphenidate produced significantly different effects on reversal learning and spatial working memory tasks within individuals. Performance on the reversal learning task was predicted by the drug-induced change in D(2)/D(3) receptor availability in postcommissural caudate, measured using [(11)C]-raclopride radioligand PET imaging, whereas performance on the spatial working memory task was predicted by changes in receptor availability in the ventral striatum. Reversal learning performance was also predicted by subjects' trait impulsivity, such that the most impulsive individuals benefited more from methylphenidate, consistent with this drug's beneficial effects on cognition in attention deficit hyperactivity disorder.

  10. Common oscillatory mechanisms across multiple memory systems

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    Headley, Drew B.; Paré, Denis

    2017-01-01

    The cortex, hippocampus, and striatum support dissociable forms of memory. While each of these regions contains specialized circuitry supporting their respective functions, all structure their activities across time with delta, theta, and gamma rhythms. We review how these oscillations are generated and how they coordinate distinct memory systems during encoding, consolidation, and retrieval. First, gamma oscillations occur in all regions and coordinate local spiking, compressing it into short population bursts. Second, gamma oscillations are modulated by delta and theta oscillations. Third, oscillatory dynamics in these memory systems can operate in either a "slow" or "fast" mode. The slow mode happens during slow-wave sleep and is characterized by large irregular activity in the hippocampus and delta oscillations in cortical and striatal circuits. The fast mode occurs during active waking and rapid eye movement (REM) sleep and is characterized by theta oscillations in the hippocampus and its targets, along with gamma oscillations in the rest of cortex. In waking, the fast mode is associated with the efficacious encoding and retrieval of declarative and procedural memories. Theta and gamma oscillations have similar relationships with encoding and retrieval across multiple forms of memory and brain regions, despite regional differences in microcircuitry and information content. Differences in the oscillatory coordination of memory systems during sleep might explain why the consolidation of some forms of memory is sensitive to slow-wave sleep, while others depend on REM. In particular, theta oscillations appear to support the consolidation of certain types of procedural memories during REM, while delta oscillations during slow-wave sleep seem to promote declarative and procedural memories.

  11. Emotional Arousal and Multiple Memory Systems in the Mammalian Brain

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    Mark G. Packard

    2012-03-01

    Full Text Available Emotional arousal induced by stress and/or anxiety can exert complex effects on learning and memory processes in mammals. Recent studies have begun to link study of the influence of emotional arousal on memory with earlier research indicating that memory is organized in multiple systems in the brain that differ in terms of the type of memory they mediate. Specifically, these studies have examined whether emotional arousal may have a differential effect on the cognitive and stimulus-response habit memory processes subserved by the hippocampus and dorsal striatum, respectively. Evidence indicates that stress or the peripheral injection of anxiogenic drugs can bias animals and humans towards the use of striatal-dependent habit memory in dual-solution tasks in which both hippocampal and stritatal-based strategies can provide an adequate solution. A bias towards the use of habit memory can also be produced by intra-basolateral amygdala administration of anxiogenic drugs, consistent with the well documented role of efferent projections of this brain region in mediating the modulatory influence of emotional arousal on memory. In some learning situations, the bias towards the use of habit memory produced by emotional arousal appears to result from an impairing effect on hippocampus-dependent cognitive memory. Further research examining the neural mechanisms linking emotion and the relative use of multiple memory systems should prove useful in view of the potential role for maladaptive habitual behaviors in various human psychopathologies.

  12. Striatal intrinsic reinforcement signals during recognition memory: relationship to response bias and dysregulation in schizophrenia

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    Daniel H Wolf

    2011-12-01

    Full Text Available Ventral striatum (VS is a critical brain region for reinforcement learning and motivation, and VS hypofunction is implicated in psychiatric disorders including schizophrenia. Providing rewards or performance feedback has been shown to activate VS. Intrinisically motivated subjects performing challenging cognitive tasks are likely to engage reinforcement circuitry even in the absence of external feedback or incentives. However, such intrinsic reinforcement responses have received little attention, have not been examined in relation to behavioral performance, and have not been evaluated for impairment in neuropsychiatric disorders such as schizophrenia. Here we used fMRI to examine a challenging 'old' vs. 'new' visual recognition task in healthy subjects and patients with schizophrenia. Targets were unique fractal stimuli previously presented as salient distractors in a visual oddball task, producing incidental memory encoding. Based on the prediction error theory of reinforcement learning, we hypothesized that correct target recognition would activate VS in controls, and that this activation would be greater in subjects with lower expectation of responding correctly as indexed by a more conservative response bias. We also predicted these effects would be reduced in patients with schizophrenia. Consistent with these predictions, controls activated VS and other reinforcement processing regions during correct recognition, with greater VS activation in those with a more conservative response bias. Patients did not show either effect, with significant group differences suggesting hyporesponsivity in patients to internally-generated feedback. These findings highlight the importance of accounting for intrinsic motivation and reward when studying cognitive tasks, and add to growing evidence of reward circuit dysfunction in schizophrenia that may impact cognition and function.

  13. Annual Research Review: The neurobehavioral development of multiple memory systems: implications for childhood and adolescent psychiatric disorders

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    Goodman, Jarid; Marsh, Rachel; Peterson, Bradley S.; Packard, Mark G.

    2014-01-01

    Extensive evidence indicates that mammalian memory is organized into multiple brains systems, including a “cognitive” memory system that depends upon the hippocampus and a stimulus-response “habit” memory system that depends upon the dorsolateral striatum. Dorsal striatal-dependent habit memory may in part influence the development and expression of some human psychopathologies, particularly those characterized by strong habit-like behavioral features. The present review considers this hypothesis as it pertains to psychopathologies that typically emerge during childhood and adolescence. These disorders include Tourette syndrome, attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, eating disorders, and autism spectrum disorders. Human and nonhuman animal research shows that the typical development of memory systems comprises the early maturation of striatal-dependent habit memory and the relatively late maturation of hippocampal-dependent cognitive memory. We speculate that the differing rates of development of these memory systems may in part contribute to the early emergence of habit-like symptoms in childhood and adolescence. In addition, abnormalities in hippocampal and striatal brain regions have been observed consistently in youth with these disorders, suggesting that the aberrant development of memory systems may also contribute to the emergence of habit-like symptoms as core pathological features of these illnesses. Considering these disorders within the context of multiple memory systems may help elucidate the pathogenesis of habit-like symptoms in childhood and adolescence, and lead to novel treatments that lessen the habit-like behavioral features of these disorders. PMID:24286520

  14. Ventral striatal activity correlates with memory confidence for old- and new-responses in a difficult recognition test.

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    Ulrike Schwarze

    Full Text Available Activity in the ventral striatum has frequently been associated with retrieval success, i.e., it is higher for hits than correct rejections. Based on the prominent role of the ventral striatum in the reward circuit, its activity has been interpreted to reflect the higher subjective value of hits compared to correct rejections in standard recognition tests. This hypothesis was supported by a recent study showing that ventral striatal activity is higher for correct rejections than hits when the value of rejections is increased by external incentives. These findings imply that the striatal response during recognition is context-sensitive and modulated by the adaptive significance of "oldness" or "newness" to the current goals. The present study is based on the idea that not only external incentives, but also other deviations from standard recognition tests which affect the subjective value of specific response types should modulate striatal activity. Therefore, we explored ventral striatal activity in an unusually difficult recognition test that was characterized by low levels of confidence and accuracy. Based on the human uncertainty aversion, in such a recognition context, the subjective value of all high confident decisions is expected to be higher than usual, i.e., also rejecting items with high certainty is deemed rewarding. In an accompanying behavioural experiment, participants rated the pleasantness of each recognition response. As hypothesized, ventral striatal activity correlated in the current unusually difficult recognition test not only with retrieval success, but also with confidence. Moreover, participants indicated that they were more satisfied by higher confidence in addition to perceived oldness of an item. Taken together, the results are in line with the hypothesis that ventral striatal activity during recognition codes the subjective value of different response types that is modulated by the context of the recognition test.

  15. The BACHD Rat Model of Huntington Disease Shows Signs of Fronto-Striatal Dysfunction in Two Operant Conditioning Tests of Short-Term Memory.

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    Clemensson, Erik Karl Håkan; Clemensson, Laura Emily; Riess, Olaf; Nguyen, Huu Phuc

    2017-01-01

    The BACHD rat is a recently developed transgenic animal model of Huntington disease, a progressive neurodegenerative disorder characterized by extensive loss of striatal neurons. Cognitive impairments are common among patients, and characterization of similar deficits in animal models of the disease is therefore of interest. The present study assessed the BACHD rats' performance in the delayed alternation and the delayed non-matching to position test, two Skinner box-based tests of short-term memory function. The transgenic rats showed impaired performance in both tests, indicating general problems with handling basic aspects of the tests, while short-term memory appeared to be intact. Similar phenotypes have been found in rats with fronto-striatal lesions, suggesting that Huntington disease-related neuropathology might be present in the BACHD rats. Further analyses indicated that the performance deficit in the delayed alternation test might be due to impaired inhibitory control, which has also been implicated in Huntington disease patients. The study ultimately suggests that the BACHD rats might suffer from neuropathology and cognitive impairments reminiscent of those of Huntington disease patients.

  16. The BACHD Rat Model of Huntington Disease Shows Signs of Fronto-Striatal Dysfunction in Two Operant Conditioning Tests of Short-Term Memory.

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    Erik Karl Håkan Clemensson

    Full Text Available The BACHD rat is a recently developed transgenic animal model of Huntington disease, a progressive neurodegenerative disorder characterized by extensive loss of striatal neurons. Cognitive impairments are common among patients, and characterization of similar deficits in animal models of the disease is therefore of interest. The present study assessed the BACHD rats' performance in the delayed alternation and the delayed non-matching to position test, two Skinner box-based tests of short-term memory function. The transgenic rats showed impaired performance in both tests, indicating general problems with handling basic aspects of the tests, while short-term memory appeared to be intact. Similar phenotypes have been found in rats with fronto-striatal lesions, suggesting that Huntington disease-related neuropathology might be present in the BACHD rats. Further analyses indicated that the performance deficit in the delayed alternation test might be due to impaired inhibitory control, which has also been implicated in Huntington disease patients. The study ultimately suggests that the BACHD rats might suffer from neuropathology and cognitive impairments reminiscent of those of Huntington disease patients.

  17. Modeling effects of intrinsic and extrinsic rewards on the competition between striatal learning systems.

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    Boedecker, Joschka; Lampe, Thomas; Riedmiller, Martin

    2013-01-01

    A common assumption in psychology, economics, and other fields holds that higher performance will result if extrinsic rewards (such as money) are offered as an incentive. While this principle seems to work well for tasks that require the execution of the same sequence of steps over and over, with little uncertainty about the process, in other cases, especially where creative problem solving is required due to the difficulty in finding the optimal sequence of actions, external rewards can actually be detrimental to task performance. Furthermore, they have the potential to undermine intrinsic motivation to do an otherwise interesting activity. In this work, we extend a computational model of the dorsomedial and dorsolateral striatal reinforcement learning systems to account for the effects of extrinsic and intrinsic rewards. The model assumes that the brain employs both a goal-directed and a habitual learning system, and competition between both is based on the trade-off between the cost of the reasoning process and value of information. The goal-directed system elicits internal rewards when its models of the environment improve, while the habitual system, being model-free, does not. Our results account for the phenomena that initial extrinsic reward leads to reduced activity after extinction compared to the case without any initial extrinsic rewards, and that performance in complex task settings drops when higher external rewards are promised. We also test the hypothesis that external rewards bias the competition in favor of the computationally efficient, but cruder and less flexible habitual system, which can negatively influence intrinsic motivation and task performance in the class of tasks we consider.

  18. Multiple memory stores and operant conditioning: A rationale for memory's complexity

    NARCIS (Netherlands)

    Meeter, M.; Veldkamp, R; Jin, Y.

    2009-01-01

    Why does the brain contain more than one memory system? Genetic algorithms can play a role in elucidating this question. Here, model animals were constructed containing a dorsal striatal layer that controlled actions, and a ventral striatal layer that controlled a dopaminergic learning signal. Both

  19. Multiple Memory Stores and Operant Conditioning: A Rationale for Memory's Complexity

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    Meeter, Martijn; Veldkamp, Rob; Jin, Yaochu

    2009-01-01

    Why does the brain contain more than one memory system? Genetic algorithms can play a role in elucidating this question. Here, model animals were constructed containing a dorsal striatal layer that controlled actions, and a ventral striatal layer that controlled a dopaminergic learning signal. Both layers could gain access to three modeled memory…

  20. Memory-Based Expert Systems

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    1992-12-01

    relevant cases quickly from a large memory -plus the requirement for an explicit theory of index content in the complex social domain where relevance often...Sep 89 - 31 Jan 92 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS " MEMORY -BASED EXPERT SYSTEMS" (U) 61102F 2304/A7 6. AUTHOR(S) Dr. Roger C. Schank 7...three problems: (1) The development of a robust memory -based parsing technology (Direct Memory Access Parsing, or DMP), (2) The development of case

  1. Annual research review: The neurobehavioral development of multiple memory systems--implications for childhood and adolescent psychiatric disorders.

    Science.gov (United States)

    Goodman, Jarid; Marsh, Rachel; Peterson, Bradley S; Packard, Mark G

    2014-06-01

    Extensive evidence indicates that mammalian memory is organized into multiple brains systems, including a 'cognitive' memory system that depends on the hippocampus and a stimulus-response 'habit' memory system that depends on the dorsolateral striatum. Dorsal striatal-dependent habit memory may in part influence the development and expression of some human psychopathologies, particularly those characterized by strong habit-like behavioral features. The present review considers this hypothesis as it pertains to psychopathologies that typically emerge during childhood and adolescence. These disorders include Tourette syndrome, attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, eating disorders, and autism spectrum disorders. Human and nonhuman animal research shows that the typical development of memory systems comprises the early maturation of striatal-dependent habit memory and the relatively late maturation of hippocampal-dependent cognitive memory. We speculate that the differing rates of development of these memory systems may in part contribute to the early emergence of habit-like symptoms in childhood and adolescence. In addition, abnormalities in hippocampal and striatal brain regions have been observed consistently in youth with these disorders, suggesting that the aberrant development of memory systems may also contribute to the emergence of habit-like symptoms as core pathological features of these illnesses. Considering these disorders within the context of multiple memory systems may help elucidate the pathogenesis of habit-like symptoms in childhood and adolescence, and lead to novel treatments that lessen the habit-like behavioral features of these disorders. © 2013 The Authors. Journal of Child Psychology and Psychiatry © 2013 Association for Child and Adolescent Mental Health.

  2. The Feasibility of Using CT-Guided ROI for Semiquantifying Striatal Dopamine Transporter Availability in a Hybrid SPECT/CT System

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    Chien-Chin Hsu

    2014-01-01

    Full Text Available A hybrid SPECT/CT system provides accurate coregistration of functional and morphological images. CT-guided region of interest (ROI for semiquantifying striatal dopamine transporter (DAT availability may be a feasible method. We therefore assessed the intra- and interobserver reproducibility of manual SPECT and CT-guided ROI methods and compared their semiquantitative data with data from MRI-guided ROIs. We enrolled twenty-eight patients who underwent Tc-99m TRODAT-1 brain SPECT/CT and brain MRI. ROIs of the striatal, caudate, putamen, and occipital cortex were manually delineated on the SPECT, CT, and MRI. ROIs from CT and MRI were transferred to the coregistered SPECT for semiquantification. The striatal, caudate, and putamen nondisplaceable binding potential (BPND were calculated. Using CT-guided ROIs had higher intra- and interobserver concordance correlation coefficients, closer Bland-Altman biases to zero, and narrower limits of agreement than using manual SPECT ROIs. The correlation coefficients of striatal, caudate, and putamen BPND were good between manual SPECT and MRI-guided ROI methods and even better between CT-guided and MRI-guided ROI methods. Conclusively, CT-guided ROI delineation for semiquantifying striatal DAT availability in a hybrid SPECT/CT system is highly reproducible, and the semiquantitative data correlate well with data from MRI-guided ROIs.

  3. The Cognitive Architecture of Spatial Navigation: Hippocampal and Striatal Contributions.

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    Chersi, Fabian; Burgess, Neil

    2015-10-07

    Spatial navigation can serve as a model system in cognitive neuroscience, in which specific neural representations, learning rules, and control strategies can be inferred from the vast experimental literature that exists across many species, including humans. Here, we review this literature, focusing on the contributions of hippocampal and striatal systems, and attempt to outline a minimal cognitive architecture that is consistent with the experimental literature and that synthesizes previous related computational modeling. The resulting architecture includes striatal reinforcement learning based on egocentric representations of sensory states and actions, incidental Hebbian association of sensory information with allocentric state representations in the hippocampus, and arbitration of the outputs of both systems based on confidence/uncertainty in medial prefrontal cortex. We discuss the relationship between this architecture and learning in model-free and model-based systems, episodic memory, imagery, and planning, including some open questions and directions for further experiments. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Western Diet Chow Consumption in Rats Induces Striatal Neuronal Activation While Reducing Dopamine Levels without Affecting Spatial Memory in the Radial Arm Maze.

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    Nguyen, Jason C D; Ali, Saher F; Kosari, Sepideh; Woodman, Owen L; Spencer, Sarah J; Killcross, A Simon; Jenkins, Trisha A

    2017-01-01

    Rats fed high fat diets have been shown to be impaired in hippocampal-dependent behavioral tasks, such as spatial recognition in the Y-maze and reference memory in the Morris water maze (MWM). It is clear from previous studies, however, that motivation and reward factor into the memory deficits associated with obesity and high-fat diet consumption, and that the prefrontal cortex and striatum and neurotransmitter dopamine play important roles in cognitive performance. In this series of studies we extend our research to investigate the effect of a high fat diet on striatal neurochemistry and performance in the delayed spatial win-shift radial arm maze task, a paradigm highly reliant on dopamine-rich brain regions, such as the striatum after high fat diet consumption. Memory performance, neuronal activation and brain dopaminergic levels were compared in rats fed a "Western" (21% fat, 0.15% cholesterol) chow diet compared to normal diet (6% fat, 0.15% cholesterol)-fed controls. Twelve weeks of dietary manipulation produced an increase in weight in western diet-fed rats, but did not affect learning and performance in the delayed spatial win-shift radial arm maze task. Concurrently, there was an observed decrease in dopamine levels in the striatum and a reduction of dopamine turnover in the hippocampus in western diet-fed rats. In a separate cohort of rats Fos levels were measured after rats had been placed in a novel arena and allowed to explore freely. In normal rats, this exposure to a unique environment did not affect neuronal activation. In contrast, rats fed a western diet were found to have significantly increased Fos expression in the striatum, but not prefrontal cortex or hippocampus. Our study demonstrates that while western diet consumption in rats produces weight gain and brain neuronal and neurotransmitter changes, it did not affect performance in the delayed spatial win-shift paradigm in the radial arm maze. We conclude that modeling the cognitive decline

  5. Noradrenergic System and Memory

    KAUST Repository

    Zenger, Manuel

    2017-07-22

    There is ample evidence indicating that noradrenaline plays an important role in memory mechanisms. Noradrenaline is thought to modulate these procsses through activation of adrenergic receptors in neurons. Astrocytes that form essential partners for synaptic function, also express alpha- and beta-adrenergic receptors. In astrocytes, noradrenaline triggers metabolic actions such as the glycogenolysis leading to an increase in l-lactate formation and release. l-Lactate can be used by neurons as a sourc of energy during memory tasks and can also induc transcription of plasticity genes in neurons. Activation of β-adrenergic receptors can also trigger gliotransmitter release resulting of intracllular calcium waves. These gliotransmitters modulate the synaptic activity and thereby can modulate long-term potentiation mechanisms. In summary, recnt evidencs indicate that noradrenaline exerts its memory-promoting effects through different modes of action both on neurons and astrocytes.

  6. Working Memory Systems in the Rat.

    Science.gov (United States)

    Bratch, Alexander; Kann, Spencer; Cain, Joshua A; Wu, Jie-En; Rivera-Reyes, Nilda; Dalecki, Stefan; Arman, Diana; Dunn, Austin; Cooper, Shiloh; Corbin, Hannah E; Doyle, Amanda R; Pizzo, Matthew J; Smith, Alexandra E; Crystal, Jonathon D

    2016-02-08

    A fundamental feature of memory in humans is the ability to simultaneously work with multiple types of information using independent memory systems. Working memory is conceptualized as two independent memory systems under executive control [1, 2]. Although there is a long history of using the term "working memory" to describe short-term memory in animals, it is not known whether multiple, independent memory systems exist in nonhumans. Here, we used two established short-term memory approaches to test the hypothesis that spatial and olfactory memory operate as independent working memory resources in the rat. In the olfactory memory task, rats chose a novel odor from a gradually incrementing set of old odors [3]. In the spatial memory task, rats searched for a depleting food source at multiple locations [4]. We presented rats with information to hold in memory in one domain (e.g., olfactory) while adding a memory load in the other domain (e.g., spatial). Control conditions equated the retention interval delay without adding a second memory load. In a further experiment, we used proactive interference [5-7] in the spatial domain to compromise spatial memory and evaluated the impact of adding an olfactory memory load. Olfactory and spatial memory are resistant to interference from the addition of a memory load in the other domain. Our data suggest that olfactory and spatial memory draw on independent working memory systems in the rat. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Stress and the engagement of multiple memory systems: integration of animal and human studies.

    Science.gov (United States)

    Schwabe, Lars

    2013-11-01

    Learning and memory can be controlled by distinct memory systems. How these systems are coordinated to optimize learning and behavior has long been unclear. Accumulating evidence indicates that stress may modulate the engagement of multiple memory systems. In particular, rodent and human studies demonstrate that stress facilitates dorsal striatum-dependent "habit" memory, at the expense of hippocampus-dependent "cognitive" memory. Based on these data, a model is proposed which states that the impact of stress on the relative use of multiple memory systems is due to (i) differential effects of hormones and neurotransmitters that are released during stressful events on hippocampal and dorsal striatal memory systems, thus changing the relative strength of and the interactions between these systems, and (ii) a modulatory influence of the amygdala which biases learning toward dorsal striatum-based memory after stress. This shift to habit memory after stress can be adaptive with respect to current performance but might contribute to psychopathology in vulnerable individuals. Copyright © 2013 Wiley Periodicals, Inc.

  8. Methamphetamine-induced changes in the mice hippocampal neuropeptide Y system: implications for memory impairment

    DEFF Research Database (Denmark)

    Gonçalves, J; Baptista, S; Olesen, MV

    2012-01-01

    , being involved in learning and memory processing. It has been demonstrated that METH induces significant alteration in mice striatal NPY, Y(1) and Y(2) receptor mRNA levels. However, the impact of this drug on the hippocampal NPY system and its consequences remain unknown. Thus, in this study, we...... investigated the effect of METH intoxication on mouse hippocampal NPY levels, NPY receptors function, and memory performance. Results show that METH increased NPY, Y(2) and Y(5) receptor mRNA levels, as well as total NPY binding accounted by opposite up- and down-regulation of Y(2) and Y(1) functional binding......, respectively. Moreover, METH-induced impairment in memory performance and AKT/mammalian target of rapamycin pathway were both prevented by the Y(2) receptor antagonist, BIIE0246. These findings demonstrate that METH interferes with the hippocampal NPY system, which seems to be associated with memory failure...

  9. Development scenarios for organizational memory information systems

    NARCIS (Netherlands)

    Wijnhoven, Alphonsus B.J.M.

    1999-01-01

    Well-managed organizational memories have been emphasized in the recent management literature as important sources for business success. Organizational memory infonnation systems (OMIS) have been conceptualized as a framework for information technologies to support these organizational memories.

  10. Mineralocorticoid receptor blockade prevents stress-induced modulation of multiple memory systems in the human brain.

    Science.gov (United States)

    Schwabe, Lars; Tegenthoff, Martin; Höffken, Oliver; Wolf, Oliver T

    2013-12-01

    Accumulating evidence suggests that stress may orchestrate the engagement of multiple memory systems in the brain. In particular, stress is thought to favor dorsal striatum-dependent procedural over hippocampus-dependent declarative memory. However, the neuroendocrine mechanisms underlying these modulatory effects of stress remain elusive, especially in humans. Here, we targeted the role of the mineralocorticoid receptor (MR) in the stress-induced modulation of dorsal striatal and hippocampal memory systems in the human brain using a combination of event-related functional magnetic resonance imaging and pharmacologic blockade of the MR. Eighty healthy participants received the MR antagonist spironolactone (300 mg) or a placebo and underwent a stressor or control manipulation before they performed, in the scanner, a classification task that can be supported by the hippocampus and the dorsal striatum. Stress after placebo did not affect learning performance but reduced explicit task knowledge and led to a relative increase in the use of more procedural learning strategies. At the neural level, stress promoted striatum-based learning at the expense of hippocampus-based learning. Functional connectivity analyses showed that this shift was associated with altered coupling of the amygdala with the hippocampus and dorsal striatum. Mineralocorticoid receptor blockade before stress prevented the stress-induced shift toward dorsal striatal procedural learning, same as the stress-induced alterations of amygdala connectivity with hippocampus and dorsal striatum, but resulted in significantly impaired performance. Our findings indicate that the stress-induced shift from hippocampal to dorsal striatal memory systems is mediated by the amygdala, required to preserve performance after stress, and dependent on the MR. © 2013 Society of Biological Psychiatry.

  11. Memory architectures for exaflop computing systems

    OpenAIRE

    Pavlović, Milan

    2016-01-01

    Most computing systems are heavily dependent on their main memories, as their primary storage, or as an intermediate cache for slower storage systems (HDDs). The capacity of memory systems, as well as their performance, have a direct impact on overall computing capabilities of the system, and are also major contributors to its initial and operating costs. Dynamic Random Access Memory (DRAM) technology has been dominating the main memory landscape since its beginnings in 1970s until today. ...

  12. Pre-Existing Differences and Diet-Induced Alterations in Striatal Dopamine Systems of Obesity-Prone Rats

    Science.gov (United States)

    Vollbrecht, Peter J.; Mabrouk, Omar S.; Nelson, Andrew D.; Kennedy, Robert T.; Ferrario, Carrie R.

    2016-01-01

    Objective Interactions between pre-existing differences in mesolimbic function and neuroadaptations induced by consumption of fatty, sugary foods are thought to contribute to human obesity. This study examined basal and cocaine-induced changes in striatal neurotransmitter levels without diet manipulation and D2/D3 dopamine receptor-mediated transmission prior to and after consumption of “junk-foods” in obesity-prone and obesity-resistant rats. Methods Microdialysis and liquid chromatography-mass spectrometry were used to determine basal and cocaine-induced changes in neurotransmitter levels in real time with cocaine-induced locomotor activity. Sensitivity to the D2/D3 dopamine receptor agonist quinpirole was examined before and after restricted junk-food exposure. Selectively bred obesity-prone and obesity-resistant rats were used. Results Cocaine-induced locomotion was greater in obesity-prone rats versus obesity-resistant rats prior to diet manipulation. Basal and cocaine-induced increases in dopamine and serotonin levels did not differ. Obesity-prone rats were more sensitive to the D2 receptor-mediated effects of quinpirole, and junk-food produced modest alterations in quinpirole sensitivity in obesity-resistant rats. Conclusions These data show that mesolimbic systems differ prior to diet manipulation in susceptible versus resistant rats, and that consumption of fatty, sugary foods produce different neuroadaptations in these populations. These differences may contribute to enhanced food craving and an inability to limit food intake in susceptible individuals. PMID:26847484

  13. Stress Effects on Multiple Memory System Interactions

    Directory of Open Access Journals (Sweden)

    Deborah Ness

    2016-01-01

    Full Text Available Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory systems, we review recent animal and human studies exploring the effects of stress on multiple memory systems. Apart from discussing the interaction between distinct memory systems in stressful situations, we will also outline the fundamental role of the amygdala in mediating such stress effects. Additionally, based on the methods applied in the herein discussed studies, we will discuss how memory translates into behaviour.

  14. Stress Effects on Multiple Memory System Interactions.

    Science.gov (United States)

    Ness, Deborah; Calabrese, Pasquale

    2016-01-01

    Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory systems, we review recent animal and human studies exploring the effects of stress on multiple memory systems. Apart from discussing the interaction between distinct memory systems in stressful situations, we will also outline the fundamental role of the amygdala in mediating such stress effects. Additionally, based on the methods applied in the herein discussed studies, we will discuss how memory translates into behaviour.

  15. Stress Effects on Multiple Memory System Interactions

    OpenAIRE

    Ness, Deborah; Calabrese, Pasquale

    2016-01-01

    Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory syst...

  16. Homodyne detection of holographic memory systems

    Science.gov (United States)

    Urness, Adam C.; Wilson, William L.; Ayres, Mark R.

    2014-09-01

    We present a homodyne detection system implemented for a page-wise holographic memory architecture. Homodyne detection by holographic memory systems enables phase quadrature multiplexing (doubling address space), and lower exposure times (increasing read transfer rates). It also enables phase modulation, which improves signal-to-noise ratio (SNR) to further increase data capacity. We believe this is the first experimental demonstration of homodyne detection for a page-wise holographic memory system suitable for a commercial design.

  17. Parsing Heterogeneous Striatal Activity

    Directory of Open Access Journals (Sweden)

    Kae Nakamura

    2017-05-01

    Full Text Available The striatum is an input channel of the basal ganglia and is well known to be involved in reward-based decision making and learning. At the macroscopic level, the striatum has been postulated to contain parallel functional modules, each of which includes neurons that perform similar computations to support selection of appropriate actions for different task contexts. At the single-neuron level, however, recent studies in monkeys and rodents have revealed heterogeneity in neuronal activity even within restricted modules of the striatum. Looking for generality in the complex striatal activity patterns, here we briefly survey several types of striatal activity, focusing on their usefulness for mediating behaviors. In particular, we focus on two types of behavioral tasks: reward-based tasks that use salient sensory cues and manipulate outcomes associated with the cues; and perceptual decision tasks that manipulate the quality of noisy sensory cues and associate all correct decisions with the same outcome. Guided by previous insights on the modular organization and general selection-related functions of the basal ganglia, we relate striatal activity patterns on these tasks to two types of computations: implementation of selection and evaluation. We suggest that a parsing with the selection/evaluation categories encourages a focus on the functional commonalities revealed by studies with different animal models and behavioral tasks, instead of a focus on aspects of striatal activity that may be specific to a particular task setting. We then highlight several questions in the selection-evaluation framework for future explorations.

  18. Optoelectronic Cache Memory System Architecture

    National Research Council Canada - National Science Library

    Chiarulli, Donald

    1999-01-01

    .... This technology enables the use of large page oriented optical memories in applications such as medical, image, and geo-spatial databases where high speed access to page structured data is essential.

  19. Evaluating operating system vulnerability to memory errors.

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Kurt Brian; Bridges, Patrick G. (University of New Mexico); Pedretti, Kevin Thomas Tauke; Mueller, Frank (North Carolina State University); Fiala, David (North Carolina State University); Brightwell, Ronald Brian

    2012-05-01

    Reliability is of great concern to the scalability of extreme-scale systems. Of particular concern are soft errors in main memory, which are a leading cause of failures on current systems and are predicted to be the leading cause on future systems. While great effort has gone into designing algorithms and applications that can continue to make progress in the presence of these errors without restarting, the most critical software running on a node, the operating system (OS), is currently left relatively unprotected. OS resiliency is of particular importance because, though this software typically represents a small footprint of a compute node's physical memory, recent studies show more memory errors in this region of memory than the remainder of the system. In this paper, we investigate the soft error vulnerability of two operating systems used in current and future high-performance computing systems: Kitten, the lightweight kernel developed at Sandia National Laboratories, and CLE, a high-performance Linux-based operating system developed by Cray. For each of these platforms, we outline major structures and subsystems that are vulnerable to soft errors and describe methods that could be used to reconstruct damaged state. Our results show the Kitten lightweight operating system may be an easier target to harden against memory errors due to its smaller memory footprint, largely deterministic state, and simpler system structure.

  20. Embedded System Synthesis under Memory Constraints

    DEFF Research Database (Denmark)

    Madsen, Jan; Bjørn-Jørgensen, Peter

    1999-01-01

    This paper presents a genetic algorithm to solve the system synthesis problem of mapping a time constrained single-rate system specification onto a given heterogeneous architecture which may contain irregular interconnection structures. The synthesis is performed under memory constraints, that is......, the algorithm takes into account the memory size of processors and the size of interface buffers of communication links, and in particular the complicated interplay of these. The presented algorithm is implemented as part of the LY-COS cosynthesis system....

  1. Exposure to predator odor influences the relative use of multiple memory systems: role of basolateral amygdala.

    Science.gov (United States)

    Leong, Kah-Chung; Packard, Mark G

    2014-03-01

    In a dual-solution plus-maze task in which both hippocampus-dependent place learning and dorsolateral striatal-dependent response learning provide an adequate solution, the relative use of multiple memory systems can be influenced by emotional state. Specifically, pre-training peripheral or intra-basolateral (BLA) administration of anxiogenic drugs result in the predominant use of response learning. The present experiments were designed to extend these findings by examining whether exposure to a putatively ethologically valid stressor would also produce a predominant use of response learning. In experiment 1, adult male Long-Evans rats were exposed to either a predator odor (trimethylthiazoline [TMT], a component of fox feces) or distilled water prior to training in a dual-solution water plus maze task. On a probe trial 24h following task acquisition, rats previously exposed to TMT predominantly displayed response learning relative to control animals. In experiment 2, rats trained on a single-solution plus maze task that required the use of response learning displayed enhanced acquisition following pre-training TMT exposure. In experiment 3, rats exposed to TMT or distilled water were trained in the dual-solution task and received post-training intra-BLA injections of the sodium channel blocker bupivacaine (1.0% solution, 0.5 μl) or saline. Relative to control animals, rats exposed to TMT predominantly displayed response learning on the probe trial, and this effect was blocked by neural inactivation of the BLA. The findings indicate that (1) the use of dorsal striatal-dependent habit memory produced by emotional arousal generalizes from anxiogenic drug administration to a putatively ecologically valid stressor (i.e. predator odor), and (2) the BLA mediates the modulatory effect of exposure to predator odor on the relative use of multiple memory systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. A Brain System for Auditory Working Memory.

    Science.gov (United States)

    Kumar, Sukhbinder; Joseph, Sabine; Gander, Phillip E; Barascud, Nicolas; Halpern, Andrea R; Griffiths, Timothy D

    2016-04-20

    The brain basis for auditory working memory, the process of actively maintaining sounds in memory over short periods of time, is controversial. Using functional magnetic resonance imaging in human participants, we demonstrate that the maintenance of single tones in memory is associated with activation in auditory cortex. In addition, sustained activation was observed in hippocampus and inferior frontal gyrus. Multivoxel pattern analysis showed that patterns of activity in auditory cortex and left inferior frontal gyrus distinguished the tone that was maintained in memory. Functional connectivity during maintenance was demonstrated between auditory cortex and both the hippocampus and inferior frontal cortex. The data support a system for auditory working memory based on the maintenance of sound-specific representations in auditory cortex by projections from higher-order areas, including the hippocampus and frontal cortex. In this work, we demonstrate a system for maintaining sound in working memory based on activity in auditory cortex, hippocampus, and frontal cortex, and functional connectivity among them. Specifically, our work makes three advances from the previous work. First, we robustly demonstrate hippocampal involvement in all phases of auditory working memory (encoding, maintenance, and retrieval): the role of hippocampus in working memory is controversial. Second, using a pattern classification technique, we show that activity in the auditory cortex and inferior frontal gyrus is specific to the maintained tones in working memory. Third, we show long-range connectivity of auditory cortex to hippocampus and frontal cortex, which may be responsible for keeping such representations active during working memory maintenance. Copyright © 2016 Kumar et al.

  3. Individual Differences in Cue-Induced Motivation and Striatal Systems in Rats Susceptible to Diet-Induced Obesity.

    Science.gov (United States)

    Robinson, Mike J F; Burghardt, Paul R; Patterson, Christa M; Nobile, Cameron W; Akil, Huda; Watson, Stanley J; Berridge, Kent C; Ferrario, Carrie R

    2015-08-01

    Pavlovian cues associated with junk-foods (caloric, highly sweet, and/or fatty foods), like the smell of brownies, can elicit craving to eat and increase the amount of food consumed. People who are more susceptible to these motivational effects of food cues may have a higher risk for becoming obese. Further, overconsumption of junk-foods leading to the development of obesity may itself heighten attraction to food cues. Here, we used a model of individual susceptibility to junk-foods diet-induced obesity to determine whether there are pre-existing and/or diet-induced increases in attraction to and motivation for sucrose-paired cues (ie, incentive salience or 'wanting'). We also assessed diet- vs obesity-associated alterations in mesolimbic function and receptor expression. We found that rats susceptible to diet-induced obesity displayed heightened conditioned approach prior to the development of obesity. In addition, after junk-food diet exposure, those rats that developed obesity also showed increased willingness to gain access to a sucrose cue. Heightened 'wanting' was not due to individual differences in the hedonic impact ('liking') of sucrose. Neurobiologically, Mu opioid receptor mRNA expression was lower in striatal 'hot-spots' that generate eating or hedonic impact only in those rats that became obese. In contrast, prolonged exposure to junk-food resulted in cross-sensitization to amphetamine-induced locomotion and downregulation of striatal D2R mRNA regardless of the development of obesity. Together these data shed light on individual differences in behavioral and neurobiological consequences of exposure to junk-food diets and the potential contribution of incentive sensitization in susceptible individuals to greater food cue-triggered motivation.

  4. Individual Differences in Cue-Induced Motivation and Striatal Systems in Rats Susceptible to Diet-Induced Obesity

    Science.gov (United States)

    Robinson, Mike JF; Burghardt, Paul R; Patterson, Christa M; Nobile, Cameron W; Akil, Huda; Watson, Stanley J; Berridge, Kent C; Ferrario, Carrie R

    2015-01-01

    Pavlovian cues associated with junk-foods (caloric, highly sweet, and/or fatty foods), like the smell of brownies, can elicit craving to eat and increase the amount of food consumed. People who are more susceptible to these motivational effects of food cues may have a higher risk for becoming obese. Further, overconsumption of junk-foods leading to the development of obesity may itself heighten attraction to food cues. Here, we used a model of individual susceptibility to junk-foods diet-induced obesity to determine whether there are pre-existing and/or diet-induced increases in attraction to and motivation for sucrose-paired cues (ie, incentive salience or ‘wanting’). We also assessed diet- vs obesity-associated alterations in mesolimbic function and receptor expression. We found that rats susceptible to diet-induced obesity displayed heightened conditioned approach prior to the development of obesity. In addition, after junk-food diet exposure, those rats that developed obesity also showed increased willingness to gain access to a sucrose cue. Heightened ‘wanting’ was not due to individual differences in the hedonic impact (‘liking’) of sucrose. Neurobiologically, Mu opioid receptor mRNA expression was lower in striatal ‘hot-spots’ that generate eating or hedonic impact only in those rats that became obese. In contrast, prolonged exposure to junk-food resulted in cross-sensitization to amphetamine-induced locomotion and downregulation of striatal D2R mRNA regardless of the development of obesity. Together these data shed light on individual differences in behavioral and neurobiological consequences of exposure to junk-food diets and the potential contribution of incentive sensitization in susceptible individuals to greater food cue-triggered motivation. PMID:25761571

  5. Impulse: Memory System Support for Scientific Applications

    Directory of Open Access Journals (Sweden)

    John B. Carter

    1999-01-01

    Full Text Available Impulse is a new memory system architecture that adds two important features to a traditional memory controller. First, Impulse supports application‐specific optimizations through configurable physical address remapping. By remapping physical addresses, applications control how their data is accessed and cached, improving their cache and bus utilization. Second, Impulse supports prefetching at the memory controller, which can hide much of the latency of DRAM accesses. Because it requires no modification to processor, cache, or bus designs, Impulse can be adopted in conventional systems. In this paper we describe the design of the Impulse architecture, and show how an Impulse memory system can improve the performance of memory‐bound scientific applications. For instance, Impulse decreases the running time of the NAS conjugate gradient benchmark by 67%. We expect that Impulse will also benefit regularly strided, memory‐bound applications of commercial importance, such as database and multimedia programs.

  6. MEMORY SYSTEMS AND THE ADDICTED BRAIN

    Directory of Open Access Journals (Sweden)

    Jarid eGoodman

    2016-02-01

    Full Text Available The view that anatomically distinct memory systems differentially contribute to the development of drug addiction and relapse has received extensive support. The present brief review revisits this hypothesis as it was originally proposed twenty years ago (White, 1996 and highlights several recent developments. Extensive research employing a variety of animal learning paradigms indicates that dissociable neural systems mediate distinct types of learning and memory. Each memory system potentially contributes unique components to the learned behavior supporting drug addiction and relapse. In particular, the shift from recreational drug use to compulsive drug abuse may reflect a neuroanatomical shift from cognitive control of behavior mediated by the hippocampus/dorsomedial striatum toward habitual control of behavior mediated by the dorsolateral striatum (DLS. In addition, stress/anxiety may constitute a cofactor that facilitates DLS-dependent memory, and this may serve as a neurobehavioral mechanism underlying the increased drug use and relapse in humans following stressful life events. Evidence supporting the multiple systems view of drug addiction comes predominantly from studies of learning and memory that have employed as reinforcers addictive substances often considered within the context of drug addiction research, including cocaine, alcohol, and amphetamines. In addition, recent evidence suggests that the memory systems approach may also be helpful for understanding topical sources of addiction that reflect emerging health concerns, including marijuana use, high-fat diet, and video game playing.

  7. A Radiation Hardened Spacecraft Mass Memory System

    Science.gov (United States)

    Dennehy, W. J.; Lawton, B.; Stufflebeam, J.

    The functional design of a Radiation Hardened Spacecraft Mass Memory System (RH/SMMS) is described. This system is configured around a 1 megabit memory device and incorporates various system and circuit design features to achieve radiation hardness. The system is modular and storage capacities of 16 to 32 megabits are achievable within modest size, weight, and power constraints. Estimates of physical characteristics (size, weight, and power) are presented for a 16 Mbit system. The RH/SMMS is organized in a disk-like architecture and offers the spacecraft designer several unique benefits such as: reduced software cost, increased autonomy and survivability, increased functionality and increased fault tolerance.

  8. Bidirectional Frontoparietal Oscillatory Systems Support Working Memory.

    Science.gov (United States)

    Johnson, Elizabeth L; Dewar, Callum D; Solbakk, Anne-Kristin; Endestad, Tor; Meling, Torstein R; Knight, Robert T

    2017-06-19

    The ability to represent and select information in working memory provides the neurobiological infrastructure for human cognition. For 80 years, dominant views of working memory have focused on the key role of prefrontal cortex (PFC) [1-8]. However, more recent work has implicated posterior cortical regions [9-12], suggesting that PFC engagement during working memory is dependent on the degree of executive demand. We provide evidence from neurological patients with discrete PFC damage that challenges the dominant models attributing working memory to PFC-dependent systems. We show that neural oscillations, which provide a mechanism for PFC to communicate with posterior cortical regions [13], independently subserve communications both to and from PFC-uncovering parallel oscillatory mechanisms for working memory. Fourteen PFC patients and 20 healthy, age-matched controls performed a working memory task where they encoded, maintained, and actively processed information about pairs of common shapes. In controls, the electroencephalogram (EEG) exhibited oscillatory activity in the low-theta range over PFC and directional connectivity from PFC to parieto-occipital regions commensurate with executive processing demands. Concurrent alpha-beta oscillations were observed over parieto-occipital regions, with directional connectivity from parieto-occipital regions to PFC, regardless of processing demands. Accuracy, PFC low-theta activity, and PFC → parieto-occipital connectivity were attenuated in patients, revealing a PFC-independent, alpha-beta system. The PFC patients still demonstrated task proficiency, which indicates that the posterior alpha-beta system provides sufficient resources for working memory. Taken together, our findings reveal neurologically dissociable PFC and parieto-occipital systems and suggest that parallel, bidirectional oscillatory systems form the basis of working memory. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Configurable memory system and method for providing atomic counting operations in a memory device

    Science.gov (United States)

    Bellofatto, Ralph E.; Gara, Alan G.; Giampapa, Mark E.; Ohmacht, Martin

    2010-09-14

    A memory system and method for providing atomic memory-based counter operations to operating systems and applications that make most efficient use of counter-backing memory and virtual and physical address space, while simplifying operating system memory management, and enabling the counter-backing memory to be used for purposes other than counter-backing storage when desired. The encoding and address decoding enabled by the invention provides all this functionality through a combination of software and hardware.

  10. Fluctuations in interacting particle systems with memory

    International Nuclear Information System (INIS)

    Harris, Rosemary J

    2015-01-01

    We consider the effects of long-range temporal correlations in many-particle systems, focusing particularly on fluctuations about the typical behaviour. For a specific class of memory dependence we discuss the modification of the large deviation principle describing the probability of rare currents and show how superdiffusive behaviour can emerge. We illustrate the general framework with detailed calculations for a memory-dependent version of the totally asymmetric simple exclusion process as well as indicating connections to other recent work

  11. A novel form of memory for auditory fear conditioning at a low-intensity unconditioned stimulus.

    Directory of Open Access Journals (Sweden)

    Ayumi Kishioka

    Full Text Available Fear is one of the most potent emotional experiences and is an adaptive component of response to potentially threatening stimuli. On the other hand, too much or inappropriate fear accounts for many common psychiatric problems. Cumulative evidence suggests that the amygdala plays a central role in the acquisition, storage and expression of fear memory. Here, we developed an inducible striatal neuron ablation system in transgenic mice. The ablation of striatal neurons in the adult brain hardly affected the auditory fear learning under the standard condition in agreement with previous studies. When conditioned with a low-intensity unconditioned stimulus, however, the formation of long-term fear memory but not short-tem memory was impaired in striatal neuron-ablated mice. Consistently, the ablation of striatal neurons 24 h after conditioning with the low-intensity unconditioned stimulus, when the long-term fear memory was formed, diminished the retention of the long-term memory. Our results reveal a novel form of the auditory fear memory depending on striatal neurons at the low-intensity unconditioned stimulus.

  12. Morphine Reward Promotes Cue-Sensitive Learning: Implication of Dorsal Striatal CREB Activity

    Directory of Open Access Journals (Sweden)

    Mathieu Baudonnat

    2017-05-01

    Full Text Available Different parallel neural circuits interact and may even compete to process and store information: whereas stimulus–response (S–R learning critically depends on the dorsal striatum (DS, spatial memory relies on the hippocampus (HPC. Strikingly, despite its potential importance for our understanding of addictive behaviors, the impact of drug rewards on memory systems dynamics has not been extensively studied. Here, we assessed long-term effects of drug- vs food reinforcement on the subsequent use of S–R vs spatial learning strategies and their neural substrates. Mice were trained in a Y-maze cue-guided task, during which either food or morphine injections into the ventral tegmental area (VTA were used as rewards. Although drug- and food-reinforced mice learned the Y-maze task equally well, drug-reinforced mice exhibited a preferential use of an S–R learning strategy when tested in a water-maze competition task designed to dissociate cue-based and spatial learning. This cognitive bias was associated with a persistent increase in the phosphorylated form of cAMP response element-binding protein phosphorylation (pCREB within the DS, and a decrease of pCREB expression in the HPC. Pharmacological inhibition of striatal PKA pathway in drug-rewarded mice limited the morphine-induced increase in levels of pCREB in DS and restored a balanced use of spatial vs cue-based learning. Our findings suggest that drug (opiate reward biases the engagement of separate memory systems toward a predominant use of the cue-dependent system via an increase in learning-related striatal pCREB activity. Persistent functional imbalance between striatal and hippocampal activity could contribute to the persistence of addictive behaviors, or counteract the efficiency of pharmacological or psychotherapeutic treatments.

  13. Systems Genetic Analyses Highlight a TGFβ-FOXO3 Dependent Striatal Astrocyte Network Conserved across Species and Associated with Stress, Sleep, and Huntington's Disease.

    Science.gov (United States)

    Scarpa, Joseph R; Jiang, Peng; Losic, Bojan; Readhead, Ben; Gao, Vance D; Dudley, Joel T; Vitaterna, Martha H; Turek, Fred W; Kasarskis, Andrew

    2016-07-01

    Recent systems-based analyses have demonstrated that sleep and stress traits emerge from shared genetic and transcriptional networks, and clinical work has elucidated the emergence of sleep dysfunction and stress susceptibility as early symptoms of Huntington's disease. Understanding the biological bases of these early non-motor symptoms may reveal therapeutic targets that prevent disease onset or slow disease progression, but the molecular mechanisms underlying this complex clinical presentation remain largely unknown. In the present work, we specifically examine the relationship between these psychiatric traits and Huntington's disease (HD) by identifying striatal transcriptional networks shared by HD, stress, and sleep phenotypes. First, we utilize a systems-based approach to examine a large publicly available human transcriptomic dataset for HD (GSE3790 from GEO) in a novel way. We use weighted gene coexpression network analysis and differential connectivity analyses to identify transcriptional networks dysregulated in HD, and we use an unbiased ranking scheme that leverages both gene- and network-level information to identify a novel astrocyte-specific network as most relevant to HD caudate. We validate this result in an independent HD cohort. Next, we computationally predict FOXO3 as a regulator of this network, and use multiple publicly available in vitro and in vivo experimental datasets to validate that this astrocyte HD network is downstream of a signaling pathway important in adult neurogenesis (TGFβ-FOXO3). We also map this HD-relevant caudate subnetwork to striatal transcriptional networks in a large (n = 100) chronically stressed (B6xA/J)F2 mouse population that has been extensively phenotyped (328 stress- and sleep-related measurements), and we show that this striatal astrocyte network is correlated to sleep and stress traits, many of which are known to be altered in HD cohorts. We identify causal regulators of this network through Bayesian network

  14. CAM: A Collaborative Object Memory System

    NARCIS (Netherlands)

    Vyas, Dhaval; Nijholt, Antinus; Kröner, Alexander

    2010-01-01

    Physical design objects such as sketches, drawings, collages, storyboards and models play an important role in supporting communication and coordination in design studios. CAM (Cooperative Artefact Memory) is a mobile-tagging based messaging system that allows designers to collaboratively store

  15. Striatal volume predicts level of video game skill acquisition.

    Science.gov (United States)

    Erickson, Kirk I; Boot, Walter R; Basak, Chandramallika; Neider, Mark B; Prakash, Ruchika S; Voss, Michelle W; Graybiel, Ann M; Simons, Daniel J; Fabiani, Monica; Gratton, Gabriele; Kramer, Arthur F

    2010-11-01

    Video game skills transfer to other tasks, but individual differences in performance and in learning and transfer rates make it difficult to identify the source of transfer benefits. We asked whether variability in initial acquisition and of improvement in performance on a demanding video game, the Space Fortress game, could be predicted by variations in the pretraining volume of either of 2 key brain regions implicated in learning and memory: the striatum, implicated in procedural learning and cognitive flexibility, and the hippocampus, implicated in declarative memory. We found that hippocampal volumes did not predict learning improvement but that striatal volumes did. Moreover, for the striatum, the volumes of the dorsal striatum predicted improvement in performance but the volumes of the ventral striatum did not. Both ventral and dorsal striatal volumes predicted early acquisition rates. Furthermore, this early-stage correlation between striatal volumes and learning held regardless of the cognitive flexibility demands of the game versions, whereas the predictive power of the dorsal striatal volumes held selectively for performance improvements in a game version emphasizing cognitive flexibility. These findings suggest a neuroanatomical basis for the superiority of training strategies that promote cognitive flexibility and transfer to untrained tasks.

  16. Open system evolution and 'memory dressing'

    International Nuclear Information System (INIS)

    Knezevic, Irena; Ferry, David K.

    2004-01-01

    Due to recent advances in quantum information, as well as in mesoscopic and nanoscale physics, the interest in the theory of open systems and decoherence has significantly increased. In this paper, we present an interesting approach to solving a time-convolutionless equation of motion for the open system reduced density matrix beyond the limit of weak coupling with the environment. Our approach is based on identifying an effective, memory-containing interaction in the equations of motion for the representation submatrices of the evolution operator (these submatices are written in a special basis, adapted for the 'partial-trace-free' approach, in the system+environment Liouville space). We then identify the 'memory dressing', a quantity crucial for solving the equation of motion for the reduced density matrix, which separates the effective from the real physical interaction. The memory dressing obeys a self-contained nonlinear equation of motion, which we solve exactly. The solution can be represented in a diagrammatic fashion after introducing an 'information exchange propagator', a quantity that describes the transfer of information to and from the system, so the cumulative effect of the information exchange results in the memory dressing. In the case of weak system-environment coupling, we present the expansion of the reduced density matrix in terms of the physical interaction up to the third order. However, our approach is capable of going beyond the weak-coupling limit, and we show how short-time behavior of an open system can be analyzed for arbitrary coupling strength. We illustrate the approach with a simple numerical example of single-particle level broadening for a two-particle interacting system on short time scales. Furthermore, we point out a way to identify the structure of decoherence-free subspaces using the present approach

  17. Visual software system for memory interleaving simulation

    Directory of Open Access Journals (Sweden)

    Milenković Katarina

    2017-01-01

    Full Text Available This paper describes the visual software system for memory interleaving simulation (VSMIS, implemented for the purpose of the course Computer Architecture and Organization 1, at the School of Electrical Engineering, University of Belgrade. The simulator enables students to expand their knowledge through practical work in the laboratory, as well as through independent work at home. VSMIS gives users the possibility to initialize parts of the system and to control simulation steps. The user has the ability to monitor simulation through graphical representation. It is possible to navigate through the entire hierarchy of the system using simple navigation. During the simulation the user can observe and set the values of the memory location. At any time, the user can reset the simulation of the system and observe it for different memory states; in addition, it is possible to save the current state of the simulation and continue with the execution of the simulation later. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III44009

  18. Molecular Regulation of Striatal Development: A Review

    Directory of Open Access Journals (Sweden)

    A. E. Evans

    2012-01-01

    Full Text Available The central nervous system is composed of the brain and the spinal cord. The brain is a complex organ that processes and coordinates activities of the body in bilaterian, higher-order animals. The development of the brain mirrors its complex function as it requires intricate genetic signalling at specific times, and deviations from this can lead to brain malformations such as anencephaly. Research into how the CNS is specified and patterned has been studied extensively in chick, fish, frog, and mice, but findings from the latter will be emphasised here as higher-order mammals show most similarity to the human brain. Specifically, we will focus on the embryonic development of an important forebrain structure, the striatum (also known as the dorsal striatum or neostriatum. Over the past decade, research on striatal development in mice has led to an influx of new information about the genes involved, but the precise orchestration between the genes, signalling molecules, and transcription factors remains unanswered. We aim to summarise what is known to date about the tightly controlled network of interacting genes that control striatal development. This paper will discuss early telencephalon patterning and dorsal ventral patterning with specific reference to the genes involved in striatal development.

  19. Strobe-margin test for plated memory systems

    Science.gov (United States)

    Anspach, T. E.; Clarke, J. W.; Constable, R. C.

    1978-01-01

    Technique measures performance of plated-wire memories. Strobe-margin test (SMT) utilizes worst-case testing and automatically gives exact strobe margin. Test is automatic; thus, memory system-level test is superior to tests at component level that use artificial test conditions. Test is significant tool in design and test of plated-wire memory systems. It can rapidly quantify memory-system margin on each production unit and impact of any design changes.

  20. A Scalable Unsegmented Multiport Memory for FPGA-Based Systems

    Directory of Open Access Journals (Sweden)

    Kevin R. Townsend

    2015-01-01

    Full Text Available On-chip multiport memory cores are crucial primitives for many modern high-performance reconfigurable architectures and multicore systems. Previous approaches for scaling memory cores come at the cost of operating frequency, communication overhead, and logic resources without increasing the storage capacity of the memory. In this paper, we present two approaches for designing multiport memory cores that are suitable for reconfigurable accelerators with substantial on-chip memory or complex communication. Our design approaches tackle these challenges by banking RAM blocks and utilizing interconnect networks which allows scaling without sacrificing logic resources. With banking, memory congestion is unavoidable and we evaluate our multiport memory cores under different memory access patterns to gain insights about different design trade-offs. We demonstrate our implementation with up to 256 memory ports using a Xilinx Virtex-7 FPGA. Our experimental results report high throughput memories with resource usage that scales with the number of ports.

  1. Huntington's Disease and Striatal Signaling

    Directory of Open Access Journals (Sweden)

    Emmanuel eRoze

    2011-08-01

    Full Text Available Huntington’s Disease (HD is the most frequent neurodegenerative disease caused by an expansion of polyglutamines (CAG. The main clinical manifestations of HD are chorea, cognitive impairment and psychiatric disorders. The transmission of HD is autosomal dominant with a complete penetrance. HD has a single genetic cause, a well-defined neuropathology, and informative pre-manifest genetic testing of the disease is available. Striatal atrophy begins as early as 15 years before disease onset and continues throughout the period of manifest illness. Therefore, patients could theoretically benefit from therapy at early stages of the disease. One important characteristic of HD is the striatal vulnerability to neurodegeneration, despite similar expression of the protein in other brain areas. Aggregation of the mutated Huntingtin (HTT, impaired axonal transport, excitotoxicity, transcriptional dysregulation as well as mitochondrial dysfunction and energy deficits, are all part of the cellular events that underlie neuronal dysfunction and striatal death. Among these non-exclusive mechanisms, an alteration of striatal signaling is thought to orchestrate the downstream events involved in the cascade of striatal dysfunction.

  2. Generation-based memory synchronization in a multiprocessor system with weakly consistent memory accesses

    Science.gov (United States)

    Ohmacht, Martin

    2014-09-09

    In a multiprocessor system, a central memory synchronization module coordinates memory synchronization requests responsive to memory access requests in flight, a generation counter, and a reclaim pointer. The central module communicates via point-to-point communication. The module includes a global OR reduce tree for each memory access requesting device, for detecting memory access requests in flight. An interface unit is implemented associated with each processor requesting synchronization. The interface unit includes multiple generation completion detectors. The generation count and reclaim pointer do not pass one another.

  3. Mass memory formatter subsystem of the adaptive intrusion data system

    International Nuclear Information System (INIS)

    Corlis, N.E.

    1980-09-01

    The Mass Memory Formatter was developed as part of the Adaptive Intrusion Data System (AIDS) to control a 2.4-megabit mass memory. The data from a Memory Controlled Processor is formatted before it is stored in the memory and reformatted during the readout mode. The data is then transmitted to a NOVA 2 minicomputer-controlled magnetic tape recorder for storage. Techniques and circuits are described

  4. Altered resting-state functional connectivity of the frontal-striatal reward system in social anxiety disorder.

    Directory of Open Access Journals (Sweden)

    Joshua Manning

    Full Text Available We investigated differences in the intrinsic functional brain organization (functional connectivity of the human reward system between healthy control participants and patients with social anxiety disorder. Functional connectivity was measured in the resting-state via functional magnetic resonance imaging (fMRI. 53 patients with social anxiety disorder and 33 healthy control participants underwent a 6-minute resting-state fMRI scan. Functional connectivity of the reward system was analyzed by calculating whole-brain temporal correlations with a bilateral nucleus accumbens seed and a ventromedial prefrontal cortex seed. Patients with social anxiety disorder, relative to the control group, had (1 decreased functional connectivity between the nucleus accumbens seed and other regions associated with reward, including ventromedial prefrontal cortex; (2 decreased functional connectivity between the ventromedial prefrontal cortex seed and lateral prefrontal regions, including the anterior and dorsolateral prefrontal cortices; and (3 increased functional connectivity between both the nucleus accumbens seed and the ventromedial prefrontal cortex seed with more posterior brain regions, including anterior cingulate cortex. Social anxiety disorder appears to be associated with widespread differences in the functional connectivity of the reward system, including markedly decreased functional connectivity between reward regions and between reward regions and lateral prefrontal cortices, and markedly increased functional connectivity between reward regions and posterior brain regions.

  5. Component neural systems for the creation of emotional memories during free viewing of a complex, real-world event

    Directory of Open Access Journals (Sweden)

    Anne Botzung

    2010-05-01

    Full Text Available To investigate the neural systems that contribute to the formation of complex, self-relevant emotional memories, dedicated fans of rival college basketball teams watched a competitive game while undergoing functional magnetic resonance imaging (fMRI. During a subsequent recognition memory task, participants were shown video clips depicting plays of the game, stemming either from previously-viewed game segments (targets or from non-viewed portions of the same game (foils. After an old-new judgment, participants provided emotional valence and intensity ratings of the clips. A data driven approach was first used to decompose the fMRI signal acquired during free viewing of the game into spatially independent components. Correlations were then calculated between the identified components and post-scanning emotion ratings for successfully encoded targets. Two components were correlated with intensity ratings, including temporal lobe regions implicated in memory and emotional functions, such as the hippocampus and amygdala, as well as a midline fronto-cingulo-parietal network implicated in social cognition and self-relevant processing. These data were supported by a general linear model analysis, which revealed additional valence effects in fronto-striatal-insular regions when plays were divided into positive and negative events according to the fan’s perspective. Overall, these findings contribute to our understanding of how emotional factors impact distributed neural systems to successfully encode dynamic, personally-relevant event sequences.

  6. Striatal dopamine release codes uncertainty in pathological gambling

    DEFF Research Database (Denmark)

    Linnet, Jakob; Mouridsen, Kim; Peterson, Ericka

    2012-01-01

    Two mechanisms of midbrain and striatal dopaminergic projections may be involved in pathological gambling: hypersensitivity to reward and sustained activation toward uncertainty. The midbrain—striatal dopamine system distinctly codes reward and uncertainty, where dopaminergic activation is a linear...... dopamine release, and we used performance on the Iowa Gambling Task (IGT) to determine overall reward and uncertainty. We hypothesized that we would find a linear function between dopamine release and IGT performance, if dopamine release coded reward in pathological gambling. If, on the other hand......, dopamine release coded uncertainty, we would find an inversely U-shaped function. The data supported an inverse U-shaped relation between striatal dopamine release and IGT performance if the pathological gambling group, but not in the healthy control group. These results are consistent with the hypothesis...

  7. Proteostasis in striatal cells and selective neurodegeneration in Huntington's disease.

    Science.gov (United States)

    Margulis, Julia; Finkbeiner, Steven

    2014-01-01

    Selective neuronal loss is a hallmark of neurodegenerative diseases, including Huntington's disease (HD). Although mutant huntingtin, the protein responsible for HD, is expressed ubiquitously, a subpopulation of neurons in the striatum is the first to succumb. In this review, we examine evidence that protein quality control pathways, including the ubiquitin proteasome system, autophagy, and chaperones, are significantly altered in striatal neurons. These alterations may increase the susceptibility of striatal neurons to mutant huntingtin-mediated toxicity. This novel view of HD pathogenesis has profound therapeutic implications: protein homeostasis pathways in the striatum may be valuable targets for treating HD and other misfolded protein disorders.

  8. Fronto-striatal atrophy correlates of neuropsychiatric dysfunction in frontotemporal dementia (FTD and Alzheimer's disease (AD

    Directory of Open Access Journals (Sweden)

    Dong Seok Yi

    Full Text Available ABSTRACT Behavioural disturbances in frontotemporal dementia (FTD are thought to reflect mainly atrophy of cortical regions. Recent studies suggest that subcortical brain regions, in particular the striatum, are also significantly affected and this pathology might play a role in the generation of behavioural symptoms. Objective: To investigate prefrontal cortical and striatal atrophy contributions to behavioural symptoms in FTD. Methods: One hundred and eighty-two participants (87 FTD patients, 39 AD patients and 56 controls were included. Behavioural profiles were established using the Cambridge Behavioural Inventory Revised (CBI-R and Frontal System Behaviour Scale (FrSBe. Atrophy in prefrontal (VMPFC, DLPFC and striatal (caudate, putamen regions was established via a 5-point visual rating scale of the MRI scans. Behavioural scores were correlated with atrophy rating scores. Results: Behavioural and atrophy ratings demonstrated that patients were significantly impaired compared to controls, with bvFTD being most severely affected. Behavioural-anatomical correlations revealed that VMPFC atrophy was closely related to abnormal behaviour and motivation disturbances. Stereotypical behaviours were associated with both VMPFC and striatal atrophy. By contrast, disturbance of eating was found to be related to striatal atrophy only. Conclusion: Frontal and striatal atrophy contributed to the behavioural disturbances seen in FTD, with some behaviours related to frontal, striatal or combined fronto-striatal pathology. Consideration of striatal contributions to the generation of behavioural disturbances should be taken into account when assessing patients with potential FTD.

  9. Transactive memory systems scale for couples: development and validation.

    Science.gov (United States)

    Hewitt, Lauren Y; Roberts, Lynne D

    2015-01-01

    People in romantic relationships can develop shared memory systems by pooling their cognitive resources, allowing each person access to more information but with less cognitive effort. Research examining such memory systems in romantic couples largely focuses on remembering word lists or performing lab-based tasks, but these types of activities do not capture the processes underlying couples' transactive memory systems, and may not be representative of the ways in which romantic couples use their shared memory systems in everyday life. We adapted an existing measure of transactive memory systems for use with romantic couples (TMSS-C), and conducted an initial validation study. In total, 397 participants who each identified as being a member of a romantic relationship of at least 3 months duration completed the study. The data provided a good fit to the anticipated three-factor structure of the components of couples' transactive memory systems (specialization, credibility and coordination), and there was reasonable evidence of both convergent and divergent validity, as well as strong evidence of test-retest reliability across a 2-week period. The TMSS-C provides a valuable tool that can quickly and easily capture the underlying components of romantic couples' transactive memory systems. It has potential to help us better understand this intriguing feature of romantic relationships, and how shared memory systems might be associated with other important features of romantic relationships.

  10. Transactive Memory Systems Scale for Couples: Development and Initial Validation

    Directory of Open Access Journals (Sweden)

    Lauren Y. Hewitt

    2015-05-01

    Full Text Available People in romantic relationships can develop shared memory systems by pooling their cognitive resources, allowing each person access to more information but with less cognitive effort. Research examining such memory systems in romantic couples largely focuses on remembering word lists or performing lab-based tasks, but these types of activities do not capture the processes underlying couples’ transactive memory systems, and may not be representative of the ways in which romantic couples use their shared memory systems in everyday life. We adapted an existing measure of transactive memory systems for use with romantic couples (TMSS-C, and conducted an initial validation study. In total, 397 participants who each identified as being a member of a romantic relationship of at least 3 months duration completed the study. The data provided a good fit to the anticipated three-factor structure of the components of couples’ transactive memory systems (specialization, credibility and coordination, and there was reasonable evidence of both convergent and divergent validity, as well as strong evidence of test-retest reliability across a two-week period. The TMSS-C provides a valuable tool that can quickly and easily capture the underlying components of romantic couples’ transactive memory systems. It has potential to help us better understand this intriguing feature of romantic relationships, and how shared memory systems might be associated with other important features of romantic relationships.

  11. Memory systems, computation, and the second law of thermodynamics

    International Nuclear Information System (INIS)

    Wolpert, D.H.

    1992-01-01

    A memory is a physical system for transferring information form one moment in time to another, where that information concerns something external to the system itself. This paper argues on information-theoretic and statistical mechanical grounds that useful memories must be of one of two types, exemplified by memory in abstract computer programs and by memory in photographs. Photograph-type memories work by exploring a collapse of state space flow to an attractor state. (This attractor state is the open-quotes initializedclose quotes state of the memory.) The central assumption of the theory of reversible computation tells us that in any such collapsing, regardless of whether the collapsing must increase in entropy of the system. In concert with the second law, this establishes the logical necessity of the empirical observation that photograph-type memories are temporally asymmetric (they can tell us about the past but not about the future). Under the assumption that human memory is a photograph-type memory, this result also explains why we humans can remember only our past and not our future. In contrast to photo-graph-type memories, computer-type memories do not require any initialization, and therefore are not directly affected by the second law. As a result, computer memories can be of the future as easily as of the past, even if the program running on the computer is logically irreversible. This is entirely in accord with the well-known temporal reversibility of the process of computation. This paper ends by arguing that the asymmetry of the psychological arrow of time is a direct consequence of the asymmetry of human memory. With the rest of this paper, this explains, explicitly and rigorously, why the psychological and thermodynamic arrows of time are correlated with one another. 24 refs

  12. RAPID: A random access picture digitizer, display, and memory system

    Science.gov (United States)

    Yakimovsky, Y.; Rayfield, M.; Eskenazi, R.

    1976-01-01

    RAPID is a system capable of providing convenient digital analysis of video data in real-time. It has two modes of operation. The first allows for continuous digitization of an EIA RS-170 video signal. Each frame in the video signal is digitized and written in 1/30 of a second into RAPID's internal memory. The second mode leaves the content of the internal memory independent of the current input video. In both modes of operation the image contained in the memory is used to generate an EIA RS-170 composite video output signal representing the digitized image in the memory so that it can be displayed on a monitor.

  13. A selective logging mechanism for hardware transactional memory systems

    OpenAIRE

    Lupon Navazo, Marc; Magklis, Grigorios; González Colás, Antonio María

    2011-01-01

    Log-based Hardware Transactional Memory (HTM) systems offer an elegant solution to handle speculative data that overflow transactional L1 caches. By keeping the pre-transactional values on a software-resident log, speculative values can be safely moved across the memory hierarchy, without requiring expensive searches on L1 misses or commits.

  14. Multiple Systems of Spatial Memory: Evidence from Described Scenes

    Science.gov (United States)

    Avraamides, Marios N.; Kelly, Jonathan W.

    2010-01-01

    Recent models in spatial cognition posit that distinct memory systems are responsible for maintaining transient and enduring spatial relations. The authors used perspective-taking performance to assess the presence of these enduring and transient spatial memories for locations encoded through verbal descriptions. Across 3 experiments, spatial…

  15. Diversity in Long-Term Synaptic Plasticity at Inhibitory Synapses of Striatal Spiny Neurons

    Science.gov (United States)

    Rueda-Orozco, Pavel E.; Mendoza, Ernesto; Hernandez, Ricardo; Aceves, Jose J.; Ibanez-Sandoval, Osvaldo; Galarraga, Elvira; Bargas, Jose

    2009-01-01

    Procedural memories and habits are posited to be stored in the basal ganglia, whose intrinsic circuitries possess important inhibitory connections arising from striatal spiny neurons. However, no information about long-term plasticity at these synapses is available. Therefore, this work describes a novel postsynaptically dependent long-term…

  16. Striatal degeneration impairs language learning: evidence from Huntington's disease.

    Science.gov (United States)

    De Diego-Balaguer, R; Couette, M; Dolbeau, G; Dürr, A; Youssov, K; Bachoud-Lévi, A-C

    2008-11-01

    Although the role of the striatum in language processing is still largely unclear, a number of recent proposals have outlined its specific contribution. Different studies report evidence converging to a picture where the striatum may be involved in those aspects of rule-application requiring non-automatized behaviour. This is the main characteristic of the earliest phases of language acquisition that require the online detection of distant dependencies and the creation of syntactic categories by means of rule learning. Learning of sequences and categorization processes in non-language domains has been known to require striatal recruitment. Thus, we hypothesized that the striatum should play a prominent role in the extraction of rules in learning a language. We studied 13 pre-symptomatic gene-carriers and 22 early stage patients of Huntington's disease (pre-HD), both characterized by a progressive degeneration of the striatum and 21 late stage patients Huntington's disease (18 stage II, two stage III and one stage IV) where cortical degeneration accompanies striatal degeneration. When presented with a simplified artificial language where words and rules could be extracted, early stage Huntington's disease patients (stage I) were impaired in the learning test, demonstrating a greater impairment in rule than word learning compared to the 20 age- and education-matched controls. Huntington's disease patients at later stages were impaired both on word and rule learning. While spared in their overall performance, gene-carriers having learned a set of abstract artificial language rules were then impaired in the transfer of those rules to similar artificial language structures. The correlation analyses among several neuropsychological tests assessing executive function showed that rule learning correlated with tests requiring working memory and attentional control, while word learning correlated with a test involving episodic memory. These learning impairments significantly

  17. Mechanisms mediating parallel action monitoring in fronto-striatal circuits.

    Science.gov (United States)

    Beste, Christian; Ness, Vanessa; Lukas, Carsten; Hoffmann, Rainer; Stüwe, Sven; Falkenstein, Michael; Saft, Carsten

    2012-08-01

    Flexible response adaptation and the control of conflicting information play a pivotal role in daily life. Yet, little is known about the neuronal mechanisms mediating parallel control of these processes. We examined these mechanisms using a multi-methodological approach that integrated data from event-related potentials (ERPs) with structural MRI data and source localisation using sLORETA. Moreover, we calculated evoked wavelet oscillations. We applied this multi-methodological approach in healthy subjects and patients in a prodromal phase of a major basal ganglia disorder (i.e., Huntington's disease), to directly focus on fronto-striatal networks. Behavioural data indicated, especially the parallel execution of conflict monitoring and flexible response adaptation was modulated across the examined cohorts. When both processes do not co-incide a high integrity of fronto-striatal loops seems to be dispensable. The neurophysiological data suggests that conflict monitoring (reflected by the N2 ERP) and working memory processes (reflected by the P3 ERP) differentially contribute to this pattern of results. Flexible response adaptation under the constraint of high conflict processing affected the N2 and P3 ERP, as well as their delta frequency band oscillations. Yet, modulatory effects were strongest for the N2 ERP and evoked wavelet oscillations in this time range. The N2 ERPs were localized in the anterior cingulate cortex (BA32, BA24). Modulations of the P3 ERP were localized in parietal areas (BA7). In addition, MRI-determined caudate head volume predicted modulations in conflict monitoring, but not working memory processes. The results show how parallel conflict monitoring and flexible adaptation of action is mediated via fronto-striatal networks. While both, response monitoring and working memory processes seem to play a role, especially response selection processes and ACC-basal ganglia networks seem to be the driving force in mediating parallel conflict

  18. Memory

    Science.gov (United States)

    ... it has to decide what is worth remembering. Memory is the process of storing and then remembering this information. There are different types of memory. Short-term memory stores information for a few ...

  19. Interacting Brain Systems Modulate Memory Consolidation

    Science.gov (United States)

    McIntyre, Christa K.; McGaugh, James L.; Williams, Cedric L.

    2011-01-01

    Emotional arousal influences the consolidation of long-term memory. This review discusses experimental approaches and relevant findings that provide the foundation for current understanding of coordinated interactions between arousal activated peripheral hormones and the brain processes that modulate memory formation. Rewarding or aversive experiences release the stress hormones epinephrine (adrenalin) and glucocorticoids from the adrenal glands into the bloodstream. The effect of these hormones on memory consolidation depends upon binding of norepinephrine to beta-adrenergic receptors in the basolateral complex of the amygdala (BLA). Much evidence indicates that the stress hormones influence release of norepinephrine in the BLA through peripheral actions on the vagus nerve which stimulates, through polysynaptic connections, cells of the locus coeruleus to release norepinephrine. The BLA influences memory storage by actions on synapses, distributed throughout the brain, that are engaged in sensory and cognitive processing at the time of amygdala activation. The implications of the activation of these stress-activated memory processes are discussed in relation to stress-related memory disorders. PMID:22085800

  20. Memory systems, processes, and tasks: taxonomic clarification via factor analysis.

    Science.gov (United States)

    Bruss, Peter J; Mitchell, David B

    2009-01-01

    The nature of various memory systems was examined using factor analysis. We reanalyzed data from 11 memory tasks previously reported in Mitchell and Bruss (2003). Four well-defined factors emerged, closely resembling episodic and semantic memory and conceptual and perceptual implicit memory, in line with both memory systems and transfer-appropriate processing accounts. To explore taxonomic issues, we ran separate analyses on the implicit tasks. Using a cross-format manipulation (pictures vs. words), we identified 3 prototypical tasks. Word fragment completion and picture fragment identification tasks were "factor pure," tapping perceptual processes uniquely. Category exemplar generation revealed its conceptual nature, yielding both cross-format priming and a picture superiority effect. In contrast, word stem completion and picture naming were more complex, revealing attributes of both processes.

  1. Cortical Thickness and Episodic Memory Impairment in Systemic Lupus Erythematosus.

    Science.gov (United States)

    Bizzo, Bernardo Canedo; Sanchez, Tiago Arruda; Tukamoto, Gustavo; Zimmermann, Nicolle; Netto, Tania Maria; Gasparetto, Emerson Leandro

    2017-01-01

    The purpose of this study was to investigate differences in brain cortical thickness of systemic lupus erythematosus (SLE) patients with and without episodic memory impairment and healthy controls. We studied 51 patients divided in 2 groups (SLE with episodic memory deficit, n = 17; SLE without episodic memory deficit, n = 34) by the Rey Auditory Verbal Learning Test and 34 healthy controls. Groups were paired based on sex, age, education, Mini-Mental State Examination score, and accumulation of disease burden. Cortical thickness from magnetic resonance imaging scans was determined using the FreeSurfer software package. SLE patients with episodic memory deficits presented reduced cortical thickness in the left supramarginal cortex and superior temporal gyrus when compared to the control group and in the right superior frontal, caudal, and rostral middle frontal and precentral gyri when compared to the SLE group without episodic memory impairment considering time since diagnosis of SLE as covaried. There were no significant differences in the cortical thickness between the SLE without episodic memory and control groups. Different memory-related cortical regions thinning were found in the episodic memory deficit group when individually compared to the groups of patients without memory impairment and healthy controls. Copyright © 2016 by the American Society of Neuroimaging.

  2. Striatal mechanisms underlying movement, reinforcement, and punishment.

    Science.gov (United States)

    Kravitz, Alexxai V; Kreitzer, Anatol C

    2012-06-01

    Direct and indirect pathway striatal neurons are known to exert opposing control over motor output. In this review, we discuss a hypothetical extension of this framework, in which direct pathway striatal neurons also mediate reinforcement and reward, and indirect pathway neurons mediate punishment and aversion.

  3. Striatal Mechanisms Underlying Movement, Reinforcement, and Punishment

    OpenAIRE

    Kravitz, Alexxai V.; Kreitzer, Anatol C.

    2012-01-01

    Direct and indirect pathway striatal neurons are known to exert opposing control over motor output. In this review, we discuss a hypothetical extension of this framework, in which direct pathway striatal neurons also mediate reinforcement and reward, and indirect pathway neurons mediate punishment and aversion.

  4. Transfer after Dual n-Back Training Depends on Striatal Activation Change.

    Science.gov (United States)

    Salminen, Tiina; Kühn, Simone; Frensch, Peter A; Schubert, Torsten

    2016-09-28

    The dual n-back working memory (WM) training paradigm (comprising auditory and visual stimuli) has gained much attention since studies have shown widespread transfer effects. By including a multimodal dual-task component, the task is demanding to the human cognitive system. We investigated whether dual n-back training improves general cognitive resources or a task-specific WM updating process in participants. We expected: (1) widespread transfer effects and the recruitment of a common neuronal network by the training and the transfer tasks and (2) narrower transfer results and that a common activation network alone would not produce transfer, but instead an activation focus on the striatum, which is associated with WM updating processes. The training group showed transfer to an untrained dual-modality WM updating task, but not to single-task versions of the training or the transfer task. They also showed diminished neuronal overlap between the training and the transfer task from pretest to posttest and an increase in striatal activation in both tasks. Furthermore, we found an association between the striatal activation increase and behavioral improvement. The control groups showed no transfer and no change in the amount of activation overlap or in striatal activation from pretest to posttest. We conclude that, instead of improving general cognitive resources (which would have required a transfer effect to all transfer tasks and that a frontal activation overlap between the tasks produced transfer), dual n-back training improved a task-specific process: WM updating of stimuli from two modalities. The current study allows for a better understanding of the cognitive and neural effects of working memory (WM) training and transfer. It shows that dual n-back training mainly improves specific processes of WM updating, and this improvement leads to narrow transfer effects to tasks involving the same processes. On a neuronal level this is accompanied by increased neural

  5. Measurement of striatal dopamine metabolism with 6-[18F]-fluoro-L-dopa and PET

    International Nuclear Information System (INIS)

    Kuwabara, Y.; Otsuka, M.; Ichiya, Y.; Yoshikai, T.; Fukumura, T.; Masuda, K.; Kato, M.; Taniwaki, T.

    1992-01-01

    Striatal dopamine metabolism was studied with 6-[ 18 F]-fluoro-L-dopa ( 18 F-DOPA) and PET. The subjects were normal controls, and patients with Parkinson's disease (PD), parkinsonism, multiple system atrophy (MSA), progressive supranuclear palsy (PSP), Alzheimer's disease (AD), Huntington's disease (HD) and other cerebral disorders. Cerebral glucose metabolism (CMRGlc) was also measured in these patients. Striatal dopamine metabolism was evaluated by the relative striatal uptake of 18 F-DOPA referring cerebellum (S/C ratio). In normal controls, the S/C ratio was 2.82 ± 0.32 (n = 6, mean ± SD) at 120 min after injection of 18 F-DOPA. The S/C ratio was low in patients with PD, parkinsonism, MSA and PSP compared to the normal controls and thus coincident with the symptoms of parkinsonism due to decrease in striatal dopamine concentration. The decrease in the striatal CMRGlc was also observed in patients with parkinsonism and PSP, and it was preserved in patients with PD, thus representing that more neurons were damaged in patients with parkinsonism and PSP than in patients with PD. A patient with AD having symptoms of parkinsonism also showed a decrease in S/C ratio. In a patient with HD, the striatal CMRGlc sharply decreased, but the S/C ratio was normal. The measurements of striatal dopamine and glucose metabolism with PET may be useful for studying the pathophysiological mechanism in patients with cerebral disorders. (author)

  6. Dissociating response systems: erasing fear from memory.

    Science.gov (United States)

    Soeter, Marieke; Kindt, Merel

    2010-07-01

    In addition to the extensive evidence in animals, we previously showed that disrupting reconsolidation by noradrenergic blockade produced amnesia for the original fear response in humans. Interestingly, the declarative memory for the fear association remained intact. These results asked for a solid replication. Moreover, given the constructive nature of memories, the intact recollection of the fear association could eventually 'rebuild' the fear memory, resulting in the spontaneous recovery of the fear response. Yet, perseverance of the amnesic effects would have substantial clinical implications, as even the most effective treatments for psychiatric disorders display high percentages of relapse. Using a differential fear conditioning procedure in humans, we replicated our previous findings by showing that administering propranolol (40mg) prior to memory reactivation eliminated the startle fear response 24h later. But most importantly, this effect persisted at one month follow-up. Notably, the propranolol manipulation not only left the declarative memory for the acquired contingency untouched, but also skin conductance discrimination. In addition, a close association between declarative knowledge and skin conductance responses was found. These findings are in line with the supposed double dissociation of fear conditioning and declarative knowledge relative to the amygdala and hippocampus in humans. They support the view that skin conductance conditioning primarily reflects contingency learning, whereas the startle response is a rather specific measure of fear. Furthermore, the results indicate the absence of a causal link between the actual knowledge of a fear association and its fear response, even though they often operate in parallel. Interventions targeting the amygdalar fear memory may be essential in specifically and persistently dampening the emotional impact of fear. From a clinical and ethical perspective, disrupting reconsolidation points to promising

  7. The memory systems of children with (central) auditory disorder.

    Science.gov (United States)

    Pires, Mayra Monteiro; Mota, Mailce Borges; Pinheiro, Maria Madalena Canina

    2015-01-01

    This study aims to investigate working, declarative, and procedural memory in children with (central) auditory processing disorder who showed poor phonological awareness. Thirty 9- and 10-year-old children participated in the study and were distributed into two groups: a control group consisting of 15 children with typical development, and an experimental group consisting of 15 children with (central) auditory processing disorder who were classified according to three behavioral tests and who showed poor phonological awareness in the CONFIAS test battery. The memory systems were assessed through the adapted tests in the program E-PRIME 2.0. The working memory was assessed by the Working Memory Test Battery for Children (WMTB-C), whereas the declarative memory was assessed by a picture-naming test and the procedural memory was assessed by means of a morphosyntactic processing test. The results showed that, when compared to the control group, children with poor phonological awareness scored lower in the working, declarative, and procedural memory tasks. The results of this study suggest that in children with (central) auditory processing disorder, phonological awareness is associated with the analyzed memory systems.

  8. Optimizing Memory Transactions for Multicore Systems

    Science.gov (United States)

    Adl-Tabatabai, Ali-Reza; Kozyrakis, Christos; Saha, Bratin

    The shift to multicore architectures will require new programming technologies that enable mainstream developers to write parallel programs that can safely take advantage of the parallelism offered by multicore processors. One challenging aspect of shared memory parallel programming is synchronization. Programmers have traditionally used locks for synchronization, but lock-based synchronization has well-known pitfalls that make it hard to use for building thread-safe and scalable software components. Memory transactions have emerged as a promising alternative to lock-based synchronization because they promise to eliminate many of the problems associated with locks. Transactional programming constructs, however, have overheads and require optimizations to make them practical. Transactions can also benefit significantly from hardware support, and multicore processors with their large transistor budgets and on-chip memory hierarchies have the opportunity to provide this support.

  9. Memory.

    Science.gov (United States)

    McKean, Kevin

    1983-01-01

    Discusses current research (including that involving amnesiacs and snails) into the nature of the memory process, differentiating between and providing examples of "fact" memory and "skill" memory. Suggests that three brain parts (thalamus, fornix, mammilary body) are involved in the memory process. (JN)

  10. Endocannabinoid-dopamine interactions in striatal synaptic plasticity

    Directory of Open Access Journals (Sweden)

    Brian Neil Mathur

    2012-04-01

    Full Text Available The nigrostriatal dopaminergic system is implicated in action control and learning. A large body of work has focused on the contribution of this system to modulation of the corticostriatal synapse, the predominant synapse type in the striatum. Signaling through the D2 dopamine receptor is necessary for endocannabinoid-mediated depression of corticostriatal glutamate release. Here we review the known details of this mechanism and discuss newly discovered signaling pathways interacting with this system that ultimately exert dynamic control of cortical input to the striatum and striatal output. This topic is timely with respect to Parkinson’s disease given recent data indicating changes in the striatal endocannabinoid system in patients with this disorder.

  11. Dissociating response systems: erasing fear from memory

    NARCIS (Netherlands)

    Soeter, A.C.; Kindt, M.

    2010-01-01

    In addition to the extensive evidence in animals, we previously showed that disrupting reconsolidation by noradrenergic blockade produced amnesia for the original fear response in humans. Interestingly, the declarative memory for the fear association remained intact. These results asked for a solid

  12. Memory Efficient Data Structures for Explicit Verification of Timed Systems

    DEFF Research Database (Denmark)

    Taankvist, Jakob Haahr; Srba, Jiri; Larsen, Kim Guldstrand

    2014-01-01

    -arc Petri nets, we explore new data structures for lowering the used memory: PTries for efficient storing of configurations and time darts for semi-symbolic description of the state-space. Both methods are implemented as a part of the tool TAPAAL and the experiments document at least one order of magnitude......Timed analysis of real-time systems can be performed using continuous (symbolic) or discrete (explicit) techniques. The explicit state-space exploration can be considerably faster for models with moderately small constants, however, at the expense of high memory consumption. In the setting of timed...... of memory savings while preserving comparable verification times....

  13. A revised limbic system model for memory, emotion and behaviour.

    Science.gov (United States)

    Catani, Marco; Dell'acqua, Flavio; Thiebaut de Schotten, Michel

    2013-09-01

    Emotion, memories and behaviour emerge from the coordinated activities of regions connected by the limbic system. Here, we propose an update of the limbic model based on the seminal work of Papez, Yakovlev and MacLean. In the revised model we identify three distinct but partially overlapping networks: (i) the Hippocampal-diencephalic and parahippocampal-retrosplenial network dedicated to memory and spatial orientation; (ii) The temporo-amygdala-orbitofrontal network for the integration of visceral sensation and emotion with semantic memory and behaviour; (iii) the default-mode network involved in autobiographical memories and introspective self-directed thinking. The three networks share cortical nodes that are emerging as principal hubs in connectomic analysis. This revised network model of the limbic system reconciles recent functional imaging findings with anatomical accounts of clinical disorders commonly associated with limbic pathology. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Brains of verbal memory specialists show anatomical differences in language, memory and visual systems.

    Science.gov (United States)

    Hartzell, James F; Davis, Ben; Melcher, David; Miceli, Gabriele; Jovicich, Jorge; Nath, Tanmay; Singh, Nandini Chatterjee; Hasson, Uri

    2016-05-01

    We studied a group of verbal memory specialists to determine whether intensive oral text memory is associated with structural features of hippocampal and lateral-temporal regions implicated in language processing. Professional Vedic Sanskrit Pandits in India train from childhood for around 10years in an ancient, formalized tradition of oral Sanskrit text memorization and recitation, mastering the exact pronunciation and invariant content of multiple 40,000-100,000 word oral texts. We conducted structural analysis of gray matter density, cortical thickness, local gyrification, and white matter structure, relative to matched controls. We found massive gray matter density and cortical thickness increases in Pandit brains in language, memory and visual systems, including i) bilateral lateral temporal cortices and ii) the anterior cingulate cortex and the hippocampus, regions associated with long and short-term memory. Differences in hippocampal morphometry matched those previously documented for expert spatial navigators and individuals with good verbal working memory. The findings provide unique insight into the brain organization implementing formalized oral knowledge systems. Copyright © 2015. Published by Elsevier Inc.

  15. Software Coherence in Multiprocessor Memory Systems. Ph.D. Thesis

    Science.gov (United States)

    Bolosky, William Joseph

    1993-01-01

    Processors are becoming faster and multiprocessor memory interconnection systems are not keeping up. Therefore, it is necessary to have threads and the memory they access as near one another as possible. Typically, this involves putting memory or caches with the processors, which gives rise to the problem of coherence: if one processor writes an address, any other processor reading that address must see the new value. This coherence can be maintained by the hardware or with software intervention. Systems of both types have been built in the past; the hardware-based systems tended to outperform the software ones. However, the ratio of processor to interconnect speed is now so high that the extra overhead of the software systems may no longer be significant. This issue is explored both by implementing a software maintained system and by introducing and using the technique of offline optimal analysis of memory reference traces. It finds that in properly built systems, software maintained coherence can perform comparably to or even better than hardware maintained coherence. The architectural features necessary for efficient software coherence to be profitable include a small page size, a fast trap mechanism, and the ability to execute instructions while remote memory references are outstanding.

  16. Age differences in brain systems supporting transient and sustained processes involved in prospective memory and working memory.

    Science.gov (United States)

    Peira, Nathalie; Ziaei, Maryam; Persson, Jonas

    2016-01-15

    In prospective memory (PM), an intention to act in response to an external event is formed, retained, and at a later stage, when the event occurs, the relevant action is performed. PM typically shows a decline in late adulthood, which might affect functions of daily living. The neural correlates of this decline are not well understood. Here, 15 young (6 female; age range=23-30years) and 16 older adults (5 female; age range=64-74years) were scanned with fMRI to examine age-related differences in brain activation associated with event-based PM using a task that facilitated the separation of transient and sustained components of PM. We show that older adults had reduced performance in conditions with high demands on prospective and working memory, while no age-difference was observed in low-demanding tasks. Across age groups, PM task performance activated separate sets of brain regions for transient and sustained responses. Age-differences in transient activation were found in fronto-striatal and MTL regions, with young adults showing more activation than older adults. Increased activation in young, compared to older adults, was also found for sustained PM activation in the IFG. These results provide new evidence that PM relies on dissociable transient and sustained cognitive processes, and that age-related deficits in PM can be explained by an inability to recruit PM-related brain networks in old age. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Striatal dopamine release codes uncertainty in pathological gambling

    DEFF Research Database (Denmark)

    Linnet, Jakob; Mouridsen, Kim; Peterson, Ericka

    2012-01-01

    Two mechanisms of midbrain and striatal dopaminergic projections may be involved in pathological gambling: hypersensitivity to reward and sustained activation toward uncertainty. The midbrain—striatal dopamine system distinctly codes reward and uncertainty, where dopaminergic activation is a linear...... function of expected reward and an inverse U-shaped function of uncertainty. In this study, we investigated the dopaminergic coding of reward and uncertainty in 18 pathological gambling sufferers and 16 healthy controls. We used positron emission tomography (PET) with the tracer [11C]raclopride to measure...... dopamine release, and we used performance on the Iowa Gambling Task (IGT) to determine overall reward and uncertainty. We hypothesized that we would find a linear function between dopamine release and IGT performance, if dopamine release coded reward in pathological gambling. If, on the other hand...

  18. A Layered Active Memory Architecture for Cognitive Vision Systems

    OpenAIRE

    Kolonias, Ilias; Christmas, William; Kittler, Josef

    2007-01-01

    Recognising actions and objects from video material has attracted growing research attention and given rise to important applications. However, injecting cognitive capabilities into computer vision systems requires an architecture more elaborate than the traditional signal processing paradigm for information processing. Inspired by biological cognitive systems, we present a memory architecture enabling cognitive processes (such as selecting the processes required for scene understanding, laye...

  19. Propagating fronts in reaction-transport systems with memory

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, A. [Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314 (United States)], E-mail: ayadav1@lsu.edu; Fedotov, Sergei [School of Mathematics, University of Manchester, Manchester M60 1DQ (United Kingdom)], E-mail: sergei.fedotov@manchester.ac.uk; Mendez, Vicenc [Grup de Fisica Estadistica, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)], E-mail: vicenc.mendez@uab.es; Horsthemke, Werner [Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314 (United States)], E-mail: whorsthe@smu.edu

    2007-11-26

    In reaction-transport systems with non-standard diffusion, the memory of the transport causes a coupling of reactions and transport. We investigate the effect of this coupling for systems with Fisher-type kinetics and obtain a general analytical expression for the front speed. We apply our results to the specific case of subdiffusion.

  20. Learning to live independently with expert systems in memory rehabilitation.

    Science.gov (United States)

    Man, D W K; Tam, S F; Hui-Chan, C W Y

    2003-01-01

    Expert systems (ES), which are a branch of artificial intelligence, has been widely used in different applications, including medical consultation and more recently in rehabilitation for assessment and intervention. The development and validation of an expert system for memory rehabilitation (ES-MR) is reported here. Through a web-based platform, ES-MR can provide experts with better decision making in providing intervention for persons with brain injuries, stroke, and dementia. The application and possible commercial production of a simultaneously developed version for "non-expert" users is proposed. This is especially useful for providing remote assistance to persons with permanent memory impairment when they reach a plateau of cognitive training and demand a prosthetic system to enhance memory for day-to-day independence. The potential use of ES-MR as a cognitive aid in conjunction with WAP mobile phones, Bluetooth technology, and Personal Digital Assistants (PDAs) is suggested as an avenue for future study.

  1. Parallel discrete ordinates algorithms on distributed and common memory systems

    International Nuclear Information System (INIS)

    Wienke, B.R.; Hiromoto, R.E.; Brickner, R.G.

    1987-01-01

    The S/sub n/ algorithm employs iterative techniques in solving the linear Boltzmann equation. These methods, both ordered and chaotic, were compared on both the Denelcor HEP and the Intel hypercube. Strategies are linked to the organization and accessibility of memory (common memory versus distributed memory architectures), with common concern for acquisition of global information. Apart from this, the inherent parallelism of the algorithm maps directly onto the two architectures. Results comparing execution times, speedup, and efficiency are based on a representative 16-group (full upscatter and downscatter) sample problem. Calculations were performed on both the Los Alamos National Laboratory (LANL) Denelcor HEP and the LANL Intel hypercube. The Denelcor HEP is a 64-bit multi-instruction, multidate MIMD machine consisting of up to 16 process execution modules (PEMs), each capable of executing 64 processes concurrently. Each PEM can cooperate on a job, or run several unrelated jobs, and share a common global memory through a crossbar switch. The Intel hypercube, on the other hand, is a distributed memory system composed of 128 processing elements, each with its own local memory. Processing elements are connected in a nearest-neighbor hypercube configuration and sharing of data among processors requires execution of explicit message-passing constructs

  2. Memory under stress: from single systems to network changes.

    Science.gov (United States)

    Schwabe, Lars

    2017-02-01

    Stressful events have profound effects on learning and memory. These effects are mainly mediated by catecholamines and glucocorticoid hormones released from the adrenals during stressful encounters. It has been known for long that both catecholamines and glucocorticoids influence the functioning of the hippocampus, a critical hub for episodic memory. However, areas implicated in other forms of memory, such as the insula or the dorsal striatum, can be affected by stress as well. Beyond changes in single memory systems, acute stress triggers the reconfiguration of large scale neural networks which sets the stage for a shift from thoughtful, 'cognitive' control of learning and memory toward more reflexive, 'habitual' processes. Stress-related alterations in amygdala connectivity with the hippocampus, dorsal striatum, and prefrontal cortex seem to play a key role in this shift. The bias toward systems proficient in threat processing and the implementation of well-established routines may facilitate coping with an acute stressor. Overreliance on these reflexive systems or the inability to shift flexibly between them, however, may represent a risk factor for psychopathology in the long-run. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  3. Photopolymerized Thiol-Ene Systems as Shape Memory Polymers

    Science.gov (United States)

    Nair, Devatha P.; Cramer, Neil B.; Scott, Timothy F.; Bowman, Christopher N.; Shandas, Robin

    2010-01-01

    In this study we introduce the use of thiol-ene photopolymers as shape memory polymer systems. The thiol-ene polymer networks are compared to a commonly utilized acrylic shape memory polymer and shown to have significantly improved properties for two different thiol-ene based polymer formulations. Using thermomechanical and mechanical analysis, we demonstrate that thiol-ene based shape memory polymer systems have comparable thermomechanical properties while also exhibiting a number of advantageous properties due to the thiol-ene polymerization mechanism which results in the formation of a homogenous polymer network with low shrinkage stress and negligible oxygen inhibition. The resulting thiol-ene shape memory polymer systems are tough and flexible as compared to the acrylic counterparts. The polymers evaluated in this study were engineered to have a glass transition temperature between 30 and 40 °C, exhibited free strain recovery of greater than 96% and constrained stress recovery of 100%. The thiol-ene polymers exhibited excellent shape fixity and a rapid and distinct shape memory actuation response. PMID:21072253

  4. The associative memory system for the FTK processor at ATLAS

    CERN Document Server

    Magalotti, D; The ATLAS collaboration; Donati, S; Luciano, P; Piendibene, M; Giannetti, P; Lanza, A; Verzellesi, G; Sakellariou, Andreas; Billereau, W; Combe, J M

    2014-01-01

    In high energy physics experiments, the most interesting processes are very rare and hidden in an extremely large level of background. As the experiment complexity, accelerator backgrounds, and instantaneous luminosity increase, more effective and accurate data selection techniques are needed. The Fast TracKer processor (FTK) is a real time tracking processor designed for the ATLAS trigger upgrade. The FTK core is the Associative Memory system. It provides massive computing power to minimize the processing time of complex tracking algorithms executed online. This paper reports on the results and performance of a new prototype of Associative Memory system.

  5. Experimental analyses of dynamical systems involving shape memory alloys

    DEFF Research Database (Denmark)

    Enemark, Søren; Savi, Marcelo A.; Santos, Ilmar F.

    2015-01-01

    The use of shape memory alloys (SMAs) in dynamical systems has an increasing importance in engineering especially due to their capacity to provide vibration reductions. In this regard, experimental tests are essential in order to show all potentialities of this kind of systems. In this work, SMA...... springs are incorporated in a dynamical system that consists of a one degree of freedom oscillator connected to a linear spring and a mass, which is also connected to the SMA spring. Two types of springs are investigated defming two distinct systems: a pseudoelastic and a shape memory system....... The characterisation of the springs is evaluated by considering differential calorimetry scanning tests and also force-displacement tests at different temperatures. Free and forced vibration experiments are made in order to investigate the dynamical behaviour of the systems. For both systems, it is observed...

  6. Motor tics evoked by striatal disinhibition in the rat

    Science.gov (United States)

    Bronfeld, Maya; Yael, Dorin; Belelovsky, Katya; Bar-Gad, Izhar

    2013-01-01

    Motor tics are sudden, brief, repetitive movements that constitute the main symptom of Tourette syndrome (TS). Multiple lines of evidence suggest the involvement of the cortico-basal ganglia system, and in particular the basal ganglia input structure—the striatum in tic formation. The striatum receives somatotopically organized cortical projections and contains an internal GABAergic network of interneurons and projection neurons' collaterals. Disruption of local striatal GABAergic connectivity has been associated with TS and was found to induce abnormal movements in model animals. We have previously described the behavioral and neurophysiological characteristics of motor tics induced in monkeys by local striatal microinjections of the GABAA antagonist bicuculline. In the current study we explored the abnormal movements induced by a similar manipulation in freely moving rats. We targeted microinjections to different parts of the dorsal striatum, and examined the effects of this manipulation on the induced tic properties, such as latency, duration, and somatic localization. Tics induced by striatal disinhibition in monkeys and rats shared multiple properties: tics began within several minutes after microinjection, were expressed solely in the contralateral side, and waxed and waned around a mean inter-tic interval of 1–4 s. A clear somatotopic organization was observed only in rats, where injections to the anterior or posterior striatum led to tics in the forelimb or hindlimb areas, respectively. These results suggest that striatal disinhibition in the rat may be used to model motor tics such as observed in TS. Establishing this reliable and accessible animal model could facilitate the study of the neural mechanisms underlying motor tics, and the testing of potential therapies for tic disorders. PMID:24065893

  7. Motor tics evoked by striatal disinhibition in the rat

    Directory of Open Access Journals (Sweden)

    Maya eBronfeld

    2013-09-01

    Full Text Available Motor tics are sudden, brief, repetitive movements that constitute the main symptom of Tourette syndrome (TS. Multiple lines of evidence suggest the involvement of the cortico-basal ganglia system, and in particular the basal ganglia input structure – the striatum in tic formation. The striatum receives somatotopically organized cortical projections and contains an internal GABAergic network of interneurons and projection neurons collaterals. Disruption of local striatal GABAergic connectivity has been associated with TS and was found to induce abnormal movements in model animals. We have previously described the behavioral and neurophysiological characteristics of motor tics induced in monkeys by local striatal microinjections of the GABAA antagonist bicuculline. In the current study we explored the abnormal movements induced by a similar manipulation in freely moving rats. We targeted microinjections to different parts of the dorsal striatum, and examined the effects of this manipulation on the induced tic properties, such as latency, duration and somatic localization. Tics induced by striatal disinhibition in monkeys and rats shared multiple properties: tics began within several minutes after microinjection, were expressed solely in the contralateral side, and waxed and waned around a mean inter-tic interval of 1-4 s. A clear somatotopic organization was observed only in rats, where injections to the anterior or posterior striatum led to tics in the forelimb or hindlimb areas, respectively. These results suggest that striatal disinhibition in the rat may be used to model motor tics such as observed in TS. Establishing this reliable and accessible animal model could facilitate the study of the neural mechanisms underlying motor tics, and the testing of potential therapies for tic disorders.

  8. Neuroinflammation alters voltage-dependent conductance in striatal astrocytes

    Science.gov (United States)

    Karpuk, Nikolay; Burkovetskaya, Maria

    2012-01-01

    Neuroinflammation has the capacity to alter normal central nervous system (CNS) homeostasis and function. The objective of the present study was to examine the effects of an inflammatory milieu on the electrophysiological properties of striatal astrocyte subpopulations with a mouse bacterial brain abscess model. Whole cell patch-clamp recordings were performed in striatal glial fibrillary acidic protein (GFAP)-green fluorescent protein (GFP)+ astrocytes neighboring abscesses at postinfection days 3 or 7 in adult mice. Cell input conductance (Gi) measurements spanning a membrane potential (Vm) surrounding resting membrane potential (RMP) revealed two prevalent astrocyte subsets. A1 and A2 astrocytes were identified by negative and positive Gi increments vs. Vm, respectively. A1 and A2 astrocytes displayed significantly different RMP, Gi, and cell membrane capacitance that were influenced by both time after bacterial exposure and astrocyte proximity to the inflammatory site. Specifically, the percentage of A1 astrocytes was decreased immediately surrounding the inflammatory lesion, whereas A2 cells were increased. These changes were particularly evident at postinfection day 7, revealing increased cell numbers with an outward current component. Furthermore, RMP was inversely modified in A1 and A2 astrocytes during neuroinflammation, and resting Gi was increased from 21 to 30 nS in the latter. In contrast, gap junction communication was significantly decreased in all astrocyte populations associated with inflamed tissues. Collectively, these findings demonstrate the heterogeneity of striatal astrocyte populations, which experience distinct electrophysiological modifications in response to CNS inflammation. PMID:22457466

  9. Memory and reward systems coproduce 'nostalgic' experiences in the brain.

    Science.gov (United States)

    Oba, Kentaro; Noriuchi, Madoka; Atomi, Tomoaki; Moriguchi, Yoshiya; Kikuchi, Yoshiaki

    2016-07-01

    People sometimes experience an emotional state known as 'nostalgia', which involves experiencing predominantly positive emotions while remembering autobiographical events. Nostalgia is thought to play an important role in psychological resilience. Previous neuroimaging studies have shown involvement of memory and reward systems in such experiences. However, it remains unclear how these two systems are collaboratively involved with nostalgia experiences. Here, we conducted a functional magnetic resonance imaging study of healthy females to investigate the relationship between memory-reward co-activation and nostalgia, using childhood-related visual stimuli. Moreover, we examined the factors constituting nostalgia and their neural correlates. We confirmed the presence of nostalgia-related activity in both memory and reward systems, including the hippocampus (HPC), substantia nigra/ventral tegmental area (SN/VTA), and ventral striatum (VS). We also found significant HPC-VS co-activation, with its strength correlating with individual 'nostalgia tendencies'. Factor analyses showed that two dimensions underlie nostalgia: emotional and personal significance and chronological remoteness, with the former correlating with caudal SN/VTA and left anterior HPC activity, and the latter correlating with rostral SN/VTA activity. These findings demonstrate the cooperative activity of memory and reward systems, where each system has a specific role in the construction of the factors that underlie the experience of nostalgia. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  10. Learning and Memory... and the Immune System

    Science.gov (United States)

    Marin, Ioana; Kipnis, Jonathan

    2013-01-01

    The nervous system and the immune system are two main regulators of homeostasis in the body. Communication between them ensures normal functioning of the organism. Immune cells and molecules are required for sculpting the circuitry and determining the activity of the nervous system. Within the parenchyma of the central nervous system (CNS),…

  11. Multiple-User, Multitasking, Virtual-Memory Computer System

    Science.gov (United States)

    Generazio, Edward R.; Roth, Don J.; Stang, David B.

    1993-01-01

    Computer system designed and programmed to serve multiple users in research laboratory. Provides for computer control and monitoring of laboratory instruments, acquisition and anlaysis of data from those instruments, and interaction with users via remote terminals. System provides fast access to shared central processing units and associated large (from megabytes to gigabytes) memories. Underlying concept of system also applicable to monitoring and control of industrial processes.

  12. Modeling Students' Memory for Application in Adaptive Educational Systems

    Science.gov (United States)

    Pelánek, Radek

    2015-01-01

    Human memory has been thoroughly studied and modeled in psychology, but mainly in laboratory setting under simplified conditions. For application in practical adaptive educational systems we need simple and robust models which can cope with aspects like varied prior knowledge or multiple-choice questions. We discuss and evaluate several models of…

  13. Portable wireless neurofeedback system of EEG alpha rhythm enhances memory.

    Science.gov (United States)

    Wei, Ting-Ying; Chang, Da-Wei; Liu, You-De; Liu, Chen-Wei; Young, Chung-Ping; Liang, Sheng-Fu; Shaw, Fu-Zen

    2017-11-13

    Effect of neurofeedback training (NFT) on enhancement of cognitive function or amelioration of clinical symptoms is inconclusive. The trainability of brain rhythm using a neurofeedback system is uncertainty because various experimental designs are used in previous studies. The current study aimed to develop a portable wireless NFT system for alpha rhythm and to validate effect of the NFT system on memory with a sham-controlled group. The proposed system contained an EEG signal analysis device and a smartphone with wireless Bluetooth low-energy technology. Instantaneous 1-s EEG power and contiguous 5-min EEG power throughout the training were developed as feedback information. The training performance and its progression were kept to boost usability of our device. Participants were blinded and randomly assigned into either the control group receiving random 4-Hz power or Alpha group receiving 8-12-Hz power. Working memory and episodic memory were assessed by the backward digital span task and word-pair task, respectively. The portable neurofeedback system had advantages of a tiny size and long-term recording and demonstrated trainability of alpha rhythm in terms of significant increase of power and duration of 8-12 Hz. Moreover, accuracies of the backward digital span task and word-pair task showed significant enhancement in the Alpha group after training compared to the control group. Our tiny portable device demonstrated success trainability of alpha rhythm and enhanced two kinds of memories. The present study suggest that the portable neurofeedback system provides an alternative intervention for memory enhancement.

  14. Striatal cholinergic interneuron regulation and circuit effects

    Directory of Open Access Journals (Sweden)

    Sean Austin Lim

    2014-10-01

    Full Text Available The striatum plays a central role in motor control and motor learning. Appropriate responses to environmental stimuli, including pursuit of reward or avoidance of aversive experience all require functional striatal circuits. These pathways integrate synaptic inputs from limbic and cortical regions including sensory, motor and motivational information to ultimately connect intention to action. Although many neurotransmitters participate in striatal circuitry, one critically important player is acetylcholine (ACh. Relative to other brain areas, the striatum contains exceptionally high levels of ACh, the enzymes that catalyze its synthesis and breakdown, as well as both nicotinic and muscarinic receptor types that mediate its postsynaptic effects. The principal source of striatal ACh is the cholinergic interneuron (ChI, which comprises only about 1-2% of all striatal cells yet sends dense arbors of projections throughout the striatum. This review summarizes recent advances in our understanding of the factors affecting the excitability of these neurons through acute effects and long term changes in their synaptic inputs. In addition, we discuss the physiological effects of ACh in the striatum, and how changes in ACh levels may contribute to disease states during striatal dysfunction.

  15. Huntington’s Disease and Striatal Signaling

    Science.gov (United States)

    Roze, Emmanuel; Cahill, Emma; Martin, Elodie; Bonnet, Cecilia; Vanhoutte, Peter; Betuing, Sandrine; Caboche, Jocelyne

    2011-01-01

    Huntington’s Disease (HD) is the most frequent neurodegenerative disease caused by an expansion of polyglutamines (CAG). The main clinical manifestations of HD are chorea, cognitive impairment, and psychiatric disorders. The transmission of HD is autosomal dominant with a complete penetrance. HD has a single genetic cause, a well-defined neuropathology, and informative pre-manifest genetic testing of the disease is available. Striatal atrophy begins as early as 15 years before disease onset and continues throughout the period of manifest illness. Therefore, patients could theoretically benefit from therapy at early stages of the disease. One important characteristic of HD is the striatal vulnerability to neurodegeneration, despite similar expression of the protein in other brain areas. Aggregation of the mutated Huntingtin (HTT), impaired axonal transport, excitotoxicity, transcriptional dysregulation as well as mitochondrial dysfunction, and energy deficits, are all part of the cellular events that underlie neuronal dysfunction and striatal death. Among these non-exclusive mechanisms, an alteration of striatal signaling is thought to orchestrate the downstream events involved in the cascade of striatal dysfunction. PMID:22007160

  16. Dopamine and the management of attentional resources: genetic markers of striatal D2 dopamine predict individual differences in the attentional blink.

    Science.gov (United States)

    Colzato, Lorenza S; Slagter, Heleen A; de Rover, Mischa; Hommel, Bernhard

    2011-11-01

    The attentional blink (AB)--a deficit in reporting the second of two target stimuli presented in close succession in a rapid sequence of distracters--has been related to processing limitations in working memory. Given that dopamine (DA) plays a crucial role working memory, the present study tested whether individual differences in the size of the AB can be predicted by differences in genetic predisposition related to the efficiency of dopaminergic pathways. Polymorphisms related to mesocortical and nigrostriatal dopaminergic pathways were considered, as well as polymorphisms related to norepinephrine (NE), a transmitter system that has also been suspected to play a role in the AB. In a sample of 157 healthy adults, we studied the dependency of the individual magnitude of the AB and the C957T polymorphism at the DRD2 gene (associated with striatal DA/D2 receptors), the DARPP32 polymorphism (associated with striatal DA/D1), the COMT Val(158)Met polymorphism (associated with frontal DA), DBH444 g/a and DBH5'-ins/del polymorphisms (polymorphisms strongly correlated with DA beta hydroxylase, the enzyme catalyzing the DA-NE conversion) and NET T-182C (a polymorphism related to the NE transporter). DRD2 C957T T/T homozygotes showed a significantly smaller AB, whereas polymorphisms associated with frontal DA and NE were unrelated to performance. This outcome pattern suggests a crucial role of the nigrostriatal dopaminergic pathway and of nigrostriatal D2 receptors, in particular, in the management of attentional resources.

  17. Lifetime-Based Memory Management for Distributed Data Processing Systems

    DEFF Research Database (Denmark)

    Lu, Lu; Shi, Xuanhua; Zhou, Yongluan

    2016-01-01

    create a large amount of long-living data objects in the heap, which may quickly saturate the garbage collector, especially when handling a large dataset, and hence would limit the scalability of the system. To eliminate this problem, we propose a lifetime-based memory management framework, which......, by automatically analyzing the user-defined functions and data types, obtains the expected lifetime of the data objects, and then allocates and releases memory space accordingly to minimize the garbage collection overhead. In particular, we present Deca, a concrete implementation of our proposal on top of Spark...... the garbage collection time by up to 99.9%, 2) to achieve up to 22.7x speed up in terms of execution time in cases without data spilling and 41.6x speedup in cases with data spilling, and 3) to consume up to 46.6% less memory....

  18. Contrasting single and multi-component working-memory systems in dual tasking

    NARCIS (Netherlands)

    Nijboer, Menno; Borst, Jelmer; van Rijn, Hedderik; Taatgen, Niels

    2016-01-01

    Working memory can be a major source of interference in dual tasking. However, there is no consensus on whether this interference is the result of a single working memory bottleneck, or of interactions between different working memory components that together form a complete working-memory system.

  19. Assessing and Changing Self-Concept: Guidelines from the Memory System.

    Science.gov (United States)

    Nurius, Paula S.

    1994-01-01

    Draws on architecture and operation of human memory to better specify self-concept form and functioning. Translates these major components and processes of memory system into practice implications for targets and methods of change: declarative knowledge versus procedural knowledge, storage memory versus working memory, and role of sensory…

  20. System and method for programmable bank selection for banked memory subsystems

    Energy Technology Data Exchange (ETDEWEB)

    Blumrich, Matthias A. (Ridgefield, CT); Chen, Dong (Croton on Hudson, NY); Gara, Alan G. (Mount Kisco, NY); Giampapa, Mark E. (Irvington, NY); Hoenicke, Dirk (Seebruck-Seeon, DE); Ohmacht, Martin (Yorktown Heights, NY); Salapura, Valentina (Chappaqua, NY); Sugavanam, Krishnan (Mahopac, NY)

    2010-09-07

    A programmable memory system and method for enabling one or more processor devices access to shared memory in a computing environment, the shared memory including one or more memory storage structures having addressable locations for storing data. The system comprises: one or more first logic devices associated with a respective one or more processor devices, each first logic device for receiving physical memory address signals and programmable for generating a respective memory storage structure select signal upon receipt of pre-determined address bit values at selected physical memory address bit locations; and, a second logic device responsive to each of the respective select signal for generating an address signal used for selecting a memory storage structure for processor access. The system thus enables each processor device of a computing environment memory storage access distributed across the one or more memory storage structures.

  1. Abstract Specification of the UBIFS File System for Flash Memory

    Science.gov (United States)

    Schierl, Andreas; Schellhorn, Gerhard; Haneberg, Dominik; Reif, Wolfgang

    Today we see an increasing demand for flash memory because it has certain advantages like resistance against kinetic shock. However, reliable data storage also requires a specialized file system knowing and handling the limitations of flash memory. This paper develops a formal, abstract model for the UBIFS flash file system, which has recently been included in the Linux kernel. We develop formal specifications for the core components of the file system: the inode-based file store, the flash index, its cached copy in the RAM and the journal to save the differences. Based on these data structures we give an abstract specification of the interface operations of UBIFS and prove some of the most important properties using the interactive verification system KIV.

  2. Optimizing NEURON Simulation Environment Using Remote Memory Access with Recursive Doubling on Distributed Memory Systems.

    Science.gov (United States)

    Shehzad, Danish; Bozkuş, Zeki

    2016-01-01

    Increase in complexity of neuronal network models escalated the efforts to make NEURON simulation environment efficient. The computational neuroscientists divided the equations into subnets amongst multiple processors for achieving better hardware performance. On parallel machines for neuronal networks, interprocessor spikes exchange consumes large section of overall simulation time. In NEURON for communication between processors Message Passing Interface (MPI) is used. MPI_Allgather collective is exercised for spikes exchange after each interval across distributed memory systems. The increase in number of processors though results in achieving concurrency and better performance but it inversely affects MPI_Allgather which increases communication time between processors. This necessitates improving communication methodology to decrease the spikes exchange time over distributed memory systems. This work has improved MPI_Allgather method using Remote Memory Access (RMA) by moving two-sided communication to one-sided communication, and use of recursive doubling mechanism facilitates achieving efficient communication between the processors in precise steps. This approach enhanced communication concurrency and has improved overall runtime making NEURON more efficient for simulation of large neuronal network models.

  3. Analyses of Markov decision process structure regarding the possible strategic use of interacting memory systems

    Directory of Open Access Journals (Sweden)

    Eric A Zilli

    2008-12-01

    Full Text Available Behavioral tasks are often used to study the different memory systems present in humans and animals. Such tasks are usually designed to isolate and measure some aspect of a single memory system. However, it is not necessarily clear that any given task actually does isolate a system or that the strategy used by a subject in the experiment is the one desired by the experimenter. We have previously shown that when tasks are written mathematically as a form of partially-observable Markov decision processes, the structure of the tasks provide information regarding the possible utility of certain memory systems. These previous analyses dealt with the disambiguation problem: given a specific ambiguous observation of the environment, is there information provided by a given memory strategy that can disambiguate that observation to allow a correct decisionµ Here we extend this approach to cases where multiple memory systems can be strategically combined in different ways. Specifically, we analyze the disambiguation arising from three ways by which episodic-like memory retrieval might be cued (by another episodic-like memory, by a semantic association, or by working memory for some earlier observation. We also consider the disambiguation arising from holding earlier working memories, episodic-like memories or semantic associations in working memory. From these analyses we can begin to develop a quantitative hierarchy among memory systems in which stimulus-response memories and semantic associations provide no disambiguation while the episodic memory system provides the most flexible

  4. Memory

    OpenAIRE

    Wager, Nadia

    2017-01-01

    This chapter will explore a response to traumatic victimisation which has divided the opinions of psychologists at an exponential rate. We will be examining amnesia for memories of childhood sexual abuse and the potential to recover these memories in adulthood. Whilst this phenomenon is generally accepted in clinical circles, it is seen as highly contentious amongst research psychologists, particularly experimental cognitive psychologists. The chapter will begin with a real case study of a wo...

  5. Shared visual attention and memory systems in the Drosophila brain.

    Directory of Open Access Journals (Sweden)

    Bruno van Swinderen

    Full Text Available BACKGROUND: Selective attention and memory seem to be related in human experience. This appears to be the case as well in simple model organisms such as the fly Drosophila melanogaster. Mutations affecting olfactory and visual memory formation in Drosophila, such as in dunce and rutabaga, also affect short-term visual processes relevant to selective attention. In particular, increased optomotor responsiveness appears to be predictive of visual attention defects in these mutants. METHODOLOGY/PRINCIPAL FINDINGS: To further explore the possible overlap between memory and visual attention systems in the fly brain, we screened a panel of 36 olfactory long term memory (LTM mutants for visual attention-like defects using an optomotor maze paradigm. Three of these mutants yielded high dunce-like optomotor responsiveness. We characterized these three strains by examining their visual distraction in the maze, their visual learning capabilities, and their brain activity responses to visual novelty. We found that one of these mutants, D0067, was almost completely identical to dunce(1 for all measures, while another, D0264, was more like wild type. Exploiting the fact that the LTM mutants are also Gal4 enhancer traps, we explored the sufficiency for the cells subserved by these elements to rescue dunce attention defects and found overlap at the level of the mushroom bodies. Finally, we demonstrate that control of synaptic function in these Gal4 expressing cells specifically modulates a 20-30 Hz local field potential associated with attention-like effects in the fly brain. CONCLUSIONS/SIGNIFICANCE: Our study uncovers genetic and neuroanatomical systems in the fly brain affecting both visual attention and odor memory phenotypes. A common component to these systems appears to be the mushroom bodies, brain structures which have been traditionally associated with odor learning but which we propose might be also involved in generating oscillatory brain activity

  6. The endocannabinoid system and associative learning and memory in zebrafish.

    Science.gov (United States)

    Ruhl, Tim; Moesbauer, Kirstin; Oellers, Nadine; von der Emde, Gerhard

    2015-09-01

    In zebrafish the medial pallium of the dorsal telencephalon represents an amygdala homolog structure, which is crucially involved in emotional associative learning and memory. Similar to the mammalian amygdala, the medial pallium contains a high density of endocannabinoid receptor CB1. To elucidate the role of the zebrafish endocannabinoid system in associative learning, we tested the influence of acute and chronic administration of receptor agonists (THC, WIN55,212-2) and antagonists (Rimonabant, AM-281) on two different learning paradigms. In an appetitively motivated two-alternative choice paradigm, animals learned to associate a certain color with a food reward. In a second set-up, a fish shuttle-box, animals associated the onset of a light stimulus with the occurrence of a subsequent electric shock (avoidance conditioning). Once fish successfully had learned to solve these behavioral tasks, acute receptor activation or inactivation had no effect on memory retrieval, suggesting that established associative memories were stable and not alterable by the endocannabinoid system. In both learning tasks, chronic treatment with receptor antagonists improved acquisition learning, and additionally facilitated reversal learning during color discrimination. In contrast, chronic CB1 activation prevented aversively motivated acquisition learning, while different effects were found on appetitively motivated acquisition learning. While THC significantly improved behavioral performance, WIN55,212-2 significantly impaired color association. Our findings suggest that the zebrafish endocannabinoid system can modulate associative learning and memory. Stimulation of the CB1 receptor might play a more specific role in acquisition and storage of aversive learning and memory, while CB1 blocking induces general enhancement of cognitive functions. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Resummed memory kernels in generalized system-bath master equations

    Science.gov (United States)

    Mavros, Michael G.; Van Voorhis, Troy

    2014-08-01

    Generalized master equations provide a concise formalism for studying reduced population dynamics. Usually, these master equations require a perturbative expansion of the memory kernels governing the dynamics; in order to prevent divergences, these expansions must be resummed. Resummation techniques of perturbation series are ubiquitous in physics, but they have not been readily studied for the time-dependent memory kernels used in generalized master equations. In this paper, we present a comparison of different resummation techniques for such memory kernels up to fourth order. We study specifically the spin-boson Hamiltonian as a model system bath Hamiltonian, treating the diabatic coupling between the two states as a perturbation. A novel derivation of the fourth-order memory kernel for the spin-boson problem is presented; then, the second- and fourth-order kernels are evaluated numerically for a variety of spin-boson parameter regimes. We find that resumming the kernels through fourth order using a Padé approximant results in divergent populations in the strong electronic coupling regime due to a singularity introduced by the nature of the resummation, and thus recommend a non-divergent exponential resummation (the "Landau-Zener resummation" of previous work). The inclusion of fourth-order effects in a Landau-Zener-resummed kernel is shown to improve both the dephasing rate and the obedience of detailed balance over simpler prescriptions like the non-interacting blip approximation, showing a relatively quick convergence on the exact answer. The results suggest that including higher-order contributions to the memory kernel of a generalized master equation and performing an appropriate resummation can provide a numerically-exact solution to system-bath dynamics for a general spectral density, opening the way to a new class of methods for treating system-bath dynamics.

  8. A Gamma Memory Neural Network for System Identification

    Science.gov (United States)

    Motter, Mark A.; Principe, Jose C.

    1992-01-01

    A gamma neural network topology is investigated for a system identification application. A discrete gamma memory structure is used in the input layer, providing delayed values of both the control inputs and the network output to the input layer. The discrete gamma memory structure implements a tapped dispersive delay line, with the amount of dispersion regulated by a single, adaptable parameter. The network is trained using static back propagation, but captures significant features of the system dynamics. The system dynamics identified with the network are the Mach number dynamics of the 16 Foot Transonic Tunnel at NASA Langley Research Center, Hampton, Virginia. The training data spans an operating range of Mach numbers from 0.4 to 1.3.

  9. Neuromorphic cognitive systems a learning and memory centered approach

    CERN Document Server

    Yu, Qiang; Hu, Jun; Tan Chen, Kay

    2017-01-01

    This book presents neuromorphic cognitive systems from a learning and memory-centered perspective. It illustrates how to build a system network of neurons to perform spike-based information processing, computing, and high-level cognitive tasks. It is beneficial to a wide spectrum of readers, including undergraduate and postgraduate students and researchers who are interested in neuromorphic computing and neuromorphic engineering, as well as engineers and professionals in industry who are involved in the design and applications of neuromorphic cognitive systems, neuromorphic sensors and processors, and cognitive robotics. The book formulates a systematic framework, from the basic mathematical and computational methods in spike-based neural encoding, learning in both single and multi-layered networks, to a near cognitive level composed of memory and cognition. Since the mechanisms for integrating spiking neurons integrate to formulate cognitive functions as in the brain are little understood, studies of neuromo...

  10. Konsep Memory Systems dalam Iklan ‘Diskon Ramadhan’

    Directory of Open Access Journals (Sweden)

    Elsye Rumondang Damanik

    2011-10-01

    Full Text Available The purpose of the article is to discuss and reminiscence the concept of memory systems and its purpose of marketing activity. Information-processed activity related to marketing activity made this concept is important to be discussed. To limit the problem discussion scope, the article will only discuss about human role as consumer in marketing activity and also the effects of memory system in helping human being to precede information related to marketing. In presenting the article, the writer had gathered data dan information through literature study from books and information from mass media. The result is that is it important for marketers to understand information-processed stages by their consumers and how the seller optimize or perhaps manipulate the stages to win the market. 

  11. Ageing and memory effects in a mechanically alloyed nanoparticle system

    International Nuclear Information System (INIS)

    Osth, Michael; Herisson, Didier; Nordblad, Per; De Toro, Jose A.; Riveiro, Jose M.

    2007-01-01

    Ageing and memory experiments have been performed to explore the non-equilibrium dynamics of the mechanically alloyed nanoparticle system Fe 30 Ag 40 W 30 , which comprises a heterogeneous ensemble of magnetic particles with average moment ∼ 10 2 μ B dispersed in a metallic non-magnetic matrix. This system has earlier, from critical slowing down analysis, been reported to enter a spin glass like state at low temperatures [J. A. de Toro et al., Phys. Rev. B 69, (2004) 224407]. The wait time dependence of the magnetic relaxation observed after the application of a weak magnetic field and the memory of the thermal history in the low temperature phase recorded on continuous heating in a weak applied field show similar features as observed in corresponding experiments on canonical spin glasses

  12. Novel tribological systems using shape memory alloys and thin films

    Science.gov (United States)

    Zhang, Yijun

    Shape memory alloys and thin films are shown to have robust indentation-induced shape memory and superelastic effects. Loading conditions that are similar to indentations are very common in tribological systems. Therefore novel tribological systems that have better wear resistance and stronger coating to substrate adhesion can be engineered using indentation-induced shape memory and superelastic effects. By incorporating superelastic NiTi thin films as interlayers between chromium nitride (CrN) and diamond-like carbon (DLC) hard coatings and aluminum substrates, it is shown that the superelasticity can improve tribological performance and increase interfacial adhesion. The NiTi interlayers were sputter deposited onto 6061 T6 aluminum and M2 steel substrates. CrN and DLC coatings were deposited by unbalanced magnetron sputter deposition. Temperature scanning X-ray diffraction and nanoindentation were used to characterize NiTi interlayers. Temperature scanning wear and scratch tests showed that superelastic NiTi interlayers improved tribological performance on aluminum substrates significantly. The two-way shape memory effect under contact loading conditions is demonstrated for the first time, which could be used to make novel tribological systems. Spherical indents in NiTi shape memory alloys and thin films had reversible depth changes that were driven by temperature cycling, after thermomechanical cycling, or one-cycle slip-plasticity deformation training. Reversible surface topography was realized after the indents were planarized. Micro- and nano- scale circular surface protrusions arose from planarized spherical indents in bulk and thin film NiTi alloy; line surface protrusions appeared from planarized scratch tracks. Functional surfaces with reversible surface topography can potentially result in novel tribological systems with reversible friction coefficient. A three dimensional constitutive model was developed to describe shape memory effects with slip

  13. Dissipation Assisted Quantum Memory with Coupled Spin Systems

    Science.gov (United States)

    Jiang, Liang; Verstraete, Frank; Cirac, Ignacio; Lukin, Mikhail

    2009-05-01

    Dissipative dynamics often destroys quantum coherences. However, one can use dissipation to suppress decoherence. A well-known example is the so-called quantum Zeno effect, in which one can freeze the evolution using dissipative processes (e.g., frequently projecting the system to its initial state). Similarly, the undesired decoherence of quantum bits can also be suppressed using controlled dissipation. We propose and analyze the use of this generalization of quantum Zeno effect for protecting the quantum information encoded in the coupled spin systems. This new approach may potentially enhance the performance of quantum memories, in systems such as nitrogen-vacancy color-centers in diamond.

  14. Effect of yogic education system and modern education system on memory

    Directory of Open Access Journals (Sweden)

    Rangan R

    2009-01-01

    Full Text Available Background/Aim: Memory is more associated with the temporal cortex than other cortical areas. The two main components of memory are spatial and verbal which relate to right and left hemispheres of the brain, respectively. Many investigations have shown the beneficial effects of yoga on memory and temporal functions of the brain. This study was aimed at comparing the effect of one Gurukula Education System (GES school based on a yoga way of life with a school using the Modern Education System (MES on memory. Materials and Methods: Forty nine boys of ages ranging from 11-13 years were selected from each of two residential schools, one MES and the other GES, providing similar ambiance and daily routines. The boys were matched for age and socioeconomic status. The GES educational program is based around integrated yoga modules while the MES provides a conventional modern education program. Memory was assessed by means of standard spatial and verbal memory tests applicable to Indian conditions before and after an academic year. Results: Between groups there was matching at start of the academic year, while after it the GES boys showed significant enhancement in both verbal and visual memory scores than MES boys (P < 0.001, Mann-Whitney test. Conclusions: The present study showed that the GES meant for total personality development adopting yoga way of life is more effective in enhancing visual and verbal memory scores than the MES.

  15. Effect of yogic education system and modern education system on memory.

    Science.gov (United States)

    Rangan, R; Nagendra, Hr; Bhat, G Ramachandra

    2009-07-01

    Memory is more associated with the temporal cortex than other cortical areas. The two main components of memory are spatial and verbal which relate to right and left hemispheres of the brain, respectively. Many investigations have shown the beneficial effects of yoga on memory and temporal functions of the brain. This study was aimed at comparing the effect of one Gurukula Education System (GES) school based on a yoga way of life with a school using the Modern Education System (MES) on memory. Forty nine boys of ages ranging from 11-13 years were selected from each of two residential schools, one MES and the other GES, providing similar ambiance and daily routines. The boys were matched for age and socioeconomic status. The GES educational program is based around integrated yoga modules while the MES provides a conventional modern education program. Memory was assessed by means of standard spatial and verbal memory tests applicable to Indian conditions before and after an academic year. Between groups there was matching at start of the academic year, while after it the GES boys showed significant enhancement in both verbal and visual memory scores than MES boys (P < 0.001, Mann-Whitney test). The present study showed that the GES meant for total personality development adopting yoga way of life is more effective in enhancing visual and verbal memory scores than the MES.

  16. Exposure to an enriched environment facilitates motor recovery and prevents short-term memory impairment and reduction of striatal BDNF in a progressive pharmacological model of parkinsonism in mice.

    Science.gov (United States)

    Campêlo, Clarissa L C; Santos, José R; Silva, Anatildes F; Dierschnabel, Aline L; Pontes, André; Cavalcante, Jeferson S; Ribeiro, Alessandra M; Silva, Regina H

    2017-06-15

    Previous studies showed that the repeated administration with a low dose of reserpine (RES) induces a gradual appearance of motor signs and cognitive deficits compatible with parkinsonism in rodents. Environmental stimulation has neuroprotective effects in animal models of neurodegenerative damage, including acutely induced parkinsonism. We investigated the effects of exposure to an enriched environment (EE) on motor, cognitive and neuronal (levels of tyrosine hydroxylase, TH and brain derived neurotrophic factor, BDNF) deficits induced by a progressive model of Parkinson's disease (PD) in mice. Male mice were repeatedly treated with vehicle or 0.1mg/kg of RES (s.c) and kept under two housing conditions: standard environment (SE) and EE. In animals kept in SE, the treatment with RES induced deficits in motor function (catalepsy test, open field and oral movements), in novel object recognition (NOR) and plus-maze discriminative avoidance tasks. The environmental stimulation facilitated the recovery of motor deficits assessed by the catalepsy test after the end of treatment. Additionally, exposure to EE prevented the memory deficit in the NOR task. Treatment with RES induced a reduction in the number of TH positive cells in SNpc and VTA, which recovered 30days after the end of treatment. Finally, RES reduced the levels of BDNF in the striatum and the exposure to the EE prevented this effect. These results suggest that plastic brain changes induced by EE promote beneficial effects on the progression of neuronal impairment related to PD. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Memories.

    Science.gov (United States)

    Brand, Judith, Ed.

    1998-01-01

    This theme issue of the journal "Exploring" covers the topic of "memories" and describes an exhibition at San Francisco's Exploratorium that ran from May 22, 1998 through January 1999 and that contained over 40 hands-on exhibits, demonstrations, artworks, images, sounds, smells, and tastes that demonstrated and depicted the biological,…

  18. On the Performance of Three In-Memory Data Systems for On Line Analytical Processing

    Directory of Open Access Journals (Sweden)

    Ionut HRUBARU

    2017-01-01

    Full Text Available In-memory database systems are among the most recent and most promising Big Data technologies, being developed and released either as brand new distributed systems or as extensions of old monolith (centralized database systems. As name suggests, in-memory systems cache all the data into special memory structures. Many are part of the NewSQL strand and target to bridge the gap between OLTP and OLAP into so-called Hybrid Transactional Analytical Systems (HTAP. This paper aims to test the performance of using such type of systems for TPCH analytical workloads. Performance is analyzed in terms of data loading, memory footprint and execution time of the TPCH query set for three in-memory data systems: Oracle, SQL Server and MemSQL. Tests are subsequently deployed on classical on-disk architectures and results compared to in-memory solutions. As in-memory is an enterprise edition feature, associated costs are also considered.

  19. Reduced striatal dopamine D2/3 receptor availability in Body Dysmorphic Disorder

    NARCIS (Netherlands)

    Vulink, Nienke C; Planting, Robin S; Figee, Martijn; Booij, Jan; Denys, D.

    Though the dopaminergic system is implicated in Obsessive Compulsive and Related Disorders (OCRD), the dopaminergic system has never been investigated in-vivo in Body Dysmorphic Disorder (BDD). In line with consistent findings of reduced striatal dopamine D2/3 receptor availability in Obsessive

  20. Reduced striatal dopamine D2/3 receptor availability in Body Dysmorphic Disorder

    NARCIS (Netherlands)

    Vulink, Nienke C.; Planting, Robin S.; Figee, Martijn; Booij, Jan; Denys, Damiaan

    2016-01-01

    Though the dopaminergic system is implicated in Obsessive Compulsive and Related Disorders (OCRD), the dopaminergic system has never been investigated in-vivo in Body Dysmorphic Disorder (BDD). In line with consistent findings of reduced striatal dopamine D2/3 receptor availability in Obsessive

  1. Reward-related learning via multiple memory systems.

    Science.gov (United States)

    Delgado, Mauricio R; Dickerson, Kathryn C

    2012-07-15

    The application of a neuroeconomic approach to the study of reward-related processes has provided significant insights in our understanding of human learning and decision making. Much of this research has focused primarily on the contributions of the corticostriatal circuitry, involved in trial-and-error reward learning. As a result, less consideration has been allotted to the potential influence of different neural mechanisms such as the hippocampus or to more common ways in human society in which information is acquired and utilized to reach a decision, such as through explicit instruction rather than trial-and-error learning. This review examines the individual contributions of multiple learning and memory neural systems and their interactions during human decision making in both normal and neuropsychiatric populations. Specifically, the anatomical and functional connectivity across multiple memory systems are highlighted to suggest that probing the role of the hippocampus and its interactions with the corticostriatal circuitry via the application of model-based neuroeconomic approaches may provide novel insights into neuropsychiatric populations that suffer from damage to one of these structures and as a consequence have deficits in learning, memory, or decision making. Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  2. The endocannabinoid system in anxiety, fear memory and habituation

    Science.gov (United States)

    Ruehle, S; Rey, A Aparisi; Remmers, F

    2012-01-01

    Evidence for the involvement of the endocannabinoid system (ECS) in anxiety and fear has been accumulated, providing leads for novel therapeutic approaches. In anxiety, a bidirectional influence of the ECS has been reported, whereby anxiolytic and anxiogenic responses have been obtained after both increases and decreases of the endocannabinoid tone. The recently developed genetic tools have revealed different but complementary roles for the cannabinoid type 1 (CB1) receptor on GABAergic and glutamatergic neuronal populations. This dual functionality, together with the plasticity of CB1 receptor expression, particularly on GABAergic neurons, as induced by stressful and rewarding experiences, gives the ECS a unique regulatory capacity for maintaining emotional homeostasis. However, the promiscuity of the endogenous ligands of the CB1 receptor complicates the interpretation of experimental data concerning ECS and anxiety. In fear memory paradigms, the ECS is mostly involved in the two opposing processes of reconsolidation and extinction of the fear memory. Whereas ECS activation deteriorates reconsolidation, proper extinction depends on intact CB1 receptor signalling. Thus, both for anxiety and fear memory processing, endocannabinoid signalling may ensure an appropriate reaction to stressful events. Therefore, the ECS can be considered as a regulatory buffer system for emotional responses. PMID:21768162

  3. Imaging of striatal dopamine transporters in rat brain with single pinhole SPECT and co-aligned MRI is highly reproducible

    International Nuclear Information System (INIS)

    Booij, Jan; Bruin, Kora de; Win, Maartje M.L. de; Lavini, Cristina Mphil; Heeten, Gerard J. den; Habraken, Jan

    2003-01-01

    A recently developed pinhole high-resolution SPECT system was used to measure striatal to non-specific binding ratios in rats (n = 9), after injection of the dopamine transporter ligand 123 I-FP-CIT, and to assess its test/retest reproducibility. For co-alignment purposes, the rat brain was imaged on a 1.5 Tesla clinical MRI scanner using a specially developed surface coil. The SPECT images showed clear striatal uptake. On the MR images, cerebral and extra-cerebral structures could be easily delineated. The mean striatal to non-specific [ 123 I]FP-CIT binding ratios of the test/retest studies were 1.7 ± 0.2 and 1.6 ± 0.2, respectively. The test/retest variability was approximately 9%. We conclude that the assessment of striatal [ 123 I]FP-CIT binding ratios in rats is highly reproducible

  4. Linear filtering of systems with memory and application to finance

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available We study the linear filtering problem for systems driven by continuous Gaussian processes V ( 1 and V ( 2 with memory described by two parameters. The processes V ( j have the virtue that they possess stationary increments and simple semimartingale representations simultaneously. They allow for straightforward parameter estimations. After giving the semimartingale representations of V ( j by innovation theory, we derive Kalman-Bucy-type filtering equations for the systems. We apply the result to the optimal portfolio problem for an investor with partial observations. We illustrate the tractability of the filtering algorithm by numerical implementations.

  5. Proteostasis in striatal cells and selective neurodegeneration in Huntington’s disease

    Science.gov (United States)

    Margulis, Julia; Finkbeiner, Steven

    2014-01-01

    Selective neuronal loss is a hallmark of neurodegenerative diseases, including Huntington’s disease (HD). Although mutant huntingtin, the protein responsible for HD, is expressed ubiquitously, a subpopulation of neurons in the striatum is the first to succumb. In this review, we examine evidence that protein quality control pathways, including the ubiquitin proteasome system, autophagy, and chaperones, are significantly altered in striatal neurons. These alterations may increase the susceptibility of striatal neurons to mutant huntingtin-mediated toxicity. This novel view of HD pathogenesis has profound therapeutic implications: protein homeostasis pathways in the striatum may be valuable targets for treating HD and other misfolded protein disorders. PMID:25147502

  6. Dysregulation of Striatal Dopamine Receptor Binding in Suicide.

    Science.gov (United States)

    Fitzgerald, Megan L; Kassir, Suham A; Underwood, Mark D; Bakalian, Mihran J; Mann, J John; Arango, Victoria

    2017-03-01

    Inconsistent evidence implicates disruptions of striatal dopaminergic indices in suicide and major depression. To determine whether there are alterations in the striatal dopamine system in suicide, we conducted a quantitative autoradiographic survey of dopamine transporter (DAT; [ 3 H]mazindol), D1 receptor ([ 3 H]SCH23390), and D2 receptor ([ 3 H]sulpiride) binding in the dorsal striatum postmortem from matched suicides and controls. Axis I and axis II psychiatric diagnosis, recent treatment history, and early life adversity (ELA) were determined by psychological autopsy. Mean DAT, D2, and D1 receptor binding did not differ in suicide. However, there was a positive correlation between D1 and D2 receptor binding in the dorsal striatum of control subjects (R 2 =0.31, p<0.05) that was not present in suicides (R 2 =0.00, p=0.97). In suicides and controls with reported ELA, there was no correlation between striatal DAT and D1 receptor binding (R 2 =0.07, p=0.33), although DAT and D1 receptor binding was positively correlated in subjects with no report of ELA (R 2 =0.32, p<0.05). After controlling for age, there were no significant ELA-related mean differences. Binding of D1 receptors and DAT throughout the striatum correlated negatively with age (D1 receptor: R 2 =0.12, p<0.05; DAT: R 2 =0.36, p<0.001). There appears to be an imbalance in dopaminergic receptor and transporter expression related to suicide that differs from that associated with ELA or age.

  7. Neuroinflammation alters voltage-dependent conductance in striatal astrocytes.

    Science.gov (United States)

    Karpuk, Nikolay; Burkovetskaya, Maria; Kielian, Tammy

    2012-07-01

    Neuroinflammation has the capacity to alter normal central nervous system (CNS) homeostasis and function. The objective of the present study was to examine the effects of an inflammatory milieu on the electrophysiological properties of striatal astrocyte subpopulations with a mouse bacterial brain abscess model. Whole cell patch-clamp recordings were performed in striatal glial fibrillary acidic protein (GFAP)-green fluorescent protein (GFP)(+) astrocytes neighboring abscesses at postinfection days 3 or 7 in adult mice. Cell input conductance (G(i)) measurements spanning a membrane potential (V(m)) surrounding resting membrane potential (RMP) revealed two prevalent astrocyte subsets. A1 and A2 astrocytes were identified by negative and positive G(i) increments vs. V(m), respectively. A1 and A2 astrocytes displayed significantly different RMP, G(i), and cell membrane capacitance that were influenced by both time after bacterial exposure and astrocyte proximity to the inflammatory site. Specifically, the percentage of A1 astrocytes was decreased immediately surrounding the inflammatory lesion, whereas A2 cells were increased. These changes were particularly evident at postinfection day 7, revealing increased cell numbers with an outward current component. Furthermore, RMP was inversely modified in A1 and A2 astrocytes during neuroinflammation, and resting G(i) was increased from 21 to 30 nS in the latter. In contrast, gap junction communication was significantly decreased in all astrocyte populations associated with inflamed tissues. Collectively, these findings demonstrate the heterogeneity of striatal astrocyte populations, which experience distinct electrophysiological modifications in response to CNS inflammation.

  8. Non-volatile main memory management methods based on a file system.

    Science.gov (United States)

    Oikawa, Shuichi

    2014-01-01

    There are upcoming non-volatile (NV) memory technologies that provide byte addressability and high performance. PCM, MRAM, and STT-RAM are such examples. Such NV memory can be used as storage because of its data persistency without power supply while it can be used as main memory because of its high performance that matches up with DRAM. There are a number of researches that investigated its uses for main memory and storage. They were, however, conducted independently. This paper presents the methods that enables the integration of the main memory and file system management for NV memory. Such integration makes NV memory simultaneously utilized as both main memory and storage. The presented methods use a file system as their basis for the NV memory management. We implemented the proposed methods in the Linux kernel, and performed the evaluation on the QEMU system emulator. The evaluation results show that 1) the proposed methods can perform comparably to the existing DRAM memory allocator and significantly better than the page swapping, 2) their performance is affected by the internal data structures of a file system, and 3) the data structures appropriate for traditional hard disk drives do not always work effectively for byte addressable NV memory. We also performed the evaluation of the effects caused by the longer access latency of NV memory by cycle-accurate full-system simulation. The results show that the effect on page allocation cost is limited if the increase of latency is moderate.

  9. Thermodynamic framework for information in nanoscale systems with memory.

    Science.gov (United States)

    Arias-Gonzalez, J Ricardo

    2017-11-28

    Information is represented by linear strings of symbols with memory that carry errors as a result of their stochastic nature. Proofreading and edition are assumed to improve certainty although such processes may not be effective. Here, we develop a thermodynamic theory for material chains made up of nanoscopic subunits with symbolic meaning in the presence of memory. This framework is based on the characterization of single sequences of symbols constructed under a protocol and is used to derive the behavior of ensembles of sequences similarly constructed. We then analyze the role of proofreading and edition in the presence of memory finding conditions to make revision an effective process, namely, to decrease the entropy of the chain. Finally, we apply our formalism to DNA replication and RNA transcription finding that Watson and Crick hybridization energies with which nucleotides are branched to the template strand during the copying process are optimal to regulate the fidelity in proofreading. These results are important in applications of information theory to a variety of solid-state physical systems and other biomolecular processes.

  10. Parallel Breadth-First Search on Distributed Memory Systems

    Energy Technology Data Exchange (ETDEWEB)

    Computational Research Division; Buluc, Aydin; Madduri, Kamesh

    2011-04-15

    Data-intensive, graph-based computations are pervasive in several scientific applications, and are known to to be quite challenging to implement on distributed memory systems. In this work, we explore the design space of parallel algorithms for Breadth-First Search (BFS), a key subroutine in several graph algorithms. We present two highly-tuned par- allel approaches for BFS on large parallel systems: a level-synchronous strategy that relies on a simple vertex-based partitioning of the graph, and a two-dimensional sparse matrix- partitioning-based approach that mitigates parallel commu- nication overhead. For both approaches, we also present hybrid versions with intra-node multithreading. Our novel hybrid two-dimensional algorithm reduces communication times by up to a factor of 3.5, relative to a common vertex based approach. Our experimental study identifies execu- tion regimes in which these approaches will be competitive, and we demonstrate extremely high performance on lead- ing distributed-memory parallel systems. For instance, for a 40,000-core parallel execution on Hopper, an AMD Magny- Cours based system, we achieve a BFS performance rate of 17.8 billion edge visits per second on an undirected graph of 4.3 billion vertices and 68.7 billion edges with skewed degree distribution.

  11. Program partitioning for NUMA multiprocessor computer systems. [Nonuniform memory access

    Energy Technology Data Exchange (ETDEWEB)

    Wolski, R.M.; Feo, J.T. (Lawrence Livermore National Lab., CA (United States))

    1993-11-01

    Program partitioning and scheduling are essential steps in programming non-shared-memory computer systems. Partitioning is the separation of program operations into sequential tasks, and scheduling is the assignment of tasks to processors. To be effective, automatic methods require an accurate representation of the model of computation and the target architecture. Current partitioning methods assume today's most prevalent models -- macro dataflow and a homogeneous/two-level multicomputer system. Based on communication channels, neither model represents well the emerging class of NUMA multiprocessor computer systems consisting of hierarchical read/write memories. Consequently, the partitions generated by extant methods do not execute well on these systems. In this paper, the authors extend the conventional graph representation of the macro-dataflow model to enable mapping heuristics to consider the complex communication options supported by NUMA architectures. They describe two such heuristics. Simulated execution times of program graphs show that the model and heuristics generate higher quality program mappings than current methods for NUMA architectures.

  12. From Augustine of Hippo's Memory Systems to Our Modern Taxonomy in Cognitive Psychology and Neuroscience of Memory: A 16-Century Nap of Intuition before Light of Evidence.

    Science.gov (United States)

    Cassel, Jean-Christophe; Cassel, Daniel; Manning, Lilianne

    2013-03-01

    Over the last half century, neuropsychologists, cognitive psychologists and cognitive neuroscientists interested in human memory have accumulated evidence showing that there is not one general memory function but a variety of memory systems deserving distinct (but for an organism, complementary) functional entities. The first attempts to organize memory systems within a taxonomic construct are often traced back to the French philosopher Maine de Biran (1766-1824), who, in his book first published in 1803, distinguished mechanical memory, sensitive memory and representative memory, without, however, providing any experimental evidence in support of his view. It turns out, however, that what might be regarded as the first elaborated taxonomic proposal is 14 centuries older and is due to Augustine of Hippo (354-430), also named St Augustine, who, in Book 10 of his Confessions, by means of an introspective process that did not aim at organizing memory systems, nevertheless distinguished and commented on sensible memory, intellectual memory, memory of memories, memory of feelings and passion, and memory of forgetting. These memories were envisaged as different and complementary instances. In the current study, after a short biographical synopsis of St Augustine, we provide an outline of the philosopher's contribution, both in terms of questions and answers, and focus on how this contribution almost perfectly fits with several viewpoints of modern psychology and neuroscience of memory about human memory functions, including the notion that episodic autobiographical memory stores events of our personal history in their what, where and when dimensions, and from there enables our mental time travel. It is not at all meant that St Augustine's elaboration was the basis for the modern taxonomy, but just that the similarity is striking, and that the architecture of our current viewpoints about memory systems might have preexisted as an outstanding intuition in the philosopher

  13. Inhibition of the striatal specific phosphodiesterase PDE10A ameliorates striatal and cortical pathology in R6/2 mouse model of Huntington's disease.

    Directory of Open Access Journals (Sweden)

    Carmela Giampà

    2010-10-01

    Full Text Available Huntington's disease is a devastating neurodegenerative condition for which there is no therapy to slow disease progression. The particular vulnerability of striatal medium spiny neurons to Huntington's pathology is hypothesized to result from transcriptional dysregulation within the cAMP and CREB signaling cascades in these neurons. To test this hypothesis, and a potential therapeutic approach, we investigated whether inhibition of the striatal-specific cyclic nucleotide phosphodiesterase PDE10A would alleviate neurological deficits and brain pathology in a highly utilized model system, the R6/2 mouse.R6/2 mice were treated with the highly selective PDE10A inhibitor TP-10 from 4 weeks of age until euthanasia. TP-10 treatment significantly reduced and delayed the development of the hind paw clasping response during tail suspension, deficits in rotarod performance, and decrease in locomotor activity in an open field. Treatment prolonged time to loss of righting reflex. These effects of PDE10A inhibition on neurological function were reflected in a significant amelioration in brain pathology, including reduction in striatal and cortical cell loss, the formation of striatal neuronal intranuclear inclusions, and the degree of microglial activation that occurs in response to the mutant huntingtin-induced brain damage. Striatal and cortical levels of phosphorylated CREB and BDNF were significantly elevated.Our findings provide experimental support for targeting the cAMP and CREB signaling pathways and more broadly transcriptional dysregulation as a therapeutic approach to Huntington's disease. It is noteworthy that PDE10A inhibition in the R6/2 mice reduces striatal pathology, consistent with the localization of the enzyme in medium spiny neurons, and also cortical pathology and the formation of neuronal nuclear inclusions. These latter findings suggest that striatal pathology may be a primary driver of these secondary pathological events. More

  14. Memory intensive functional architecture for distributed computer control systems

    International Nuclear Information System (INIS)

    Dimmler, D.G.

    1983-10-01

    A memory-intensive functional architectue for distributed data-acquisition, monitoring, and control systems with large numbers of nodes has been conceptually developed and applied in several large-scale and some smaller systems. This discussion concentrates on: (1) the basic architecture; (2) recent expansions of the architecture which now become feasible in view of the rapidly developing component technologies in microprocessors and functional large-scale integration circuits; and (3) implementation of some key hardware and software structures and one system implementation which is a system for performing control and data acquisition of a neutron spectrometer at the Brookhaven High Flux Beam Reactor. The spectrometer is equipped with a large-area position-sensitive neutron detector

  15. FPGA-based prototype storage system with phase change memory

    Science.gov (United States)

    Li, Gezi; Chen, Xiaogang; Chen, Bomy; Li, Shunfen; Zhou, Mi; Han, Wenbing; Song, Zhitang

    2016-10-01

    With the ever-increasing amount of data being stored via social media, mobile telephony base stations, and network devices etc. the database systems face severe bandwidth bottlenecks when moving vast amounts of data from storage to the processing nodes. At the same time, Storage Class Memory (SCM) technologies such as Phase Change Memory (PCM) with unique features like fast read access, high density, non-volatility, byte-addressability, positive response to increasing temperature, superior scalability, and zero standby leakage have changed the landscape of modern computing and storage systems. In such a scenario, we present a storage system called FLEET which can off-load partial or whole SQL queries to the storage engine from CPU. FLEET uses an FPGA rather than conventional CPUs to implement the off-load engine due to its highly parallel nature. We have implemented an initial prototype of FLEET with PCM-based storage. The results demonstrate that significant performance and CPU utilization gains can be achieved by pushing selected query processing components inside in PCM-based storage.

  16. Shape memory system with integrated actuation using embedded particles

    Science.gov (United States)

    Buckley, Patrick R [New York, NY; Maitland, Duncan J [Pleasant Hill, CA

    2009-09-22

    A shape memory material with integrated actuation using embedded particles. One embodiment provides a shape memory material apparatus comprising a shape memory material body and magnetic pieces in the shape memory material body. Another embodiment provides a method of actuating a device to perform an activity on a subject comprising the steps of positioning a shape memory material body in a desired position with regard to the subject, the shape memory material body capable of being formed in a specific primary shape, reformed into a secondary stable shape, and controllably actuated to recover the specific primary shape; including pieces in the shape memory material body; and actuating the shape memory material body using the pieces causing the shape memory material body to be controllably actuated to recover the specific primary shape and perform the activity on the subject.

  17. Shape memory system with integrated actuation using embedded particles

    Science.gov (United States)

    Buckley, Patrick R.; Maitland, Duncan J.

    2014-04-01

    A shape memory material with integrated actuation using embedded particles. One embodiment provides a shape memory material apparatus comprising a shape memory material body and magnetic pieces in the shape memory material body. Another embodiment provides a method of actuating a device to perform an activity on a subject comprising the steps of positioning a shape memory material body in a desired position with regard to the subject, the shape memory material body capable of being formed in a specific primary shape, reformed into a secondary stable shape, and controllably actuated to recover the specific primary shape; including pieces in the shape memory material body; and actuating the shape memory material body using the pieces causing the shape memory material body to be controllably actuated to recover the specific primary shape and perform the activity on the subject.

  18. Adenosine Receptor Heteromers and their Integrative Role in Striatal Function

    Directory of Open Access Journals (Sweden)

    Sergi Ferré

    2007-01-01

    Full Text Available By analyzing the functional role of adenosine receptor heteromers, we review a series of new concepts that should modify our classical views of neurotransmission in the central nervous system (CNS. Neurotransmitter receptors cannot be considered as single functional units anymore. Heteromerization of neurotransmitter receptors confers functional entities that possess different biochemical characteristics with respect to the individual components of the heteromer. Some of these characteristics can be used as a “biochemical fingerprint” to identify neurotransmitter receptor heteromers in the CNS. This is exemplified by changes in binding characteristics that are dependent on coactivation of the receptor units of different adenosine receptor heteromers. Neurotransmitter receptor heteromers can act as “processors” of computations that modulate cell signaling, sometimes critically involved in the control of pre- and postsynaptic neurotransmission. For instance, the adenosine A1-A2A receptor heteromer acts as a concentration-dependent switch that controls striatal glutamatergic neurotransmission. Neurotransmitter receptor heteromers play a particularly important integrative role in the “local module” (the minimal portion of one or more neurons and/or one or more glial cells that operates as an independent integrative unit, where they act as processors mediating computations that convey information from diverse volume-transmitted signals. For instance, the adenosine A2A-dopamine D2 receptor heteromers work as integrators of two different neurotransmitters in the striatal spine module.

  19. Memory controllers for real-time embedded systems predictable and composable real-time systems

    CERN Document Server

    Akesson, Benny

    2012-01-01

      Verification of real-time requirements in systems-on-chip becomes more complex as more applications are integrated. Predictable and composable systems can manage the increasing complexity using formal verification and simulation.  This book explains the concepts of predictability and composability and shows how to apply them to the design and analysis of a memory controller, which is a key component in any real-time system. This book is generally intended for readers interested in Systems-on-Chips with real-time applications.   It is especially well-suited for readers looking to use SDRAM memories in systems with hard or firm real-time requirements. There is a strong focus on real-time concepts, such as predictability and composability, as well as a brief discussion about memory controller architectures for high-performance computing. Readers will learn step-by-step how to go from an unpredictable SDRAM memory, offering highly variable bandwidth and latency, to a predictable and composable shared memory...

  20. The effect on memory of chronic prednisone treatment in patients with systemic disease.

    Science.gov (United States)

    Keenan, P A; Jacobson, M W; Soleymani, R M; Mayes, M D; Stress, M E; Yaldoo, D T

    1996-12-01

    There have been no systematic investigations of the effects of glucocorticoid treatment on memory in a clinical population despite experimental and clinical evidence that such treatment could cause memory disturbance. We conducted both cross-sectional and longitudinal studies. In Study 1, we administered tests of both hippocampal-dependent explicit memory and hippocampal-independent implicit memory to twenty-five prednisone-treated patients with systemic disease without CNS involvement and 25 matched clinical controls. All treated patients were taking doses of 5 to 40 mg of prednisone daily for at least 1 year. The glucocorticoid-treated group performed worse than the controls on tests of explicit memory, but the groups did not differ on the implicit memory task. Multiple regression analyses suggested that elderly patients are more susceptible to memory impairment with less protracted treatment. The results of Study 2, a prospective, longitudinal study of the effects of prednisone on memory across 3 months of therapy, suggest that even acute treatment can adversely affect memory. The observed alteration in memory was not secondary to inattention, affective disturbance, generalized global cognitive decline, or severity of disease. Results reported here, combined with previous clinical and experimental reports, indicate that the risk of memory impairment should be carefully considered before initiating treatment with glucocorticoids. Conversely, use of glucocorticoids should be considered in the differential diagnosis of memory loss. Finally, the potential benefit of anti-inflammatory treatment in Alzheimer's disease might be counterbalanced by possible iatrogenic memory impairment, at least when synthetic glucocorticoids are considered.

  1. Interaction between Neurogenesis and Hippocampal Memory System: New Vistas

    Science.gov (United States)

    Abrous, Djoher Nora; Wojtowicz, Jan Martin

    2015-01-01

    During the last decade, the questions on the functionality of adult neurogenesis have changed their emphasis from if to how the adult-born neurons participate in a variety of memory processes. The emerging answers are complex because we are overwhelmed by a variety of behavioral tasks that apparently require new neurons to be performed optimally. With few exceptions, the hippocampal memory system seems to use the newly generated neurons for multiple roles. Adult neurogenesis has given the dentate gyrus new capabilities not previously thought possible within the scope of traditional synaptic plasticity. Looking at these new developments from the perspective of past discoveries, the science of adult neurogenesis has emerged from its initial phase of being, first, a surprising oddity and, later, exciting possibility, to the present state of being an integral part of mainstream neuroscience. The answers to many remaining questions regarding adult neurogenesis will come along only with our growing understanding of the functionality of the brain as a whole. This, in turn, will require integration of multiple levels of organization from molecules and cells to circuits and systems, ultimately resulting in comprehension of behavioral outcomes. PMID:26032718

  2. Flash memory management system and method utilizing multiple block list windows

    Science.gov (United States)

    Chow, James (Inventor); Gender, Thomas K. (Inventor)

    2005-01-01

    The present invention provides a flash memory management system and method with increased performance. The flash memory management system provides the ability to efficiently manage and allocate flash memory use in a way that improves reliability and longevity, while maintaining good performance levels. The flash memory management system includes a free block mechanism, a disk maintenance mechanism, and a bad block detection mechanism. The free block mechanism provides efficient sorting of free blocks to facilitate selecting low use blocks for writing. The disk maintenance mechanism provides for the ability to efficiently clean flash memory blocks during processor idle times. The bad block detection mechanism provides the ability to better detect when a block of flash memory is likely to go bad. The flash status mechanism stores information in fast access memory that describes the content and status of the data in the flash disk. The new bank detection mechanism provides the ability to automatically detect when new banks of flash memory are added to the system. Together, these mechanisms provide a flash memory management system that can improve the operational efficiency of systems that utilize flash memory.

  3. MEMORY MODULATION

    Science.gov (United States)

    Roozendaal, Benno; McGaugh, James L.

    2011-01-01

    Our memories are not all created equally strong: Some experiences are well remembered while others are remembered poorly, if at all. Research on memory modulation investigates the neurobiological processes and systems that contribute to such differences in the strength of our memories. Extensive evidence from both animal and human research indicates that emotionally significant experiences activate hormonal and brain systems that regulate the consolidation of newly acquired memories. These effects are integrated through noradrenergic activation of the basolateral amygdala which regulates memory consolidation via interactions with many other brain regions involved in consolidating memories of recent experiences. Modulatory systems not only influence neurobiological processes underlying the consolidation of new information, but also affect other mnemonic processes, including memory extinction, memory recall and working memory. In contrast to their enhancing effects on consolidation, adrenal stress hormones impair memory retrieval and working memory. Such effects, as with memory consolidation, require noradrenergic activation of the basolateral amygdala and interactions with other brain regions. PMID:22122145

  4. Simultaneous 99mTc and 123I dual-isotope brain striatal phantom single photon emission computed tomography: validation of 99mTc-TRODAT-1 and 123I-IBZM simultaneous dopamine system brain imaging.

    Science.gov (United States)

    Kao, Pan-Fu; Wey, Shiaw-Pyng; Yang, An-Shoei

    2009-11-01

    [2[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3,2,1]-oct-2-yl]-methyl](2-mercaptoethyl)-amino]ethyl]amino]ethanethiolato(3-)-N2,N2',S2,S2]oxo-[1R-exo-exo)])-[99mTc]-technetium (99mTc-TRODAT-1) and 123I-iodobenzamide (123I-IBZM) are radiotracers for brain dopamine pre- and postsynaptic neuron imaging. The purpose of this study was to evaluate imaging parameters and crossed energy interference using simultaneous single photon emission computed tomography (SPECT) 99mTc and 123I data acquisition. A five-compartment brain striatal phantom was filled with 99mTc and/or 123I radioactive solutions with different striatal-to-background ratios, ranging from 3:1 to 9:1. SPECT data were acquired with energy window settings of 15% for the centered window at 140 keV for 99mTc and a 10% asymmetric window at 159 keV for 123I. The experiments were carried out using either individual (99mTc or 123I only) or both radionuclides. The striatal-to-background ratios and energy crossed interference between 99mTc and 123I were calculated. The phantom SPECT images demonstrated that the energy crossed interferences from 123I to 99mTc, and vice versa, were 22 +/- 12.4% and 0.4 +/- 1.0%, respectively. A net interference of 7.1 +/- 4.0% for the counts in the 15% centered 99mTc window can be expected from 123I and a net interference of 1.6 +/- 3.3% for the counts in the 10% asymmetric 123I window was derived from 99mTc. The correlation of striatal-to-background ratios between single isotope and simultaneous dual-isotope was excellent (R2 = 0.99). The imaging parameters used in this simultaneous dualisotope SPECT imaging could be used in future clinical practice for imaging patients with movement disorders by using 99mTc-TRODAT-1 and 123I-IBZM. The striatal-to-background ratios were not affected by the crossed interference between 99mTc and 123I.

  5. Simultaneous 99mTC and 123I Dual-Isotope Brain Striatal Phantom Single Photon Emission Computed Tomography: Validation of 99mTC-Trodat-1 and 123I-IBZM Simultaneous Dopamine System Brain Imaging

    Directory of Open Access Journals (Sweden)

    Pan-Fu Kao

    2009-11-01

    Full Text Available [2[[2-[[[3-(4-chlorophenyl-8-methyl-8-azabicyclo[3,2,1]-oct-2-yl]-methyl](2-mercaptoethylamino]ethyl]amino]ethanethiolato(3--N2,N2′,S2,S2]oxo-[1R-exo-exo]-[99mTc]-technetium (99mTc-TRODAT-1 and 123I-iodobenzamide (123I-IBZM are radiotracers for brain dopamine preand postsynaptic neuron imaging. The purpose of this study was to evaluate imaging parameters and crossed energy interference using simultaneous single photon emission computed tomography (SPECT 99mTc and 123I data acquisition. A five-compartment brain striatal phantom was filled with 99mTc and/or 123I radioactive solutions with different striatal-to-background ratios, ranging from 3:1 to 9:1. SPECT data were acquired with energy window settings of 15% for the centered window at 140 keV for 99mTc and a 10% asymmetric window at 159 keV for 123I. The experiments were carried out using either individual (99mTc or 123I only or both radionuclides. The striatal-to-background ratios and energy crossed interference between 99mTc and 123I were calculated. The phantom SPECT images demonstrated that the energy crossed interferences from 123I to 99mTc, and vice versa, were 22 ± 12.4% and 0.4 ± 1.0%, respectively. A net interference of 7.1 ± 4.0% for the counts in the 15% centered 99mTc window can be expected from 123I and a net interference of 1.6 ± 3.3% for the counts in the 10% asymmetric 123I window was derived from 99mTc. The correlation of striatal-to-background ratios between single isotope and simultaneous dual-isotope was excellent (R2 = 0.99. The imaging parameters used in this simultaneous dual-isotope SPECT imaging could be used in future clinical practice for imaging patients with movement disorders by using 99mTc-TRODAT-1 and 123I-IBZM. The striatal-to-background ratios were not affected by the crossed interference between 99mTc and 123I.

  6. Dermatoglyphic asymmetries and fronto-striatal dysfunction in young-adults reporting non-clinical psychosis

    Science.gov (United States)

    Mittal, Vijay A.; Dean, Derek J.; Pelletier, Andrea

    2012-01-01

    Objective Growing evidence indicates that non-clinical psychotic-like experiences occur in otherwise healthy individuals, suggesting that psychosis may occur on a continuum. However, little is know about how the diathesis for formal psychosis maps on to individuals at the non-clinical side of this continuum. Our current understanding of the pathophysiology of schizophrenia implicates certain key factors such as early developmental abnormalities and fronto-striatal dysfunction. To date, no studies have examined these core factors in the context of non-clinical psychosis. Method A total of 221 young adults were assessed for distressing attenuated positive symptoms (DAPS), dermatoglyphic asymmetries (a marker of early developmental insult), and procedural memory (a proxy for fronto-striatal function). Results Participants reporting DAPS (n=16; 7.2%) and no-DAPS (n=205; 92.7%) were split into two groups. The DAPS group showed significantly elevated depression, elevated dermatoglyphic asymmetries, and a pattern of procedural learning consistent with other studies with formally psychotic patients. Conclusion The results indicate that the non-clinical side of the psychosis continuum also shares key vulnerability factors implicated in schizophrenia, suggesting that both early developmental disruption and abnormalities in fronto-striatal function are core aspects underlying the disorder. PMID:22519833

  7. Dermatoglyphic asymmetries and fronto-striatal dysfunction in young adults reporting non-clinical psychosis.

    Science.gov (United States)

    Mittal, V A; Dean, D J; Pelletier, A

    2012-10-01

    Growing evidence indicates that non-clinical psychotic-like experiences occur in otherwise healthy individuals, suggesting that psychosis may occur on a continuum. However, little is known about how the diathesis for formal psychosis maps on to individuals at the non-clinical side of this continuum. Our current understanding of the pathophysiology of schizophrenia implicates certain key factors such as early developmental abnormalities and fronto-striatal dysfunction. To date, no studies have examined these core factors in the context of non-clinical psychosis. A total of 221 young adults were assessed for distressing attenuated positive symptoms (DAPS), dermatoglyphic asymmetries (a marker of early developmental insult), and procedural memory (a proxy for fronto-striatal function). Participants reporting DAPS (n = 16; 7.2%) and no-DAPS (n = 205; 92.7%) were split into two groups. The DAPS group showed significantly elevated depression, elevated dermatoglyphic asymmetries, and a pattern of procedural learning consistent with other studies with formally psychotic patients. The results indicate that the non-clinical side of the psychosis continuum also shares key vulnerability factors implicated in schizophrenia, suggesting that both early developmental disruption and abnormalities in fronto-striatal function are core aspects underlying the disorder. © 2012 John Wiley & Sons A/S.

  8. Energy-aware memory management for embedded multimedia systems a computer-aided design approach

    CERN Document Server

    Balasa, Florin

    2011-01-01

    Energy-Aware Memory Management for Embedded Multimedia Systems: A Computer-Aided Design Approach presents recent computer-aided design (CAD) ideas that address memory management tasks, particularly the optimization of energy consumption in the memory subsystem. It explains how to efficiently implement CAD solutions, including theoretical methods and novel algorithms. The book covers various energy-aware design techniques, including data-dependence analysis techniques, memory size estimation methods, extensions of mapping approaches, and memory banking approaches. It shows how these techniques

  9. Ecosystem biophysical memory in the southwestern North America climate system

    International Nuclear Information System (INIS)

    Forzieri, G; Feyen, L; Vivoni, E R

    2013-01-01

    To elucidate the potential role of vegetation to act as a memory source in the southwestern North America climate system, we explore correlation structures of remotely sensed vegetation dynamics with precipitation, temperature and teleconnection indices over 1982–2006 for six ecoregions. We found that lagged correlations between vegetation dynamics and climate variables are modulated by the dominance of monsoonal or Mediterranean regimes and ecosystem-specific physiological processes. Subtropical and tropical ecosystems exhibit a one month lag positive correlation with precipitation, a zero- to one-month lag negative correlation with temperature, and modest negative effects of sea surface temperature (SST). Mountain forests have a zero month lag negative correlation with precipitation, a zero–one month lag negative correlation with temperature, and no significant correlation with SSTs. Deserts show a strong one–four month lag positive correlation with precipitation, a low zero–two month lag negative correlation with temperature, and a high four–eight month lag positive correlation with SSTs. The ecoregion-specific biophysical memories identified offer an opportunity to improve the predictability of land–atmosphere interactions and vegetation feedbacks onto climate. (letter)

  10. High Performance Polar Decomposition on Distributed Memory Systems

    KAUST Repository

    Sukkari, Dalal E.

    2016-08-08

    The polar decomposition of a dense matrix is an important operation in linear algebra. It can be directly calculated through the singular value decomposition (SVD) or iteratively using the QR dynamically-weighted Halley algorithm (QDWH). The former is difficult to parallelize due to the preponderant number of memory-bound operations during the bidiagonal reduction. We investigate the latter scenario, which performs more floating-point operations but exposes at the same time more parallelism, and therefore, runs closer to the theoretical peak performance of the system, thanks to more compute-bound matrix operations. Profiling results show the performance scalability of QDWH for calculating the polar decomposition using around 9200 MPI processes on well and ill-conditioned matrices of 100K×100K problem size. We study then the performance impact of the QDWH-based polar decomposition as a pre-processing step toward calculating the SVD itself. The new distributed-memory implementation of the QDWH-SVD solver achieves up to five-fold speedup against current state-of-the-art vendor SVD implementations. © Springer International Publishing Switzerland 2016.

  11. Influences of multiple memory systems on auditory mental image acuity.

    Science.gov (United States)

    Navarro Cebrian, Ana; Janata, Petr

    2010-05-01

    The influence of different memory systems and associated attentional processes on the acuity of auditory images, formed for the purpose of making intonation judgments, was examined across three experiments using three different task types (cued-attention, imagery, and two-tone discrimination). In experiment 1 the influence of implicit long-term memory for musical scale structure was manipulated by varying the scale degree (leading tone versus tonic) of the probe note about which a judgment had to be made. In experiments 2 and 3 the ability of short-term absolute pitch knowledge to develop was manipulated by presenting blocks of trials in the same key or in seven different keys. The acuity of auditory images depended on all of these manipulations. Within individual listeners, thresholds in the two-tone discrimination and cued-attention conditions were closely related. In many listeners, cued-attention thresholds were similar to thresholds in the imagery condition, and depended on the amount of training individual listeners had in playing a musical instrument. The results indicate that mental images formed at a sensory/cognitive interface for the purpose of making perceptual decisions are highly malleable.

  12. Dynamical Systems Analysis Applied to Working Memory Data

    Directory of Open Access Journals (Sweden)

    Fidan eGasimova

    2014-07-01

    Full Text Available In the present paper we investigate weekly fluctuations in the working memory capacity (WMC assessed over a period of two years. We use dynamical system analysis, specifically a second order linear differential equation, to model weekly variability in WMC in a sample of 112 9th graders. In our longitudinal data we use a B-spline imputation method to deal with missing data. The results show a significant negative frequency parameter in the data, indicating a cyclical pattern in weekly memory updating performance across time. We use a multilevel modeling approach to capture individual differences in model parameters and find that a higher initial performance level and a slower improvement at the MU task is associated with a slower frequency of oscillation. Additionally, we conduct a simulation study examining the analysis procedure’s performance using different numbers of B-spline knots and values of time delay embedding dimensions. Results show that the number of knots in the B-spline imputation influence accuracy more than the number of embedding dimensions.

  13. Massively Parallel Polar Decomposition on Distributed-Memory Systems

    KAUST Repository

    Ltaief, Hatem

    2018-01-01

    We present a high-performance implementation of the Polar Decomposition (PD) on distributed-memory systems. Building upon on the QR-based Dynamically Weighted Halley (QDWH) algorithm, the key idea lies in finding the best rational approximation for the scalar sign function, which also corresponds to the polar factor for symmetric matrices, to further accelerate the QDWH convergence. Based on the Zolotarev rational functions—introduced by Zolotarev (ZOLO) in 1877— this new PD algorithm ZOLO-PD converges within two iterations even for ill-conditioned matrices, instead of the original six iterations needed for QDWH. ZOLO-PD uses the property of Zolotarev functions that optimality is maintained when two functions are composed in an appropriate manner. The resulting ZOLO-PD has a convergence rate up to seventeen, in contrast to the cubic convergence rate for QDWH. This comes at the price of higher arithmetic costs and memory footprint. These extra floating-point operations can, however, be processed in an embarrassingly parallel fashion. We demonstrate performance using up to 102, 400 cores on two supercomputers. We demonstrate that, in the presence of a large number of processing units, ZOLO-PD is able to outperform QDWH by up to 2.3X speedup, especially in situations where QDWH runs out of work, for instance, in the strong scaling mode of operation.

  14. Organization of the two-level memory in the image processing system on scanning measuring projectors

    International Nuclear Information System (INIS)

    Sychev, A.Yu.

    1977-01-01

    Discussed are the problems of improving the efficiency of the system for processing pictures taken in bubble chambers with the use of scanning measuring projectors. The system comprises 20 to 30 pro ectors linked with the ICL-1903A computer provided with a mainframe memory, 64 kilobytes in size. Because of the insufficient size of a mainframe memory, a part of the programs and data is located in a second-level memory, i.e. in an external memory. The analytical model described herein is used to analyze the effect of the memory organization on the characteristics of the system. It is shown that organization of pure procedures and introduction of the centralized control of the tWo-leVel memory result in substantial improvement of the efficiency of the picture processing system

  15. Working Memory in the Classroom: An Inside Look at the Central Executive.

    Science.gov (United States)

    Barker, Lauren A

    2016-01-01

    This article provides a review of working memory and its application to educational settings. A discussion of the varying definitions of working memory is presented. Special attention is given to the various multidisciplinary professionals who work with students with working memory deficits, and their unique understanding of the construct. Definitions and theories of working memory are briefly summarized and provide the foundation for understanding practical applications of working memory to assessment and intervention. Although definitions and models of working memory abound, there is limited consensus regarding universally accepted definitions and models. Current research indicates that developing new models of working memory may be an appropriate paradigm shift at this time. The integration of individual practitioner's knowledge regarding academic achievement, working memory and processing speed could provide a foundation for the future development of new working memory models. Future directions for research should aim to explain how tasks and behaviors are supported by the substrates of the cortico-striatal and the cerebro-cerebellar systems. Translation of neurobiological information into educational contexts will be helpful to inform all practitioners' knowledge of working memory constructs. It will also allow for universally accepted definitions and models of working memory to arise and facilitate more effective collaboration between disciplines working in educational setting.

  16. Striatal dopamine transporter binding correlates with serum BDNF levels in patients with striatal dopaminergic neurodegeneration

    DEFF Research Database (Denmark)

    Ziebell, Morten; Khalid, Usman; Klein, Anders B

    2012-01-01

    BDNF levels in patients with parkinsonism. Twenty-one patients with abnormal in vivo striatal dopamine transporter (DAT) binding as evidenced with [(123)I]PE2I SPECT brain scanning were included. Samples for serum BDNF levels were collected at the time of the SPECT scanning, and BDNF was measured...

  17. Neurocognitive systems related to real-world prospective memory.

    Directory of Open Access Journals (Sweden)

    Grégoria Kalpouzos

    Full Text Available BACKGROUND: Prospective memory (PM denotes the ability to remember to perform actions in the future. It has been argued that standard laboratory paradigms fail to capture core aspects of PM. METHODOLOGY/PRINCIPAL FINDINGS: We combined functional MRI, virtual reality, eye-tracking and verbal reports to explore the dynamic allocation of neurocognitive processes during a naturalistic PM task where individuals performed errands in a realistic model of their residential town. Based on eye movement data and verbal reports, we modeled PM as an iterative loop of five sustained and transient phases: intention maintenance before target detection (TD, TD, intention maintenance after TD, action, and switching, the latter representing the activation of a new intention in mind. The fMRI analyses revealed continuous engagement of a top-down fronto-parietal network throughout the entire task, likely subserving goal maintenance in mind. In addition, a shift was observed from a perceptual (occipital system while searching for places to go, to a mnemonic (temporo-parietal, fronto-hippocampal system for remembering what actions to perform after TD. Updating of the top-down fronto-parietal network occurred at both TD and switching, the latter likely also being characterized by frontopolar activity. CONCLUSION/SIGNIFICANCE: Taken together, these findings show how brain systems complementary interact during real-world PM, and support a more complete model of PM that can be applied to naturalistic PM tasks and that we named PROspective MEmory DYnamic (PROMEDY model because of its dynamics on both multi-phase iteration and the interactions of distinct neurocognitive networks.

  18. GDNF control of the glutamatergic cortico-striatal pathway requires tonic activation of adenosine A2A Receptors

    Science.gov (United States)

    Gomes, Catarina A.R.V.; Simões, Patrícia F.; Canas, Paula M.; Quiroz, César; Sebastião, Ana M.; Ferré, Sergi; Cunha, Rodrigo A.; Ribeiro, Joaquim A.

    2009-01-01

    Glial cell line-derived neurotrophic factor (GDNF) affords neuroprotection in Parkinson’s disease in accordance with its ability to bolster nigrostriatal innervation. We previously found that GDNF facilitates dopamine release in a manner dependent on adenosine A2A receptor activation. Since motor dysfunction also involves modifications of striatal glutamatergic innervation, we now tested if GDNF and its receptor system, Ret (rearranged during transfection) and GFRα1 (GDNF family receptor alpha 1) controlled the cortico-striatal glutamatergic pathway in an A2A receptor-dependent manner. GDNF (10 ng/ml) enhanced (by ≈13%) glutamate release from rat striatal nerve endings, an effect potentiated (up to ≈ 30%) by the A2A receptor agonist CGS 21680 (10 nM) and prevented by the A2A receptor antagonist, SCH 58261 (50 nM). Triple immunocytochemical studies revealed that Ret and GFRα1 were located in 50% of rat striatal glutamatergic terminals (immunopositive for vesicular glutamate transporters-1/2), where they were found to be co-located with A2A receptors. Activation of the glutamatergic system upon in vivo electrical stimulation of the rat cortico-striatal input induced striatal Ret phosphoprylation that was prevented by pre-treatment with the A2A receptor antagonist, MSX-3 (3 mg/kg). The results provide the first functional and morphological evidence that GDNF controls cortico-striatal glutamatergic pathways in a manner largely dependent on the co-activation of adenosine A2A receptors. PMID:19141075

  19. Apathy and striatal dopamine transporter levels in de-novo, untreated Parkinson's disease patients.

    Science.gov (United States)

    Santangelo, Gabriella; Vitale, Carmine; Picillo, Marina; Cuoco, Sofia; Moccia, Marcello; Pezzella, Domenica; Erro, Roberto; Longo, Katia; Vicidomini, Caterina; Pellecchia, Maria Teresa; Amboni, Marianna; Brunetti, Arturo; Salvatore, Marco; Barone, Paolo; Pappatà, Sabina

    2015-05-01

    Apathy is a neuropsychiatric symptom in Parkinson's Disease (PD) which has a negative impact on quality of life and might be related in part to damage of presynaptic dopaminergic system. Little is known about relationship between striatal dopamine levels and apathy in PD patients without dementia and/or depression. The aim of the present study was to investigate the relationship between "pure apathy" and striatal dopamine uptake in untreated, drug-naïve PD patients without clinically significant dementia and/or depression. Fourteen PD patients with pure apathy and 14 PD patients without apathy, matched for age, side of motor symptoms at onset, motor disability and disease duration, underwent both neuropsychological and behavioral examination including self-rated version of the Apathy Evaluation Scale (AES-S). All patients underwent 123 I-FP-CIT (DaT-SCAN) SPECT to assess dopamine transporter (DAT) striatal uptake. PD patients with apathy showed lower DAT levels in the striatum than non-apathetic patients. After Bonferroni correction the difference between groups was significant in the right caudate. Apathy is associated with reduced striatal dopamine transporter levels, independent of motor disability and depression in non-demented PD patients. These findings suggest that dysfunction of dopaminergic innervation in the striatum and particularly in the right caudate may contribute to development of apathy in early PD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Glutamine triggers long-lasting increase in striatal network activity in vitro.

    Science.gov (United States)

    Fleischer, Wiebke; Theiss, Stephan; Schnitzler, Alfons; Sergeeva, Olga

    2017-04-01

    Accumulation of ammonium and glutamine in blood and brain is a key factor in hepatic encephalopathy (HE) - a neuropsychiatric syndrome characterized by various cognitive and motor deficits. MRI imaging identified abnormalities notably in the basal ganglia of HE patients, including its major input station, the striatum. While neurotoxic effects of ammonia have been extensively studied, glutamine is primarily perceived as "detoxified" form of ammonia. We applied ammonium and glutamine to striatal and cortical cells from newborn rats cultured on microelectrode arrays. Glutamine, but not ammonium significantly increased spontaneous spike rate with a long-lasting excitation outlasting washout. This effect was more prominent in striatal than in cortical cultures. Calcium imaging revealed that glutamine application caused a rise in intracellular calcium that depended both on system A amino acid transport and activation of ionotropic glutamate receptors. This pointed to downstream glutamate release that was triggered by intracellular glutamine. Using an enzymatic assay kit we confirmed glutamine-provoked glutamate release from striatal cells. Real-time PCR and immunocytochemistry demonstrated the presence of vesicular glutamate transporters (VGLUT1 and VGLUT2) necessary for synaptic glutamate release in striatal neurons. We conclude that extracellular glutamine is taken up by neurons, triggers synaptic release of glutamate which is then taken up by astrocytes and again converted to glutamine. This feedback-loop causes a sustained long-lasting excitation of network activity. Thus, apart from ammonia also its "detoxified" form glutamine might be responsible for the neuropsychiatric symptoms in HE. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Creative cognition and dopaminergic modulation of fronto-striatal networks: Integrative review and research agenda.

    Science.gov (United States)

    Boot, Nathalie; Baas, Matthijs; van Gaal, Simon; Cools, Roshan; De Dreu, Carsten K W

    2017-07-01

    Creative cognition is key to human functioning yet the underlying neurobiological mechanisms are sparsely addressed and poorly understood. Here we address the possibility that creative cognition is a function of dopaminergic modulation in fronto-striatal brain circuitries. It is proposed that (i) creative cognition benefits from both flexible and persistent processing, (ii) striatal dopamine and the integrity of the nigrostriatal dopaminergic pathway is associated with flexible processing, while (iii) prefrontal dopamine and the integrity of the mesocortical dopaminergic pathway is associated with persistent processing. We examine this possibility in light of studies linking creative ideation, divergent thinking, and creative problem-solving to polymorphisms in dopamine receptor genes, indirect markers and manipulations of the dopaminergic system, and clinical populations with dysregulated dopaminergic activity. Combined, studies suggest a functional differentiation between striatal and prefrontal dopamine: moderate (but not low or high) levels of striatal dopamine benefit creative cognition by facilitating flexible processes, and moderate (but not low or high) levels of prefrontal dopamine enable persistence-driven creativity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. A system for simulating shared memory in heterogeneous distributed-memory networks with specialization for robotics applications

    Energy Technology Data Exchange (ETDEWEB)

    Jones, J.P.; Bangs, A.L.; Butler, P.L.

    1991-01-01

    Hetero Helix is a programming environment which simulates shared memory on a heterogeneous network of distributed-memory computers. The machines in the network may vary with respect to their native operating systems and internal representation of numbers. Hetero Helix presents a simple programming model to developers, and also considers the needs of designers, system integrators, and maintainers. The key software technology underlying Hetero Helix is the use of a compiler'' which analyzes the data structures in shared memory and automatically generates code which translates data representations from the format native to each machine into a common format, and vice versa. The design of Hetero Helix was motivated in particular by the requirements of robotics applications. Hetero Helix has been used successfully in an integration effort involving 27 CPUs in a heterogeneous network and a body of software totaling roughly 100,00 lines of code. 25 refs., 6 figs.

  3. Programs for Testing Processor-in-Memory Computing Systems

    Science.gov (United States)

    Katz, Daniel S.

    2006-01-01

    The Multithreaded Microbenchmarks for Processor-In-Memory (PIM) Compilers, Simulators, and Hardware are computer programs arranged in a series for use in testing the performances of PIM computing systems, including compilers, simulators, and hardware. The programs at the beginning of the series test basic functionality; the programs at subsequent positions in the series test increasingly complex functionality. The programs are intended to be used while designing a PIM system, and can be used to verify that compilers, simulators, and hardware work correctly. The programs can also be used to enable designers of these system components to examine tradeoffs in implementation. Finally, these programs can be run on non-PIM hardware (either single-threaded or multithreaded) using the POSIX pthreads standard to verify that the benchmarks themselves operate correctly. [POSIX (Portable Operating System Interface for UNIX) is a set of standards that define how programs and operating systems interact with each other. pthreads is a library of pre-emptive thread routines that comply with one of the POSIX standards.

  4. Interface methods for using intranet portal organizational memory information system.

    Science.gov (United States)

    Ji, Yong Gu; Salvendy, Gavriel

    2004-12-01

    In this paper, an intranet portal is considered as an information infrastructure (organizational memory information system, OMIS) supporting organizational learning. The properties and the hierarchical structure of information and knowledge in an intranet portal OMIS was identified as a problem for navigation tools of an intranet portal interface. The problem relates to navigation and retrieval functions of intranet portal OMIS and is expected to adversely affect user performance, satisfaction, and usefulness. To solve the problem, a conceptual model for navigation tools of an intranet portal interface was proposed and an experiment using a crossover design was conducted with 10 participants. In the experiment, a separate access method (tabbed tree tool) was compared to an unified access method (single tree tool). The results indicate that each information/knowledge repository for which a user has a different structural knowledge should be handled separately with a separate access to increase user satisfaction and the usefulness of the OMIS and to improve user performance in navigation.

  5. Transactive memory system links work team characteristics and performance.

    Science.gov (United States)

    Zhang, Zhi-Xue; Hempel, Paul S; Han, Yu-Lan; Tjosvold, Dean

    2007-11-01

    Teamwork and coordination of expertise among team members with different backgrounds are increasingly recognized as important for team effectiveness. Recently, researchers have examined how team members rely on transactive memory system (TMS; D. M. Wegner, 1987) to share their distributed knowledge and expertise. To establish the ecological validity and generality of TMS research findings, this study sampled 104 work teams from a variety of organizational settings in China and examined the relationships between team characteristics, TMS, and team performance. The results suggest that task interdependence, cooperative goal interdependence, and support for innovation are positively related to work teams' TMS and that TMS is related to team performance; moreover, structural equation analysis indicates that TMS mediates the team characteristics-performance links. Findings have implications both for team leaders to manage their work teams effectively and for team members to improve their team performance. (c) 2007 APA

  6. BLACKCOMB2: Hardware-software co-design for non-volatile memory in exascale systems

    Energy Technology Data Exchange (ETDEWEB)

    Mudge, Trevor [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-12-15

    This work was part of a larger project, Blackcomb2, centered at Oak Ridge National Labs (Jeff Vetter PI) to investigate the opportunities for replacing or supplementing DRAM main memory with nonvolatile memory (NVmemory) in Exascale memory systems. The goal was to reduce the energy consumed by in future supercomputer memory systems and to improve their resiliency. Building on the accomplishments of the original Blackcomb Project, funded in 2010, the goal for Blackcomb2 was to identify, evaluate, and optimize the most promising emerging memory technologies, architecture hardware and software technologies, which are essential to provide the necessary memory capacity, performance, resilience, and energy efficiency in Exascale systems. Capacity and energy are the key drivers.

  7. Further human evidence for striatal dopamine release induced by administration of ∆9-tetrahydrocannabinol (THC): selectivity to limbic striatum.

    Science.gov (United States)

    Bossong, Matthijs G; Mehta, Mitul A; van Berckel, Bart N M; Howes, Oliver D; Kahn, René S; Stokes, Paul R A

    2015-08-01

    Elevated dopamine function is thought to play a key role in both the rewarding effects of addictive drugs and the pathophysiology of schizophrenia. Accumulating epidemiological evidence indicates that cannabis use is a risk factor for the development of schizophrenia. However, human neurochemical imaging studies that examined the impact of ∆9-tetrahydrocannabinol (THC), the main psychoactive component in cannabis, on striatal dopamine release have provided inconsistent results. The objective of this study is to assess the effect of a THC challenge on human striatal dopamine release in a large sample of healthy participants. We combined human neurochemical imaging data from two previous studies that used [(11)C]raclopride positron emission tomography (PET) (n = 7 and n = 13, respectively) to examine the effect of THC on striatal dopamine neurotransmission in humans. PET images were re-analysed to overcome differences in PET data analysis. THC administration induced a significant reduction in [(11)C]raclopride binding in the limbic striatum (-3.65 %, from 2.39 ± 0.26 to 2.30 ± 0.23, p = 0.023). This is consistent with increased dopamine levels in this region. No significant differences between THC and placebo were found in other striatal subdivisions. In the largest data set of healthy participants so far, we provide evidence for a modest increase in human striatal dopamine transmission after administration of THC compared to other drugs of abuse. This finding suggests limited involvement of the endocannabinoid system in regulating human striatal dopamine release and thereby challenges the hypothesis that an increase in striatal dopamine levels after cannabis use is the primary biological mechanism underlying the associated higher risk of schizophrenia.

  8. Growth hormone (GH) is a survival rather than a proliferative factor for embryonic striatal neural precursor cells.

    Science.gov (United States)

    Regalado-Santiago, Citlalli; López-Meraz, María Leonor; Santiago-García, Juan; Fernández-Pomares, Cynthia; Juárez-Aguilar, Enrique

    2013-10-01

    A possible role of GH during central nervous system (CNS) development has been suggested by the presence of this hormone and its receptor in brain areas before its production by the pituitary gland. Although several effects have been reported for GH, the specific role of this hormone during CNS development remains unclear. Here, we examined the effect of GH on proliferation, survival and neurosphere formation in primary cultures of striatal tissue from 14-day-old (E14) mouse embryos. GH receptor gene expression was confirmed by RT-PCR. Primary cultures of embryonic striatal cells were treated with different doses of GH in serum free media, then the number of neurospheres was determined. To examine the GH effect on proliferation and survival of the striatal primary cultures, bromodeoxyuridine (BrdU) and TUNEL immunoreactivity was conducted. In the presence of the epidermal growth factor (EGF), GH increased the formation of neurospheres, with a maximal response at 10 ng/ml, higher doses were inhibitory. In absence of EGF, GH failed to stimulate neurosphere formation. Proliferation rate in the primary striatal cultures was inhibited by 24 or 48 h incubation with GH. However, in the absence of EGF, GH increased BrdU incorporation. GH treatment decreases the rate of apoptosis of nestin and GFAP positive cells in the primary striatal cultures, enhancing neurosphere formation. Our in vitro data demonstrate that GH plays a survival role on the original population of embryonic striatal cells, improving Neural Precursor Cells (NPCs) expansion. We suggest that this GH action could be predominant during striatal neurodevelopment. © 2013.

  9. The Associative Memory System Infrastructure of the ATLAS Fast Tracker

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00525014; The ATLAS collaboration

    2016-01-01

    The Associative Memory (AM) system of the Fast Tracker (FTK) processor has been designed to perform pattern matching using the hit information of the ATLAS experiment silicon tracker. The AM is the heart of FTK and is mainly based on the use of ASICs (AM chips) designed on purpose to execute pattern matching with a high degree of parallelism. It finds track candidates at low resolution that are seeds for a full resolution track fitting. The AM system implementation is based on a collection of boards, named “Serial Link Processor” (AMBSLP), since it is based on a network of 900 2 Gb/s serial links to sustain huge data traffic. The AMBSLP has high power consumption (~250 W) and the AM system needs custom power and cooling. This presentation reports on the integration of the AMBSLP inside FTK, the infrastructure needed to run and cool the system which foresees many AMBSLPs in the same crate, the performance of the produced prototypes tested in the global FTK integration, an important milestone to be satisfie...

  10. Protein Degradation by Ubiquitin-Proteasome System in Formation and Labilization of Contextual Conditioning Memory

    Science.gov (United States)

    Fustiñana, María Sol; de la Fuente, Verónica; Federman, Noel; Freudenthal, Ramiro; Romano, Arturo

    2014-01-01

    The ubiquitin-proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this…

  11. Organizational memory and the completeness of process modeling in ERP systems

    NARCIS (Netherlands)

    van Stijn, E.J.; Wensley, A.K.P.

    2001-01-01

    Enterprise resource planning (ERP) systems not only have a broad functional scope promising to support many different business processes, they also embed many different aspects of the company’s organizational memory. Disparities can exist between those memory contents in the ERP system and related

  12. A single-system model predicts recognition memory and repetition priming in amnesia

    NARCIS (Netherlands)

    Berry, C.J.; Kessels, R.P.C.; Wester, A.J.; Shanks, D.R.

    2014-01-01

    We challenge the claim that there are distinct neural systems for explicit and implicit memory by demonstrating that a formal single-system model predicts the pattern of recognition memory (explicit) and repetition priming (implicit) in amnesia. In the current investigation, human participants with

  13. Data systems and computer science space data systems: Onboard memory and storage

    Science.gov (United States)

    Shull, Tom

    1991-01-01

    The topics are presented in viewgraph form and include the following: technical objectives; technology challenges; state-of-the-art assessment; mass storage comparison; SODR drive and system concepts; program description; vertical Bloch line (VBL) device concept; relationship to external programs; and backup charts for memory and storage.

  14. Limbic systems for emotion and for memory, but no single limbic system.

    Science.gov (United States)

    Rolls, Edmund T

    2015-01-01

    The concept of a (single) limbic system is shown to be outmoded. Instead, anatomical, neurophysiological, functional neuroimaging, and neuropsychological evidence is described that anterior limbic and related structures including the orbitofrontal cortex and amygdala are involved in emotion, reward valuation, and reward-related decision-making (but not memory), with the value representations transmitted to the anterior cingulate cortex for action-outcome learning. In this 'emotion limbic system' a computational principle is that feedforward pattern association networks learn associations from visual, olfactory and auditory stimuli, to primary reinforcers such as taste, touch, and pain. In primates including humans this learning can be very rapid and rule-based, with the orbitofrontal cortex overshadowing the amygdala in this learning important for social and emotional behaviour. Complementary evidence is described showing that the hippocampus and limbic structures to which it is connected including the posterior cingulate cortex and the fornix-mammillary body-anterior thalamus-posterior cingulate circuit are involved in episodic or event memory, but not emotion. This 'hippocampal system' receives information from neocortical areas about spatial location, and objects, and can rapidly associate this information together by the different computational principle of autoassociation in the CA3 region of the hippocampus involving feedback. The system can later recall the whole of this information in the CA3 region from any component, a feedback process, and can recall the information back to neocortical areas, again a feedback (to neocortex) recall process. Emotion can enter this memory system from the orbitofrontal cortex etc., and be recalled back to the orbitofrontal cortex etc. during memory recall, but the emotional and hippocampal networks or 'limbic systems' operate by different computational principles, and operate independently of each other except insofar as an

  15. Regulation of drugs affecting striatal cholinergic activity by corticostriatal projections

    International Nuclear Information System (INIS)

    Ladinsky, H.

    1986-01-01

    Research demonstrates that the chronic degeneration of the corticostriatal excitatory pathway makes the cholinergic neurons of the striatum insensitive to the neuropharmacological action of a number of different drugs. Female rats were used; they were killed and after the i.v. infusion of tritium-choline precursor, choline acetyltransferase activity was measured. Striatal noradrenaline, dopamine and serotonin content was measured by electrochemical detection coupled with high pressure liquid chromatography. Uptake of tritium-glutamic acid was estimated. The data were analyzed statistically. It is shown that there is evidence that the effects of a number of drugs capable of depressing cholinergic activity through receptor-mediated responses are operative only if the corticostriatal pathway is integral. Neuropharmacological responses in the brain appear to be the result of an interaction between several major neurotransmitter systems

  16. Shape memory alloys applied to improve rotor-bearing system dynamics - an experimental investigation

    DEFF Research Database (Denmark)

    Enemark, Søren; Santos, Ilmar; Savi, Marcelo A.

    2015-01-01

    hysteretic stress-strain relations which may be utilized for damping purposes. These ideas are tested in this study on a dedicated test-rig, consisting of a rigid shaft and disc held vertically by passive magnetic bearings, where the damping is low. The bearing housings is flexibly supported by shape memory......tor-bearing systems have critical speeds and to pass through them is an ongoing challenge in the field of mechanical engineering. The incorporation of shape memory alloys in rotating systems has an increasing importance to improve system performance and to avoid potential damaging situations when...... passing through critical speeds. In this work, the feasibility of applying shape memory alloys to a rotating system is experimentally investigated. Shape memory alloys can change their stiffness with temperature variations and thus they may change system dynamics. Shape memory alloys also exhibit...

  17. An Artificial Flexible Visual Memory System Based on an UV-Motivated Memristor.

    Science.gov (United States)

    Chen, Shuai; Lou, Zheng; Chen, Di; Shen, Guozhen

    2018-02-01

    For the mimicry of human visual memory, a prominent challenge is how to detect and store the image information by electronic devices, which demands a multifunctional integration to sense light like eyes and to memorize image information like the brain by transforming optical signals to electrical signals that can be recognized by electronic devices. Although current image sensors can perceive simple images in real time, the image information fades away when the external image stimuli are removed. The deficiency between the state-of-the-art image sensors and visual memory system inspires the logical integration of image sensors and memory devices to realize the sensing and memory process toward light information for the bionic design of human visual memory. Hence, a facile architecture is designed to construct artificial flexible visual memory system by employing an UV-motivated memristor. The visual memory arrays can realize the detection and memory process of UV light distribution with a patterned image for a long-term retention and the stored image information can be reset by a negative voltage sweep and reprogrammed to the same or an other image distribution, which proves the effective reusability. These results provide new opportunities for the mimicry of human visual memory and enable the flexible visual memory device to be applied in future wearable electronics, electronic eyes, multifunctional robotics, and auxiliary equipment for visual handicapped. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The ferromagnetic shape memory system Fe-Pd-Cu

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, S. [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, 44801 Bochum (Germany); Gruner, M.E. [Faculty of Physics and Center for Nanointegration, CeNIDE, University of Duisburg-Essen, 47048 Duisburg (Germany); Irsen, S. [Forschungszentrum caesar, Electron Microscopy, 53175 Bonn (Germany); Buschbeck, J. [IFW Dresden, P.O. Box: 270116, 01171 Dresden (Germany); Bechtold, C. [Inorganic Functional Materials, Christian-Albrechts-University, 24143 Kiel (Germany); Kock, I. [I. Physikalisches Institut, Georg-August-University Goettingen, 37077 Goettingen (Germany); Mayr, S.G. [I. Physikalisches Institut, Georg-August-University Goettingen, 37077 Goettingen (Germany)] [Leibniz-Institut fuer Oberflaechenmodifizierung eV, Translationszentrum fuer regenerative Medizin und Fakultaet fuer Physik und Geowissenschaften, University Leipzig, 04318 Leipzig (Germany); Savan, A.; Thienhaus, S. [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, 44801 Bochum (Germany); Quandt, E. [Inorganic Functional Materials, Christian-Albrechts-University, 24143 Kiel (Germany); Faehler, S. [IFW Dresden, P.O. Box: 270116, 01171 Dresden (Germany); Entel, P. [Faculty of Physics and Center for Nanointegration, CeNIDE, University of Duisburg-Essen, 47048 Duisburg (Germany); Ludwig, A., E-mail: alfred.ludwig@rub.de [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, 44801 Bochum (Germany)

    2010-10-15

    A new ferromagnetic shape memory thin film system, Fe-Pd-Cu, was developed using ab initio calculations, combinatorial fabrication and high-throughput experimentation methods. Reversible martensitic transformations are found in extended compositional regions, which have increased fcc-fct transformation temperatures in comparison to previously published results. High resolution transmission electron microscopy verified the existence of a homogeneous ternary phase without precipitates. Curie temperature, saturation polarization and orbital magnetism are only moderately decreased by alloying with nonmagnetic Cu. Compared to the binary system; enhanced Invar-type thermal expansion anomalies in terms of an increased volume magnetostriction are predicted. Complementary experiments on splat-fabricated bulk Fe-Pd-Cu samples showed an enhanced stability of the disordered transforming Fe{sub 70}Pd{sub 30} phase against decomposition. From the comparison of bulk and thin film results, it can be inferred that, for ternary systems, the Fe content, rather than the valence electron concentration, should be regarded as the decisive factor determining the fcc-fct transformation temperature.

  19. How Theaters Remember: Cultures of Memory in Institutionalized Systems

    Directory of Open Access Journals (Sweden)

    Milena Dragićević Šešić

    2014-11-01

    Full Text Available The aim of this study is to explore organizational policies and strategies regarding the institutional memory of Belgrade’s repertoire theaters. The concept of institutional (organizational memory has not been developed within the culture of memory theory. The role of theater in the culture of memory has been researched mostly through studies of its repertoire, corresponding to how theaters deal with issues of glory, guilt, or shame. This study explores how theaters rethink their own past and organizational culture, how they use their capacity for re-imagining themselves, for clarifying their role and function in different historical moments. The objective of this research is to identify the main institutional policies and types of strategies used for preserving institutional memory through key narratives of remembering, and key methods of inter-generational transfer. The sample comprises of four Belgrade-based public repertoire theaters: the Yugoslav Dramatic Theater (JDP, the Belgrade Dramatic Theater (BDP, Atelje 212, and Bitef Theater. Specific attention is given to the means of transmission, of individual (episodic memories into the collective consciousness, influencing organizational cultures and shaping a theater’s identity (semantic memory. Research has shown that there are important differences in active policies of preserving institutional memory among Belgrade’s theaters. Different organizational and programming strategies were implemented in order to safeguard institutional identity and memory, particularly in theaters with a permanent ensemble. The major difference is between theaters whose culture of memory might be called “non-existent” (Bitef, or “in storage” (BDP, and those succeeding in creating a functional memory (JDP, Atelje 212.

  20. Protein degradation by ubiquitin–proteasome system in formation and labilization of contextual conditioning memory

    Science.gov (United States)

    Sol Fustiñana, María; de la Fuente, Verónica; Federman, Noel; Freudenthal, Ramiro

    2014-01-01

    The ubiquitin–proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this case, the inhibition of the UPS during consolidation impairs memory. Similar results were reported for memory reconsolidation. However, in other cases, the inhibition of UPS had no effect on memory consolidation and reconsolidation but impedes the amnesic action of protein synthesis inhibition after retrieval. The last finding suggests a specific action of the UPS inhibitor on memory labilization. However, another interpretation is possible in terms of the synthesis/degradation balance of positive and negative elements in neural plasticity, as was found in the case of long-term potentiation. To evaluate these alternative interpretations, other reconsolidation-interfering drugs than translation inhibitors should be tested. Here we analyzed initially the UPS inhibitor effect in contextual conditioning in crabs. We found that UPS inhibition during consolidation impaired long-term memory. In contrast, UPS inhibition did not affect memory reconsolidation after contextual retrieval but, in fact, impeded memory labilization, blocking the action of drugs that does not affect directly the protein synthesis. To extend these finding to vertebrates, we performed similar experiments in contextual fear memory in mice. We found that the UPS inhibitor in hippocampus affected memory consolidation and blocked memory labilization after retrieval. These findings exclude alternative interpretations to the requirement of UPS in memory labilization and give evidence of this mechanism in both vertebrates and invertebrates. PMID:25135196

  1. Very Dense High Speed 3u VPX Memory and Processing Space Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Today, memory and payload processing systems for space applications are typically designed for a specific application for a specific mission. Many of these systems...

  2. Novel procedure for characterizing nonlinear systems with memory: 2017 update

    Science.gov (United States)

    Nuttall, Albert H.; Katz, Richard A.; Hughes, Derke R.; Koch, Robert M.

    2017-05-01

    The present article discusses novel improvements in nonlinear signal processing made by the prime algorithm developer, Dr. Albert H. Nuttall and co-authors, a consortium of research scientists from the Naval Undersea Warfare Center Division, Newport, RI. The algorithm, called the Nuttall-Wiener-Volterra or 'NWV' algorithm is named for its principal contributors [1], [2],[ 3] . The NWV algorithm significantly reduces the computational workload for characterizing nonlinear systems with memory. Following this formulation, two measurement waveforms are required in order to characterize a specified nonlinear system under consideration: (1) an excitation input waveform, x(t) (the transmitted signal); and, (2) a response output waveform, z(t) (the received signal). Given these two measurement waveforms for a given propagation channel, a 'kernel' or 'channel response', h= [h0,h1,h2,h3] between the two measurement points, is computed via a least squares approach that optimizes modeled kernel values by performing a best fit between measured response z(t) and a modeled response y(t). New techniques significantly diminish the exponential growth of the number of computed kernel coefficients at second and third order and alleviate the Curse of Dimensionality (COD) in order to realize practical nonlinear solutions of scientific and engineering interest.

  3. Regulation of bat echolocation pulse acoustics by striatal dopamine.

    Science.gov (United States)

    Tressler, Jedediah; Schwartz, Christine; Wellman, Paul; Hughes, Samuel; Smotherman, Michael

    2011-10-01

    The ability to control the bandwidth, amplitude and duration of echolocation pulses is a crucial aspect of echolocation performance but few details are known about the neural mechanisms underlying the control of these voice parameters in any mammal. The basal ganglia (BG) are a suite of forebrain nuclei centrally involved in sensory-motor control and are characterized by their dependence on dopamine. We hypothesized that pharmacological manipulation of brain dopamine levels could reveal how BG circuits might influence the acoustic structure of bat echolocation pulses. A single intraperitoneal injection of a low dose (5 mg kg(-1)) of the neurotoxin 1-methyl-4-phenylpyridine (MPTP), which selectively targets dopamine-producing cells of the substantia nigra, produced a rapid degradation in pulse acoustic structure and eliminated the bat's ability to make compensatory changes in pulse amplitude in response to background noise, i.e. the Lombard response. However, high-performance liquid chromatography (HPLC) measurements of striatal dopamine concentrations revealed that the main effect of MPTP was a fourfold increase rather than the predicted decrease in striatal dopamine levels. After first using autoradiographic methods to confirm the presence and location of D(1)- and D(2)-type dopamine receptors in the bat striatum, systemic injections of receptor subtype-specific agonists showed that MPTP's effects on pulse acoustics were mimicked by a D(2)-type dopamine receptor agonist (Quinpirole) but not by a D(1)-type dopamine receptor agonist (SKF82958). The results suggest that BG circuits have the capacity to influence echolocation pulse acoustics, particularly via D(2)-type dopamine receptor-mediated pathways, and may therefore represent an important mechanism for vocal control in bats.

  4. Neonatal exposure to antiepileptic drugs disrupts striatal synaptic development.

    Science.gov (United States)

    Forcelli, Patrick A; Janssen, Megan J; Vicini, Stefano; Gale, Karen

    2012-09-01

    Drug exposure during critical periods of brain development may adversely affect nervous system function, posing a challenge for treating infants. This is of particular concern for treating neonatal seizures, as early life exposure to drugs such as phenobarbital is associated with adverse neurological outcomes in patients and induction of neuronal apoptosis in animal models. The functional significance of the preclinical neurotoxicity has been questioned due to the absence of evidence for functional impairment associated with drug-induced developmental apoptosis. We used patch-clamp recordings to examine functional synaptic maturation in striatal medium spiny neurons from neonatal rats exposed to antiepileptic drugs with proapoptotic action (phenobarbital, phenytoin, lamotrigine) and without proapoptotic action (levetiracetam). Phenobarbital-exposed rats were also assessed for reversal learning at weaning. Recordings from control animals revealed increased inhibitory and excitatory synaptic connectivity between postnatal day (P)10 and P18. This maturation was absent in rats exposed at P7 to a single dose of phenobarbital, phenytoin, or lamotrigine. Additionally, phenobarbital exposure impaired striatal-mediated behavior on P25. Neuroprotective pretreatment with melatonin, which prevents drug-induced neurodevelopmental apoptosis, prevented the drug-induced disruption in maturation. Levetiracetam was found not to disrupt synaptic development. Our results provide the first evidence that exposure to antiepileptic drugs during a sensitive postnatal period impairs physiological maturation of synapses in neurons that survive the initial drug insult. These findings suggest a mechanism by which early life exposure to antiepileptic drugs can impact cognitive and behavioral outcomes, underscoring the need to identify therapies that control seizures without compromising synaptic maturation. Copyright © 2012 American Neurological Association.

  5. Quantum predictions for an unmeasured system cannot be simulated with a finite-memory classical system

    Science.gov (United States)

    Tavakoli, Armin; Cabello, Adán

    2018-03-01

    We consider an ideal experiment in which unlimited nonprojective quantum measurements are sequentially performed on a system that is initially entangled with a distant one. At each step of the sequence, the measurements are randomly chosen between two. However, regardless of which measurement is chosen or which outcome is obtained, the quantum state of the pair always remains entangled. We show that the classical simulation of the reduced state of the distant system requires not only unlimited rounds of communication, but also that the distant system has infinite memory. Otherwise, a thermodynamical argument predicts heating at a distance. Our proposal can be used for experimentally ruling out nonlocal finite-memory classical models of quantum theory.

  6. Current Topics Regarding the Function of the Medial Temporal Lobe Memory System.

    Science.gov (United States)

    Clark, Robert E

    2018-01-05

    The first clear insight that the medial temporal lobe of the human brain was in fact a system of anatomically connected structures that were organized into a memory system came in 1957 from the observations by Brenda Milner of the noted amnesic patient H.M. Subsequent work in humans, monkeys, and rodents has identified all of the components of the medial temporal lobe (MTL) that formed the memory system. Currently, work is ongoing to identify the specific contributions each structure in the medial temporal lobe makes towards the formation and storage of long-term declarative memory. The historical background of this work is described including what insights the study of noted neurologic patients H.M. and E.P. provided for understanding the function of the medial temporal lobe. The development of an animal model of medial temporal lobe function is described. Additionally, the insights that lead to the understanding that the brain contains multiple, anatomically discrete, memory systems are described. Finally, three current topics of debate are addressed: First, does the perirhinal cortex exclusively support memory, or does it support both memory and higher order visual perception? Second, is there an anatomical separation between recollection and familiarity ? Third, is the organization of spatial memory different between humans and rats, or perhaps the difference is between the working memory capacities of the two species?

  7. Imaging Evidence for Disturbances in Multiple Learning and Memory Systems in Persons with Autism Spectrum Disorders

    Science.gov (United States)

    Goh, Suzanne; Peterson, Bradley S.

    2012-01-01

    Aim: The aim of this article is to review neuroimaging studies of autism spectrum disorders (ASD) that examine declarative, socio-emotional, and procedural learning and memory systems. Method: We conducted a search of PubMed from 1996 to 2010 using the terms "autism,""learning,""memory," and "neuroimaging." We limited our review to studies…

  8. Stress Response Recruits the Hippocampal Endocannabinoid System for the Modulation of Fear Memory

    Science.gov (United States)

    Alvares, Lucas de Oliveira; Engelke, Douglas Senna; Diehl, Felipe; Scheffer-Teixeira, Robson; Haubrich, Josue; Cassini, Lindsey de Freitas; Molina, Victor Alejandro; Quillfeldt, Jorge Alberto

    2010-01-01

    The modulation of memory processes is one of the several functions of the endocannabinoid system (ECS) in the brain, with CB1 receptors highly expressed in areas such as the dorsal hippocampus. Experimental evidence suggested an important role of the ECS in aversively motivated memories. Similarly, glucocorticoids released in response to stress…

  9. Interference and memory capacity effects in memristive systems

    Science.gov (United States)

    Hermiz, John; Chang, Ting; Du, Chao; Lu, Wei

    2013-02-01

    Short-term memory implies the existence of a capacity limit beyond which memory cannot be securely formed and retained. The underlying mechanisms are believed to be two primary factors: decay and interference. Here, we demonstrate through both simulation and experiment that the memory capacity effect can be implemented in a parallel memristor circuit, where decay and interference are achieved by the inherent ion diffusion in the device and the competition for current supply in the circuit, respectively. This study suggests it is possible to emulate high-level biological behaviors with memristor circuits and will stimulate continued studies on memristor-based neuromorphic circuits.

  10. Striatal and extra-striatal dopamine transporter in cannabis and tobacco addiction: a high resolution PET study

    International Nuclear Information System (INIS)

    Leroy, C.; Martinot, J.L.; Duchesnay, E.; Artiges, E.; Ribeiro, M.J.; Trichard, Ch.; Karila, L.; Lukasiewicz, M.; Benyamina, A.; Reynaud, M.; Martinot, J.L.; Duchesnay, E.; Artiges, E.; Comtat, C.; Artiges, E.; Trichard, Ch.

    2011-01-01

    The dopamine (DA) system is known to be involved in the reward and dependence mechanisms of addiction. However, modifications in dopaminergic neurotransmission associated with long-term tobacco and cannabis use have been poorly documented in vivo. In order to assess striatal and extra-striatal dopamine transporter (DAT) availability in tobacco and cannabis addiction, three groups of male age-matched subjects were compared: 11 healthy non-smoker subjects, 14 tobacco-dependent smokers (17.6 ± 5.3 cigarettes/day for 12.1 ± 8.5 years) and 13 cannabis and tobacco smokers (CTS) (4.8 ± 5.3 cannabis joints/day for 8.7 ± 3.9 years). DAT availability was examined in positron emission tomography (HRRT) with a high resolution research tomograph after injection of [ 11 C]PE2I, a selective DAT radioligand. Region of interest and voxel-by-voxel approaches using a simplified reference tissue model were performed for the between-group comparison of DAT availability. Measurements in the dorsal striatum from both analyses were concordant and showed a mean 20% lower DAT availability in drug users compared with controls. Whole-brain analysis also revealed lower DAT availability in the ventral striatum, the midbrain, the middle cingulate and the thalamus (ranging from -15 to -30%). The DAT availability was slightly lower in all regions in CTS than in subjects who smoke tobacco only, but the difference does not reach a significant level. These results support the existence of a decrease in DAT availability associated with tobacco and cannabis addictions involving all dopaminergic brain circuits. These findings are consistent with the idea of a global decrease in cerebral DA activity in dependent subjects. (authors)

  11. NI Based System for Seu Testing of Memory Chips for Avionics

    Directory of Open Access Journals (Sweden)

    Boruzdina Anna

    2016-01-01

    Full Text Available This paper presents the results of implementation of National Instrument based system for Single Event Upset testing of memory chips into neutron generator experimental facility, which used for SEU tests for avionics purposes. Basic SEU testing algorithm with error correction and constant errors detection is presented. The issues of radiation shielding of NI based system are discussed and solved. The examples of experimental results show the applicability of the presented system for SEU memory testing under neutrons influence.

  12. Impairments of exploration and memory after systemic or prelimbic D1-receptor antagonism in rats

    DEFF Research Database (Denmark)

    Clausen, Bettina; Schachtman, Todd R.; Mark, Louise T.

    2011-01-01

    , was administered to rats via routes that either did or did not affect spontaneous exploration: systemic or prelimbic administration, respectively. Effects were tested in spatial and non-spatial memory tasks selected for their requirements for self-initiated exploration of stimuli to be remembered in order...... to examine the effects on memory: cross-maze and object recognition task. Systemic administration reduced spatial exploration in cross-maze as well as in an open field test, and also reduced object exploration. Spatial (hippocampus-dependent) short-term memory was inhibited in the cross-maze and non......D1-receptor antagonism is known to impair rodent memory but also inhibits spontaneous exploration of stimuli to be remembered. Hypo-exploration could contribute to impaired memory by influencing event processing. In order to explore this effect, the D1 receptor antagonist, SCH23390...

  13. A model for memory systems based on processing modes rather than consciousness.

    Science.gov (United States)

    Henke, Katharina

    2010-07-01

    Prominent models of human long-term memory distinguish between memory systems on the basis of whether learning and retrieval occur consciously or unconsciously. Episodic memory formation requires the rapid encoding of associations between different aspects of an event which, according to these models, depends on the hippocampus and on consciousness. However, recent evidence indicates that the hippocampus mediates rapid associative learning with and without consciousness in humans and animals, for long-term and short-term retention. Consciousness seems to be a poor criterion for differentiating between declarative (or explicit) and non declarative (or implicit) types of memory. A new model is therefore required in which memory systems are distinguished based on the processing operations involved rather than by consciousness.

  14. Assessment of striatal & postural deformities in patients with Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Sanjay Pandey

    2016-01-01

    Interpretation & conclusions: Our results showed that striatal and postural deformities were common and present in about half of the patients with PD. These deformities we more common in patients with advanced stage of PD.

  15. Prefrontal cortex and striatal activation by feedback in Parkinson's disease

    NARCIS (Netherlands)

    Keitz, Martijn; Koerts, Janneke; Kortekaas, Rudie; Renken, Remco; de Jong, Bauke M.; Leenders, Klaus L.

    2008-01-01

    Positive feedbacks reinforce goal-directed behavior and evoke pleasure. in Parkinson's disease (PD) the striatal dysfunction impairs motor performance, but also may lead to decreased positive feedback (reward) processing. This study investigates two types of positive feedback processing (monetary

  16. Striatal dysfunction in attention deficit and hyperkinetic disorder

    Energy Technology Data Exchange (ETDEWEB)

    Lou, H.C.; Henriksen, L.; Bruhn, P.; Borner, H.; Nielsen, J.B.

    1989-01-01

    We have previously reported that periventricular structures are hypoperfused in attention deficit and hyperactivity disorder (ADHD). This study has expanded the number of patients, who were divided into two groups: six patients with pure ADHD, and 13 patients with ADHD in combination with other neurologic symptoms. By using xenon 133 inhalation and emission tomography, the regional cerebral blood flow distribution was determined and compared with a control group. Striatal regions were found to be hypoperfused and, by inference, hypofunctional in both groups. This hypoperfusion was statistically significant in the right striatum in ADHD, and in both striatal regions in ADHD with other neuropsychologic and neurologic symptoms. The primary sensory and sensorimotor cortical regions were highly perfused. Methylphenidate increased flow to striatal and posterior periventricular regions, and tended to decrease flow to primary sensory regions. Low striatal activity, partially reversible with methylphenidate, appears to be a cardinal feature in ADHD.

  17. Striatal dysfunction in attention deficit and hyperkinetic disorder

    International Nuclear Information System (INIS)

    Lou, H.C.; Henriksen, L.; Bruhn, P.; Borner, H.; Nielsen, J.B.

    1989-01-01

    We have previously reported that periventricular structures are hypoperfused in attention deficit and hyperactivity disorder (ADHD). This study has expanded the number of patients, who were divided into two groups: six patients with pure ADHD, and 13 patients with ADHD in combination with other neurologic symptoms. By using xenon 133 inhalation and emission tomography, the regional cerebral blood flow distribution was determined and compared with a control group. Striatal regions were found to be hypoperfused and, by inference, hypofunctional in both groups. This hypoperfusion was statistically significant in the right striatum in ADHD, and in both striatal regions in ADHD with other neuropsychologic and neurologic symptoms. The primary sensory and sensorimotor cortical regions were highly perfused. Methylphenidate increased flow to striatal and posterior periventricular regions, and tended to decrease flow to primary sensory regions. Low striatal activity, partially reversible with methylphenidate, appears to be a cardinal feature in ADHD

  18. Memory disorders in children

    OpenAIRE

    Majerus, Steve; Van der Linden, Martial

    2013-01-01

    Memory disorders are a frequent consequence of a variety of childhood neurological conditions. We will review the characteristics of memory disorders as a function of the main four memory systems: short-term memory, episodic memory, semantic memory, and procedural memory. For each system, we will identify the most typical cerebral and/or genetic correlates, and we will discuss the impact of impairment of each memory system on everyday life functioning. © 2013 Elsevier B.V.

  19. Reduced striatal dopamine D2/3 receptor availability in Body Dysmorphic Disorder.

    Science.gov (United States)

    Vulink, Nienke C; Planting, Robin S; Figee, Martijn; Booij, Jan; Denys, Damiaan

    2016-02-01

    Though the dopaminergic system is implicated in Obsessive Compulsive and Related Disorders (OCRD), the dopaminergic system has never been investigated in-vivo in Body Dysmorphic Disorder (BDD). In line with consistent findings of reduced striatal dopamine D2/3 receptor availability in Obsessive Compulsive Disorder (OCD), we hypothesized that the dopamine D2/3 receptor availability in the striatum will be lower in patients with BDD in comparison to healthy subjects. Striatal dopamine D2/3 receptor Binding Potential (BPND) was examined in 12 drug-free BDD patients and 12 control subjects pairwise matched by age, sex, and handedness using [(123)I]iodobenzamide Single Photon Emission Computed Tomography (SPECT; bolus/constant infusion technique). Regions of interest were the caudate nucleus and the putamen. BPND was calculated as the ratio of specific striatal to binding in the occipital cortex (representing nonspecific binding). Compared to controls, dopamine D2/3 receptor BPND was significantly lower in BDD, both in the putamen (p=0.017) and caudate nucleus (p=0.022). This study provides the first evidence of a disturbed dopaminergic system in BDD patients. Although previously BDD was classified as a separate disorder (somatoform disorder), our findings give pathophysiological support for the recent reclassification of BDD to the OCRD in DSM-5. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  20. System Consolidation of Spatial Memories in Mice: Effects of Enriched Environment

    Directory of Open Access Journals (Sweden)

    Joyce Bonaccorsi

    2013-01-01

    Full Text Available Environmental enrichment (EE is known to enhance learning and memory. Declarative memories are thought to undergo a first rapid and local consolidation process, followed by a prolonged process of system consolidation, which consist in a time-dependent gradual reorganization of brain regions supporting remote memory storage and crucial for the formation of enduring memories. At present, it is not known whether EE can affect the process of declarative memory system consolidation. We characterized the time course of hippocampal and cortical activation following recall of progressively more remote spatial memories. Wild-type mice either exposed to EE for 40 days or left in standard environment were subjected to spatial learning in the Morris water maze and to the probe test 1, 10, 20, 30, and 50 days after learning. Following the probe test, regional expression of the inducible immediate early gene c-Fos was mapped by immunohistochemistry, as an indicator of neuronal activity. We found that activation of the medial prefrontal cortex (mPFC, suggested to have a privileged role in processing remote spatial memories, was evident at shorter time intervals after learning in EE mice; in addition, EE induced the progressive activation of a distributed cortical network not activated in non-EE mice. This suggests that EE not only accelerates the process of mPFC recruitment but also recruits additional cortical areas into the network supporting remote spatial memories.

  1. Striatal grafts in a rat model of Huntington's disease

    DEFF Research Database (Denmark)

    Guzman, R; Meyer, M; Lövblad, K O

    1999-01-01

    Survival and integration into the host brain of grafted tissue are crucial factors in neurotransplantation approaches. The present study explored the feasibility of using a clinical MR scanner to study striatal graft development in a rat model of Huntington's disease. Rat fetal lateral ganglionic...... eminences grown as free-floating roller-tube cultures can be successfully grafted in a rat Huntington model and that a clinical MR scanner offers a useful noninvasive tool for studying striatal graft development....

  2. Striatal direct and indirect pathways control decision-making behavior

    OpenAIRE

    Macpherson, Tom; Morita, Makiko; Hikida, Takatoshi

    2014-01-01

    Despite our ever-changing environment, animals are remarkably adept at selecting courses of action that are predictive of optimal outcomes. While requiring the contribution of a number of brain regions, a vast body of evidence implicates striatal mechanisms of associative learning and action selection to be critical to this ability. While numerous models of striatal-based decision-making have been developed, it is only recently that we have begun to understand the precise contributions of spe...

  3. An Examination of the Associations among Multiple Memory Systems, Past Tense, and Vocabulary in Typically Developing 5-Year-Old

    Science.gov (United States)

    Lum, Jarrad A. G.; Kidd, Evan

    2012-01-01

    Purpose: Considerable research has investigated the role of verbal working memory in language development in children with and without language problems. Much less is currently known about the relationship between language and the declarative and procedural memory systems. This study examined whether these 2 memory systems were related to…

  4. The role of the dorsal striatum in extinction: A memory systems perspective.

    Science.gov (United States)

    Goodman, Jarid; Packard, Mark G

    2018-04-01

    The present review describes a role for the dorsal striatum in extinction. Evidence from brain lesion and pharmacological studies indicate that the dorsolateral region of the striatum (DLS) mediates extinction in various maze learning and instrumental learning tasks. Within the context of a multiple memory systems view, the role of the DLS in extinction appears to be selective. Specifically, the DLS mediates extinction of habit memory and is not required for extinction of cognitive memory. Thus, extinction mechanisms mediated by the DLS may involve response-produced inhibition (e.g. inhibition of existing stimulus-response associations or formation of new inhibitory stimulus-response associations), as opposed to cognitive mechanisms (e.g. changes in expectation). Evidence also suggests that NMDA-dependent forms of synaptic plasticity may be part of the mechanism through which the DLS mediates extinction of habit memory. In addition, in some learning situations, DLS inactivation enhances extinction, suggesting a competitive interaction between multiple memory systems during extinction training. Consistent with a multiple memory systems perspective, it is suggested that the DLS represents one of several distinct neural systems that specialize in extinction of different kinds of memory. The relevance of these findings to the development of behavioral and pharmacological therapies that target the maladaptive habit-like symptoms in human psychopathology is also briefly considered. Published by Elsevier Inc.

  5. Embedded memory design for multi-core and systems on chip

    CERN Document Server

    Mohammad, Baker

    2014-01-01

    This book describes the various tradeoffs systems designers face when designing embedded memory.  Readers designing multi-core systems and systems on chip will benefit from the discussion of different topics from memory architecture, array organization, circuit design techniques and design for test.  The presentation enables a multi-disciplinary approach to chip design, which bridges the gap between the architecture level and circuit level, in order to address yield, reliability and power-related issues for embedded memory.  ·         Provides a comprehensive overview of embedded memory design and associated challenges and choices; ·         Explains tradeoffs and dependencies across different disciplines involved with multi-core and system on chip memory design; ·         Includes detailed discussion of memory hierarchy and its impact on energy and performance; ·         Uses real product examples to demonstrate embedded memory design flow from architecture, to circuit ...

  6. Propagation of soil moisture memory into the climate system

    Science.gov (United States)

    Orth, R.; Seneviratne, S. I.

    2012-04-01

    Soil moisture is known for its integrative behaviour and resulting memory characteristics. Associated anomalies can persist for weeks or even months into the future, making initial soil moisture an important potential component in weather forecasting. This is particularly crucial given the role of soil moisture for land-atmosphere interactions and its impacts on the water and energy balances on continents. We present here an analysis of the characteristics of soil moisture memory and of its propagation into runoff and evapotranspiration in Europe, based on available measurements from several sites across the continent and expanding a previous analysis focused on soil moisture [1]. We identify the main drivers of soil moisture memory at the analysed sites, as well as their role for the propagation of soil moisture persistence into runoff and evapotranspiration memory characteristics. We focus on temporal and spatial variations in these relationships and identify seasonal and latitudinal differences in the persistence of soil moisture, evapotranspiration and runoff. Finally, we assess the role of these persistence characteristics for the development of agricultural and hydrological droughts. [1] Orth and Seneviratne: Analysis of soil moisture memory from observations in Europe; submitted to J. Geophysical Research.

  7. Neonatal astrocyte damage is sufficient to trigger progressive striatal degeneration in a rat model of glutaric acidemia-I.

    Directory of Open Access Journals (Sweden)

    Silvia Olivera-Bravo

    Full Text Available BACKGROUND: We have investigated whether an acute metabolic damage to astrocytes during the neonatal period may critically disrupt subsequent brain development, leading to neurodevelopmental disorders. Astrocytes are vulnerable to glutaric acid (GA, a dicarboxylic acid that accumulates in millimolar concentrations in Glutaric Acidemia I (GA-I, an inherited neurometabolic childhood disease characterized by degeneration of striatal neurons. While GA induces astrocyte mitochondrial dysfunction, oxidative stress and subsequent increased proliferation, it is presently unknown whether such astrocytic dysfunction is sufficient to trigger striatal neuronal loss. METHODOLOGY/PRINCIPAL FINDINGS: A single intracerebroventricular dose of GA was administered to rat pups at postnatal day 0 (P0 to induce an acute, transient rise of GA levels in the central nervous system (CNS. GA administration potently elicited proliferation of astrocytes expressing S100β followed by GFAP astrocytosis and nitrotyrosine staining lasting until P45. Remarkably, GA did not induce acute neuronal loss assessed by FluoroJade C and NeuN cell count. Instead, neuronal death appeared several days after GA treatment and progressively increased until P45, suggesting a delayed onset of striatal degeneration. The axonal bundles perforating the striatum were disorganized following GA administration. In cell cultures, GA did not affect survival of either striatal astrocytes or neurons, even at high concentrations. However, astrocytes activated by a short exposure to GA caused neuronal death through the production of soluble factors. Iron porphyrin antioxidants prevented GA-induced astrocyte proliferation and striatal degeneration in vivo, as well as astrocyte-mediated neuronal loss in vitro. CONCLUSIONS/SIGNIFICANCE: Taken together, these results indicate that a transient metabolic insult with GA induces long lasting phenotypic changes in astrocytes that cause them to promote striatal

  8. A single-system model predicts recognition memory and repetition priming in amnesia.

    Science.gov (United States)

    Berry, Christopher J; Kessels, Roy P C; Wester, Arie J; Shanks, David R

    2014-08-13

    We challenge the claim that there are distinct neural systems for explicit and implicit memory by demonstrating that a formal single-system model predicts the pattern of recognition memory (explicit) and repetition priming (implicit) in amnesia. In the current investigation, human participants with amnesia categorized pictures of objects at study and then, at test, identified fragmented versions of studied (old) and nonstudied (new) objects (providing a measure of priming), and made a recognition memory judgment (old vs new) for each object. Numerous results in the amnesic patients were predicted in advance by the single-system model, as follows: (1) deficits in recognition memory and priming were evident relative to a control group; (2) items judged as old were identified at greater levels of fragmentation than items judged new, regardless of whether the items were actually old or new; and (3) the magnitude of the priming effect (the identification advantage for old vs new items) overall was greater than that of items judged new. Model evidence measures also favored the single-system model over two formal multiple-systems models. The findings support the single-system model, which explains the pattern of recognition and priming in amnesia primarily as a reduction in the strength of a single dimension of memory strength, rather than a selective explicit memory system deficit. Copyright © 2014 the authors 0270-6474/14/3410963-12$15.00/0.

  9. Insulin in the nervous system and the mind: Functions in metabolism, memory, and mood

    OpenAIRE

    Lee, Seung-Hwan; Zabolotny, Janice M.; Huang, Hu; Lee, Hyon; Kim, Young-Bum

    2016-01-01

    Background: Insulin, a pleotrophic hormone, has diverse effects in the body. Recent work has highlighted the important role of insulin's action in the nervous system on glucose and energy homeostasis, memory, and mood. Scope of review: Here we review experimental and clinical work that has broadened the understanding of insulin's diverse functions in the central and peripheral nervous systems, including glucose and body weight homeostasis, memory and mood, with particular emphasis on intra...

  10. Dopamine D1-like receptors depress excitatory synaptic transmissions in striatal neurons after transient forebrain ischemia.

    Science.gov (United States)

    Zhang, Yuchun; Deng, Ping; Ruan, Yiwen; Xu, Zao C

    2008-08-01

    Spiny neurons in the neostriatum are highly vulnerable to ischemia. Despite an enormous body of research suggesting that dopamine is involved in ischemia-induced neuronal loss in the striatum, it remains unclear how dopamine interacts with the glutamatergic excitotoxicity that is widely accepted as a major cause of ischemic cell death. Our study was designed to investigate the effects of dopamine D1 receptor (D1R) activation on excitatory neurotransmission in postischemic striatal neurons. We used the 4-vessel occlusion ischemia model and brain slice preparations. Whole-cell voltage-clamp recording was performed on striatal neurons to measure excitatory postsynaptic currents (EPSCs). Systemic administration of a D1R agonist after ischemia and hematoxylin/eosin staining were performed to evaluate the effects of D1R activation on ischemia-induced neuronal degeneration in the striatum. D1R activation depressed EPSCs in postischemic striatal neurons. The depression was attributable to inhibition of presynaptic release. An activator of cAMP-dependent protein kinase A (PKA) mimicked the depressive effects of D1R activation. Bath application of a PKA inhibitor blocked the depression of EPSCs, whereas intracellular postsynaptic application of the PKA inhibitor had no effect. The D1R agonist failed to reduce EPSC amplitude in the presence of an adenosine A1 receptor antagonist. Systemic administration of a D1R agonist after ischemia significantly attenuated ischemia-induced cell death in the striatum. These results indicate that D1R activation presynaptically depresses excitatory synaptic transmission in striatal neurons after ischemia through activation of PKA and adenosine A1 receptors and thus demonstrate a novel mechanism of D1R-mediated protection against ischemia.

  11. Episodic memory impairment in systemic lupus erythematosus: involvement of thalamic structures.

    Science.gov (United States)

    Zimmermann, Nicolle; Corrêa, Diogo Goulart; Netto, Tania Maria; Kubo, Tadeu; Pereira, Denis Batista; Fonseca, Rochele Paz; Gasparetto, Emerson Leandro

    2015-02-01

    Episodic memory deficits in systemic lupus erythematosus (SLE) have been frequently reported in the literature; however, little is known about the neural correlates of these deficits. We investigated differences in the volumes of different brain structures of SLE patients with and without episodic memory impairments diagnosed by the Rey Auditory Verbal Learning Test (RAVLT). Groups were paired based on age, education, sex, Mini Mental State Examination score, accumulation of disease burden (SLICC), and focused attention dimension score. Patients underwent magnetic resonance imaging (MRI). Cortical volumetric reconstruction and segmentation of the MR images were performed with the FreeSurfer software program. SLE patients with episodic memory deficits presented shorter time of diagnosis than SLE patients without episodic memory deficits. ANOVA revealed that SLE patients with episodic memory deficits had a larger third ventricle volume than SLE patients without episodic memory deficits and controls. Additionally, covariance analysis indicated group effects on the bilateral thalamus and on the third ventricle. Our findings indicate that episodic memory may be impaired in SLE patients with normal hippocampal volume. In addition, the thalamus may undergo volumetric changes associated with episodic memory loss in SLE.

  12. Metabolic learning and memory formation by the brain influence systemic metabolic homeostasis.

    Science.gov (United States)

    Zhang, Yumin; Liu, Gang; Yan, Jingqi; Zhang, Yalin; Li, Bo; Cai, Dongsheng

    2015-04-07

    Metabolic homeostasis is regulated by the brain, but whether this regulation involves learning and memory of metabolic information remains unexplored. Here we use a calorie-based, taste-independent learning/memory paradigm to show that Drosophila form metabolic memories that help in balancing food choice with caloric intake; however, this metabolic learning or memory is lost under chronic high-calorie feeding. We show that loss of individual learning/memory-regulating genes causes a metabolic learning defect, leading to elevated trehalose and lipid levels. Importantly, this function of metabolic learning requires not only the mushroom body but also the hypothalamus-like pars intercerebralis, while NF-κB activation in the pars intercerebralis mimics chronic overnutrition in that it causes metabolic learning impairment and disorders. Finally, we evaluate this concept of metabolic learning/memory in mice, suggesting that the hypothalamus is involved in a form of nutritional learning and memory, which is critical for determining resistance or susceptibility to obesity. In conclusion, our data indicate that the brain, and potentially the hypothalamus, direct metabolic learning and the formation of memories, which contribute to the control of systemic metabolic homeostasis.

  13. Metabolic learning and memory formation by the brain influence systemic metabolic homeostasis

    Science.gov (United States)

    Zhang, Yumin; Liu, Gang; Yan, Jingqi; Zhang, Yalin; Li, Bo; Cai, Dongsheng

    2015-01-01

    Metabolic homeostasis is regulated by the brain, whether this regulation involves learning and memory of metabolic information remains unexplored. Here we use a calorie-based, taste-independent learning/memory paradigm to show that Drosophila form metabolic memories that help balancing food choice with caloric intake; however, this metabolic learning or memory is lost under chronic high-calorie feeding. We show that loss of individual learning/memory-regulating genes causes a metabolic learning defect, leading to elevated trehalose and lipids levels. Importantly, this function of metabolic learning requires not only the mushroom body but the hypothalamus-like pars intercerebralis, while NF-κB activation in the pars intercerebralis mimics chronic overnutrition in that it causes metabolic learning impairment and disorders. Finally, we evaluate this concept of metabolic learning/memory in mice, suggesting the hypothalamus is involved in a form of nutritional learning and memory, which is critical for determining resistance or susceptibility to obesity. In conclusion, our data indicate the brain, and potentially the hypothalamus, direct metabolic learning and the formation of memories, which contribute to the control of systemic metabolic homeostasis. PMID:25848677

  14. How does a specific learning and memory system in the mammalian brain gain control of behavior?

    Science.gov (United States)

    McDonald, Robert J; Hong, Nancy S

    2013-11-01

    This review addresses a fundamental, yet poorly understood set of issues in systems neuroscience. The issues revolve around conceptualizations of the organization of learning and memory in the mammalian brain. One intriguing, and somewhat popular, conceptualization is the idea that there are multiple learning and memory systems in the mammalian brain and they interact in different ways to influence and/or control behavior. This approach has generated interesting empirical and theoretical work supporting this view. One issue that needs to be addressed is how these systems influence or gain control of voluntary behavior. To address this issue, we clearly specify what we mean by a learning and memory system. We then review two types of processes that might influence which memory system gains control of behavior. One set of processes are external factors that can affect which system controls behavior in a given situation including task parameters like the kind of information available to the subject, types of training experience, and amount of training. The second set of processes are brain mechanisms that might influence what memory system controls behavior in a given situation including executive functions mediated by the prefrontal cortex; switching mechanisms mediated by ascending neurotransmitter systems, the unique role of the hippocampus during learning. The issue of trait differences in control of different learning and memory systems will also be considered in which trait differences in learning and memory function are thought to potentially emerge from differences in level of prefrontal influence, differences in plasticity processes, differences in ascending neurotransmitter control, differential access to effector systems like motivational and motor systems. Finally, we present scenarios in which different mechanisms might interact. This review was conceived to become a jumping off point for new work directed at understanding these issues. The outcome of

  15. Systemic Lisbon Battery: Normative Data for Memory and Attention Assessments.

    Science.gov (United States)

    Gamito, Pedro; Morais, Diogo; Oliveira, Jorge; Ferreira Lopes, Paulo; Picareli, Luís Felipe; Matias, Marcelo; Correia, Sara; Brito, Rodrigo

    2016-05-04

    Memory and attention are two cognitive domains pivotal for the performance of instrumental activities of daily living (IADLs). The assessment of these functions is still widely carried out with pencil-and-paper tests, which lack ecological validity. The evaluation of cognitive and memory functions while the patients are performing IADLs should contribute to the ecological validity of the evaluation process. The objective of this study is to establish normative data from virtual reality (VR) IADLs designed to activate memory and attention functions. A total of 243 non-clinical participants carried out a paper-and-pencil Mini-Mental State Examination (MMSE) and performed 3 VR activities: art gallery visual matching task, supermarket shopping task, and memory fruit matching game. The data (execution time and errors, and money spent in the case of the supermarket activity) was automatically generated from the app. Outcomes were computed using non-parametric statistics, due to non-normality of distributions. Age, academic qualifications, and computer experience all had significant effects on most measures. Normative values for different levels of these measures were defined. Age, academic qualifications, and computer experience should be taken into account while using our VR-based platform for cognitive assessment purposes. ©Pedro Gamito, Diogo Morais, Jorge Oliveira, Paulo Ferreira Lopes, Luís Felipe Picareli, Marcelo Matias, Sara Correia, Rodrigo Brito. Originally published in JMIR Rehabilitation and Assistive Technology (http://rehab.jmir.org), 04.05.2016.

  16. Memory handling in the ATLAS submission system from job definition to sites limits

    CERN Document Server

    Forti, Alessandra; The ATLAS collaboration

    2016-01-01

    The ATLAS workload management system is a pilot system based on a late binding philosophy that avoided for many years to pass fine grained job requirements to the batch system. In particular for memory most of the requirements were set to request 4GB vmem as defined in the EGI portal VO card, i.e. 2GB RAM + 2GB swap. However in the past few years several changes have happened in the operating system kernel and in the applications that make such a definition of memory to use for requesting slots obsolete and ATLAS has introduced the new PRODSYS2 workload management which has a more flexible system to evaluate the memory requirements and to submit to appropriate queues. The work stemmed in particular from the introduction of 64bit multicore workloads and the increased memory requirements of some of the single core applications. This paper describes the overall review and changes of memory handling starting from the definition of tasks, the way tasks memory requirements are set using scout jobs and the new memor...

  17. Discrete Serotonin Systems Mediate Memory Enhancement and Escape Latencies after Unpredicted Aversive Experience in Drosophila Place Memory

    Directory of Open Access Journals (Sweden)

    Divya Sitaraman

    2017-12-01

    Full Text Available Feedback mechanisms in operant learning are critical for animals to increase reward or reduce punishment. However, not all conditions have a behavior that can readily resolve an event. Animals must then try out different behaviors to better their situation through outcome learning. This form of learning allows for novel solutions and with positive experience can lead to unexpected behavioral routines. Learned helplessness, as a type of outcome learning, manifests in part as increases in escape latency in the face of repeated unpredicted shocks. Little is known about the mechanisms of outcome learning. When fruit fly Drosophilamelanogaster are exposed to unpredicted high temperatures in a place learning paradigm, flies both increase escape latencies and have a higher memory when given control of a place/temperature contingency. Here we describe discrete serotonin neuronal circuits that mediate aversive reinforcement, escape latencies, and memory levels after place learning in the presence and absence of unexpected aversive events. The results show that two features of learned helplessness depend on the same modulatory system as aversive reinforcement. Moreover, changes in aversive reinforcement and escape latency depend on local neural circuit modulation, while memory enhancement requires larger modulation of multiple behavioral control circuits.

  18. Quinolinic acid induces disrupts cytoskeletal homeostasis in striatal neurons. Protective role of astrocyte-neuron interaction.

    Science.gov (United States)

    Pierozan, Paula; Ferreira, Fernanda; de Lima, Bárbara Ortiz; Pessoa-Pureur, Regina

    2015-02-01

    Quinolinic acid (QUIN) is an endogenous metabolite of the kynurenine pathway involved in several neurological disorders. Among the several mechanisms involved in QUIN-mediated toxicity, disruption of the cytoskeleton has been demonstrated in striatally injected rats and in striatal slices. The present work searched for the actions of QUIN in primary striatal neurons. Neurons exposed to 10 µM QUIN presented hyperphosphorylated neurofilament (NF) subunits (NFL, NFM, and NFH). Hyperphosphorylation was abrogated in the presence of protein kinase A and protein kinase C inhibitors H89 (20 μM) and staurosporine (10 nM), respectively, as well as by specific antagonists to N-methyl-D-aspartate (50 µM DL-AP5) and metabotropic glutamate receptor 1 (100 µM MPEP). Also, intra- and extracellular Ca(2+) chelators (10 µM BAPTA-AM and 1 mM EGTA, respectively) and Ca(2+) influx through L-type voltage-dependent Ca(2+) channel (10 µM verapamil) are implicated in QUIN-mediated effects. Cells immunostained for the neuronal markers βIII-tubulin and microtubule-associated protein 2 showed altered neurite/neuron ratios and neurite outgrowth. NF hyperphosphorylation and morphological alterations were totally prevented by conditioned medium from QUIN-treated astrocytes. Cocultured astrocytes and neurons interacted with one another reciprocally, protecting them against QUIN injury. Cocultured cells preserved their cytoskeletal organization and cell morphology together with unaltered activity of the phosphorylating system associated with the cytoskeleton. This article describes cytoskeletal disruption as one of the most relevant actions of QUIN toxicity in striatal neurons in culture with soluble factors secreted by astrocytes, with neuron-astrocyte interaction playing a role in neuroprotection. © 2014 Wiley Periodicals, Inc.

  19. Ventral striatal dopamine synthesis capacity predicts financial extravagance in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Andrew David Lawrence

    2013-02-01

    Full Text Available Impulse control disorders (ICDs, including disordered gambling, can occur in a significant number of patients with Parkinson’s disease (PD receiving dopaminergic therapy. The neurobiology underlying susceptibility to such problems is unclear, but risk likely results from an interaction between dopaminergic medication and a pre-existing trait vulnerability. Impulse control and addictive disorders form part of a broader psychopathological spectrum of disorders, which share a common underlying genetic vulnerability, referred to as externalizing. The broad externalizing risk factor is a continuously varying trait reflecting vulnerability to various impulse control problems, manifested at the overt level by disinhibitory symptoms and at the personality level by antecedent traits such as impulsivity and novelty/sensation seeking. Trait ‘disinhibition’ is thus a core endophenotype of ICDs, and a key target for neurobiological investigation. The ventral striatal dopamine system has been hypothesized to underlie individual variation in behavioural disinhibition. Here, we examined whether individual differences in ventral striatal dopamine synthesis capacity predicted individual variation in disinhibitory temperament traits in individuals with PD. Eighteen early-stage male PD patients underwent 6-[18F]Fluoro-L-DOPA (FDOPA positron emission tomography (PET scanning to measure striatal dopamine synthesis capacity, and completed a measure of disinhibited personality. Consistent with our predictions, we found that levels of ventral, but not dorsal, striatal dopamine synthesis capacity predicted disinhibited personality, particularly a propensity for financial extravagance. Our results are consistent with recent preclinical models of vulnerability to behavioural disinhibition and addiction proneness, and provide novel insights into the neurobiology of potential vulnerability to impulse control problems in PD and other disorders.

  20. A direct ROI quantification method for inherent PVE correction: accuracy assessment in striatal SPECT measurements

    Energy Technology Data Exchange (ETDEWEB)

    Vanzi, Eleonora; De Cristofaro, Maria T.; Sotgia, Barbara; Mascalchi, Mario; Formiconi, Andreas R. [University of Florence, Clinical Pathophysiology, Florence (Italy); Ramat, Silvia [University of Florence, Neurological and Psychiatric Sciences, Florence (Italy)

    2007-09-15

    The clinical potential of striatal imaging with dopamine transporter (DAT) SPECT tracers is hampered by the limited capability to recover activity concentration ratios due to partial volume effects (PVE). We evaluated the accuracy of a least squares method that allows retrieval of activity in regions of interest directly from projections (LS-ROI). An Alderson striatal phantom was filled with striatal to background ratios of 6:1, 9:1 and 28:1; the striatal and background ROIs were drawn on a coregistered X-ray CT of the phantom. The activity ratios of these ROIs were derived both with the LS-ROI method and with conventional SPECT EM reconstruction (EM-SPECT). Moreover, the two methods were compared in seven patients with motor symptoms who were examined with N-3-fluoropropyl-2-{beta}-carboxymethoxy-3-{beta}-(4-iodophenyl) (FP-CIT) SPECT, calculating the binding potential (BP). In the phantom study, the activity ratios obtained with EM-SPECT were 3.5, 5.3 and 17.0, respectively, whereas the LS-ROI method resulted in ratios of 6.2, 9.0 and 27.3, respectively. With the LS-ROI method, the BP in the seven patients was approximately 60% higher than with EM-SPECT; a linear correlation between the LS-ROI and the EM estimates was found (r = 0.98, p = 0.03). The LS-ROI PVE correction capability is mainly due to the fact that the ill-conditioning of the LS-ROI approach is lower than that of the EM-SPECT one. The LS-ROI seems to be feasible and accurate in the examination of the dopaminergic system. This approach can be fruitful in monitoring of disease progression and in clinical trials of dopaminergic drugs. (orig.)

  1. Disrupted functional connectivity of striatal sub-regions in Bell's palsy patients

    Directory of Open Access Journals (Sweden)

    Wenwen Song

    2017-01-01

    Full Text Available The striatum plays an important role in controlling motor function in humans, and its degeneration has the ability to cause severe motor disorders. More specifically, previous studies have demonstrated a disruption in the connectivity of the cortico-striatal loop in patients suffering from motor disorders caused by dopamine dysregulation, such as Parkinson's disease. However, little is known about striatal functional connectivity in patients with motor dysfunction not caused by dopamine dysregulation. In this study, we used early-state Bell's palsy (BP patients (within 14 days of onset to investigate how functional connectivity between the striatum and motor cortex is affected by peripheral nerve injury in which the dopamine system remains fully functional. We found a significant increase in the connectivity between the contralateral putamen, and the ipsilateral primary sensory (S1 and motor cortex (M1 in BP patients compared to healthy controls. We also found increased connectivity between the ventral striatum and supplementary motor area (SMA, and the dorsal caudate and medial prefrontal lobe in BP patients compared to healthy controls. Our results demonstrate that the entirety of the striatum is affected following acute peripheral nerve injury, and suggests that this disrupted striatal functional connectivity may reflect a compensatory mechanism for the sensory-motor mismatch caused by BP.

  2. Tamoxifen counteracts estradiol induced effects on striatal and hypophyseal dopamine receptors

    International Nuclear Information System (INIS)

    Ferretti, C.; Blengio, M.; Ghi, P.; Racca, S.; Genazzani, E.; Portaleone, P.

    1988-01-01

    We investigated the ability of Tamoxifen (TAM), an antiestrogen drug, to counteract the modification induced by estrogens on dopamine (DA) receptors on striatum and on adenohypophysis of ovex female rats. Subacute treatment with 17β-estradiol (E 2 ) at both low (0.1 μg/kg) and high (20 μg/kg) doses confirmed its ability to increase the number of striatal 3 H-Spiperone ( 3 H-SPI) binding sites in a dose dependent manner. By contrast in the pituitary, only high doses of estrogen were effective in reducing the number of DA receptors. We treated ovex female rats for 15 days with TAM alone or associated with E 2 , to see if these estrogenic effects could be suppressed by an antiestrogenic drug. TAM did not affect the number of striatal DA receptors, but significantly increased the adenohypophy-seal DA binding sites, without varying their affinity. No changes were observed in pituitary and striatal DA receptor density, even when TAM was injected in association with estradiol. In conclusions: TAM is able to counteract the effects estrogens have on DA receptors. However there is some evidence that it could influence the pituitary DA systems independently of it antiestrogenic activity

  3. Tamoxifen counteracts estradiol induced effects on striatal and hypophyseal dopamine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Ferretti, C.; Blengio, M.; Ghi, P.; Racca, S.; Genazzani, E.; Portaleone, P.

    1988-01-01

    We investigated the ability of Tamoxifen (TAM), an antiestrogen drug, to counteract the modification induced by estrogens on dopamine (DA) receptors on striatum and on adenohypophysis of ovex female rats. Subacute treatment with 17..beta..-estradiol (E/sub 2/) at both low (0.1 ..mu..g/kg) and high (20 ..mu..g/kg) doses confirmed its ability to increase the number of striatal /sup 3/H-Spiperone (/sup 3/H-SPI) binding sites in a dose dependent manner. By contrast in the pituitary, only high doses of estrogen were effective in reducing the number of DA receptors. We treated ovex female rats for 15 days with TAM alone or associated with E/sub 2/, to see if these estrogenic effects could be suppressed by an antiestrogenic drug. TAM did not affect the number of striatal DA receptors, but significantly increased the adenohypophy-seal DA binding sites, without varying their affinity. No changes were observed in pituitary and striatal DA receptor density, even when TAM was injected in association with estradiol. In conclusions: TAM is able to counteract the effects estrogens have on DA receptors. However there is some evidence that it could influence the pituitary DA systems independently of it antiestrogenic activity.

  4. In Vitro Manganese Exposure Disrupts MAPK Signaling Pathways in Striatal and Hippocampal Slices from Immature Rats

    Directory of Open Access Journals (Sweden)

    Tanara Vieira Peres

    2013-01-01

    Full Text Available The molecular mechanisms mediating manganese (Mn-induced neurotoxicity, particularly in the immature central nervous system, have yet to be completely understood. In this study, we investigated whether mitogen-activated protein kinases (MAPKs and tyrosine hydroxylase (TH could represent potential targets of Mn in striatal and hippocampal slices obtained from immature rats (14 days old. The aim of this study was to evaluate if the MAPK pathways are modulated after subtoxic Mn exposure, which do not significantly affect cell viability. The concentrations of manganese chloride (MnCl2; 10–1,000 μM caused no change in cell viability in slices exposed for 3 or 6 hours. However, Mn exposure significantly increased extracellular signal-regulated kinase (ERK 1/2, as well as c-Jun N-terminal kinase (JNK 1/2/3 phosphorylation at both 3 and 6 hours incubations, in both brain structures. Furthermore, Mn exposure did not change the total content or phosphorylation of TH at the serine 40 site in striatal slices. Thus, Mn at concentrations that do not disrupt cell viability causes activation of MAPKs (ERK1/2 and JNK1/2/3 in immature hippocampal and striatal slices. These findings suggest that altered intracellular MAPKs signaling pathways may represent an early event concerning the effects of Mn in the immature brain.

  5. Individual differences in algebraic cognition: Relation to the approximate number and semantic memory systems.

    Science.gov (United States)

    Geary, David C; Hoard, Mary K; Nugent, Lara; Rouder, Jeffrey N

    2015-12-01

    The relation between performance on measures of algebraic cognition and acuity of the approximate number system (ANS) and memory for addition facts was assessed for 171 ninth graders (92 girls) while controlling for parental education, sex, reading achievement, speed of numeral processing, fluency of symbolic number processing, intelligence, and the central executive component of working memory. The algebraic tasks assessed accuracy in placing x,y pairs in the coordinate plane, speed and accuracy of expression evaluation, and schema memory for algebra equations. ANS acuity was related to accuracy of placements in the coordinate plane and expression evaluation but not to schema memory. Frequency of fact retrieval errors was related to schema memory but not to coordinate plane or expression evaluation accuracy. The results suggest that the ANS may contribute to or be influenced by spatial-numerical and numerical-only quantity judgments in algebraic contexts, whereas difficulties in committing addition facts to long-term memory may presage slow formation of memories for the basic structure of algebra equations. More generally, the results suggest that different brain and cognitive systems are engaged during the learning of different components of algebraic competence while controlling for demographic and domain general abilities. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Memory handling in the ATLAS submission system from job definition to sites limits

    Science.gov (United States)

    Forti, A. C.; Walker, R.; Maeno, T.; Love, P.; Rauschmayr, N.; Filipcic, A.; Di Girolamo, A.

    2017-10-01

    In the past few years the increased luminosity of the LHC, changes in the linux kernel and a move to a 64bit architecture have affected the ATLAS jobs memory usage and the ATLAS workload management system had to be adapted to be more flexible and pass memory parameters to the batch systems, which in the past wasn’t a necessity. This paper describes the steps required to add the capability to better handle memory requirements, included the review of how each component definition and parametrization of the memory is mapped to the other components, and what changes had to be applied to make the submission chain work. These changes go from the definition of tasks and the way tasks memory requirements are set using scout jobs, through the new memory tool developed to do that, to how these values are used by the submission component of the system and how the jobs are treated by the sites through the CEs, batch systems and ultimately the kernel.

  7. Memory handling in the ATLAS submission system from job definition to sites limits

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00027700; The ATLAS collaboration; Walker, Rodney; Maeno, Tadashi; Love, Peter; Rauschmayr, Nathalie; Filipcic, Andrej; Di Girolamo, Alessandro

    2017-01-01

    In the past few years the increased luminosity of the LHC, changes in the linux kernel and a move to a 64bit architecture have affected the ATLAS jobs memory usage and the ATLAS workload management system had to be adapted to be more flexible and pass memory parameters to the batch systems, which in the past wasn’t a necessity. This paper describes the steps required to add the capability to better handle memory requirements, included the review of how each component definition and parametrization of the memory is mapped to the other components, and what changes had to be applied to make the submission chain work. These changes go from the definition of tasks and the way tasks memory requirements are set using scout jobs, through the new memory tool developed to do that, to how these values are used by the submission component of the system and how the jobs are treated by the sites through the CEs, batch systems and ultimately the kernel.

  8. Sensory Entrainment Mechanisms in Auditory Perception: Neural Synchronization Cortico-Striatal Activation

    Science.gov (United States)

    Sameiro-Barbosa, Catia M.; Geiser, Eveline

    2016-01-01

    The auditory system displays modulations in sensitivity that can align with the temporal structure of the acoustic environment. This sensory entrainment can facilitate sensory perception and is particularly relevant for audition. Systems neuroscience is slowly uncovering the neural mechanisms underlying the behaviorally observed sensory entrainment effects in the human sensory system. The present article summarizes the prominent behavioral effects of sensory entrainment and reviews our current understanding of the neural basis of sensory entrainment, such as synchronized neural oscillations, and potentially, neural activation in the cortico-striatal system. PMID:27559306

  9. Energy-aware Thread and Data Management in Heterogeneous Multi-core, Multi-memory Systems

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chun-Yi [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2014-12-16

    By 2004, microprocessor design focused on multicore scaling—increasing the number of cores per die in each generation—as the primary strategy for improving performance. These multicore processors typically equip multiple memory subsystems to improve data throughput. In addition, these systems employ heterogeneous processors such as GPUs and heterogeneous memories like non-volatile memory to improve performance, capacity, and energy efficiency. With the increasing volume of hardware resources and system complexity caused by heterogeneity, future systems will require intelligent ways to manage hardware resources. Early research to improve performance and energy efficiency on heterogeneous, multi-core, multi-memory systems focused on tuning a single primitive or at best a few primitives in the systems. The key limitation of past efforts is their lack of a holistic approach to resource management that balances the tradeoff between performance and energy consumption. In addition, the shift from simple, homogeneous systems to these heterogeneous, multicore, multi-memory systems requires in-depth understanding of efficient resource management for scalable execution, including new models that capture the interchange between performance and energy, smarter resource management strategies, and novel low-level performance/energy tuning primitives and runtime systems. Tuning an application to control available resources efficiently has become a daunting challenge; managing resources in automation is still a dark art since the tradeoffs among programming, energy, and performance remain insufficiently understood. In this dissertation, I have developed theories, models, and resource management techniques to enable energy-efficient execution of parallel applications through thread and data management in these heterogeneous multi-core, multi-memory systems. I study the effect of dynamic concurrent throttling on the performance and energy of multi-core, non-uniform memory access

  10. A Hybrid Approach to Processing Big Data Graphs on Memory-Restricted Systems

    KAUST Repository

    Harshvardhan,

    2015-05-01

    With the advent of big-data, processing large graphs quickly has become increasingly important. Most existing approaches either utilize in-memory processing techniques that can only process graphs that fit completely in RAM, or disk-based techniques that sacrifice performance. In this work, we propose a novel RAM-Disk hybrid approach to graph processing that can scale well from a single shared-memory node to large distributed-memory systems. It works by partitioning the graph into sub graphs that fit in RAM and uses a paging-like technique to load sub graphs. We show that without modifying the algorithms, this approach can scale from small memory-constrained systems (such as tablets) to large-scale distributed machines with 16, 000+ cores.

  11. Compromised fronto-striatal functioning in HIV: an fMRI investigation of semantic event sequencing.

    Science.gov (United States)

    Melrose, Rebecca J; Tinaz, Sule; Castelo, J Mimi Boer; Courtney, Maureen G; Stern, Chantal E

    2008-04-09

    The human immunodeficiency virus (HIV) damages fronto-striatal regions, and is associated with deficits in executive functioning. We recently developed a semantic event sequencing task based on the Picture Arrangement subtest of the Wechsler Adult Intelligence Scale-III for use with functional magnetic resonance imaging (fMRI) and found recruitment of dorsolateral prefrontal cortex and basal ganglia in healthy participants. To assess the impact of HIV on the functioning of the basal ganglia and prefrontal cortex, we administered this task to 11 HIV+ and 11 Control participants matched for age and education. Neuropsychological evaluation demonstrated that the HIV+ group had mild impairment in memory retrieval and motor functioning, but was not demented. Morphometric measurements suggested no atrophy in basal ganglia regions. The results of the fMRI analysis revealed hypoactivation of the left caudate, left dorsolateral prefrontal cortex, and bilateral ventral prefrontal cortex in the HIV+ group. Functional connectivity analysis demonstrated less functional connectivity between the caudate and prefrontal cortex and basal ganglia regions in the HIV+ group. In contrast, the HIV+ group demonstrated increased activation of right postcentral/supramarginal gyrus, and greater connectivity between the caudate and this same anterior parietal region. The results of this study extend previous investigations by demonstrating compromised function of the caudate and connected prefrontal regions in HIV during cognition. This disruption of fronto-striatal circuitry likely precedes the development of cognitive impairment in HIV.

  12. Hierarchy of Processing Memories in the Human Visual System

    Science.gov (United States)

    Williamson, S. J.; Uusitalo, M. A.

    1997-03-01

    Magnetic source imaging, obtained with an array of 122 superconducting sensors, reveals a dynamical organization of visual cortical areas suggesting that the participation of local memories is an essential component of visual information processing. Response recovery studies provide evidence that each responding cortical area supports a memory function with a well-defined lifetime. The areas fell into two groups: the earliest in occipital lobes with lifetimes ranging from 0.1 to 0.6 s, and the later ones in temporal, parietal, and frontal areas with lifetimes ranging from 7 to 30 s. Also, within each group the areas responding later tended to have longer lifetimes. These hierarchical features introduce a dynamic element that is lacking in many contemporary models of visual processing.

  13. Sleep-dependent consolidation in multiple memory systems

    OpenAIRE

    Schönauer, Monika

    2014-01-01

    Before newly formed memories can last for the long-term, they must undergo a period of consolidation. It has been shown that sleep facilitates this process. One hypothesis about how this may occur is that learning-related neuronal activity is replayed during following sleep periods. Such a reactivation of neural activity patterns has been repeatedly shown in the hippocampal formation in animals. Hippocampally-induced reactivation can also be observed in other brain areas like the neocortex an...

  14. Analysis of Neural Systems Involved in Modulation of Memory Storage

    Science.gov (United States)

    1993-02-01

    blocked by concurrent infusion of low doses of the adrenergic agonist clenbuterol . Furthermore, low and otherwise ineffective doses of the adrenergic...we found that the retention-enhancing effects of clenbuterol were blocked by a low dose of the cholinergic antagonist atropine. In addition, a low dose...Involvement of the amygdala in the memory-enhancing effects of clenbuterol . Psychopharmacology, 1991, 104, 541-544. McGaugh, J.L. Neuromodulation and

  15. Memory recall in a process control system: a measure of expertise and display effectiveness.

    Science.gov (United States)

    Vicente, K J

    1992-07-01

    Previous research has shown that memory-recall performance is correlated with domain expertise. In this study, a process control system was selected as a vehicle for conducting research on memory recall. The primary purposes of the present work were to determine if the classic expertise effects originally obtained in chess generalize to this novel domain and to evaluate the validity of memory recall as a measure of display effectiveness. Experts and novices viewed dynamic event sequences showing the behavior of a thermal-hydraulic system with two different displays, one that only contained information about the physical components in the system (P) and another that also contained information about higher order functional variables (P+F). There were three types of trials: normal, where the system was operating correctly; fault, where a single fault was introduced; and random, where the system's behavior did not obey physical laws. On each trial, subjects were asked to recall the final state of the system and to diagnose the system state. The P+F display resulted in superior diagnosis performance compared with the P display. With regard to memory, there was some evidence of an interaction between trial type and expertise, with experts outperforming novices but primarily on meaningful trials. In addition, memory for the subset of variables most critical to diagnosis was better with the P+F display than with the P display, thereby indicating that memory recall can be a sensitive measure of display effectiveness. The results also clarify a theoretical problem that has existed for some time in the literature, namely, the conditions under which expertise advantages are to be expected in memory-recall tasks. Collectively, these findings point to the potential benefits of adopting an applied context as a test bed for basic research issues.

  16. Memory management and compiler support for rapid recovery from failures in computer systems

    Science.gov (United States)

    Fuchs, W. K.

    1991-01-01

    This paper describes recent developments in the use of memory management and compiler technology to support rapid recovery from failures in computer systems. The techniques described include cache coherence protocols for user transparent checkpointing in multiprocessor systems, compiler-based checkpoint placement, compiler-based code modification for multiple instruction retry, and forward recovery in distributed systems utilizing optimistic execution.

  17. Involvement of the amygdala in memory storage: Interaction with other brain systems

    Science.gov (United States)

    McGaugh, James L.; Cahill, Larry; Roozendaal, Benno

    1996-01-01

    There is extensive evidence that the amygdala is involved in affectively influenced memory. The central hypothesis guiding the research reviewed in this paper is that emotional arousal activates the amygdala and that such activation results in the modulation of memory storage occurring in other brain regions. Several lines of evidence support this view. First, the effects of stress-related hormones (epinephrine and glucocorticoids) are mediated by influences involving the amygdala. In rats, lesions of the amygdala and the stria terminalis block the effects of posttraining administration of epinephrine and glucocorticoids on memory. Furthermore, memory is enhanced by posttraining intra-amygdala infusions of drugs that activate β-adrenergic and glucocorticoid receptors. Additionally, infusion of β-adrenergic blockers into the amygdala blocks the memory-modulating effects of epinephrine and glucocorticoids, as well as those of drugs affecting opiate and GABAergic systems. Second, an intact amygdala is not required for expression of retention. Inactivation of the amygdala prior to retention testing (by posttraining lesions or drug infusions) does not block retention performance. Third, findings of studies using human subjects are consistent with those of animal experiments. β-Blockers and amygdala lesions attenuate the effects of emotional arousal on memory. Additionally, 3-week recall of emotional material is highly correlated with positron-emission tomography activation (cerebral glucose metabolism) of the right amygdala during encoding. These findings provide strong evidence supporting the hypothesis that the amygdala is involved in modulating long-term memory storage. PMID:8942964

  18. The development of brain systems associated with successful memory retrieval of scenes.

    Science.gov (United States)

    Ofen, Noa; Chai, Xiaoqian J; Schuil, Karen D I; Whitfield-Gabrieli, Susan; Gabrieli, John D E

    2012-07-18

    Neuroanatomical and psychological evidence suggests prolonged maturation of declarative memory systems in the human brain from childhood into young adulthood. Here, we examine functional brain development during successful memory retrieval of scenes in children, adolescents, and young adults ages 8-21 via functional magnetic resonance imaging. Recognition memory improved with age, specifically for accurate identification of studied scenes (hits). Successful retrieval (correct old-new decisions for studied vs unstudied scenes) was associated with activations in frontal, parietal, and medial temporal lobe (MTL) regions. Activations associated with successful retrieval increased with age in left parietal cortex (BA7), bilateral prefrontal, and bilateral caudate regions. In contrast, activations associated with successful retrieval did not change with age in the MTL. Psychophysiological interaction analysis revealed that there were, however, age-relate changes in differential connectivity for successful retrieval between MTL and prefrontal regions. These results suggest that neocortical regions related to attentional or strategic control show the greatest developmental changes for memory retrieval of scenes. Furthermore, these results suggest that functional interactions between MTL and prefrontal regions during memory retrieval also develop into young adulthood. The developmental increase of memory-related activations in frontal and parietal regions for retrieval of scenes and the absence of such an increase in MTL regions parallels what has been observed for memory encoding of scenes.

  19. Cognitive memory.

    Science.gov (United States)

    Widrow, Bernard; Aragon, Juan Carlos

    2013-05-01

    Regarding the workings of the human mind, memory and pattern recognition seem to be intertwined. You generally do not have one without the other. Taking inspiration from life experience, a new form of computer memory has been devised. Certain conjectures about human memory are keys to the central idea. The design of a practical and useful "cognitive" memory system is contemplated, a memory system that may also serve as a model for many aspects of human memory. The new memory does not function like a computer memory where specific data is stored in specific numbered registers and retrieval is done by reading the contents of the specified memory register, or done by matching key words as with a document search. Incoming sensory data would be stored at the next available empty memory location, and indeed could be stored redundantly at several empty locations. The stored sensory data would neither have key words nor would it be located in known or specified memory locations. Sensory inputs concerning a single object or subject are stored together as patterns in a single "file folder" or "memory folder". When the contents of the folder are retrieved, sights, sounds, tactile feel, smell, etc., are obtained all at the same time. Retrieval would be initiated by a query or a prompt signal from a current set of sensory inputs or patterns. A search through the memory would be made to locate stored data that correlates with or relates to the prompt input. The search would be done by a retrieval system whose first stage makes use of autoassociative artificial neural networks and whose second stage relies on exhaustive search. Applications of cognitive memory systems have been made to visual aircraft identification, aircraft navigation, and human facial recognition. Concerning human memory, reasons are given why it is unlikely that long-term memory is stored in the synapses of the brain's neural networks. Reasons are given suggesting that long-term memory is stored in DNA or RNA

  20. Does human presynaptic striatal dopamine function predict social conformity?

    Science.gov (United States)

    Stokes, Paul R A; Benecke, Aaf; Puraite, Julita; Bloomfield, Michael A P; Shotbolt, Paul; Reeves, Suzanne J; Lingford-Hughes, Anne R; Howes, Oliver; Egerton, Alice

    2014-03-01

    Socially desirable responding (SDR) is a personality trait which reflects either a tendency to present oneself in an overly positive manner to others, consistent with social conformity (impression management (IM)), or the tendency to view one's own behaviour in an overly positive light (self-deceptive enhancement (SDE)). Neurochemical imaging studies report an inverse relationship between SDR and dorsal striatal dopamine D₂/₃ receptor availability. This may reflect an association between SDR and D₂/₃ receptor expression, synaptic dopamine levels or a combination of the two. In this study, we used a [¹⁸F]-DOPA positron emission tomography (PET) image database to investigate whether SDR is associated with presynaptic dopamine function. Striatal [¹⁸F]-DOPA uptake, (k(i)(cer), min⁻¹), was determined in two independent healthy participant cohorts (n=27 and 19), by Patlak analysis using a cerebellar reference region. SDR was assessed using the revised Eysenck Personality Questionnaire (EPQ-R) Lie scale, and IM and SDE were measured using the Paulhus Deception Scales. No significant associations were detected between Lie, SDE or IM scores and striatal [¹⁸F]-DOPA k(i)(cer). These results indicate that presynaptic striatal dopamine function is not associated with social conformity and suggests that social conformity may be associated with striatal D₂/₃ receptor expression rather than with synaptic dopamine levels.

  1. Memory Modulation

    NARCIS (Netherlands)

    Roozendaal, Benno; McGaugh, James L.

    2011-01-01

    Our memories are not all created equally strong: Some experiences are well remembered while others are remembered poorly, if at all. Research on memory modulation investigates the neurobiological processes and systems that contribute to such differences in the strength of our memories. Extensive

  2. Reduced Striatal Dopamine Transporters in People with Internet Addiction Disorder

    Directory of Open Access Journals (Sweden)

    Haifeng Hou

    2012-01-01

    Full Text Available In recent years, internet addiction disorder (IAD has become more prevalent worldwide and the recognition of its devastating impact on the users and society has rapidly increased. However, the neurobiological mechanism of IAD has not bee fully expressed. The present study was designed to determine if the striatal dopamine transporter (DAT levels measured by T99mc-TRODAT-1 single photon emission computed tomography (SPECT brain scans were altered in individuals with IAD. SPECT brain scans were acquired on 5 male IAD subjects and 9 healthy age-matched controls. The volume (V and weight (W of bilateral corpus striatum as well as the T99mc-TRODAT-1 uptake ratio of corpus striatum/the whole brain (Ra were calculated using mathematical models. It was displayed that DAT expression level of striatum was significantly decreased and the V, W, and Ra were greatly reduced in the individuals with IAD compared to controls. Taken together, these results suggest that IAD may cause serious damages to the brain and the neuroimaging findings further illustrate IAD is associated with dysfunctions in the dopaminergic brain systems. Our findings also support the claim that IAD may share similar neurobiological abnormalities with other addictive disorders.

  3. Contributions of Hippocampus and Striatum to Memory-Guided Behavior Depend on Past Experience

    Science.gov (United States)

    2016-01-01

    The hippocampal and striatal memory systems are thought to operate independently and in parallel in supporting cognitive memory and habits, respectively. Much of the evidence for this principle comes from double dissociation data, in which damage to brain structure A causes deficits in Task 1 but not Task 2, whereas damage to structure B produces the reverse pattern of effects. Typically, animals are explicitly trained in one task. Here, we investigated whether this principle continues to hold when animals concurrently learn two types of tasks. Rats were trained on a plus maze in either a spatial navigation or a cue–response task (sequential training), whereas a third set of rats acquired both (concurrent training). Subsequently, the rats underwent either sham surgery or neurotoxic lesions of the hippocampus (HPC), medial dorsal striatum (DSM), or lateral dorsal striatum (DSL), followed by retention testing. Finally, rats in the sequential training condition also acquired the novel “other” task. When rats learned one task, HPC and DSL selectively supported spatial navigation and cue response, respectively. However, when rats learned both tasks, HPC and DSL additionally supported the behavior incongruent with the processing style of the corresponding memory system. Thus, in certain conditions, the hippocampal and striatal memory systems can operate cooperatively and in synergism. DSM significantly contributed to performance regardless of task or training procedure. Experience with the cue–response task facilitated subsequent spatial learning, whereas experience with spatial navigation delayed both concurrent and subsequent response learning. These findings suggest that there are multiple operational principles that govern memory networks. SIGNIFICANCE STATEMENT Currently, we distinguish among several types of memories, each supported by a distinct neural circuit. The memory systems are thought to operate independently and in parallel. Here, we demonstrate

  4. Presynaptic Dopamine Synthesis Capacity in Schizophrenia and Striatal Blood Flow Change During Antipsychotic Treatment and Medication-Free Conditions.

    Science.gov (United States)

    Eisenberg, Daniel Paul; Yankowitz, Lisa; Ianni, Angela M; Rubinstein, Dani Y; Kohn, Philip D; Hegarty, Catherine E; Gregory, Michael D; Apud, José A; Berman, Karen F

    2017-10-01

    Standard-of-care biological treatment of schizophrenia remains dependent upon antipsychotic medications, which demonstrate D 2 receptor affinity and elicit variable, partial clinical responses via neural mechanisms that are not entirely understood. In the striatum, where D 2 receptors are abundant, antipsychotic medications may affect neural function in studies of animals, healthy volunteers, and patients, yet the relevance of this to pharmacotherapeutic actions remains unresolved. In this same brain region, some individuals with schizophrenia may demonstrate phenotypes consistent with exaggerated dopaminergic signaling, including alterations in dopamine synthesis capacity; however, the hypothesis that dopamine system characteristics underlie variance in medication-induced regional blood flow changes has not been directly tested. We therefore studied a cohort of 30 individuals with schizophrenia using longitudinal, multi-session [ 15 O]-water and [ 18 F]-FDOPA positron emission tomography to determine striatal blood flow during active atypical antipsychotic medication treatment and after at least 3 weeks of placebo treatment, along with presynaptic dopamine synthesis capacity (ie, DOPA decarboxylase activity). Regional striatal blood flow was significantly higher during active treatment than during the placebo condition. Furthermore, medication-related increases in ventral striatal blood flow were associated with more robust amelioration of excited factor symptoms during active medication and with higher dopamine synthesis capacity. These data indicate that atypical medications enact measureable physiological alterations in limbic striatal circuitry that vary as a function of dopaminergic tone and may have relevance to aspects of therapeutic responses.

  5. Differences in spontaneously avoiding or approaching mice reflect differences in CB1-mediated signaling of dorsal striatal transmission.

    Directory of Open Access Journals (Sweden)

    Daniela Laricchiuta

    Full Text Available Approach or avoidance behaviors are accompanied by perceptual vigilance for, affective reactivity to and behavioral predisposition towards rewarding or punitive stimuli, respectively. We detected three subpopulations of C57BL/6J mice that responded with avoiding, balancing or approaching behaviors not induced by any experimental manipulation but spontaneously displayed in an approach/avoidance conflict task. Although the detailed neuronal mechanisms underlying the balancing between approach and avoidance are not fully clarified, there is growing evidence that endocannabinoid system (ECS plays a critical role in the control of these balancing actions. The sensitivity of dorsal striatal synapses to the activation of cannabinoid CB1 receptors was investigated in the subpopulations of spontaneously avoiding, balancing or approaching mice. Avoiding animals displayed decreased control of CB1 receptors on GABAergic striatal transmission and in parallel increase of behavioral inhibition. Conversely, approaching animals exhibited increased control of CB1 receptors and in parallel increase of explorative behavior. Balancing animals reacted with balanced responses between approach and avoidance patterns. Treating avoiding animals with URB597 (fatty acid amide hydrolase inhibitor or approaching animals with AM251 (CB1 receptor inverse agonist reverted their respective behavioral and electrophysiological patterns. Therefore, enhanced or reduced CB1-mediated control on dorsal striatal transmission represents the synaptic hallmark of the approach or avoidance behavior, respectively. Thus, the opposite spontaneous responses to conflicting stimuli are modulated by a different involvement of endocannabinoid signaling of dorsal striatal neurons in the range of temperamental traits related to individual differences.

  6. Memory Efficient VLSI Implementation of Real-Time Motion Detection System Using FPGA Platform

    Directory of Open Access Journals (Sweden)

    Sanjay Singh

    2017-06-01

    Full Text Available Motion detection is the heart of a potentially complex automated video surveillance system, intended to be used as a standalone system. Therefore, in addition to being accurate and robust, a successful motion detection technique must also be economical in the use of computational resources on selected FPGA development platform. This is because many other complex algorithms of an automated video surveillance system also run on the same platform. Keeping this key requirement as main focus, a memory efficient VLSI architecture for real-time motion detection and its implementation on FPGA platform is presented in this paper. This is accomplished by proposing a new memory efficient motion detection scheme and designing its VLSI architecture. The complete real-time motion detection system using the proposed memory efficient architecture along with proper input/output interfaces is implemented on Xilinx ML510 (Virtex-5 FX130T FPGA development platform and is capable of operating at 154.55 MHz clock frequency. Memory requirement of the proposed architecture is reduced by 41% compared to the standard clustering based motion detection architecture. The new memory efficient system robustly and automatically detects motion in real-world scenarios (both for the static backgrounds and the pseudo-stationary backgrounds in real-time for standard PAL (720 × 576 size color video.

  7. Visual perception and memory systems: from cortex to medial temporal lobe.

    Science.gov (United States)

    Khan, Zafar U; Martín-Montañez, Elisa; Baxter, Mark G

    2011-05-01

    Visual perception and memory are the most important components of vision processing in the brain. It was thought that the perceptual aspect of a visual stimulus occurs in visual cortical areas and that this serves as the substrate for the formation of visual memory in a distinct part of the brain called the medial temporal lobe. However, current evidence indicates that there is no functional separation of areas. Entire visual cortical pathways and connecting medial temporal lobe are important for both perception and visual memory. Though some aspects of this view are debated, evidence from both sides will be explored here. In this review, we will discuss the anatomical and functional architecture of the entire system and the implications of these structures in visual perception and memory.

  8. A new lumbar posterior fixation system, the memory metal spinal system: an in-vitro mechanical evaluation.

    Science.gov (United States)

    Kok, Dennis; Firkins, Paul John; Wapstra, Frits H; Veldhuizen, Albert G

    2013-09-18

    Spinal systems that are currently available for correction of spinal deformities or degeneration such as lumbar spondylolisthesis or degenerative disc disease use components manufactured from stainless steel or titanium and typically comprise two spinal rods with associated connection devices (for example: DePuy Spines Titanium Moss Miami Spinal System). The Memory Metal Spinal System of this study consists of a single square spinal rod made of a nickel titanium alloy (Nitinol) used in conjunction with connecting transverse bridges and pedicle screws made of Ti-alloy. Nitinol is best known for its shape memory effect, but is also characterized by its higher flexibility when compared to either stainless steel or titanium. A higher fusion rate with less degeneration of adjacent segments may result because of the elastic properties of the memory metal. In addition, the use of a single, unilateral rod may be of great value for a TLIF procedure. Our objective is to evaluate the mechanical properties of the new Memory Metal Spinal System compared to the Titanium Moss Miami Spinal System. An in-vitro mechanical evaluation of the lumbar Memory Metal Spinal System was conducted. The test protocol followed ASTM Standard F1717-96, "Standard Test Methods for Static and Fatigue for Spinal Implant Constructs in a Corpectomy Model." 1. Static axial testing in a load to failure mode in compression bending, 2. Static testing in a load to failure mode in torsion, 3. Cyclical testing to estimate the maximum run out load value at 5.0 x 10^6 cycles. In the biomechanical testing for static axial compression bending there was no statistical difference between the 2% yield strength and the stiffness of the two types of spinal constructs. In axial compression bending fatigue testing, the Memory Metal Spinal System construct showed a 50% increase in fatigue life compared to the Titanium Moss Miami Spinal System. In static torsional testing the Memory Metal Spinal System constructs showed an

  9. A simple algorithm for subregional striatal uptake analysis with partial volume correction in dopaminergic PET imaging

    International Nuclear Information System (INIS)

    Lue Kunhan; Lin Hsinhon; Chuang Kehshih; Kao Chihhao, K.; Hsieh Hungjen; Liu Shuhsin

    2014-01-01

    In positron emission tomography (PET) of the dopaminergic system, quantitative measurements of nigrostriatal dopamine function are useful for differential diagnosis. A subregional analysis of striatal uptake enables the diagnostic performance to be more powerful. However, the partial volume effect (PVE) induces an underestimation of the true radioactivity concentration in small structures. This work proposes a simple algorithm for subregional analysis of striatal uptake with partial volume correction (PVC) in dopaminergic PET imaging. The PVC algorithm analyzes the separate striatal subregions and takes into account the PVE based on the recovery coefficient (RC). The RC is defined as the ratio of the PVE-uncorrected to PVE-corrected radioactivity concentration, and is derived from a combination of the traditional volume of interest (VOI) analysis and the large VOI technique. The clinical studies, comprising 11 patients with Parkinson's disease (PD) and 6 healthy subjects, were used to assess the impact of PVC on the quantitative measurements. Simulations on a numerical phantom that mimicked realistic healthy and neurodegenerative situations were used to evaluate the performance of the proposed PVC algorithm. In both the clinical and the simulation studies, the striatal-to-occipital ratio (SOR) values for the entire striatum and its subregions were calculated with and without PVC. In the clinical studies, the SOR values in each structure (caudate, anterior putamen, posterior putamen, putamen, and striatum) were significantly higher by using PVC in contrast to those without. Among the PD patients, the SOR values in each structure and quantitative disease severity ratings were shown to be significantly related only when PVC was used. For the simulation studies, the average absolute percentage error of the SOR estimates before and after PVC were 22.74% and 1.54% in the healthy situation, respectively; those in the neurodegenerative situation were 20.69% and 2

  10. Is there a relation between novelty seeking, striatal dopamine release and frontal cortical thickness?

    Directory of Open Access Journals (Sweden)

    Natalia Jaworska

    Full Text Available Novelty-seeking (NS and impulsive personality traits have been proposed to reflect an interplay between fronto-cortical and limbic systems, including the limbic striatum (LS. Although neuroimaging studies have provided some evidence for this, most are comprised of small samples and many report surprisingly large effects given the challenges of trying to relate a snapshot of brain function or structure to an entity as complex as personality. The current work tested a priori hypotheses about associations between striatal dopamine (DA release, cortical thickness (CT, and NS in a large sample of healthy adults.Fifty-two healthy adults (45M/7F; age: 23.8±4.93 underwent two positron emission tomography scans with [11C]raclopride (specific for striatal DA D2/3 receptors with or without amphetamine (0.3 mg/kg, p.o.. Structural magnetic resonance image scans were acquired, as were Tridimensional Personality Questionnaire data. Amphetamine-induced changes in [11C]raclopride binding potential values (ΔBPND were examined in the limbic, sensorimotor (SMS and associative (AST striatum. CT measures, adjusted for whole brain volume, were extracted from the dorsolateral sensorimotor and ventromedial/limbic cortices.BPND values were lower in the amphetamine vs. no-drug sessions, with the largest effect in the LS. When comparing low vs. high LS ΔBPND groups (median split, higher NS2 (impulsiveness scores were found in the high ΔBPND group. Partial correlations (age and gender as covariates yielded a negative relation between ASTS ΔBPND and sensorimotor CT; trends for inverse associations existed between ΔBPND values in other striatal regions and frontal CT. In other words, the greater the amphetamine-induced striatal DA response, the thinner the frontal cortex.These data expand upon previously reported associations between striatal DA release in the LS and both NS related impulsiveness and CT in the largest sample reported to date. The findings add to the

  11. Insulin in the nervous system and the mind: Functions in metabolism, memory, and mood.

    Science.gov (United States)

    Lee, Seung-Hwan; Zabolotny, Janice M; Huang, Hu; Lee, Hyon; Kim, Young-Bum

    2016-08-01

    Insulin, a pleotrophic hormone, has diverse effects in the body. Recent work has highlighted the important role of insulin's action in the nervous system on glucose and energy homeostasis, memory, and mood. Here we review experimental and clinical work that has broadened the understanding of insulin's diverse functions in the central and peripheral nervous systems, including glucose and body weight homeostasis, memory and mood, with particular emphasis on intranasal insulin. Implications for the treatment of obesity, type 2 diabetes, dementia, and mood disorders are discussed in the context of brain insulin action. Intranasal insulin may have potential in the treatment of central nervous system-related metabolic disorders.

  12. Re-emergence of striatal cholinergic interneurons in movement disorders.

    Science.gov (United States)

    Pisani, Antonio; Bernardi, Giorgio; Ding, Jun; Surmeier, D James

    2007-10-01

    Twenty years ago, striatal cholinergic neurons were central figures in models of basal ganglia function. But since then, they have receded in importance. Recent studies are likely to lead to their re-emergence in our thinking. Cholinergic interneurons have been implicated as key players in the induction of synaptic plasticity and motor learning, as well as in motor dysfunction. In Parkinson's disease and dystonia, diminished striatal dopaminergic signalling leads to increased release of acetylcholine by interneurons, distorting network function and inducing structural changes that undoubtedly contribute to the symptoms. By contrast, in Huntington's disease and progressive supranuclear palsy, there is a fall in striatal cholinergic markers. This review gives an overview of these recent experimental and clinical studies, placing them within the context of the pathogenesis of movement disorders.

  13. Reduced striatal D2 receptor binding in myoclonus-dystonia

    International Nuclear Information System (INIS)

    Beukers, R.J.; Weisscher, N.; Tijssen, M.A.J.; Booij, J.; Zijlstra, F.; Amelsvoort, T.A.M.J. van

    2009-01-01

    To study striatal dopamine D 2 receptor availability in DYT11 mutation carriers of the autosomal dominantly inherited disorder myoclonus-dystonia (M-D). Fifteen DYT11 mutation carriers (11 clinically affected) and 15 age- and sex-matched controls were studied using 123 I-IBZM SPECT. Specific striatal binding ratios were calculated using standard templates for striatum and occipital areas. Multivariate analysis with corrections for ageing and smoking showed significantly lower specific striatal to occipital IBZM uptake ratios (SORs) both in the left and right striatum in clinically affected patients and also in all DYT11 mutation carriers compared to control subjects. Our findings are consistent with the theory of reduced dopamine D 2 receptor (D2R) availability in dystonia, although the possibility of increased endogenous dopamine, and consequently, competitive D2R occupancy cannot be ruled out. (orig.)

  14. Shape memory alloy heat engines and energy harvesting systems

    Science.gov (United States)

    Browne, Alan L; Johnson, Nancy L; Keefe, Andrew C; Alexander, Paul W; Sarosi, Peter Maxwell; Herrera, Guillermo A; Yates, James Ryan

    2013-12-17

    A heat engine includes a first rotatable pulley and a second rotatable pulled spaced from the first rotatable pulley. A shape memory alloy (SMA) element is disposed about respective portions of the pulleys at an SMA pulley ratio. The SMA element includes first spring coil and a first fiber core within the first spring coil. A timing cable is disposed about disposed about respective portions of the pulleys at a timing pulley ratio, which is different than the SMA pulley ratio. The SMA element converts a thermal energy gradient between the hot region and the cold region into mechanical energy.

  15. Computing with memory for energy-efficient robust systems

    CERN Document Server

    Paul, Somnath

    2013-01-01

    This book analyzes energy and reliability as major challenges faced by designers of computing frameworks in the nanometer technology regime.  The authors describe the existing solutions to address these challenges and then reveal a new reconfigurable computing platform, which leverages high-density nanoscale memory for both data storage and computation to maximize the energy-efficiency and reliability. The energy and reliability benefits of this new paradigm are illustrated and the design challenges are discussed. Various hardware and software aspects of this exciting computing paradigm are de

  16. Impairment of striatal mitochondrial function by acute paraquat poisoning.

    Science.gov (United States)

    Czerniczyniec, Analía; Lanza, E M; Karadayian, A G; Bustamante, J; Lores-Arnaiz, S

    2015-10-01

    Mitochondria are essential for survival. Their primary function is to support aerobic respiration and to provide energy for intracellular metabolic pathways. Paraquat is a redox cycling agent capable of generating reactive oxygen species. The aim of the present study was to evaluate changes in cortical and striatal mitochondrial function in an experimental model of acute paraquat toxicity and to compare if the brain areas and the molecular mechanisms involved were similar to those observed after chronic exposure. Sprague-Dawley rats received paraquat (25 mg/Kg i.p.) or saline and were sacrificed after 24 h. Paraquat treatment decreased complex I and IV activity by 37 and 21 % respectively in striatal mitochondria. Paraquat inhibited striatal state 4 and state 3 KCN-sensitive respiration by 80 % and 62 % respectively, indicating a direct effect on respiratory chain. An increase of 2.2 fold in state 4 and 2.3 fold in state 3 in KCN-insensitive respiration was observed in striatal mitochondria from paraquat animals, suggesting that paraquat redox cycling also consumed oxygen. Paraquat treatment increased hydrogen peroxide production (150 %), TBARS production (42 %) and cardiolipin oxidation/depletion (12 %) in striatal mitochondria. Also, changes in mitochondrial polarization was induced after paraquat treatment. However, no changes were observed in any of these parameters in cortical mitochondria from paraquat treated-animals. These results suggest that paraquat treatment induced a clear striatal mitochondrial dysfunction due to both paraquat redox cycling reactions and impairment of the mitochondrial electron transport, causing oxidative damage. As a consequence, mitochondrial dysfunction could probably lead to alterations in cellular bioenergetics.

  17. Dopamine D1-histamine H3 Receptor Heteromers Provide a Selective Link to MAPK Signaling in GABAergic Neurons of the Direct Striatal Pathway*

    Science.gov (United States)

    Moreno, Estefanía; Hoffmann, Hanne; Gonzalez-Sepúlveda, Marta; Navarro, Gemma; Casadó, Vicent; Cortés, Antoni; Mallol, Josefa; Vignes, Michel; McCormick, Peter J.; Canela, Enric I.; Lluís, Carme; Moratalla, Rosario; Ferré, Sergi; Ortiz, Jordi; Franco, Rafael

    2011-01-01

    Previously, using artificial cell systems, we identified receptor heteromers between the dopamine D1 or D2 receptors and the histamine H3 receptor. In addition, we demonstrated two biochemical characteristics of the dopamine D1 receptor-histamine H3 receptor heteromer. We have now extended this work to show the dopamine D1 receptor-histamine H3 receptor heteromer exists in the brain and serves to provide a novel link between the MAPK pathway and the GABAergic neurons in the direct striatal efferent pathway. Using the biochemical characteristics identified previously, we found that the ability of H3 receptor activation to stimulate p44 and p42 extracellular signal-regulated MAPK (ERK 1/2) phosphorylation was only observed in striatal slices of mice expressing D1 receptors but not in D1 receptor-deficient mice. On the other hand, the ability of both D1 and H3 receptor antagonists to block MAPK activation induced by either D1 or H3 receptor agonists was also found in striatal slices. Taken together, these data indicate the occurrence of D1-H3 receptor complexes in the striatum and, more importantly, that H3 receptor agonist-induced ERK 1/2 phosphorylation in striatal slices is mediated by D1-H3 receptor heteromers. Moreover, H3 receptor-mediated phospho-ERK 1/2 labeling co-distributed with D1 receptor-containing but not with D2 receptor-containing striatal neurons. These results indicate that D1-H3 receptor heteromers work as processors integrating dopamine- and histamine-related signals involved in controlling the function of striatal neurons of the direct striatal pathway. PMID:21173143

  18. The Effect of Governance on Global Software Development: An Empirical Research in Transactive Memory Systems.

    NARCIS (Netherlands)

    Manteli, C.; van den Hooff, B.J.; van Vliet, J.C.

    2014-01-01

    Context The way global software development (GSD) activities are managed impacts knowledge transactions between team members. The first is captured in governance decisions, and the latter in a transactive memory system (TMS), a shared cognitive system for encoding, storing and retrieving knowledge

  19. Nonlinear dynamics of a pseudoelastic shape memory alloy system - theory and experiment

    DEFF Research Database (Denmark)

    Enemark, Søren; A Savi, M.; Santos, Ilmar

    2014-01-01

    In this work, a helical spring made from a pseudoelastic shape memory alloy was embedded in a dynamic system also composed of a mass, a linear spring and an excitation system. The mechanical behaviour of shape memory alloys is highly complex, involving hysteresis, which leads to damping...... capabilities and varying stiffness. Besides, these properties depend on the temperature and pretension conditions. Because of these capabilities, shape memory alloys are interesting in relation to engineering design of dynamic systems. A theoretical model based on a modification of the 1D Brinson model...... was established. Basically, the hardening and the sub-loop behaviour were altered. The model parameters were extracted from force–displacement tests of the spring at different constant temperatures as well as from differential scanning calorimetry. Model predictions were compared with experimental results of free...

  20. A comparative approach to the principal mechanisms of different memory systems

    Science.gov (United States)

    Rensing, Ludger; Koch, Michael; Becker, Annette

    2009-12-01

    The term “memory” applies not only to the preservation of information in neuronal and immune systems but also to phenomena observed for example in plants, single cells, and RNA viruses. We here compare the different forms of information storage with respect to possible common features. The latter may be characterized by (1) selection of pre-existing information, (2) activation of memory systems often including transcriptional, and translational, as well as epigenetic and genetic mechanisms, (3) subsequent consolidation of the activated state in a latent form ( standby mode), and (4) reactivation of the latent state of memory systems when the organism is exposed to the same (or conditioned) signal or to previous selective constraints. These features apparently also exist in the “evolutionary memory,” i.e., in evolving populations which have highly variable mutant spectra.

  1. Performance Analysis of a Reconfigurable Shared Memory Multiprocessor System for Embedded Applications

    Directory of Open Access Journals (Sweden)

    Darcy Cook

    2014-11-01

    Full Text Available This paper presents a method to predict performance of multiple processor cores in a reconfigurable system for embedded applications. A multiprocessor framework is developed with the capability of reconfigurable processors in a shared memory system optimized for stream-oriented data and signal processing applications. The framework features a discrete time Markov based stochastic tool, which is used to analyze memory contention in the shared memory architecture, and to predict the performance increase (speed of execution when the number of processors is varied. Performance predictions for variations of other system parameters, such as different task allocations and the number of pipeline stages are possible as well. The results of the prediction tool were verified by experimental results of a green screen application developed and run on a Xilinx Virtex-II Pro FPGA with MicroBlaze soft processors.

  2. A fully automated Drosophila olfactory classical conditioning and testing system for behavioral learning and memory assessment.

    Science.gov (United States)

    Jiang, Hui; Hanna, Eriny; Gatto, Cheryl L; Page, Terry L; Bhuva, Bharat; Broadie, Kendal

    2016-03-01

    Aversive olfactory classical conditioning has been the standard method to assess Drosophila learning and memory behavior for decades, yet training and testing are conducted manually under exceedingly labor-intensive conditions. To overcome this severe limitation, a fully automated, inexpensive system has been developed, which allows accurate and efficient Pavlovian associative learning/memory analyses for high-throughput pharmacological and genetic studies. The automated system employs a linear actuator coupled to an odorant T-maze with airflow-mediated transfer of animals between training and testing stages. Odorant, airflow and electrical shock delivery are automatically administered and monitored during training trials. Control software allows operator-input variables to define parameters of Drosophila learning, short-term memory and long-term memory assays. The approach allows accurate learning/memory determinations with operational fail-safes. Automated learning indices (immediately post-training) and memory indices (after 24h) are comparable to traditional manual experiments, while minimizing experimenter involvement. The automated system provides vast improvements over labor-intensive manual approaches with no experimenter involvement required during either training or testing phases. It provides quality control tracking of airflow rates, odorant delivery and electrical shock treatments, and an expanded platform for high-throughput studies of combinational drug tests and genetic screens. The design uses inexpensive hardware and software for a total cost of ∼$500US, making it affordable to a wide range of investigators. This study demonstrates the design, construction and testing of a fully automated Drosophila olfactory classical association apparatus to provide low-labor, high-fidelity, quality-monitored, high-throughput and inexpensive learning and memory behavioral assays. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Overlap in the functional neural systems involved in semantic and episodic memory retrieval.

    Science.gov (United States)

    Rajah, M N; McIntosh, A R

    2005-03-01

    Neuroimaging and neuropsychological data suggest that episodic and semantic memory may be mediated by distinct neural systems. However, an alternative perspective is that episodic and semantic memory represent different modes of processing within a single declarative memory system. To examine whether the multiple or the unitary system view better represents the data we conducted a network analysis using multivariate partial least squares (PLS ) activation analysis followed by covariance structural equation modeling (SEM) of positron emission tomography data obtained while healthy adults performed episodic and semantic verbal retrieval tasks. It is argued that if performance of episodic and semantic retrieval tasks are mediated by different memory systems, then there should differences in both regional activations and interregional correlations related to each type of retrieval task, respectively. The PLS results identified brain regions that were differentially active during episodic retrieval versus semantic retrieval. Regions that showed maximal differences in regional activity between episodic retrieval tasks were used to construct separate functional models for episodic and semantic retrieval. Omnibus tests of these functional models failed to find a significant difference across tasks for both functional models. The pattern of path coefficients for the episodic retrieval model were not different across tasks, nor were the path coefficients for the semantic retrieval model. The SEM results suggest that the same memory network/system was engaged across tasks, given the similarities in path coefficients. Therefore, activation differences between episodic and semantic retrieval may ref lect variation along a continuum of processing during task performance within the context of a single memory system.

  4. A Review of TiNiPdCu Alloy System for High Temperature Shape Memory Applications

    Science.gov (United States)

    Khan, M. Imran; Kim, Hee Young; Miyazaki, Shuichi

    2015-06-01

    High temperature shape memory alloys (HTSMAs) are important smart materials and possess a significant potential to improve many engineering systems. Many TiNi-based high temperature ternary alloy systems have been reported in literature including TiNiPd, TiNiPt, TiNiZr, TiNiAu, TiNiHf, etc. Some quaternary additions of certain elements in the above systems have been successful to further improve many important shape memory and mechanical properties. The success criteria for an HTSMA become strict in terms of its cyclic stability, maximum recoverable strain, creep resistance, and corrosion resistance at high temperatures. TiNiPdCu alloy system has been recently proposed as a promising HTSMA. Unique nanoscaled precipitates formed in TiNiPdCu-based HTSMAs are found to be stable at temperatures above 773 K, while keeping the benefits of ease of fabrication. It is expected that this alloy system possesses significant potential especially for the high temperature shape memory applications. Till now many research reports have been published on this alloy system. In the present work, a comprehensive review of the TiNiPdCu system is presented in terms of thermomechanical behavior, nanoscale precipitation mechanism, microstructural features, high temperature shape memory and mechanical properties, and the important parameters to control the high temperature performance of these alloys.

  5. Multiple memory systems, multiple time points: how science can inform treatment to control the expression of unwanted emotional memories

    Science.gov (United States)

    Lau-Zhu, Alex; Henson, Richard N.; Holmes, Emily A.

    2018-01-01

    Memories that have strong emotions associated with them are particularly resilient to forgetting. This is not necessarily problematic, however some aspects of memory can be. In particular, the involuntary expression of those memories, e.g. intrusive memories after trauma, are core to certain psychological disorders. Since the beginning of this century, research using animal models shows that it is possible to change the underlying memory, for example by interfering with its consolidation or reconsolidation. While the idea of targeting maladaptive memories is promising for the treatment of stress and anxiety disorders, a direct application of the procedures used in non-human animals to humans in clinical settings is not straightforward. In translational research, more attention needs to be paid to specifying what aspect of memory (i) can be modified and (ii) should be modified. This requires a clear conceptualization of what aspect of memory is being targeted, and how different memory expressions may map onto clinical symptoms. Furthermore, memory processes are dynamic, so procedural details concerning timing are crucial when implementing a treatment and when assessing its effectiveness. To target emotional memory in its full complexity, including its malleability, science cannot rely on a single method, species or paradigm. Rather, a constructive dialogue is needed between multiple levels of research, all the way ‘from mice to mental health’. This article is part of a discussion meeting issue ‘Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists'. PMID:29352036

  6. Image detection and compression for memory efficient system analysis

    Science.gov (United States)

    Bayraktar, Mustafa

    2015-02-01

    The advances in digital signal processing have been progressing towards efficient use of memory and processing. Both of these factors can be utilized efficiently by using feasible techniques of image storage by computing the minimum information of image which will enhance computation in later processes. Scale Invariant Feature Transform (SIFT) can be utilized to estimate and retrieve of an image. In computer vision, SIFT can be implemented to recognize the image by comparing its key features from SIFT saved key point descriptors. The main advantage of SIFT is that it doesn't only remove the redundant information from an image but also reduces the key points by matching their orientation and adding them together in different windows of image [1]. Another key property of this approach is that it works on highly contrasted images more efficiently because it`s design is based on collecting key points from the contrast shades of image.

  7. Memory protection

    Science.gov (United States)

    Denning, Peter J.

    1988-01-01

    Accidental overwriting of files or of memory regions belonging to other programs, browsing of personal files by superusers, Trojan horses, and viruses are examples of breakdowns in workstations and personal computers that would be significantly reduced by memory protection. Memory protection is the capability of an operating system and supporting hardware to delimit segments of memory, to control whether segments can be read from or written into, and to confine accesses of a program to its segments alone. The absence of memory protection in many operating systems today is the result of a bias toward a narrow definition of performance as maximum instruction-execution rate. A broader definition, including the time to get the job done, makes clear that cost of recovery from memory interference errors reduces expected performance. The mechanisms of memory protection are well understood, powerful, efficient, and elegant. They add to performance in the broad sense without reducing instruction execution rate.

  8. From Augustine of Hippo’s Memory Systems to Our Modern Taxonomy in Cognitive Psychology and Neuroscience of Memory: A 16-Century Nap of Intuition before Light of Evidence

    Directory of Open Access Journals (Sweden)

    Jean-Christophe Cassel

    2012-12-01

    Full Text Available Over the last half century, neuropsychologists, cognitive psychologists and cognitive neuroscientists interested in human memory have accumulated evidence showing that there is not one general memory function but a variety of memory systems deserving distinct (but for an organism, complementary functional entities. The first attempts to organize memory systems within a taxonomic construct are often traced back to the French philosopher Maine de Biran (1766–1824, who, in his book first published in 1803, distinguished mechanical memory, sensitive memory and representative memory, without, however, providing any experimental evidence in support of his view. It turns out, however, that what might be regarded as the first elaborated taxonomic proposal is 14 centuries older and is due to Augustine of Hippo (354–430, also named St Augustine, who, in Book 10 of his Confessions, by means of an introspective process that did not aim at organizing memory systems, nevertheless distinguished and commented on sensible memory, intellectual memory, memory of memories, memory of feelings and passion, and memory of forgetting. These memories were envisaged as different and complementary instances. In the current study, after a short biographical synopsis of St Augustine, we provide an outline of the philosopher’s contribution, both in terms of questions and answers, and focus on how this contribution almost perfectly fits with several viewpoints of modern psychology and neuroscience of memory about human memory functions, including the notion that episodic autobiographical memory stores events of our personal history in their what, where and when dimensions, and from there enables our mental time travel. It is not at all meant that St Augustine’s elaboration was the basis for the modern taxonomy, but just that the similarity is striking, and that the architecture of our current viewpoints about memory systems might have preexisted as an outstanding

  9. Disruption of the ErbB signaling in adolescence increases striatal dopamine levels and affects learning and hedonic-like behavior in the adult mouse.

    Science.gov (United States)

    Golani, Idit; Tadmor, Hagar; Buonanno, Andres; Kremer, Ilana; Shamir, Alon

    2014-11-01

    The ErbB signaling pathway has been genetically and functionally implicated in schizophrenia. Numerous findings support the dysregulation of Neuregulin (NRG) and epidermal growth factor (EGF) signaling in schizophrenia. However, it is unclear whether alterations of these pathways in the adult brain or during development are involved in the pathophysiology of schizophrenia. Herein we characterized the behavioral profile and molecular changes resulting from pharmacologically blocking the ErbB signaling pathway during a critical period in the development of decision making, planning, judgments, emotions, social cognition and cognitive skills, namely adolescence. We demonstrate that chronic administration of the pan-ErbB kinase inhibitor JNJ-28871063 (JNJ) to adolescent mice elevated striatal dopamine levels and reduced preference for sucrose without affecting locomotor activity and exploratory behavior. In adulthood, adolescent JNJ-treated mice continue to consume less sucrose and needed significantly more correct-response trials to reach the learning criterion during the discrimination phase of the T-maze reversal learning task than their saline-injected controls. In addition, JNJ mice exhibited deficit in reference memory but not in working memory as measured in the radial arm maze. Inhibition of the pathway during adolescence did not affect exploratory behavior and locomotor activity in the open field, social interaction, social memory, and reversal learning in adult mice. Our data suggest that alteration of ErbB signaling during adolescence resulted in changes in the dopaminergic systems that emerge in pathological learning and hedonic behavior in adulthood, and pinpoints the possible role of the pathway in the development of cognitive skills and motivated behavior. Copyright © 2014 Elsevier B.V. and ECNP. All rights reserved.

  10. Interaction between attentional systems and episodic memory encoding: the impact of conflict on binding of information.

    Science.gov (United States)

    Sperduti, Marco; Armougum, Allan; Makowski, Dominique; Blondé, Philippe; Piolino, Pascale

    2017-12-01

    Episodic memory (EM) is defined as a long-term memory system that stores information that can be retrieved along with details of the context of the original events (binding). Several studies have shown that manipulation of attention during encoding can impact subsequent memory performance. An influential model of attention distinguishes between three partially independent attentional networks: the alerting, the orienting and the executive or conflict resolution component. To date, the impact of the engagement of these sub-systems during encoding on item and relational context binding has not been investigated. Here, we developed a new task combining the Attentional Network Test and an incidental episodic memory encoding task to study this issue. We reported that when the alerting network was not solicited, resolving conflict hindered item encoding. Moreover, resolving conflict, independently of the cueing condition, had a negative impact on context binding. These novel findings could have a potential impact in the understanding EM formation, and memory disorders in different populations, including healthy elderly people.

  11. Neural system for updating object working memory from different sources: sensory stimuli or long-term memory.

    Science.gov (United States)

    Roth, Jennifer K; Courtney, Susan M

    2007-11-15

    Working memory (WM) is the active maintenance of currently relevant information so that it is available for use. A crucial component of WM is the ability to update the contents when new information becomes more relevant than previously maintained information. New information can come from different sources, including from sensory stimuli (SS) or from long-term memory (LTM). Updating WM may involve a single neural system regardless of source, distinct systems for each source, or a common network with additional regions involved specifically in sensory or LTM processes. The current series of experiments indicates that a single fronto-parietal network (including supplementary motor area, parietal, left inferior frontal junction, middle frontal gyrus) is active in updating WM regardless of the source of information. Bilateral cuneus was more active during updating WM from LTM than updating from SS, but the activity in this region was attributable to recalling information from LTM regardless of whether that information was to be entered into WM for future use or not. No regions were found to be more active during updating from SS than updating from LTM. Functional connectivity analysis revealed that different regions within this common update network were differentially more correlated with visual processing regions when participants updated from SS, and more correlated with LTM processing regions when participants updated from the contents of LTM. These results suggest that a single neural mechanism is responsible for controlling the contents of WM regardless of whether that information originates from a sensory stimulus or from LTM. This network of regions involved in updating WM interacts with the rest of the brain differently depending on the source of newly relevant information.

  12. Dysregulation of striatal projection neurons in Parkinson's disease.

    Science.gov (United States)

    Beck, Goichi; Singh, Arun; Papa, Stella M

    2018-03-01

    The loss of nigrostriatal dopamine (DA) is the primary cause of motor dysfunction in Parkinson's disease (PD), but the underlying striatal mechanisms remain unclear. In spite of abundant literature portraying structural, biochemical and plasticity changes of striatal projection neurons (SPNs), in the past there has been a data vacuum from the natural human disease and its close model in non-human primates. Recently, single-cell recordings in advanced parkinsonian primates have generated new insights into the altered function of SPNs. Currently, there are also human data that provide direct evidence of profoundly dysregulated SPN activity in PD. Here, we review primate recordings that are impacting our understanding of the striatal dysfunction after DA loss, particularly through the analysis of physiologic correlates of parkinsonian motor behaviors. In contrast to recordings in rodents, data obtained in primates and patients demonstrate similar major abnormalities of the spontaneous SPN firing in the alert parkinsonian state. Furthermore, these studies also show altered SPN responses to DA replacement in the advanced parkinsonian state. Clearly, there is yet much to learn about the striatal discharges in PD, but studies using primate models are contributing unique information to advance our understanding of pathophysiologic mechanisms.

  13. Dorsal striatal dopamine, food preference and health perception in humans

    NARCIS (Netherlands)

    Wallace, D.L.; Aarts, E.; Dang, L.C.; Greer, S.M.; Jagust, W.J.; D'Esposito, M.

    2014-01-01

    To date, few studies have explored the neurochemical mechanisms supporting individual differences in food preference in humans. Here we investigate how dorsal striatal dopamine, as measured by the positron emission tomography (PET) tracer [(18)F]fluorometatyrosine (FMT), correlates with food-related

  14. Memory and reward systems coproduce ‘nostalgic’ experiences in the brain

    Science.gov (United States)

    Oba, Kentaro; Noriuchi, Madoka; Atomi, Tomoaki; Moriguchi, Yoshiya

    2016-01-01

    People sometimes experience an emotional state known as ‘nostalgia’, which involves experiencing predominantly positive emotions while remembering autobiographical events. Nostalgia is thought to play an important role in psychological resilience. Previous neuroimaging studies have shown involvement of memory and reward systems in such experiences. However, it remains unclear how these two systems are collaboratively involved with nostalgia experiences. Here, we conducted a functional magnetic resonance imaging study of healthy females to investigate the relationship between memory-reward co-activation and nostalgia, using childhood-related visual stimuli. Moreover, we examined the factors constituting nostalgia and their neural correlates. We confirmed the presence of nostalgia-related activity in both memory and reward systems, including the hippocampus (HPC), substantia nigra/ventral tegmental area (SN/VTA), and ventral striatum (VS). We also found significant HPC-VS co-activation, with its strength correlating with individual ‘nostalgia tendencies’. Factor analyses showed that two dimensions underlie nostalgia: emotional and personal significance and chronological remoteness, with the former correlating with caudal SN/VTA and left anterior HPC activity, and the latter correlating with rostral SN/VTA activity. These findings demonstrate the cooperative activity of memory and reward systems, where each system has a specific role in the construction of the factors that underlie the experience of nostalgia. PMID:26060325

  15. Emerging memories

    Science.gov (United States)

    Baldi, Livio; Bez, Roberto; Sandhu, Gurtej

    2014-12-01

    Memory is a key component of any data processing system. Following the classical Turing machine approach, memories hold both the data to be processed and the rules for processing them. In the history of microelectronics, the distinction has been rather between working memory, which is exemplified by DRAM, and storage memory, exemplified by NAND. These two types of memory devices now represent 90% of all memory market and 25% of the total semiconductor market, and have been the technology drivers in the last decades. Even if radically different in characteristics, they are however based on the same storage mechanism: charge storage, and this mechanism seems to be near to reaching its physical limits. The search for new alternative memory approaches, based on more scalable mechanisms, has therefore gained new momentum. The status of incumbent memory technologies and their scaling limitations will be discussed. Emerging memory technologies will be analyzed, starting from the ones that are already present for niche applications, and which are getting new attention, thanks to recent technology breakthroughs. Maturity level, physical limitations and potential for scaling will be compared to existing memories. At the end the possible future composition of memory systems will be discussed.

  16. STRUKTUR DAN PROSES MEMORI

    Directory of Open Access Journals (Sweden)

    Magda Bhinnety

    2015-09-01

    Full Text Available This paper describes structures and processes of human memory system according to the modal model. Sensory memory is described as the first system to store information from outside world. Short‐term memory, or now called working memory, represents a system characterized by limited ability in storing as well as retrieving information. Long‐term memory on the hand stores information larger in amount and longer than short‐term memory

  17. Bioinspired Soft Actuation System Using Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Matteo Cianchetti

    2014-07-01

    Full Text Available Soft robotics requires technologies that are capable of generating forces even though the bodies are composed of very light, flexible and soft elements. A soft actuation mechanism was developed in this work, taking inspiration from the arm of the Octopus vulgaris, specifically from the muscular hydrostat which represents its constitutive muscular structure. On the basis of the authors’ previous works on shape memory alloy (SMA springs used as soft actuators, a specific arrangement of such SMA springs is presented, which is combined with a flexible braided sleeve featuring a conical shape and a motor-driven cable. This robot arm is able to perform tasks in water such as grasping, multi-bending gestures, shortening and elongation along its longitudinal axis. The whole structure of the arm is described in detail and experimental results on workspace, bending and grasping capabilities and generated forces are presented. Moreover, this paper demonstrates that it is possible to realize a self-contained octopus-like robotic arm with no rigid parts, highly adaptable and suitable to be mounted on underwater vehicles. Its softness allows interaction with all types of objects with very low risks of damage and limited safety issues, while at the same time producing relatively high forces when necessary.

  18. Application of complex programmable logic devices in memory radiation effects test system

    International Nuclear Information System (INIS)

    Li Yonghong; He Chaohui; Yang Hailiang; He Baoping

    2005-01-01

    The application of the complex programmable logic device (CPLD) in electronics is emphatically discussed. The method of using software MAX + plus II and CPLD are introduced. A new test system for memory radiation effects is established by using CPLD devices-EPM7128C84-15. The old test system's function are realized and, moreover, a number of small scale integrated circuits are reduced and the test system's reliability is improved. (authors)

  19. Elimination of ``memory`` from sample handling and inlet system of a mass spectrometer

    Science.gov (United States)

    Chastgner, P.

    1991-05-08

    This paper describes a method for preparing the sample handling and inlet system of a mass spectrometer for analysis of a subsequent sample following analysis of a previous sample comprising the flushing of the system interior with supercritical CO{sub 2} and venting the interior. The method eliminates the effect of system ``memory`` on the subsequent analysis, especially following persistent samples such as xenon and krypton.

  20. Striatal dysfunction in X-linked dystonia-parkinsonism is associated with disease progression.

    Science.gov (United States)

    Brüggemann, N; Rosales, R L; Waugh, J L; Blood, A J; Domingo, A; Heldmann, M; Jamora, R D; Münchau, A; Münte, T F; Lee, L V; Buchmann, I; Klein, C

    2017-05-01

    X-linked dystonia-parkinsonism (XDP) is an inherited neurodegenerative adult-onset movement disorder associated with striatal atrophy. As the dopaminergic system has not yet been systemically studied in this basal ganglia model disease, it is unclear whether nigrostriatal dysfunction contributes to parkinsonism in XDP. Pre- and post-synaptic dopaminergic function was assessed in XDP. A total of 10 123 jod-benzamide (IBZM) single-photon emission computed tomography (SPECT) images were obtained for nine patients aged 42.3 ± 9.5 years (SD; range 30-52) and one asymptomatic mutation carrier (38 years), and four ioflupane (FP-CIT) SPECT images were obtained for four patients, aged 41.5 ± 11.6 years (range 30-52 years). Structural magnetic resonance imaging was also performed for all mutation carriers and 10 matched healthy controls. All patients were men who suffered from severe, disabling segmental or generalized dystonia and had varying degrees of parkinsonism. IBZM SPECT images were pathological in 8/9 symptomatic patients with distinct reduced post-synaptic tracer uptake in the caudate nucleus and putamen, and unremarkable in the asymptomatic mutation carrier. Longer disease duration was correlated with lower IBZM binding ratios. All subjects exhibited slightly reduced FP-CIT uptake values compared to controls for each analyzed region (-37% to -41%) which may be linked to basal ganglia volume loss. Visual inspection revealed physiological FP-CIT uptake in 1/4 patients. This nuclear imaging study provides evidence that the functional decline of post-synaptic dopaminergic neurotransmission is related to disease duration and ongoing neurodegeneration. Given the severe striatal cell loss which could be verified with post-synaptic nuclear imaging, both parkinsonism and dystonia in XDP are probably mainly due to striatal dysfunction. © 2017 EAN.

  1. Single-Chip Computers With Microelectromechanical Systems-Based Magnetic Memory

    NARCIS (Netherlands)

    Carley, L. Richard; Bain, James A.; Fedder, Gary K.; Greve, David W.; Guillou, David F.; Lu, Michael S.C.; Mukherjee, Tamal; Santhanam, Suresh; Abelmann, Leon; Min, Seungook

    This article describes an approach for implementing a complete computer system (CPU, RAM, I/O, and nonvolatile mass memory) on a single integrated-circuit substrate (a chip)—hence, the name "single-chip computer." The approach presented combines advances in the field of microelectromechanical

  2. Scripting for construction of a transactive memory system in multidisciplinary CSCL environments

    NARCIS (Netherlands)

    Noroozi, O.; Biemans, H.J.A.; Weinberger, A.; Mulder, M.; Chizari, M.

    2013-01-01

    Establishing a Transactive Memory System (TMS) is essential for groups of learners, when they are multidisciplinary and collaborate online. Environments for Computer-Supported Collaborative Learning (CSCL) could be designed to facilitate the TMS. This study investigates how various aspects of a TMS

  3. LU Factorization with Partial Pivoting for a Multi-CPU, Multi-GPU Shared Memory System

    Energy Technology Data Exchange (ETDEWEB)

    Kurzak, Jakub [Univ. of Tennessee, Knoxville, TN (United States); Luszczek, Pitior [Univ. of Tennessee, Knoxville, TN (United States); Faverge, Mathieu [Univ. of Tennessee, Knoxville, TN (United States); Dongarra, Jack [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Manchester (United Kingdom)

    2012-03-01

    LU factorization with partial pivoting is a canonical numerical procedure and the main component of the High Performance LINPACK benchmark. This article presents an implementation of the algorithm for a hybrid, shared memory, system with standard CPU cores and GPU accelerators. Performance in excess of one TeraFLOPS is achieved using four AMD Magny Cours CPUs and four NVIDIA Fermi GPUs.

  4. ERP evaluation of auditory sensory memory systems in adults with intellectual disability.

    Science.gov (United States)

    Ikeda, Kazunari; Hashimoto, Souichi; Hayashi, Akiko; Kanno, Atsushi

    2009-01-01

    Auditory sensory memory stage can be functionally divided into two subsystems; transient-detector system and permanent feature-detector system (Naatanen, 1992). We assessed these systems in persons with intellectual disability by measuring event-related potentials (ERPs) N1 and mismatch negativity (MMN), which reflect the two auditory subsystems, respectively. Added to these, P3a (an ERP reflecting stage after sensory memory) was evaluated. Either synthesized vowels or simple tones were delivered during a passive oddball paradigm to adults with and without intellectual disability. ERPs were recorded from midline scalp sites (Fz, Cz, and Pz). Relative to control group, participants with the disability exhibited greater N1 latency and less MMN amplitude. The results for N1 amplitude and MMN latency were basically comparable between both groups. IQ scores in participants with the disability revealed no significant relation with N1 and MMN measures, whereas the IQ scores tended to increase significantly as P3a latency reduced. These outcomes suggest that persons with intellectual disability might own discrete malfunctions for the two detector systems in auditory sensory-memory stage. Moreover, the processes following sensory memory might be partly related to a determinant of mental development.

  5. Recommendations for learners are different: Applying memory-based recommender system techniques to lifelong learning

    NARCIS (Netherlands)

    Drachsler, Hendrik; Hummel, Hans; Koper, Rob

    2007-01-01

    Drachsler, H., Hummel, H. G. K., & Koper, R. (2007). Recommendations for learners are different: applying memory-based recommender system techniques to lifelong learning. Paper presented at the SIRTEL workshop at the EC-TEL 2007 Conference. September, 17-20, 2007, Crete, Greece.

  6. Functional status of masticatory system, executive function and episodic memory in older persons

    NARCIS (Netherlands)

    Scherder, E.; Posthuma, W.; Bakker, T.; Vuijk, P. J.; Lobbezoo, F.

    Findings from human experimental studies suggest that mastication positively influences cognitive function. The participants in those studies were relatively young. The goal of this study was to examine the relationship between the functional status of the masticatory system, episodic memory, and

  7. Generalization through the Recurrent Interaction of Episodic Memories: A Model of the Hippocampal System

    Science.gov (United States)

    Kumaran, Dharshan; McClelland, James L.

    2012-01-01

    In this article, we present a perspective on the role of the hippocampal system in generalization, instantiated in a computational model called REMERGE (recurrency and episodic memory results in generalization). We expose a fundamental, but neglected, tension between prevailing computational theories that emphasize the function of the hippocampus…

  8. Local nondestructive data reading in three-dimensional memory systems based on the optical Kerr effect

    International Nuclear Information System (INIS)

    Zheltikov, Aleksei M; Koroteev, Nikolai I; Naumov, A N; Fedotov, Andrei B; Magnitskiy, Sergey A; Sidorov-Biryukov, D A

    1998-01-01

    An investigation was made of the characteristics of the optical Kerr effect in a spiropyran solution. It was found that this effect makes it possible to distinguish the coloured and uncoloured forms of spiropyran and that it represents a promising method for nondestructive data reading in three-dimensional optical memory systems based on photochromic materials. (letters to the editor)

  9. Cocaine Self-Administration Alters the Relative Effectiveness of Multiple Memory Systems during Extinction

    Science.gov (United States)

    Gabriele, Amanda; Setlow, Barry; Packard, Mark G.

    2009-01-01

    Rats were trained to run a straight-alley maze for an oral cocaine or sucrose vehicle solution reward, followed by either response or latent extinction training procedures that engage neuroanatomically dissociable "habit" and "cognitive" memory systems, respectively. In the response extinction condition, rats performed a runway approach response…

  10. Convergence to equilibria for a three-dimensional conserved phase-field system with memory

    Directory of Open Access Journals (Sweden)

    Gianluca Mola

    2008-02-01

    Full Text Available We consider a conserved phase-field system with thermal memory on a tridimensional bounded domain. Assuming that the nonlinearity is real analytic, we use a Lojasiewicz-Simon type inequality to study the convergence to steady states of single trajectories. We also give an estimate of the convergence rate.

  11. Distribution of return point memory states for systems with stochastic inputs

    International Nuclear Information System (INIS)

    Amann, A; Brokate, M; Rachinskii, D; Temnov, G

    2011-01-01

    We consider the long term effect of stochastic inputs on the state of an open loop system which exhibits the so-called return point memory. An example of such a system is the Preisach model; more generally, systems with the Preisach type input-state relationship, such as in spin-interaction models, are considered. We focus on the characterisation of the expected memory configuration after the system has been effected by the input for sufficiently long period of time. In the case where the input is given by a discrete time random walk process, or the Wiener process, simple closed form expressions for the probability density of the vector of the main input extrema recorded by the memory state, and scaling laws for the dimension of this vector, are derived. If the input is given by a general continuous Markov process, we show that the distribution of previous memory elements can be obtained from a Markov chain scheme which is derived from the solution of an associated one-dimensional escape type problem. Formulas for transition probabilities defining this Markov chain scheme are presented. Moreover, explicit formulas for the conditional probability densities of previous main extrema are obtained for the Ornstein-Uhlenbeck input process. The analytical results are confirmed by numerical experiments.

  12. Memory Effects and Coverage Dependence of Surface Diffusion in a Model Adsorption System

    DEFF Research Database (Denmark)

    Vattulainen, Ilpo Tapio; Ying, S. C.; Ala-Nissila, T.

    1999-01-01

    We study the coverage dependence of surface diffusion coefficients for a strongly interacting adsorption system O/W(110) via Monte Carlo simulations of a lattice-gas model. In particular, we consider the nature and emergence of memory effects as contained in the corresponding correlation factors...... diffusion is found to decay following a power law after an initial transient period. This behavior persists until the hydrodynamic regime is reached, after which the memory effect decays exponentially. The time required to reach the hydrodynamical regime and the related exponential decay is strongly...

  13. Memory controllers for mixed-time-criticality systems architectures, methodologies and trade-offs

    CERN Document Server

    Goossens, Sven; Akesson, Benny; Goossens, Kees

    2016-01-01

    This book discusses the design and performance analysis of SDRAM controllers that cater to both real-time and best-effort applications, i.e. mixed-time-criticality memory controllers. The authors describe the state of the art, and then focus on an architecture template for reconfigurable memory controllers that addresses effectively the quickly evolving set of SDRAM standards, in terms of worst-case timing and power analysis, as well as implementation. A prototype implementation of the controller in SystemC and synthesizable VHDL for an FPGA development board are used as a proof of concept of the architecture template.

  14. Remote memories are enhanced by COMT activity through dysregulation of the endocannabinoid system in the prefrontal cortex.

    Science.gov (United States)

    Scheggia, D; Zamberletti, E; Realini, N; Mereu, M; Contarini, G; Ferretti, V; Managò, F; Margiani, G; Brunoro, R; Rubino, T; De Luca, M A; Piomelli, D; Parolaro, D; Papaleo, F

    2018-04-01

    The prefrontal cortex (PFC) is a crucial hub for the flexible modulation of recent memories (executive functions) as well as for the stable organization of remote memories. Dopamine in the PFC is implicated in both these processes and genetic variants affecting its neurotransmission might control the unique balance between cognitive stability and flexibility present in each individual. Functional genetic variants in the catechol-O-methyltransferase (COMT) gene result in a different catabolism of dopamine in the PFC. However, despite the established role played by COMT genetic variation in executive functions, its impact on remote memory formation and recall is still poorly explored. Here we report that transgenic mice overexpressing the human COMT-Val gene (COMT-Val-tg) present exaggerated remote memories (>50 days) while having unaltered recent memories (remote memories as silencing COMT Val overexpression starting from 30 days after the initial aversive conditioning normalized remote memories. COMT genetic overactivity produced a selective overdrive of the endocannabinoid system within the PFC, but not in the striatum and hippocampus, which was associated with enhanced remote memories. Indeed, acute pharmacological blockade of CB1 receptors was sufficient to rescue the altered remote memory recall in COMT-Val-tg mice and increased PFC dopamine levels. These results demonstrate that COMT genetic variations modulate the retrieval of remote memories through the dysregulation of the endocannabinoid system in the PFC.

  15. Gastric Bypass Surgery Recruits a Gut PPAR-α-Striatal D1R Pathway to Reduce Fat Appetite in Obese Rats

    DEFF Research Database (Denmark)

    Hankir, Mohammed K; Seyfried, Florian; Hintschich, Constantin A

    2017-01-01

    Bariatric surgery remains the single most effective long-term treatment modality for morbid obesity, achieved mainly by lowering caloric intake through as yet ill-defined mechanisms. Here we show in rats that Roux-en-Y gastric bypass (RYGB)-like rerouting of ingested fat mobilizes lower small...... intestine production of the fat-satiety molecule oleoylethanolamide (OEA). This was associated with vagus nerve-driven increases in dorsal striatal dopamine release. We also demonstrate that RYGB upregulates striatal dopamine 1 receptor (D1R) expression specifically under high-fat diet feeding conditions....... Mechanistically, interfering with local OEA, vagal, and dorsal striatal D1R signaling negated the beneficial effects of RYGB on fat intake and preferences. These findings delineate a molecular/systems pathway through which bariatric surgery improves feeding behavior and may aid in the development of novel weight...

  16. Behavioral and Neural Manifestations of Reward Memory in Carriers of Low-Expressing versus High-Expressing Genetic Variants of the Dopamine D2 Receptor

    Science.gov (United States)

    Richter, Anni; Barman, Adriana; Wüstenberg, Torsten; Soch, Joram; Schanze, Denny; Deibele, Anna; Behnisch, Gusalija; Assmann, Anne; Klein, Marieke; Zenker, Martin; Seidenbecher, Constanze; Schott, Björn H.

    2017-01-01

    Dopamine is critically important in the neural manifestation of motivated behavior, and alterations in the human dopaminergic system have been implicated in the etiology of motivation-related psychiatric disorders, most prominently addiction. Patients with chronic addiction exhibit reduced dopamine D2 receptor (DRD2) availability in the striatum, and the DRD2 TaqIA (rs1800497) and C957T (rs6277) genetic polymorphisms have previously been linked to individual differences in striatal dopamine metabolism and clinical risk for alcohol and nicotine dependence. Here, we investigated the hypothesis that the variants of these polymorphisms would show increased reward-related memory formation, which has previously been shown to jointly engage the mesolimbic dopaminergic system and the hippocampus, as a potential intermediate phenotype for addiction memory. To this end, we performed functional magnetic resonance imaging (fMRI) in 62 young, healthy individuals genotyped for DRD2 TaqIA and C957T variants. Participants performed an incentive delay task, followed by a recognition memory task 24 h later. We observed effects of both genotypes on the overall recognition performance with carriers of low-expressing variants, namely TaqIA A1 carriers and C957T C homozygotes, showing better performance than the other genotype groups. In addition to the better memory performance, C957T C homozygotes also exhibited a response bias for cues predicting monetary reward. At the neural level, the C957T polymorphism was associated with a genotype-related modulation of right hippocampal and striatal fMRI responses predictive of subsequent recognition confidence for reward-predicting items. Our results indicate that genetic variations associated with DRD2 expression affect explicit memory, specifically for rewarded stimuli. We suggest that the relatively better memory for rewarded stimuli in carriers of low-expressing DRD2 variants may reflect an intermediate phenotype of addiction memory. PMID

  17. The Role of the Oculomotor System in Updating Visual-Spatial Working Memory across Saccades.

    Science.gov (United States)

    Boon, Paul J; Belopolsky, Artem V; Theeuwes, Jan

    2016-01-01

    Visual-spatial working memory (VSWM) helps us to maintain and manipulate visual information in the absence of sensory input. It has been proposed that VSWM is an emergent property of the oculomotor system. In the present study we investigated the role of the oculomotor system in updating of spatial working memory representations across saccades. Participants had to maintain a location in memory while making a saccade to a different location. During the saccade the target was displaced, which went unnoticed by the participants. After executing the saccade, participants had to indicate the memorized location. If memory updating fully relies on cancellation driven by extraretinal oculomotor signals, the displacement should have no effect on the perceived location of the memorized stimulus. However, if postsaccadic retinal information about the location of the saccade target is used, the perceived location will be shifted according to the target displacement. As it has been suggested that maintenance of accurate spatial representations across saccades is especially important for action control, we used different ways of reporting the location held in memory; a match-to-sample task, a mouse click or by making another saccade. The results showed a small systematic target displacement bias in all response modalities. Parametric manipulation of the distance between the to-be-memorized stimulus and saccade target revealed that target displacement bias increased over time and changed its spatial profile from being initially centered on locations around the saccade target to becoming spatially global. Taken together results suggest that we neither rely exclusively on extraretinal nor on retinal information in updating working memory representations across saccades. The relative contribution of retinal signals is not fixed but depends on both the time available to integrate these signals as well as the distance between the saccade target and the remembered location.

  18. Dynamics of Shape Memory Alloy Systems, Phase 2

    Science.gov (United States)

    2015-12-22

    T.A. Netto, Shock and Vibration, v.2015, Article ID 739381, pp.1-15, 2015. ISSN 1070-9622. doi:10.1155/2015/739381. 19. “Analysis of Magneto ...conditions: comparison between elastic (left) and SMA (right) systems. The temperature dependence provides important characteristic to the system. One...smooth SMA system. Figure 11 – Comparison of elastic and SMA response for a non-smooth oscillator. DISTRIBUTION A: Distribution approved for

  19. An Associative Memory Chip for the Trigger System of the ATLAS Experiment

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00380893; The ATLAS collaboration; Liberali, Valentino; Crescioli, Francesco; Beretta, Matteo; Frontini, Luca; Annovi, Alberto; Stabile, Alberto

    2016-01-01

    The AM06 is the 6th version of a large associative memory chip designed in 65 nm CMOS tech- nology. The AM06 operates as a highly parallel ASIC processor for pattern recognition in the ATLAS experiment at CERN. It is the core of the Fast TracKer electronic system, which is tai- lored for on-line track finding in the trigger system of the ATLAS experiment. The Fast TracKer system is able to process events up to 100 MHz in real time. The AM06 is a complex chip, and it has been designed combining full-custom memory arrays, standard logic cells and IP blocks. It contains memory banks that store data organized in 18 bit words; a group of 8 words is called a pattern. The chip silicon area is 168 mm2; it contains 421 millions of transistors and it stores 217 patterns. Moreover, the associative memory is suitable also for other interdisciplinary appli- cations (i.e., general purpose image filtering and analysis). In the near future we plan to design a more powerful and flexible chip in 28 nm CMOS technology.

  20. Adult neurogenesis in the olfactory system shapes odor memory and perception.

    Science.gov (United States)

    Gheusi, Gilles; Lledo, Pierre-Marie

    2014-01-01

    The olfactory system is a dynamic place. In mammals, not only are sensory neurons located in the sensory organ renewed through adult life, but also its first central relay is reconstructed by continuous neuronal recruitment. Despite these numerous morphological and physiological changes, olfaction is a unique sensory modality endowed with a privileged link to memory. This raises a clear conundrum; how does the olfactory system balance its neuronal turnover with its participation in long-term memory? This review concentrates on the functional aspects of adult neurogenesis, addressing how the integration of late-born neurons participates in olfactory perception and memory. After outlining the properties of adult neurogenesis in the olfactory system, and after describing their regulation by internal and environmental factors, we ask how the process of odorant perception can be influenced by constant neuronal turnover. We then explore the possible functional roles that newborn neurons might have for olfactory memory. Throughout this review, and as we concentrate almost exclusively on mammalian models, we stress the idea that adult neurogenesis is yet another form of plasticity used by the brain to copes with a constantly changing olfactory world. © 2014 Elsevier B.V. All rights reserved.

  1. A Primitive Memory System for Attention Deployments: Some Recent Challenges and Their Resolution

    Directory of Open Access Journals (Sweden)

    Árni Kristjánsson

    2011-05-01

    Full Text Available In the past my colleagues and I have presented evidence for the existence of a primitive memory for attention deployments. This memory system orients attention to features and locations of recent behavioral importance. A large part of the proposal is that the memory system facilitates attentional selection of features in the environment such as color, orientation, etc. I will review the findings behind these proposals. The bulk of this evidence comes from studies of history effects in vision, such as priming of visual search, and implicit learning in exogenously cued attention shifts. In addition, recent challenges to this view will be discussed (in particular, arguments that the facilitation from repetition in visual search tasks occurs at a relatively late stage of perceptual processing. Our recent investigations of these proposals suggest that there is indeed evidence for higher-level priming effects in visual search under certain conditions, but those findings do not challenge the basic proposals regarding the primitive memory system, since the evidence for feature-specific facilitation is robust.

  2. Memory systems in the rat: effects of reward probability, context, and congruency between working and reference memory.

    Science.gov (United States)

    Roberts, William A; Guitar, Nicole A; Marsh, Heidi L; MacDonald, Hayden

    2016-05-01

    The interaction of working and reference memory was studied in rats on an eight-arm radial maze. In two experiments, rats were trained to perform working memory and reference memory tasks. On working memory trials, they were allowed to enter four randomly chosen arms for reward in a study phase and then had to choose the unentered arms for reward in a test phase. On reference memory trials, they had to learn to visit the same four arms on the maze on every trial for reward. Retention was tested on working memory trials in which the interval between the study and test phase was 15 s, 15 min, or 30 min. At each retention interval, tests were performed in which the correct WM arms were either congruent or incongruent with the correct RM arms. Both experiments showed that congruency interacted with retention interval, yielding more forgetting at 30 min on incongruent trials than on congruent trials. The effect of reference memory strength on the congruency effect was examined in Experiment 1, and the effect of associating different contexts with working and reference memory on the congruency effect was studied in Experiment 2.

  3. Association of Novelty Seeking Scores and Striatal Dopamine D2/D3 Receptor Availability of Healthy Volunteers: Single Photon Emission Computed Tomography With 123I-iodobenzamide

    Directory of Open Access Journals (Sweden)

    Hsiang Yu Huang

    2010-10-01

    Full Text Available It has been speculated that novelty seeking (NS behavior is related to the dopaminergic system. Fifty-two subjects completed the Tridimensional Personality Questionnaire and underwent single photon emission computed tomography with 123I-iodobenzamide. A marginally positive correlation was noted between NS and striatal dopamine D2/D3 receptor availability (r = 0.25, p =0.07. A positive association was noted between the NS scores and left striatal D2/D3 receptor availability (r= 0.29, p =0.04. The results suggest that a relationship might exist between NS score and dopaminergic activity.

  4. TRPC1 Deletion Causes Striatal Neuronal Cell Apoptosis and Proteomic Alterations in Mice

    Directory of Open Access Journals (Sweden)

    Dian Wang

    2018-03-01

    Full Text Available Transient receptor potential channel 1 (TRPC1 is widely expressed throughout the nervous system, while its biological role remains unclear. In this study, we showed that TRPC1 deletion caused striatal neuronal loss and significantly increased TUNEL-positive and 8-hydroxy-2′-deoxyguanosine (8-OHdG staining in the striatum. Proteomic analysis by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE coupled with mass spectrometry (MS revealed a total of 51 differentially expressed proteins (26 increased and 25 decreased in the stratum of TRPC1 knockout (TRPC1−/− mice compared to that of wild type (WT mice. Bioinformatics analysis showed these dysregulated proteins included: oxidative stress-related proteins, synaptic proteins, endoplasmic reticulum (ER stress-related proteins and apoptosis-related proteins. STRING analysis showed these differential proteins have a well-established interaction network. Based on the proteomic data, we revealed by Western-blot analysis that TRPC1 deletion caused ER stress as evidenced by the dysregulation of GRP78 and PERK activation-related signaling pathway, and elevated oxidative stress as suggested by increased 8-OHdG staining, increased NADH dehydrogenase (ubiquinone flavoprotein 2 (NDUV2 and decreased protein deglycase (DJ-1, two oxidative stress-related proteins. In addition, we also demonstrated that TRPC1 deletion led to significantly increased apoptosis in striatum with concurrent decrease in both 14–3–3Z and dynamin-1 (D2 dopamine (DA receptor binding, two apoptosis-related proteins. Taken together, we concluded that TRPC1 deletion might cause striatal neuronal apoptosis by disturbing multiple biological processes (i.e., ER stress, oxidative stress and apoptosis-related signaling. These data suggest that TRPC1 may be a key player in the regulation of striatal cellular survival and death.

  5. Abnormal striatal dopaminergic neurotransmission during rest and task production in spasmodic dysphonia.

    Science.gov (United States)

    Simonyan, Kristina; Berman, Brian D; Herscovitch, Peter; Hallett, Mark

    2013-09-11

    Spasmodic dysphonia is a primary focal dystonia characterized by involuntary spasms in the laryngeal muscles during speech production. The pathophysiology of spasmodic dysphonia is thought to involve structural and functional abnormalities in the basal ganglia-thalamo-cortical circuitry; however, neurochemical correlates underpinning these abnormalities as well as their relations to spasmodic dysphonia symptoms remain unknown. We used positron emission tomography with the radioligand [(11)C]raclopride (RAC) to study striatal dopaminergic neurotransmission at the resting state and during production of symptomatic sentences and asymptomatic finger tapping in spasmodic dysphonia patients. We found that patients, compared to healthy controls, had bilaterally decreased RAC binding potential (BP) to striatal dopamine D2/D3 receptors on average by 29.2%, which was associated with decreased RAC displacement (RAC ΔBP) in the left striatum during symptomatic speaking (group average difference 10.2%), but increased RAC ΔBP in the bilateral striatum during asymptomatic tapping (group average difference 10.1%). Patients with more severe voice symptoms and subclinically longer reaction time to initiate the tapping sequence had greater RAC ΔBP measures, while longer duration of spasmodic dysphonia was associated with a decrease in task-induced RAC ΔBP. Decreased dopaminergic transmission during symptomatic speech production may represent a disorder-specific pathophysiological trait involved in symptom generation, whereas increased dopaminergic function during unaffected task performance may be explained by a compensatory adaptation of the nigrostriatal dopaminergic system possibly due to decreased striatal D2/D3 receptor availability. These changes can be linked to the clinical and subclinical features of spasmodic dysphonia and may represent the neurochemical basis of basal ganglia alterations in this disorder.

  6. Advanced Signal Processing and Command Synthesis for Memory-Limited Complex Systems

    Directory of Open Access Journals (Sweden)

    Cristian Toma

    2012-01-01

    Full Text Available This paper presents advanced signal processing methods and command synthesis for memory-limited complex systems. For accurate measurements performed on limited time interval, some specific methods should be added. For signal processing, a robust filtering and sampling procedure performed on a specific working interval is required, so as the influence of low-amplitude and high-frequency fluctuations to be diminished. This study shows that such a signal processing method for the case of memory-limited complex systems requires the use of certain differentiation/integration procedures performed by oscillating systems, so as robust results suitable for efficient command synthesis to be available. A brief comparison with uncertainty aspects in modern physics (where quantum aspects can be considered as features of complex systems is also presented.

  7. Context-sensitive autoassociative memories as expert systems in medical diagnosis

    Directory of Open Access Journals (Sweden)

    Olivera Fernando

    2006-11-01

    Full Text Available Abstract Background The complexity of our contemporary medical practice has impelled the development of different decision-support aids based on artificial intelligence and neural networks. Distributed associative memories are neural network models that fit perfectly well to the vision of cognition emerging from current neurosciences. Methods We present the context-dependent autoassociative memory model. The sets of diseases and symptoms are mapped onto a pair of basis of orthogonal vectors. A matrix memory stores the associations between the signs and symptoms, and their corresponding diseases. A minimal numerical example is presented to show how to instruct the memory and how the system works. In order to provide a quick appreciation of the validity of the model and its potential clinical relevance we implemented an application with real data. A memory was trained with published data of neonates with suspected late-onset sepsis in a neonatal intensive care unit (NICU. A set of personal clinical observations was used as a test set to evaluate the capacity of the model to discriminate between septic and non-septic neonates on the basis of clinical and laboratory findings. Results We show here that matrix memory models with associations modulated by context can perform automatic medical diagnosis. The sequential availability of new information over time makes the system progress in a narrowing process that reduces the range of diagnostic possibilities. At each step the system provides a probabilistic map of the different possible diagnoses to that moment. The system can incorporate the clinical experience, building in that way a representative database of historical data that captures geo-demographical differences between patient populations. The trained model succeeds in diagnosing late-onset sepsis within the test set of infants in the NICU: sensitivity 100%; specificity 80%; percentage of true positives 91%; percentage of true negatives 100

  8. Levodopa administration modulates striatal processing of punishment-associated items in healthy participants.

    Science.gov (United States)

    Wittmann, Bianca C; D'Esposito, Mark

    2015-01-01

    Appetitive and aversive processes share a number of features such as their relevance for action and learning. On a neural level, reward and its predictors are associated with increased firing of dopaminergic neurons, whereas punishment processing has been linked to the serotonergic system and to decreases in dopamine transmission. Recent data indicate, however, that the dopaminergic system also responds to aversive stimuli and associated actions. In this pharmacological functional magnetic resonance imaging study, we investigated the contribution of the dopaminergic system to reward and punishment processing in humans. Two groups of participants received either placebo or the dopamine precursor levodopa and were scanned during alternating reward and punishment anticipation blocks. Levodopa administration increased striatal activations for cues presented in punishment blocks. In an interaction with individual personality scores, levodopa also enhanced striatal activation for punishment-predictive compared with neutral cues in participants scoring higher on the novelty-seeking dimension. These data support recent indications that dopamine contributes to punishment processing and suggest that the novelty-seeking trait is a measure of susceptibility to drug effects on motivation. These findings are also consistent with the possibility of an inverted U-shaped response function of dopamine in the striatum, suggesting an optimal level of dopamine release for motivational processing.

  9. The Basolateral Amygdala and Nucleus Accumbens Core Mediate Dissociable Aspects of Drug Memory Reconsolidation

    Science.gov (United States)

    Theberge, Florence R. M.; Milton, Amy L.; Belin, David; Lee, Jonathan L. C.; Everitt, Barry J.

    2010-01-01

    A distributed limbic-corticostriatal circuitry is implicated in cue-induced drug craving and relapse. Exposure to drug-paired cues not only precipitates relapse, but also triggers the reactivation and reconsolidation of the cue-drug memory. However, the limbic cortical-striatal circuitry underlying drug memory reconsolidation is unclear. The aim…

  10. Oscillatory multiplexing of neural population codes for interval timing and working memory

    NARCIS (Netherlands)

    Gu, Bon-Mi; van Rijn, Hedderik; Meck, Warren H.

    Interval timing and working memory are critical components of cognition that are supported by neural oscillations in prefrontal-striatal-hippocampal circuits. In this review, the properties of interval timing and working memory are explored in terms of behavioral, anatomical, pharmacological, and

  11. Learning classifier systems with memory condition to solve non-Markov problems

    OpenAIRE

    Zang, Zhaoxiang; Li, Dehua; Wang, Junying

    2012-01-01

    In the family of Learning Classifier Systems, the classifier system XCS has been successfully used for many applications. However, the standard XCS has no memory mechanism and can only learn optimal policy in Markov environments, where the optimal action is determined solely by the state of current sensory input. In practice, most environments are partially observable environments on agent's sensation, which are also known as non-Markov environments. Within these environments, XCS either fail...

  12. The Hypocretin/Orexin System Mediates the Extinction of Fear Memories

    OpenAIRE

    Flores, África; Valls-Comamala, Victòria; Costa, Giulia; Saravia, Rocío; Maldonado, Rafael; Berrendero, Fernando

    2014-01-01

    Anxiety disorders are often associated with an inability to extinguish learned fear responses. The hypocretin/orexin system is involved in the regulation of emotional states and could also participate in the consolidation and extinction of aversive memories. Using hypocretin receptor-1 and hypocretin receptor-2 antagonists, hypocretin-1 and hypocretin-2 peptides, and hypocretin receptor-1 knockout mice, we investigated the role of the hypocretin system in cue- and context-dependent fear condi...

  13. System planning of Nagano Olympic Memorial Arena; Naganoshi Olympic kinen arena

    Energy Technology Data Exchange (ETDEWEB)

    Omae, Y.; Nakamura, M. [Kume Sekkei Co. Ltd., Tokyo (Japan); Hayakawa, M.; Kondo, J. [Kajima Corp., Tokyo (Japan); Ito, T. [Daidan Co. Ltd., Osaka (Japan); Yosoyama, Y. [Suga Engineering Co. Ltd., Tokyo (Japan)

    1999-11-05

    Nagano Olympic Memorial Arena, well known as hosting the Speed Skate Competition in 1998 Winter Olympic Game, is the first multi-purpose facility with 400 m long ice-skate rink in Japan. The superior system for saving energy and resources is the main concept of the arena. This system covers not only the Olympic Game but also multi-functional general usage. The world records and the variety of use are the proof of the accomplishment. (author)

  14. Petri Games: Synthesis of Distributed Systems with Causal Memory

    Directory of Open Access Journals (Sweden)

    Bernd Finkbeiner

    2014-08-01

    Full Text Available We present a new multiplayer game model for the interaction and the flow of information in a distributed system. The players are tokens on a Petri net. As long as the players move in independent parts of the net, they do not know of each other; when they synchronize at a joint transition, each player gets informed of the causal history of the other player. We show that for Petri games with a single environment player and an arbitrary bounded number of system players, deciding the existence of a safety strategy for the system players is EXPTIME-complete.

  15. A FPGA-based Measurement System for Nonvolatile Semiconductor Memory Characterization

    Science.gov (United States)

    Bu, Jiankang; White, Marvin

    2002-03-01

    Low voltage, long retention, high density SONOS nonvolatile semiconductor memory (NVSM) devices are ideally suited for PCMCIA, FLASH and 'smart' cards. The SONOS memory transistor requires characterization with an accurate, rapid measurement system with minimum disturbance to the device. The FPGA-based measurement system includes three parts: 1) a pattern generator implemented with XILINX FPGAs and corresponding software, 2) a high-speed, constant-current, threshold voltage detection circuit, 3) and a data evaluation program, implemented with a LABVIEW program. Fig. 1 shows the general block diagram of the FPGA-based measurement system. The function generator is designed and simulated with XILINX Foundation Software. Under the control of the specific erase/write/read pulses, the analog detect circuit applies operational modes to the SONOS device under test (DUT) and determines the change of the memory-state of the SONOS nonvolatile memory transistor. The TEK460 digitizes the analog threshold voltage output and sends to the PC computer. The data is filtered and averaged with a LABVIEWTM program running on the PC computer and displayed on the monitor in real time. We have implemented the pattern generator with XILINX FPGAs. Fig. 2 shows the block diagram of the pattern generator. We realized the logic control by a method of state machine design. Fig. 3 shows a small part of the state machine. The flexibility of the FPGAs enhances the capabilities of this system and allows measurement variations without hardware changes. The characterization of the nonvolatile memory transistor device under test (DUT), as function of programming voltage and time, is achieved by a high-speed, constant-current threshold voltage detection circuit. The analog detection circuit incorporating fast analog switches controlled digitally with the FPGAs. The schematic circuit diagram is shown in Fig. 4. The various operational modes for the DUT are realized with control signals applied to the

  16. A HETEROGENEOUS MULTIPROCESSOR SYSTEM-ON-CHIP ARCHITECTURE INCORPORATING MEMORY ALLOCATION

    Directory of Open Access Journals (Sweden)

    T.Thillaikkarasi

    2010-06-01

    Full Text Available This paper describes the development of a Multiprocessor System-on-Chip (MPSoC with a novel interconnect architecture incorporating memory allocation. It addresses the problem of mapping a process network with data dependent behavior and soft real time constraints onto the heterogeneous multiprocessor System on Chip (SoC architectures and focuses on a memory allocation step which is based on an integer linear programming model. An application is modeled as Kahn Process Network (KPN which makes the parallelism present in the application explicit. The main contribution of our work is an MILP based approach which can be used to map the KPN of streaming applications with data dependent behavior and interleaved computation and communication. Our solution minimizes hardware cost while taking into account the performance constraints. One of the salient features of our work is that it takes into account the additional overheads because of data communication conflicts. It permits to obtain an optimal distributed shared memory architecture minimizing the global cost to access the shared data in the application, and the memory cost. Our approach allows automatic generation of an architecture-level specification of the application.

  17. The hypocretin/orexin system mediates the extinction of fear memories.

    Science.gov (United States)

    Flores, África; Valls-Comamala, Victòria; Costa, Giulia; Saravia, Rocío; Maldonado, Rafael; Berrendero, Fernando

    2014-11-01

    Anxiety disorders are often associated with an inability to extinguish learned fear responses. The hypocretin/orexin system is involved in the regulation of emotional states and could also participate in the consolidation and extinction of aversive memories. Using hypocretin receptor-1 and hypocretin receptor-2 antagonists, hypocretin-1 and hypocretin-2 peptides, and hypocretin receptor-1 knockout mice, we investigated the role of the hypocretin system in cue- and context-dependent fear conditioning and extinction. Hypocretins were crucial for the consolidation of fear conditioning, and this effect was mainly observed in memories with a high emotional component. Notably, after the acquisition of fear memory, hypocretin receptor-1 blockade facilitated fear extinction, whereas hypocretin-1 administration impaired this extinction process. The extinction-facilitating effects of the hypocretin receptor-1 antagonist SB334867 were associated with increased expression of cFos in the basolateral amygdala and the infralimbic cortex. Intra-amygdala, but neither intra-infralimbic prefrontal cortex nor intra-dorsohippocampal infusion of SB334867 enhanced fear extinction. These results reveal a key role for hypocretins in the extinction of aversive memories and suggest that hypocretin receptor-1 blockade could represent a novel therapeutic target for the treatment of diseases associated with inappropriate retention of fear, such as post-traumatic stress disorder and phobias.

  18. Power profiling of Cholesky and QR factorizations on distributed memory systems

    KAUST Repository

    Bosilca, George

    2012-08-30

    This paper presents the power profile of two high performance dense linear algebra libraries on distributed memory systems, ScaLAPACK and DPLASMA. From the algorithmic perspective, their methodologies are opposite. The former is based on block algorithms and relies on multithreaded BLAS and a two-dimensional block cyclic data distribution to achieve high parallel performance. The latter is based on tile algorithms running on top of a tile data layout and uses fine-grained task parallelism combined with a dynamic distributed scheduler (DAGuE) to leverage distributed memory systems. We present performance results (Gflop/s) as well as the power profile (Watts) of two common dense factorizations needed to solve linear systems of equations, namely Cholesky and QR. The reported numbers show that DPLASMA surpasses ScaLAPACK not only in terms of performance (up to 2X speedup) but also in terms of energy efficiency (up to 62 %). © 2012 Springer-Verlag (outside the USA).

  19. Effects of caffeine on striatal neurotransmission: focus on cannabinoid CB1 receptors.

    Science.gov (United States)

    Rossi, Silvia; De Chiara, Valentina; Musella, Alessandra; Mataluni, Giorgia; Sacchetti, Lucia; Siracusano, Alberto; Bernardi, Giorgio; Usiello, Alessandro; Centonze, Diego

    2010-04-01

    Caffeine is the most commonly self-administered psychoactive substance worldwide. At usual doses, the effects of caffeine on vigilance, attention, mood and arousal largely depend on the modulation of central adenosine receptors. The present review article describes the action of caffeine within the striatum, to provide a possible molecular mechanism at the basis of the psychomotor and reinforcing properties of this pharmacological agent. The striatum is in fact a subcortical area involved in sensorimotor, cognitive, and emotional processes, and recent experimental findings showed that chronic caffeine consumption enhances the sensitivity of striatal GABAergic synapses to the stimulation of cannabinoid CB1 receptors. The endocannabinoid system is involved in the psychoactive effects of many compounds, and adenosine A2A receptors (the main receptor target of caffeine) elicit a permissive effect towards CB1 receptors, thus suggesting that A2A-CB1 receptor interaction plays a major role in the generation and maintenance of caffeine reinforcing behavior. Aim of this review is to describe the effects of caffeine on striatal neurotransmission with special reference to the modulation of the endocannabinoid system.

  20. Hippocampal and striatal involvement in cognitive tasks: a computational model

    OpenAIRE

    Fabian, Chersi; Neil, Burgess

    2018-01-01

    The hippocampus and the striatum support episodic and procedural memory, respectively, and "place" and "response" learning within spatial navigation. Recently this dichotomy has been linked to "model-based" and "model-free" reinforcement learning. Here we present a well-constrained neural model of how both systems support spatial navigation, and apply the same model to more abstract problems such as sequential decision making. In particular, we show that if a task can be transformed into a Ma...

  1. Measuring memory.

    Science.gov (United States)

    Baddeley, A

    1988-01-01

    Three broad approaches to the measurement of memory functioning will be described. The first of these involves using memory as a general indicator of any dysfunction in the central nervous system. This approach will be illustrated using Sternberg's short-term memory scanning paradigm. Its strengths are that such tests are often very sensitive, but they are often very difficult to interpret both theoretically and in practical terms. A second approach is to use a range of tasks selected so as to tap different aspects of human memory. Such an approach is of considerably more theoretical interest, and is discussed in more detail by Eysenck (this volume). Its weaknesses are that theories of memory are still changing relatively quickly, and that mapping such results onto memory outside the laboratory is often complex. A third approach is to attempt a more direct measure of everyday memory. The use of questionnaires for this purpose will be critically discussed, and a new test of everyday memory will be described. This test, the Rivermead Behavioural Memory Test, correlates well with observations of memory lapses in patients, and appears to offer a promising new line of development.

  2. The Role of Epigenetic Regulation in Transcriptional Memory in the Immune System.

    Science.gov (United States)

    Woodworth, A M; Holloway, A F

    The immune system is exquisitely poised to identify, respond to, and eradicate pathogens from the body, as well as to produce a more rapid and augmented response to a subsequent encounter with the pathogen. These cellular responses rely on the highly coordinated and rapid activation of gene expression programs as well as the ability of the cell to retain a memory of the initial gene response. It is clear that chromatin structure and epigenetic mechanisms play a crucial role in determining these gene responses, and in fact the immune system has proved an instructive model for investigating the multifaceted mechanisms through which the chromatin landscape contributes to gene expression programs. These mechanisms include modifications to the DNA and histone proteins, the positioning, composition, and remodeling of nucleosomes, as well as the formation of higher-order chromatin structures. Moreover, it is now apparent that epigenetic mechanisms also provide an instrument by which cells can retain memory of the initial transcriptional response, "priming" the genome so that it can respond more quickly to subsequent exposure to the signal. Here, we use the immune system as a model to demonstrate the complex interplay between transcription factors and the chromatin landscape required to orchestrate precise gene responses to external stimuli and further to demonstrate how these interactions can establish memory of past transcriptional events. We focus on what we have learnt from the immune system and how this can inform our understanding of other cellular systems. © 2017 Elsevier Inc. All rights reserved.

  3. Striatal Vulnerability in Huntington’s Disease: Neuroprotection Versus Neurotoxicity

    Directory of Open Access Journals (Sweden)

    Ryoma Morigaki

    2017-06-01

    Full Text Available Huntington’s disease (HD is an autosomal dominant neurodegenerative disease caused by the expansion of a CAG trinucleotide repeat encoding an abnormally long polyglutamine tract (PolyQ in the huntingtin (Htt protein. In HD, striking neuropathological changes occur in the striatum, including loss of medium spiny neurons and parvalbumin-expressing interneurons accompanied by neurodegeneration of the striosome and matrix compartments, leading to progressive impairment of reasoning, walking and speaking abilities. The precise cause of striatal pathology in HD is still unknown; however, accumulating clinical and experimental evidence suggests multiple plausible pathophysiological mechanisms underlying striatal neurodegeneration in HD. Here, we review and discuss the characteristic neurodegenerative patterns observed in the striatum of HD patients and consider the role of various huntingtin-related and striatum-enriched proteins in neurotoxicity and neuroprotection.

  4. Centrality of striatal cholinergic transmission in basal ganglia function

    Directory of Open Access Journals (Sweden)

    Paola eBonsi

    2011-02-01

    Full Text Available Work over the past two decades revealed a previously unexpected role for striatal cholinergic interneurons in the context of basal ganglia function. The recognition that these interneurons are essential in synaptic plasticity and motor learning represents a significant step ahead in deciphering how the striatum processes cortical inputs, and why pathological circumstances cause motor dysfunction.Loss of the reciprocal modulation between dopaminergic inputs and the intrinsic cholinergic innervation within the striatum appears to be the trigger for pathophysiological changes occurring in basal ganglia disorders. Accordingly, there is now compelling evidence showing profound changes in cholinergic markers in these disorders, in particular Parkinson’s disease and dystonia.Based on converging experimental and clinical evidence, we provide an overview of the role of striatal cholinergic transmission in physiological and pathological conditions, in the context of the pathogenesis of movement disorders.

  5. Test Methods for Telemetry Systems and Subsystems. Volume 5: Test Methods for Digital Recorder/Reproducer Systems and Recorder Memory Modules

    Science.gov (United States)

    2016-09-26

    REPRODUCER SYSTEMS AND RECORDER MEMORY MODULES ABERDEEN TEST CENTER DUGWAY PROVING GROUND REAGAN TEST SITE WHITE SANDS MISSILE RANGE YUMA...ARNOLD ENGINEERING DEVELOPMENT COMPLEX NATIONAL AERONAUTICS AND SPACE ADMINISTRATION DISTRIBUTION A: APPROVED FOR PUBLIC RELEASE; DISTRIBUTION...AND SUBSYSTEMS VOLUME V TEST METHODS FOR DIGITAL RECORDER/REPRODUCER SYSTEMS AND RECORDER MEMORY MODULES September 2016

  6. System of common usage on the base of external memory devices and the SM-3 computer

    International Nuclear Information System (INIS)

    Baluka, G.; Vasin, A.Yu.; Ermakov, V.A.; Zhukov, G.P.; Zimin, G.N.; Namsraj, Yu.; Ostrovnoj, A.I.; Savvateev, A.S.; Salamatin, I.M.; Yanovskij, G.Ya.

    1980-01-01

    An easily modified system of common usage on the base of external memories and a SM-3 minicomputer replacing some pulse analysers is described. The system has merits of PA and is more advantageous with regard to effectiveness of equipment using, the possibility of changing configuration and functions, the data protection against losses due to user errors and some failures, price of one registration channel, place occupied. The system of common usage is intended for the IBR-2 pulse reactor computing centre. It is designed using the SANPO system means for SM-3 computer [ru

  7. Neuroglial plasticity at striatal glutamatergic synapses in Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Rosa M Villalba

    2011-08-01

    Full Text Available Striatal dopamine denervation is the pathological hallmark of Parkinson’s disease (PD. Another major pathological change described in animal models and PD patients is a significant reduction in the density of dendritic spines on medium spiny striatal projection neurons. Simultaneously, the ultrastructural features of the neuronal synaptic elements at the remaining corticostriatal and thalamostriatal glutamatergic axo-spinous synapses undergo complex ultrastructural remodeling consistent with increased synaptic activity (Villalba et al., 2011. The concept of tripartite synapses (TS was introduced a decade ago, according to which astrocytes process and exchange information with neuronal synaptic elements at glutamatergic synapses (Araque et al., 1999a. Although there has been compelling evidence that astrocytes are integral functional elements of tripartite glutamatergic synaptic complexes in the cerebral cortex and hippocampus, their exact functional role, degree of plasticity and preponderance in other CNS regions remain poorly understood. In this review, we discuss our recent findings showing that neuronal elements at cortical and thalamic glutamatergic synapses undergo significant plastic changes in the striatum of MPTP-treated parkinsonian monkeys. We also present new ultrastructural data that demonstrate a significant expansion of the astrocytic coverage of striatal TS synapses in the parkinsonian state, providing further evidence for ultrastructural compensatory changes that affect both neuronal and glial elements at TS. Together with our limited understanding of the mechanisms by which astrocytes respond to changes in neuronal activity and extracellular transmitter homeostasis, the role of both neuronal and glial components of excitatory synapses must be considered, if one hopes to take advantage of glia-neuronal communication knowledge to better understand the pathophysiology of striatal processing in parkinsonism, and develop new PD

  8. Thermalization, Error Correction, and Memory Lifetime for Ising Anyon Systems

    Directory of Open Access Journals (Sweden)

    Courtney G. Brell

    2014-09-01

    Full Text Available We consider two-dimensional lattice models that support Ising anyonic excitations and are coupled to a thermal bath. We propose a phenomenological model for the resulting short-time dynamics that includes pair creation, hopping, braiding, and fusion of anyons. By explicitly constructing topological quantum error-correcting codes for this class of system, we use our thermalization model to estimate the lifetime of the quantum information stored in the encoded spaces. To decode and correct errors in these codes, we adapt several existing topological decoders to the non-Abelian setting. We perform large-scale numerical simulations of these two-dimensional Ising anyon systems and find that the thresholds of these models range from 13% to 25%. To our knowledge, these are the first numerical threshold estimates for quantum codes without explicit additive structure.

  9. In vivo neurochemical characterization of clothianidin induced striatal dopamine release.

    Science.gov (United States)

    Faro, L R F; Oliveira, I M; Durán, R; Alfonso, M

    2012-12-16

    Clothianidin (CLO) is a neonicotinoid insecticide with selective action on nicotinic acetylcholine receptors. The aim of this study was to determine the neurochemical basis for CLO-induced striatal dopamine release using the microdialysis technique in freely moving and conscious rats. Intrastriatal administration of CLO (3.5mM), produced an increase in both spontaneous (2462 ± 627% with respect to basal values) and KCl-evoked (4672 ± 706% with respect to basal values) dopamine release. This effect was attenuated in Ca(2+)-free medium, and was prevented in reserpine pre-treated animals or in presence of tetrodotoxin (TTX). To investigate the involvement of dopamine transporter (DAT), the effect of CLO was observed in presence of nomifensine. The coadministration of CLO and nomifensine produced an additive effect on striatal dopamine release. The results suggest that the effect of CLO on striatal dopamine release is predominantly mediated by an exocytotic mechanism, Ca(2+), vesicular and TTX-dependent and not by a mechanism mediated by dopamine transporter. Published by Elsevier Ireland Ltd.

  10. Transient and steady-state selection in the striatal microcircuit

    Directory of Open Access Journals (Sweden)

    Adam eTomkins

    2014-01-01

    Full Text Available Although the basal ganglia have been widely studied and implicated in signal processing and action selection, little information is known about the active role the striatal microcircuit plays in action selection in the basal ganglia-thalamo-cortical loops. To address this knowledge gap we use a large scale three dimensional spiking model of the striatum, combined with a rate coded model of the basal ganglia-thalamo-cortical loop, to asses the computational role the striatum plays in action selection. We identify a robust transient phenomena generated by the striatal microcircuit, which temporarily enhances the difference between two competing cortical inputs. We show that this transient is sufficient to modulate decision making in the basal ganglia-thalamo-cortical circuit. We also find that the transient selection originates from a novel adaptation effect in single striatal projection neurons, which is amenable to experimental testing. Finally, we compared transient selection with models implementing classical steady-state selection. We challenged both forms of model to account for recent reports of paradoxically enhanced response selection in Huntington's Disease patients. We found that steady-state selection was uniformly impaired under all simulated Huntington's conditions, but transient selection was enhanced given a sufficient Huntington's-like increase in NMDA receptor sensitivity. Thus our models provide an intriguing hypothesis for the mechanisms underlying the paradoxical cognitive improvements in manifest Huntington's patients.

  11. Fractal analysis of striatal dopamine re-uptake sites

    International Nuclear Information System (INIS)

    Kuikka, J.T.; Bergstroem, K.A.; Tiihonen, J.; Raesaenen, P.; Karhu, J.

    1997-01-01

    Spatial variation in regional blood flow, metabolism and receptor density within the brain and in other organs is measurable even with a low spatial resolution technique such as emission tomography. It has been previously shown that the observed variance increases with increasing number of subregions in the organ/tissue studied. This resolution-dependent variance can be described by fractal analysis. We studied striatal dopamine re-uptake sites in 39 healthy volunteers with high-resolution single-photon emission tomography using iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl)tropane ([ 123 I]β-CIT). The mean fractal dimension was 1.15±0.07. The results indicate that regional striatal dopamine re-uptake sites involve considerable spatial heterogeneity which is higher than the uniform density (dimension=1.00) but much lower than complete randomness (dimension=1.50). There was a gender difference, with females having a higher heterogeneity in both the left and the right striatum. In addition, we found striatal asymmetry (left-to-right heterogeneity ratio of 1.19±0.15; P<0.001), suggesting functional hemispheric lateralization consistent with the control of motor behaviour and integrative functions. (orig.). With 5 figs., 1 tab

  12. PMCAP: A Threat Model of Process Memory Data on the Windows Operating System

    Directory of Open Access Journals (Sweden)

    Jiaye Pan

    2017-01-01

    Full Text Available Research on endpoint security involves both traditional PC platform and prevalent mobile platform, among which the analysis of software vulnerability and malware is one of the important contents. For researchers, it is necessary to carry out nonstop exploration of the insecure factors in order to better protect the endpoints. Driven by this motivation, we propose a new threat model named Process Memory Captor (PMCAP on the Windows operating system which threatens the live process volatile memory data. Compared with other threats, PMCAP aims at dynamic data in the process memory and uses a noninvasive approach for data extraction. In this paper we describe and analyze the model and then give a detailed implementation taking four popular web browsers IE, Edge, Chrome, and Firefox as examples. Finally, the model is verified through real experiments and case studies. Compared with existing technologies, PMCAP can extract valuable data at a lower cost; some techniques in the model are also suitable for memory forensics and malware analysis.

  13. Correctness of Concurrent Executions of Closed Nested Transactions in Transactional Memory Systems

    Science.gov (United States)

    Peri, Sathya; Vidyasankar, Krishnamurthy

    A generally agreed upon requirement for correctness of concurrent executions in Transactional Memory systems is that all transactions including the aborted ones read consistent values. Opacity is a recently proposed correctness criterion that satisfies the above requirement. Our first contribution in this paper is extending the opacity definition for closed nested transactions. Secondly, we define conflicts appropriate for optimistic executions which are commonly used in Software Transactional Memory systems. Using these conflicts, we define a restricted, conflict-preserving, class of opacity for closed nested transactions the membership of which can be tested in polynomial time. As our third contribution, we propose a correctness criterion that defines a class of schedules where aborted transactions do not affect consistency of the other transactions. We define a conflict-preserving subclass of this class as well. Both the class definitions and the conflict definition are new for nested transactions.

  14. Counterbalancing Regulation in Response Memory of a Positively Autoregulated Two-Component System.

    Science.gov (United States)

    Gao, Rong; Godfrey, Katherine A; Sufian, Mahir A; Stock, Ann M

    2017-09-15

    Fluctuations in nutrient availability often result in recurrent exposures to the same stimulus conditions. The ability to memorize the past event and use the "memory" to make adjustments to current behaviors can lead to a more efficient adaptation to the recurring stimulus. A short-term phenotypic memory can be conferred via carryover of the response proteins to facilitate the recurrent response, but the additional accumulation of response proteins can lead to a deviation from response homeostasis. We used the Escherichia coli PhoB/PhoR two-component system (TCS) as a model system to study how cells cope with the recurrence of environmental phosphate (Pi) starvation conditions. We discovered that "memory" of prior Pi starvation can exert distinct effects through two regulatory pathways, the TCS signaling pathway and the stress response pathway. Although carryover of TCS proteins can lead to higher initial levels of transcription factor PhoB and a faster initial response in prestarved cells than in cells not starved, the response enhancement can be overcome by an earlier and greater repression of promoter activity in prestarved cells due to the memory of the stress response. The repression counterbalances the carryover of the response proteins, leading to a homeostatic response whether or not cells are prestimulated. A computational model based on sigma factor competition was developed to understand the memory of stress response and to predict the homeostasis of other PhoB-regulated response proteins. Our insight into the history-dependent PhoBR response may provide a general understanding of how TCSs respond to recurring stimuli and adapt to fluctuating environmental conditions. IMPORTANCE Bacterial cells in their natural environments experience scenarios that are far more complex than are typically replicated in laboratory experiments. The architectures of signaling systems and the integration of multiple adaptive pathways have evolved to deal with such complexity

  15. Decreased striatal D2 receptor density associated with severe behavioral abnormality in Alzheimer's disease

    International Nuclear Information System (INIS)

    Tanaka, Yasuhiro; Meguro, Kenichi; Yamaguchi, Satoshi

    2003-01-01

    Since patients manifesting behavioral and psychological symptoms of dementia (BPSD) are a burden for their families and caregivers, the underlying neurobiological mechanism of this condition should be clarified. Using positron emission tomography (PET), we previously reported that wandering behavior in dementia was associated with a disturbed dopaminergic neuron system. We herein investigated the relationship between the severity of BPSD and the striatal D 2 receptor density in Alzheimer's disease (AD). Ten patients with probable AD as per the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) and the AD and Related Disorders Association (ADRDA) criteria and five normal subjects were examined with PET. The tracer used was [ 11 C]raclopride (D 2 antagonist). The uptake of [ 11 C]raclopride was calculated as the estimation of binding potential (BP) of the striatum to the cerebellum. The AD patients were institutionalized in multiple nursing homes, and their BPSD were evaluated by the Behavioral Pathology in AD Frequency Weighted Severity Scale (BEHAVE-AD-FW) scale (Reisberg). There was a significant inverse Spearman's correlation between BEHAVE-AD-FW score and the BP, especially between the score of the behavioral domain and the BP values. The BP was found to be lower in severer BPSD patients. Patients with AD who manifest severe BPSD may have some dysfunction of striatal dopamine metabolism compared with those without BPSD. (author)

  16. Cortico-striatal oxidative status, dopamine turnover and relation with stereotypy in the deer mouse.

    Science.gov (United States)

    Güldenpfennig, Marianne; Wolmarans, De Wet; du Preez, Jan L; Stein, Dan J; Harvey, Brian H

    2011-06-01

    The deer mouse presents with spontaneous stereotypic movements that resemble the repetitive behaviours of obsessive-compulsive disorder (OCD), and demonstrates a selective response to serotonin reuptake inhibitors. OCD has been linked to altered redox status and since increased dopamine signalling can promote stereotypies as well as oxidative stress, we investigated whether the severity of deer mouse stereotypy may be associated with altered dopamine turnover and cortico-striatal redox status. Deer mice were separated into high (HSB), low (LSB) and non-stereotypy (NS) groups. Frontal cortical and striatal dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), as well as superoxide dismutase (SOD) activity, reduced (GSH) and oxidised (GSSG) glutathione and glutathione redox index, were analysed as markers for regional dopamine turnover and oxidative stress, respectively. Dopamine and its metabolites and SOD activity did not differ across the stereotypy groups. Significantly reduced GSH and GSSG and increased glutathione redox index were only observed in the frontal cortex of HSB animals. Frontal cortical GSH and GSSG were inversely correlated while glutathione redox index was positively correlated with stereotypy. Deer mouse stereotypy is thus characterised by a deficient glutathione system in the frontal cortex but not striatum, and provides a therapeutic rationale for using glutathione-active antioxidants in OCD. The evidence for a primary frontal lesion has importance for future OCD research. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. DRD4 and striatal modulation of the link between childhood behavioral inhibition and adolescent anxiety

    Science.gov (United States)

    Hardee, Jillian E.; Guyer, Amanda E.; Benson, Brenda E.; Nelson, Eric E.; Gorodetsky, Elena; Goldman, David; Fox, Nathan A.; Pine, Daniel S.; Ernst, Monique

    2014-01-01

    Behavioral inhibition (BI), a temperament characterized by vigilance to novelty, sensitivity to approach–withdrawal cues and social reticence in childhood, is associated with risk for anxiety in adolescence. Independent studies link reward hyper-responsivity to BI, adolescent anxiety and dopamine gene variants. This exploratory study extends these observations by examining the impact of DRD4 genotype and reward hyper-responsivity on the BI–anxiety link. Adolescents (N = 78) completed a monetary incentive delay task in the fMRI environment. Participants were characterized based on a continuous score of BI and the 7-repeat allele (7R+) of the DRD4 functional polymorphism. Parent-report and self-report measures of anxiety were also collected. Across the entire sample, striatal activation increased systematically with increases in the magnitude of anticipated monetary gains and losses. DRD4 status moderated the relation between BI and activation in the caudate nucleus. Childhood BI was associated with parent report of adolescent anxiety among 7R+ participants with elevated levels of striatal response to incentive cues. DRD4 genotype influenced the relations among neural response to incentives, early childhood BI and anxiety. The findings help refine our understanding of the role reward-related brain systems play in the emergence of anxiety in temperamentally at-risk individuals, building a foundation for future larger scale studies. PMID:23314010

  18. Effects of isomers of apomorphines on dopamine receptors in striatal and limbic tissue of rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Kula, N.S.; Baldessarini, R.J.; Bromley, S.; Neumeyer, J.L.

    1985-09-16

    The optical isomers of apomorphine (APO) and N-propylnorapomorphine (NPA) were interacted with three biochemical indices of dopamine (Da) receptors in extrapyramidal and limbic preparations of rat brain tissues. There were consistent isomeric preferences for the R(-) configuration of both DA analogs in stimulation adenylate cyclase (D-1 sites) and in competing for high affinity binding of /sup 3/H-spiroperidol (D-2 sites) and of /sup 3/H-ADTN (DA agonist binding sites) in striatal tissue, with lesser isomeric differences in the limbic tissue. The S(+) apomorphines did not inhibit stimulation of adenylate cyclase by DA. The tendency for greater activity of higher apparent affinity of R(-) apomorphines in striatum may reflect the evidently greater abundance of receptor sites in that region. There were only small regional differences in interactions of the apomorphine isomers with all three receptor sites, except for a strong preference of (-)NPA for striatal D-2 sites. These results do not parallel our recent observations indicating potent and selective antidopaminergic actions of S(+) apomorphines in the rat limbic system. They suggest caution in assuming close parallels between current biochemical functional, especially behavioral, methods of evaluating dopamine receptors of mammalian brain.

  19. [3H]Dopamine accumulation and release from striatal slices in young, mature and senescent rats

    International Nuclear Information System (INIS)

    Thompson, J.M.

    1981-01-01

    Examinations of [ 3 H]dopamine ([ 3 H]DA) release following KCl or amphetamine administration in striatal slices from young (7 month), mature (12 month) and senescent (24 month) Wistar rats showed no age-related changes. Further, the amount of [ 3 H]DA accumulated in the striatal slices showed no changes with age. Thus, previously reported age-related deficits in motor behavior (i.e. rotational) are not produced by changes in striatal DA accumulation or release. (Auth.)

  20. Global and Local Page Replacement Algorithms on Virtual Memory Systems for Image Processing

    OpenAIRE

    WADA, Ben Tsutom

    1985-01-01

    Three virtual memory systems for image processing, different one another in frame allocation algorithms and page replacement algorithms, were examined experimentally upon their page-fault characteristics. The hypothesis, that global page replacement algorithms are susceptible to thrashing, held in the raster scan experiment, while it did not in another non raster-scan experiment. The results of the experiments may be useful also in making parallel image processors more efficient, while they a...

  1. Information Systems and Corporate Memory: design for staff turn-over

    OpenAIRE

    Colin Sharp; Neil Lewis

    1993-01-01

    The "information age" is reliant upon the information skill-base of people and the storage and access of complete data. Staff turn-over and "down-sizing" as well as the rate of organisational change places increased pressure on the designers of corporate information systems to keep up with the organizational demands. Especially relevant are the "soft" aspects of the corporate information needs of organizations. The term "corporate memory" is introduced to explain the relatively informal colle...

  2. Differences in striatal dopamine transporter density between tremor dominant and non-tremor Parkinson's disease

    Energy Technology Data Exchange (ETDEWEB)

    Kaasinen, Valtteri; Kinos, Maija; Joutsa, Juho [University of Turku and Turku University Hospital, Division of Clinical Neurosciences, Turku (Finland); University of Turku and Turku University Hospital, Turku PET Centre, Turku (Finland); Seppaenen, Marko [University of Turku and Turku University Hospital, Turku PET Centre, Turku (Finland); University of Turku and Turku University Hospital, Department of Clinical Physiology and Nuclear Medicine, Turku (Finland); Noponen, Tommi [University of Turku and Turku University Hospital, Department of Clinical Physiology and Nuclear Medicine, Turku (Finland)

    2014-10-15

    Parkinson's disease (PD) can manifest with a tremor-dominant or a non-tremor (akinetic-rigid) phenotype. Although the tremor-dominant subtype may show a better prognosis, there is limited information on the phenotypic differences regarding the level of striatal dopamine transmission. The present study investigated striatal dopamine transporter (DAT) binding characteristics in a large sample of patients with and without tremor. [{sup 123}I]FP-CIT SPECT scans of 231 patients with a clinical diagnosis of PD and abnormal FP-CIT binding (157 with tremor, 74 without tremor) and 230 control patients with normal FP-CIT binding (148 with tremor, 82 without tremor) were analysed using an automated region-of-interest analysis of the scans (BRASS). Specific striatal binding ratios were compared between phenotypes and groups using age, sex, and symptom duration, predominant side of symptoms, dopaminergic medications and scanner as covariates. Patients with PD had 28.1 - 65.0 % lower binding in all striatal regions compared to controls (p < 0.001). The mean FP-CIT caudate nucleus uptake and the left caudate nucleus uptake were higher in PD patients with tremor than in PD patients without tremor (mean 9.0 % higher, left 10.5 % higher; p < 0.05), whereas there were no differences between tremor and non-tremor control patients. No significant effects of tremor on DAT binding were observed in the anterior or posterior putamen. The motor phenotype is associated with the extent of caudate dopamine terminal loss in PD, as dopamine function is relatively more preserved in tremor patients. Symptom type is related to caudate dopamine function only in association with Parkinsonian dopaminergic degeneration, not in intact dopamine systems in patients with non-PD tremor. (orig.)

  3. Timing of caloric intake during weight loss differentially affects striatal dopamine transporter and thalamic serotonin transporter binding.

    Science.gov (United States)

    Versteeg, Ruth I; Schrantee, Anouk; Adriaanse, Sofie M; Unmehopa, Unga A; Booij, Jan; Reneman, Liesbeth; Fliers, Eric; la Fleur, Susanne E; Serlie, Mireille J

    2017-10-01

    Recent studies have shown that meal timing throughout the day contributes to maintaining or regaining weight after hypocaloric diets. Although brain serotonin and dopamine are well known to be involved in regulating feeding, it is unknown whether meal timing during energy restriction affects these neurotransmitter systems. We studied the effect of a 4 wk hypocaloric diet with either 50% of daily calories consumed at breakfast (BF group) or at dinner (D group) on hypothalamic and thalamic serotonin transporter (SERT) binding and on striatal dopamine transporter (DAT) binding. The BF and D groups lost a similar amount of weight. Striatal DAT and thalamic SERT binding increased in the BF group, while decreasing in the D group after the diet (ΔDAT 0.37 ± 0.63 vs. -0.53 ± 0.77, respectively; P = 0.005; ΔSERT 0.12 ± 0.25 vs. -0.13 ± 0.26 respectively, P = 0.032). Additional voxel-based analysis showed an increase in DAT binding in the ventral striatum in the BF group and a decrease in the dorsal striatum in the D group. During weight loss, striatal DAT and thalamic SERT binding increased weight independently when 50% of daily calories were consumed at breakfast, whereas it decreased when caloric intake was highest at dinner. These findings may contribute to the earlier reported favorable effect of meal timing on weight maintenance after hypocaloric diets.-Versteeg, R. I., Schrantee, A., Adriaanse, S. M., Unmehopa, U. A., Booij, J., Reneman, L., Fliers, E., la Fleur, S. E., Serlie, M. J. Timing of caloric intake during weight loss differentially affects striatal dopamine transporter and thalamic serotonin transporter binding. © FASEB.

  4. The Associative Memory Serial Link Processor of the ALTAS Fast TracKer Processing System

    CERN Document Server

    Sotiropoulou, Calliope Louisa; The ATLAS collaboration

    2017-01-01

    The upgraded Trigger and Data Acquisition (TDAQ) system of the ATLAS experiment at the LHC will improve the capability of the detector to select the events with the greatest scientific potential. The Fast TracKer (FTK) is one of the ATLAS TDAQ upgrades that is presently under commissioning. FTK is a custom hardware system that feeds the High Level Trigger (HLT) with charged particle tracks reconstructed from hits in silicon detectors at the rate of 105 events per second. The main processing element of FTK is the Associative Memory (AM) system that is used to perform pattern matching with a high degree of parallelism. Its implementation is called the AM Board Serial Link Processor (AMBSLP) and it is a very efficient pattern matching machine that handles in parallel massive data samples. The AMBSLP consists of two types of boards: the Little Associative Memory Board (LAMB), a mezzanine where the AM chips are mounted, and the Associative Memory Board (AMB), a 9U VME motherboard that hosts four LAMB daughter-boar...

  5. Generalized Floquet theory: application to dynamical systems with memory and Bloch's theorem for nonlocal potentials.

    Science.gov (United States)

    Traversa, Fabio L; Di Ventra, Massimiliano; Bonani, Fabrizio

    2013-04-26

    Floquet theory is a powerful tool in the analysis of many physical phenomena, and extended to spatial coordinates provides the basis for Bloch's theorem. However, in its original formulation it is limited to linear systems with periodic coefficients. Here, we extend the theory by proving a theorem for the general class of systems including linear operators commuting with the period-shift operator. The present theorem greatly expands the range of applicability of Floquet theory to a multitude of phenomena that were previously inaccessible with this type of analysis, such as dynamical systems with memory. As an important extension, we also prove Bloch's theorem for nonlocal potentials.

  6. Anatomical coupling between distinct metacognitive systems for memory and visual perception.

    Science.gov (United States)

    McCurdy, Li Yan; Maniscalco, Brian; Metcalfe, Janet; Liu, Ka Yuet; de Lange, Floris P; Lau, Hakwan

    2013-01-30

    A recent study found that, across individuals, gray matter volume in the frontal polar region was correlated with visual metacognition capacity (i.e., how well one's confidence ratings distinguish between correct and incorrect judgments). A question arises as to whether the putative metacognitive mechanisms in this region are also used in other metacognitive tasks involving, for example, memory. A novel psychophysical measure allowed us to assess metacognitive efficiency separately in a visual and a memory task, while taking variations in basic task performance capacity into account. We found that, across individuals, metacognitive efficiencies positively correlated between the two tasks. However, voxel-based morphometry analysis revealed distinct brain structures for the two kinds of metacognition. Replicating a previous finding, variation in visual metacognitive efficiency was correlated with volume of frontal polar regions. However, variation in memory metacognitive efficiency was correlated with volume of the precuneus. There was also a weak correlation between visual metacognitive efficiency and precuneus volume, which may account for the behavioral correlation between visual and memory metacognition (i.e., the precuneus may contain common mechanisms for both types of metacognition). However, we also found that gray matter volumes of the frontal polar and precuneus regions themselves correlated across individuals, and a formal model comparison analysis suggested that this structural covariation was sufficient to account for the behavioral correlation of metacognition in the two tasks. These results highlight the importance of the precuneus in higher-order memory processing and suggest that there may be functionally distinct metacognitive systems in the human brain.

  7. Working Memory Load Strengthens Reward Prediction Errors.

    Science.gov (United States)

    Collins, Anne G E; Ciullo, Brittany; Frank, Michael J; Badre, David

    2017-04-19

    Reinforcement learning (RL) in simple instrumental tasks is usually modeled as a monolithic process in which reward prediction errors (RPEs) are used to update expected values of choice options. This modeling ignores the different contributions of different memory and decision-making systems thought to contribute even to simple learning. In an fMRI experiment, we investigated how working memory (WM) and incremental RL processes interact to guide human learning. WM load was manipulated by varying the number of stimuli to be learned across blocks. Behavioral results and computational modeling confirmed that learning was best explained as a mixture of two mechanisms: a fast, capacity-limited, and delay-sensitive WM process together with slower RL. Model-based analysis of fMRI data showed that striatum and lateral prefrontal cortex were sensitive to RPE, as shown previously, but, critically, these signals were reduced when the learning problem was within capacity of WM. The degree of this neural interaction related to individual differences in the use of WM to guide behavioral learning. These results indicate that the two systems do not process information independently, but rather interact during learning. SIGNIFICANCE STATEMENT Reinforcement learning (RL) theory has been remarkably productive at improving our understanding of instrumental learning as well as dopaminergic and striatal network function across many mammalian species. However, this neural network is only one contributor to human learning and other mechanisms such as prefrontal cortex working memory also play a key role. Our results also show that these other players interact with the dopaminergic RL system, interfering with its key computation of reward prediction errors. Copyright © 2017 the authors 0270-6474/17/374332-11$15.00/0.

  8. Grey matter abnormalities within cortico-limbic-striatal circuits in acute and weight-restored anorexia nervosa patients.

    Science.gov (United States)

    Friederich, Hans-Christoph; Walther, Stephan; Bendszus, Martin; Biller, Armin; Thomann, Philipp; Zeigermann, Susanne; Katus, Tobias; Brunner, Romuald; Zastrow, Arne; Herzog, Wolfgang

    2012-01-16

    Functional disturbances within cortico-striatal control systems have been implicated in the psychobiology (i.e. impaired cognitive-behavioral flexibility, perfectionist personality) of anorexia nervosa. The aim of the present study was to investigate the morphometry of brain regions within cortico-striatal networks in acute anorexia nervosa (AN) as well as long-term weight-restored anorexia nervosa (AN-WR) patients. A total of 39 participants: 12 AN, 13 AN-WR patients, and 14 healthy controls (HC) underwent high-resolution, T1-weighted magnetic resonance imaging (MRI), a cognitive-behavioral flexibility task, and a psychometric assessment. Group differences in local grey matter volume (GMV) were analyzed using whole brain voxel-based morphometry (VBM) and brain-atlas based automatic volumetry computation (IBASPM). Individual differences in total GMV were considered as a covariate in all analyses. In the regional brain morphometry, AN patients, as compared to HC, showed decreased GMVs (VBM and volumetry) in the anterior cingulate cortex (ACC), the supplementary motor area (SMA), and in subcortical regions (amygdala, putamen: VBM only). AN-WR compared to HC showed decreased GMV (VBM and volumetry) in the ACC and SMA, whereas GMV of the subcortical region showed no differences. The findings of the study suggest that structural abnormalities of the ACC and SMA were independent of the disease stage, whereas subcortical limbic-striatal changes were state dependent. Copyright © 2010 Elsevier Inc. All rights reserved.

  9. Increased ventral-striatal activity during monetary decision making is a marker of problem poker gambling severity.

    Science.gov (United States)

    Brevers, Damien; Noël, Xavier; He, Qinghua; Melrose, James A; Bechara, Antoine

    2016-05-01

    The aim of this study was to examine the impact of different neural systems on monetary decision making in frequent poker gamblers, who vary in their degree of problem gambling. Fifteen frequent poker players, ranging from non-problem to high-problem gambling, and 15 non-gambler controls were scanned using functional magnetic resonance imaging (fMRI) while performing the Iowa Gambling Task (IGT). During IGT deck selection, between-group fMRI analyses showed that frequent poker gamblers exhibited higher ventral-striatal but lower dorsolateral prefrontal and orbitofrontal activations as compared with controls. Moreover, using functional connectivity analyses, we observed higher ventral-striatal connectivity in poker players, and in regions involved in attentional/motor control (posterior cingulate), visual (occipital gyrus) and auditory (temporal gyrus) processing. In poker gamblers, scores of problem gambling severity were positively associated with ventral-striatal activations and with the connectivity between the ventral-striatum seed and the occipital fusiform gyrus and the middle temporal gyrus. Present results are consistent with findings from recent brain imaging studies showing that gambling disorder is associated with heightened motivational-reward processes during monetary decision making, which may hamper one's ability to moderate his level of monetary risk taking. © 2015 Society for the Study of Addiction.

  10. Cortico-hippocampal systems involved in memory and cognition: the PMAT framework.

    Science.gov (United States)

    Ritchey, Maureen; Libby, Laura A; Ranganath, Charan

    2015-01-01

    In this chapter, we review evidence that the cortical pathways to the hippocampus appear to extend from two large-scale cortical systems: a posterior medial (PM) system that includes the parahippocampal cortex and retrosplenial cortex, and an anterior temporal (AT) system that includes the perirhinal cortex. This "PMAT" framework accounts for differences in the anatomical and functional connectivity of the medial temporal lobes, which may underpin differences in cognitive function between the systems. The PM and AT systems make distinct contributions to memory and to other cognitive domains, and convergent findings suggest that they are involved in processing information about contexts and items, respectively. In order to support the full complement of memory-guided behavior, the two systems must interact, and the hippocampal and ventromedial prefrontal cortex may serve as sites of integration between the two systems. We conclude that when considering the "connected hippocampus," inquiry should extend beyond the medial temporal lobes to include the large-scale cortical systems of which they are a part. © 2015 Elsevier B.V. All rights reserved.

  11. Systems consolidation revisited, but not revised: The promise and limits of optogenetics in the study of memory.

    Science.gov (United States)

    Hardt, Oliver; Nadel, Lynn

    2017-12-05

    Episodic memories (in humans) and event-like memories (in non-human animals) require the hippocampus for some time after acquisition, but at remote points seem to depend more on cortical areas instead. Systems consolidation refers to the process that promotes this reorganization of memory. Various theoretical frameworks accounting for this process have been proposed, but clear evidence favoring one or another of these positions has been lacking. Addressing this issue, a recent study deployed some of the most advanced neurobiological technologies - optogenetics and calcium imaging - and provided high resolution, precise observations regarding brain systems involved in recent and remote contextual fear memories. We critically review these findings within their historical context and conclude that they do not resolve the debate concerning systems consolidation. This is because the relevant question concerning the quality of memory at recent and remote time points has not been answered: Does the memory reorganization taking place during systems consolidation result in changes to the content of memory? Copyright © 2017 Elsevier B.V. All rights reserved.

  12. InSync Adaptive Traffic Control System for the Veterans Memorial Hwy Corridor on Long Island, NY

    Science.gov (United States)

    2012-08-01

    This report documents Rhythm Engineerings adaptive traffic control system field installation performed : by New York State Department of Transportation (NYSDOT) along Veterans Memorial Hwy in Long : Island, NY. This report reviews the reason for t...

  13. The effects of gestational and chronic atrazine exposure on motor behaviors and striatal dopamine in male Sprague-Dawley rats

    International Nuclear Information System (INIS)

    Walters, Jennifer L.; Lansdell, Theresa A.; Lookingland, Keith J.; Baker, Lisa E.

    2015-01-01

    This study sought to investigate the effects of environmentally relevant gestational followed by continued chronic exposure to the herbicide, atrazine, on motor function, cognition, and neurochemical indices of nigrostriatal dopamine (DA) activity in male rats. Dams were treated with 100 μg/kg atrazine, 10 mg/kg atrazine, or vehicle on gestational day 1 through postnatal day 21. Upon weaning, male offspring continued daily vehicle or atrazine gavage treatments for an additional six months. Subjects were tested in a series of behavioral assays, and 24 h after the last treatment, tissue samples from the striatum were analyzed for DA and 3,4-dihydroxyphenylacetic acid (DOPAC). At 10 mg/kg, this herbicide was found to produce modest disruptions in motor functioning, and at both dose levels it significantly lowered striatal DA and DOPAC concentrations. These results suggest that exposures to atrazine have the potential to disrupt nigrostriatal DA neurons and behaviors associated with motor functioning. - Highlights: • Male rats received gestational and chronic exposure to ATZ (10 mg/kg and 100 μg/kg). • ATZ altered locomotor activity and impaired motor coordination. • ATZ lowered striatal DA and DOPAC concentrations. • ATZ produced a potential anxiogenic effect. • ATZ did not impair performance in learning and memory assessments.

  14. A distributed-memory hierarchical solver for general sparse linear systems

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chao [Stanford Univ., CA (United States). Inst. for Computational and Mathematical Engineering; Pouransari, Hadi [Stanford Univ., CA (United States). Dept. of Mechanical Engineering; Rajamanickam, Sivasankaran [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Center for Computing Research; Boman, Erik G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Center for Computing Research; Darve, Eric [Stanford Univ., CA (United States). Inst. for Computational and Mathematical Engineering and Dept. of Mechanical Engineering

    2017-12-20

    We present a parallel hierarchical solver for general sparse linear systems on distributed-memory machines. For large-scale problems, this fully algebraic algorithm is faster and more memory-efficient than sparse direct solvers because it exploits the low-rank structure of fill-in blocks. Depending on the accuracy of low-rank approximations, the hierarchical solver can be used either as a direct solver or as a preconditioner. The parallel algorithm is based on data decomposition and requires only local communication for updating boundary data on every processor. Moreover, the computation-to-communication ratio of the parallel algorithm is approximately the volume-to-surface-area ratio of the subdomain owned by every processor. We also provide various numerical results to demonstrate the versatility and scalability of the parallel algorithm.

  15. An examination of the associations among multiple memory systems, past tense, and vocabulary in typically developing 5-year-old children.

    Science.gov (United States)

    Lum, Jarrad A G; Kidd, Evan

    2012-08-01

    Considerable research has investigated the role of verbal working memory in language development in children with and without language problems. Much less is currently known about the relationship between language and the declarative and procedural memory systems. This study examined whether these 2 memory systems were related to typically developing children's past tense and lexical knowledge. Fifty-eight typically developing children approximately 5 years of age completed a battery of linguistic and nonlinguistic tasks, including tests of vocabulary, past tense production, and procedural and declarative memory. The results showed that declarative and procedural memory were not correlated with either regular or irregular past tense use. A significant correlation was observed between declarative memory and vocabulary. The results of the study were not consistent with the view that the declarative and procedural memory systems support children's use of the regular and irregular past tense. However, evidence was found suggesting that declarative memory supports vocabulary in this age group.

  16. THE MEMORY SYSTEM ENGAGED DURING ACQUISITION DETERMINES THE EFFECTIVENESS OF DIFFERENT EXTINCTION PROTOCOLS

    Directory of Open Access Journals (Sweden)

    Jarid eGoodman

    2015-11-01

    Full Text Available Previous research indicates that extinction of rodent maze behavior may occur without explicit performance of the previously required response. In latent extinction, confining an animal to a previously rewarded goal location without reinforcement is typically sufficient to produce extinction of maze learning. However, previous studies have not determined whether latent extinction may be successfully employed to extinguish all types of memory acquired in the maze, or whether only specific types of memory may be vulnerable to latent extinction. The present study examined whether latent extinction may be effective across two plus-maze tasks that depend on anatomically distinct neural systems. Adult male Long-Evans rats were trained in a hippocampus-dependent place learning task (experiment 1, in which animals were trained to approach a consistent spatial location for food reward. A separate group of rats were trained in a dorsolateral striatum-dependent response learning task (experiment 2, in which animals were trained to make a consistent egocentric body-turn response for food reward. Following training, animals received response extinction or latent extinction. For response extinction, animals were given the opportunity to execute the original running approach response toward the empty food cup. For latent extinction, animals were confined to the original goal locations with the empty food cup, thus preventing them from making the original running approach response. Results indicate that, relative to no extinction, latent extinction was effective at extinguishing memory in the place learning task, but remained ineffective in the response learning task. In contrast, typical response extinction remained very effective at extinguishing memory in both place and response learning tasks. The present findings confirm that extinction of maze learning may occur with or without overt performance of the previously acquired response, but that the

  17. 3-Nitropropionic acid neurotoxicity in organotypic striatal and corticostriatal slice cultures is dependent on glucose and glutamate

    DEFF Research Database (Denmark)

    Storgaard, J; Kornblit, B T; Zimmer, J

    2000-01-01

    Mitochondrial inhibition by 3-nitropropionic acid (3-NPA) causes striatal degeneration reminiscent of Huntington's disease. We studied 3-NPA neurotoxicity and possible indirect excitotoxicity in organotypic striatal and corticostriatal slice cultures. Neurotoxicity was quantified by assay...

  18. Adenosine–cannabinoid receptor interactions. Implications for striatal function

    Science.gov (United States)

    Ferré, Sergi; Lluís, Carme; Justinova, Zuzana; Quiroz, César; Orru, Marco; Navarro, Gemma; Canela, Enric I; Franco, Rafael; Goldberg, Steven R

    2010-01-01

    Adenosine and endocannabinoids are very ubiquitous non-classical neurotransmitters that exert a modulatory role on the transmission of other more ‘classical’ neurotransmitters. In this review we will focus on their common role as modulators of dopamine and glutamate neurotransmission in the striatum, the main input structure of the basal ganglia. We will pay particular attention to the role of adenosine A2A receptors and cannabinoid CB1 receptors. Experimental results suggest that presynaptic CB1 receptors interacting with A2A receptors in cortico-striatal glutamatergic terminals that make synaptic contact with dynorphinergic medium-sized spiny neurons (MSNs) are involved in the motor-depressant and addictive effects of cannabinoids. On the other hand, postsynaptic CB1 receptors interacting with A2A and D2 receptors in the dendritic spines of enkephalinergic MSNs and postsynaptic CB1 receptors in the dendritic spines of dynorphinergic MSN are probably involved in the cataleptogenic effects of cannabinoids. These receptor interactions most probably depend on the existence of a variety of heteromers of A2A, CB1 and D2 receptors in different elements of striatal spine modules. Drugs selective for the different striatal A2A and CB1 receptor heteromers could be used for the treatment of neuropsychiatric disorders and drug addiction and they could provide effective drugs with fewer side effects than currently used drugs. This article is part of a themed issue on Cannabinoids. To view the editorial for this themed issue visit http://dx.doi.org/10.1111/j.1476-5381.2010.00831.x PMID:20590556

  19. Impaired striatal Akt signaling disrupts dopamine homeostasis and increases feeding.

    Directory of Open Access Journals (Sweden)

    Nicole Speed

    Full Text Available The prevalence of obesity has increased dramatically worldwide. The obesity epidemic begs for novel concepts and therapeutic targets that cohesively address "food-abuse" disorders. We demonstrate a molecular link between impairment of a central kinase (Akt involved in insulin signaling induced by exposure to a high-fat (HF diet and dysregulation of higher order circuitry involved in feeding. Dopamine (DA rich brain structures, such as striatum, provide motivation stimuli for feeding. In these central circuitries, DA dysfunction is posited to contribute to obesity pathogenesis. We identified a mechanistic link between metabolic dysregulation and the maladaptive behaviors that potentiate weight gain. Insulin, a hormone in the periphery, also acts centrally to regulate both homeostatic and reward-based HF feeding. It regulates DA homeostasis, in part, by controlling a key element in DA clearance, the DA transporter (DAT. Upon HF feeding, nigro-striatal neurons rapidly develop insulin signaling deficiencies, causing increased HF calorie intake.We show that consumption of fat-rich food impairs striatal activation of the insulin-activated signaling kinase, Akt. HF-induced Akt impairment, in turn, reduces DAT cell surface expression and function, thereby decreasing DA homeostasis and amphetamine (AMPH-induced DA efflux. In addition, HF-mediated dysregulation of Akt signaling impairs DA-related behaviors such as (AMPH-induced locomotion and increased caloric intake. We restored nigro-striatal Akt phosphorylation using recombinant viral vector expression technology. We observed a rescue of DAT expression in HF fed rats, which was associated with a return of locomotor responses to AMPH and normalization of HF diet-induced hyperphagia.Acquired disruption of brain insulin action may confer risk for and/or underlie "food-abuse" disorders and the recalcitrance of obesity. This molecular model, thus, explains how even short-term exposure to "the fast food

  20. Memory, microprocessor, and ASIC

    CERN Document Server

    Chen, Wai-Kai

    2003-01-01

    System Timing. ROM/PROM/EPROM. SRAM. Embedded Memory. Flash Memories. Dynamic Random Access Memory. Low-Power Memory Circuits. Timing and Signal Integrity Analysis. Microprocessor Design Verification. Microprocessor Layout Method. Architecture. ASIC Design. Logic Synthesis for Field Programmable Gate Array (EPGA) Technology. Testability Concepts and DFT. ATPG and BIST. CAD Tools for BIST/DFT and Delay Faults.

  1. Applying Hamming Code to Memory System of Safety Grade PLC (POSAFE-Q) Processor Module

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taehee; Hwang, Sungjae; Park, Gangmin [POSCO Nuclear Technology, Seoul (Korea, Republic of)

    2013-05-15

    If some errors such as inverted bits occur in the memory, instructions and data will be corrupted. As a result, the PLC may execute the wrong instructions or refer to the wrong data. Hamming Code can be considered as the solution for mitigating this mis operation. In this paper, we apply hamming Code, then, we inspect whether hamming code is suitable for to the memory system of the processor module. In this paper, we applied hamming code to existing safety grade PLC (POSAFE-Q). Inspection data are collected and they will be referred for improving the PLC in terms of the soundness. In our future work, we will try to improve time delay caused by hamming calculation. It will include CPLD optimization and memory architecture or parts alteration. In addition to these hamming code-based works, we will explore any methodologies such as mirroring for the soundness of safety grade PLC. Hamming code-based works can correct bit errors, but they have limitation in multi bits errors.

  2. Applying Hamming Code to Memory System of Safety Grade PLC (POSAFE-Q) Processor Module

    International Nuclear Information System (INIS)

    Kim, Taehee; Hwang, Sungjae; Park, Gangmin

    2013-01-01

    If some errors such as inverted bits occur in the memory, instructions and data will be corrupted. As a result, the PLC may execute the wrong instructions or refer to the wrong data. Hamming Code can be considered as the solution for mitigating this mis operation. In this paper, we apply hamming Code, then, we inspect whether hamming code is suitable for to the memory system of the processor module. In this paper, we applied hamming code to existing safety grade PLC (POSAFE-Q). Inspection data are collected and they will be referred for improving the PLC in terms of the soundness. In our future work, we will try to improve time delay caused by hamming calculation. It will include CPLD optimization and memory architecture or parts alteration. In addition to these hamming code-based works, we will explore any methodologies such as mirroring for the soundness of safety grade PLC. Hamming code-based works can correct bit errors, but they have limitation in multi bits errors

  3. The Memory System You Can't Avoid it, You Can't Ignore it, You Can't Fake it

    CERN Document Server

    Jacob, Bruce

    2009-01-01

    Today, computer-system optimization, at both the hardware and software levels, must consider the details of the memory system in its analysis; failing to do so yields systems that are increasingly inefficient as those systems become more complex. This lecture seeks to introduce the reader to the most important details of the memory system; it targets both computer scientists and computer engineers in industry and in academia. Roughly speaking, computer scientists are the users of the memory system and computer engineers are the designers of the memory system. Both can benefit tremendously from

  4. Systemic inhibition of mTOR kinase via rapamycin disrupts consolidation and reconsolidation of auditory fear memory.

    Science.gov (United States)

    Mac Callum, Phillip E; Hebert, Mark; Adamec, Robert E; Blundell, Jacqueline

    2014-07-01

    The mammalian target of rapamycin (mTOR) kinase is a critical regulator of mRNA translation and is known to be involved in various long lasting forms of synaptic and behavioural plasticity. However, information concerning the temporal pattern of mTOR activation and susceptibility to pharmacological intervention during both consolidation and reconsolidation of long-term memory (LTM) remains scant. Male C57BL/6 mice were injected systemically with rapamycin at various time points following conditioning or retrieval in an auditory fear conditioning paradigm, and compared to vehicle (and/or anisomycin) controls for subsequent memory recall. Systemic blockade of mTOR with rapamycin immediately or 12h after training or reactivation impairs both consolidation and reconsolidation of an auditory fear memory. Further behavioural analysis revealed that the enduring effects of rapamycin on reconsolidation are dependent upon reactivation of the memory trace. Rapamycin, however, has no effect on short-term memory or the ability to retrieve an established fear memory. Collectively, our data suggest that biphasic mTOR signalling is essential for both consolidation and reconsolidation-like activities that contribute to the formation, re-stabilization, and persistence of long term auditory-fear memories, while not influencing other aspects of the memory trace. These findings also provide evidence for a cogent treatment model for reducing the emotional strength of established, traumatic memories analogous to those observed in acquired anxiety disorders such as posttraumatic stress disorder (PTSD) and specific phobias, through pharmacologic blockade of mTOR using systemic rapamycin following reactivation. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. An ASIC memory buffer controller for a high speed disk system

    Science.gov (United States)

    Hodson, Robert F.; Campbell, Steve

    1993-01-01

    The need for large capacity, high speed mass memory storage devices has become increasingly evident at NASA during the past decade. High performance mass storage systems are crucial to present and future NASA systems. Spaceborne data storage system requirements have grown in response to the increasing amounts of data generated and processed by orbiting scientific experiments. Predictions indicate increases in the volume of data by orders of magnitude during the next decade. Current predictions are for storage capacities on the order of terabits (Tb), with data rates exceeding one gigabit per second (Gbps). As part of the design effort for a state of the art mass storage system, NASA Langley has designed a 144 CMOS ASIC to support high speed data transfers. This paper discusses the system architecture, ASIC design and some of the lessons learned in the development process.

  6. Biomechanical study of posterior wall acetabular fracture fixation using acetabular tridimensional memory alloy-fixation system.

    Science.gov (United States)

    Xin-wei, Liu; Shuo-gui, Xu; Chun-cai, Zhang; Qing-ge, Fu; Pan-feng, Wang

    2010-05-01

    We developed the acetabular tridimensional memory alloy-fixation system (ATMFS), which is made of NiTi shape memory alloy, according to the specific mechanical properties of biological memory material, nitinol alloy and measured distribution of contact area and pressure between the acetabulum and the femoral head of cadaveric pelvis. Six formalin-preserved cadaveric pelvis were used for this investigation. Pressure-sensitive film was used to measure contact area and pressure within the anterior, superior, and posterior regions of the acetabulum. The pelvis were loaded under the following four conditions: (1) intact; (2) following a creation posterior wall fracture defect; (3) following reduction and standard internal fixation with reconstruction plate; (4) following reduction and internal fixation with a new shape memory alloy device named ATMFS. A posterior wall fracture was created along an arc of 40-90 degrees about the acetabular rim. Creation of a posterior wall defect resulted in increased load in the superior acetabulum (1422N) as compared to the intact condition (762N, P=0.007). Following reduction and internal fixation, the load distributed to the superior acetabulum (1486N) was not statistically different from the defect condition. Following the fixation with ATMFS, the load seen at the superior region of the actabulum (936N) was less than fixation with reconstruction plate and was not different from intact state (P=0.4). These data indicate that the use of ATMFS as a fracture internal fixation device resulted a partial restoration of joint loading parameters toward the intact state. ATMFS fixation may result in a clinical benefit. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Cognitive emotion regulation modulates the balance of competing influences on ventral striatal aversive prediction error signals.

    Science.gov (United States)

    Mulej Bratec, Satja; Xie, Xiyao; Wang, Yijun; Schilbach, Leonhard; Zimmer, Claus; Wohlschläger, Afra M; Riedl, Valentin; Sorg, Christian

    2017-02-15

    Cognitive emotion regulation (CER) is a critical human ability to face aversive emotional stimuli in a flexible way, via recruitment of specific prefrontal brain circuits. Animal research reveals a central role of ventral striatum in emotional behavior, for both aversive conditioning, with striatum signaling aversive prediction errors (aPE), and for integrating competing influences of distinct striatal inputs from regions such as the prefrontal cortex (PFC), amygdala, hippocampus and ventral tegmental area (VTA). Translating these ventral striatal findings from animal research to human CER, we hypothesized that successful CER would affect the balance of competing influences of striatal afferents on striatal aPE signals, in a way favoring PFC as opposed to 'subcortical' (i.e., non-isocortical) striatal inputs. Using aversive Pavlovian conditioning with and without CER during fMRI, we found that during CER, superior regulators indeed reduced the modulatory impact of 'subcortical' striatal afferents (hippocampus, amygdala and VTA) on ventral striatal aPE signals, while keeping the PFC impact intact. In contrast, inferior regulators showed an opposite pattern. Our results demonstrate that ventral striatal aPE signals and associated competing modulatory inputs are critical mechanisms underlying successful cognitive regulation of aversive emotions in humans. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Reciprocal influences of nigral cells and striatal patch neurons in dissociated co-cultures

    NARCIS (Netherlands)

    Aronica, E.; Costantini, L. C.; Snyder-Keller, A.

    1996-01-01

    Our previous work has shown that the functional efficacy of nigral tissue transplants into dopamine (DA)-depleted rats is increased when embryonic striatal tissue is included (Costantini et al.: Exp Neurol 127:219-231, 1994). To examine further the influence of striatal patch neurons in this regard,

  9. GABAERGIC MODULATION OF STRIATAL CHOLINERGIC INTERNEURONS - AN IN-VIVO MICRODIALYSIS STUDY

    NARCIS (Netherlands)

    DEBOER, P; WESTERINK, BHC

    Striatal cholinergic interneurons have been shown to receive input from striatal gamma-aminobutyric acid (GABA)-containing cell elements. GABA is known to act on two different types of receptors, the GABA(A) and the GABA(B) receptor. Using in vivo microdialysis, we have studied the effect of

  10. No association between striatal dopamine transporter binding and body mass index

    DEFF Research Database (Denmark)

    van de Giessen, Elsmarieke; Hesse, Swen; Caan, Matthan W A

    2013-01-01

    Dopamine is one among several neurotransmitters that regulate food intake and overeating. Thus, it has been linked to the pathophysiology of obesity and high body mass index (BMI). Striatal dopamine D(2) receptor availability is lower in obesity and there are indications that striatal dopamine tr...

  11. Tensile-compressive asymmetry influence on shape memory alloy system dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Savi, Marcelo A. [Universidade Federal do Rio de Janeiro, COPPE - Department of Mechanical Engineering, P.O. Box 68.503, 21.941.972 Rio de Janeiro (Brazil)], E-mail: savi@mecanica.ufrj.br; Sa, Milton A.N. [Universidade Federal do Rio de Janeiro, COPPE - Department of Mechanical Engineering, P.O. Box 68.503, 21.941.972 Rio de Janeiro (Brazil); Paiva, Alberto [Universidade Federal Fluminense, Escola de Engenharia Industrial e Metalurgica de Volta Redonda, 27.255.250 Volta Redonda, RJ (Brazil)], E-mail: paiva@lavi.coppe.ufrj.br; Pacheco, Pedro M.C.L. [CEFET/RJ - Department of Mechanical Engineering, 20.271.110 Rio de Janeiro, RJ (Brazil)], E-mail: calas@cefet-rj.br

    2008-05-15

    The remarkable properties of shape memory alloys (SMAs) are attracting much technological interest in several science and engineering fields, varying from medical to aerospace applications. Hysteretic response of these systems is one of their essential characteristics being related to the martensitic phase transformation. The dynamical response of systems with SMA actuators presents a rich behavior due to their intrinsic nonlinear characteristic. Since experimental results show that SMAs present an asymmetric behavior when subjected to tensile or compressive loads, it is important to evaluate the influence of this kind of behavior in the nonlinear dynamics of mechanical systems with SMA devices. This article discusses the nonlinear dynamics of shape memory alloy systems, considering the influence of tensile-compressive asymmetry in the thermomechanical behavior of SMAs. An iterative numerical procedure based on the operator split technique, the orthogonal projection algorithm and the fourth-order Runge-Kutta method is developed to deal with nonlinearities in the formulation. A numerical investigation is carried out showing some qualitative results such as chaotic-like response and multi-stability behavior for a single degree of freedom SMA oscillator.

  12. Information Systems and Corporate Memory: design for staff turn-over

    Directory of Open Access Journals (Sweden)

    Colin Sharp

    1993-11-01

    Full Text Available The "information age" is reliant upon the information skill-base of people and the storage and access of complete data. Staff turn-over and "down-sizing" as well as the rate of organisational change places increased pressure on the designers of corporate information systems to keep up with the organizational demands. Especially relevant are the "soft" aspects of the corporate information needs of organizations. The term "corporate memory" is introduced to explain the relatively informal collective and individual knowledge of employees gained through their experience and position in the organization. This paper elaborates the issues concerned with the "corporate soft data", and makes suggestions for research, as well as for planners of corporate information systems in organizations facing major down-sizing or related changes. It is concluded that there are a number of readily obtainable sources of soft data in the organization and these data should be analysed for inclusion in system development. If organizations are to become learning systems and not just keep repeating the same mistakes, they need to review all aspects of corporate memory, especially the soft data sources and losses.

  13. What vaccination studies tell us about immunological memory within the innate immune system of cultured shrimp and crayfish.

    Science.gov (United States)

    Chang, Yu-Hsuan; Kumar, Ramya; Ng, Tze Hann; Wang, Han-Ching

    2018-03-01

    The possibility of immunological memory in invertebrates is a topic that has recently attracted a lot of attention. Today, even vertebrates are known to exhibit innate immune responses that show memory-like properties, and since these responses are triggered by cells that are involved in the innate immune system, it seems that immune specificity and immune memory do not necessarily require the presence of B cells and T cells after all. This kind of immune response has been called "immune priming" or "trained immunity". In this report, we review recent observations and our current understanding of immunological memory within the innate immune system in cultured shrimp and crayfish after vaccination with live vaccine, killed vaccine and subunit vaccines. We also discuss the possible mechanisms involved in this immune response. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effects of reversible inactivation of thalamo-striatal circuitry on delayed matching trained with retractable levers.

    Science.gov (United States)

    Porter, M C; Koch, J; Mair, R G

    2001-02-15

    The intralaminar thalamic nuclei are characterized by their prominent projections to striatum. Lesions of the intralaminar nuclei have been found to impair delayed matching trained with retractable levers. Comparable impairments have been observed for rats with lesions of the olfactory tubercle, involving ventral areas of striatum and pallidum. We conducted two experiments to test the functional dependence of thalamic and striatal lesions on the delayed matching task. In experiment 1, we determined the effects of inactivating the intralaminar nuclei with bilateral lidocaine infusions. In experiment 2, we compared the effects of unilateral thalamic inactivations in rats with unilateral olfactory tubercle lesions. We trained rats to perform the delayed matching task to criterion and then implanted dual cannulas aimed at the bilaterally symmetrical areas in the intralaminar nuclei. Rats in experiment 2 were also given a unilateral olfactory tubercle lesion. The results of experiment 1 showed dose-dependent impairments for bilateral infusions that were qualitatively similar, although of lesser severity than delayed matching impairments observed in previous studies for rats with lesions involving extensive areas of the intralaminar nuclei. A comparable impairment was observed in experiment 2 when thalamus was inactivated on the side opposite the olfactory tubercle lesion. Performances were significantly worse when thalamus was inactivated on the contra-lesion than on the ipsi-lesion side of the brain. These results are discussed in terms of the role of ventral striatum and related thalamic nuclei in memory.

  15. Thermally responsive polymer systems for self-healing, reversible adhesion and shape memory applications

    Science.gov (United States)

    Luo, Xiaofan

    Responsive polymers are "smart" materials that are capable of performing prescribed, dynamic functions under an applied stimulus. In this dissertation, we explore several novel design strategies to develop thermally responsive polymers and polymer composites for self-healing, reversible adhesion and shape memory applications. In the first case described in Chapters 2 and 3, a thermally triggered self-healing material was prepared by blending a high-temperature epoxy resin with a thermoplastic polymer, poly(epsilon-caprolactone) (PCL). The initially miscible system undergoes polymerization induced phase separation (PIPS) during the curing of epoxy and yields a variety of compositionally dependent morphologies. At a particular PCL loading, the cured blend displays a "bricks-and-mortar" morphology in which epoxy exists as interconnected spheres ("bricks") within a continuous PCL matrix ("mortar"). A heat induced "bleeding" phenomenon was observed in the form of spontaneous wetting of all free surfaces by the molten PCL, and is attributed to the volumetric thermal expansion of PCL above its melting point in excess of epoxy brick expansion, which we term differential expansive bleeding (DEB). This DEB is capable of healing damage such as cracks. In controlled self-healing experiments, heating of a cracked specimen led to PCL bleeding from the bulk that yields a liquid layer bridging the crack gap. Upon cooling, a "scar" composed of PCL crystals was formed at the site of the crack, restoring a significant portion of mechanical strength. We further utilized DEB to enable strong and thermally-reversible adhesion of the material to itself and to metallic substrates, without any requirement for macroscopic softening or flow. After that, Chapters 4--6 present a novel composite strategy for the design and fabrication of shape memory polymer composites. The basic approach involves physically combining two or more functional components into an interpenetrating fiber

  16. Modified stretched exponential model of computer system resources management limitations-The case of cache memory

    Science.gov (United States)

    Strzałka, Dominik; Dymora, Paweł; Mazurek, Mirosław

    2018-02-01

    In this paper we present some preliminary results in the field of computer systems management with relation to Tsallis thermostatistics and the ubiquitous problem of hardware limited resources. In the case of systems with non-deterministic behaviour, management of their resources is a key point that guarantees theirs acceptable performance and proper working. This is very wide problem that stands for many challenges in financial, transport, water and food, health, etc. areas. We focus on computer systems with attention paid to cache memory and propose to use an analytical model that is able to connect non-extensive entropy formalism, long-range dependencies, management of system resources and queuing theory. Obtained analytical results are related to the practical experiment showing interesting and valuable results.

  17. Striatal neuroinflammation promotes Parkinsonism in rats.

    Directory of Open Access Journals (Sweden)

    Dong-Young Choi

    Full Text Available Sporadic Parkinson's disease (PD is a progressive neurodegenerative disorder with unknown cause, but it has been suggested that neuroinflammation may play a role in pathogenesis of the disease. Neuroinflammatory component in process of PD neurodegeneration was proposed by postmortem, epidemiological and animal model studies. However, it remains unclear how neuroinflammatory factors contribute to dopaminergic neuronal death in PD.In this study, we analyzed the relationship among inducible nitric oxide synthase (iNOS-derived NO, mitochondrial dysfunction and dopaminergic neurodegeneration to examine the possibility that microglial neuroinflammation may induce dopaminergic neuronal loss in the substantia nigra. Unilateral injection of lipopolysaccharide (LPS into the striatum of rat was followed by immunocytochemical, histological, neurochemical and biochemical analyses. In addition, behavioral assessments including cylinder test and amphetamine-induced rotational behavior test were employed to validate ipsilateral damage to the dopamine nigrostriatal pathway. LPS injection caused progressive degeneration of the dopamine nigrostriatal system, which was accompanied by motor impairments including asymmetric usage of forelimbs and amphetamine-induced turning behavior in animals. Interestingly, some of the remaining nigral dopaminergic neurons had intracytoplasmic accumulation of alpha-synuclein and ubiquitin. Furthermore, defect in the mitochondrial respiratory chain, and extensive S-nitrosylation/nitration of mitochondrial complex I were detected prior to the dopaminergic neuronal loss. The mitochondrial injury was prevented by treatment with L-N(6-(l-iminoethyl-lysine, an iNOS inhibitor, suggesting that iNOS-derived NO is associated with the mitochondrial impairment.These results implicate neuroinflammation-induced S-nitrosylation/nitration of mitochondrial complex I in mitochondrial malfunction and subsequent degeneration of the nigral dopamine

  18. Analytical derivation of traffic patterns in cache-coherent shared-memory systems

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Sparsø, Jens

    2011-01-01

    This paper presents an analytical method to derive the worst-case traffic pattern caused by a task graph mapped to a cache-coherent shared-memory system. Our analysis allows designers to rapidly evaluate the impact of different mappings of tasks to IP cores on the traffic pattern. The accuracy...... varies with the application’s data sharing pattern, and is around 65% in the average case and 1% in the best case when considering the traffic pattern as a whole. For individual connections, our method produces tight worst-case bandwidths....

  19. Development of measurement system for radiation effect on static random access memory based field programmable gate array

    International Nuclear Information System (INIS)

    Yao Zhibin; He Baoping; Zhang Fengqi; Guo Hongxia; Luo Yinhong; Wang Yuanming; Zhang Keying

    2009-01-01

    Based on the detailed investigation in field programmable gate array(FPGA) radiation effects theory, a measurement system for radiation effects on static random access memory(SRAM)-based FPGA was developed. The testing principle of internal memory, function and power current was introduced. The hardware and software implement means of system were presented. Some important parameters for radiation effects on SRAM-based FPGA, such as configuration RAM upset section, block RAM upset section, function fault section and single event latchup section can be gained with this system. The transmission distance of the system can be over 50 m and the maximum number of tested gates can reach one million. (authors)

  20. The phosphorylation status and cytoskeletal remodeling of striatal astrocytes treated with quinolinic acid

    International Nuclear Information System (INIS)

    Pierozan, Paula; Ferreira, Fernanda; Ortiz de Lima, Bárbara; Gonçalves Fernandes, Carolina; Totarelli Monteforte, Priscila; Castro Medaglia, Natalia de; Bincoletto, Claudia; Soubhi Smaili, Soraya; Pessoa-Pureur, Regina

    2014-01-01

    Quinolinic acid (QUIN) is a glutamate agonist which markedly enhances the vulnerability of neural cells to excitotoxicity. QUIN is produced from the amino acid tryptophan through the kynurenine pathway (KP). Dysregulation of this pathway is associated with neurodegenerative conditions. In this study we treated striatal astrocytes in culture with QUIN and assayed the endogenous phosphorylating system associated with glial fibrillary acidic protein (GFAP) and vimentin as well as cytoskeletal remodeling. After 24 h incubation with 100 µM QUIN, cells were exposed to 32 P-orthophosphate and/or protein kinase A (PKA), protein kinase dependent of Ca 2+ /calmodulin II (PKCaMII) or protein kinase C (PKC) inhibitors, H89 (20 μM), KN93 (10 μM) and staurosporin (10 nM), respectively. Results showed that hyperphosphorylation was abrogated by PKA and PKC inhibitors but not by the PKCaMII inhibitor. The specific antagonists to ionotropic NMDA and non-NMDA (50 µM DL-AP5 and CNQX, respectively) glutamate receptors as well as to metabotropic glutamate receptor (mGLUR; 50 µM MCPG), mGLUR1 (100 µM MPEP) and mGLUR5 (10 µM 4C3HPG) prevented the hyperphosphorylation provoked by QUIN. Also, intra and extracellular Ca 2+ quelators (1 mM EGTA; 10 µM BAPTA-AM, respectively) prevented QUIN-mediated effect, while Ca 2+ influx through voltage-dependent Ca 2+ channel type L (L-VDCC) (blocker: 10 µM verapamil) is not implicated in this effect. Morphological analysis showed dramatically altered actin cytoskeleton with concomitant change of morphology to fusiform and/or flattened cells with retracted cytoplasm and disruption of the GFAP meshwork, supporting misregulation of actin cytoskeleton. Both hyperphosphorylation and cytoskeletal remodeling were reversed 24 h after QUIN removal. Astrocytes are highly plastic cells and the vulnerability of astrocyte cytoskeleton may have important implications for understanding the neurotoxicity of QUIN in neurodegenerative disorders. - Highlights:

  1. The phosphorylation status and cytoskeletal remodeling of striatal astrocytes treated with quinolinic acid

    Energy Technology Data Exchange (ETDEWEB)

    Pierozan, Paula; Ferreira, Fernanda; Ortiz de Lima, Bárbara; Gonçalves Fernandes, Carolina [Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90035-003 (Brazil); Totarelli Monteforte, Priscila; Castro Medaglia, Natalia de; Bincoletto, Claudia; Soubhi Smaili, Soraya [Departamento de Farmacologia, Universidade Federal de São Paulo (UNIFESP/EPM), São Paulo, SP (Brazil); Pessoa-Pureur, Regina, E-mail: rpureur@ufrgs.br [Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 90035-003 (Brazil)

    2014-04-01

    Quinolinic acid (QUIN) is a glutamate agonist which markedly enhances the vulnerability of neural cells to excitotoxicity. QUIN is produced from the amino acid tryptophan through the kynurenine pathway (KP). Dysregulation of this pathway is associated with neurodegenerative conditions. In this study we treated striatal astrocytes in culture with QUIN and assayed the endogenous phosphorylating system associated with glial fibrillary acidic protein (GFAP) and vimentin as well as cytoskeletal remodeling. After 24 h incubation with 100 µM QUIN, cells were exposed to {sup 32}P-orthophosphate and/or protein kinase A (PKA), protein kinase dependent of Ca{sup 2+}/calmodulin II (PKCaMII) or protein kinase C (PKC) inhibitors, H89 (20 μM), KN93 (10 μM) and staurosporin (10 nM), respectively. Results showed that hyperphosphorylation was abrogated by PKA and PKC inhibitors but not by the PKCaMII inhibitor. The specific antagonists to ionotropic NMDA and non-NMDA (50 µM DL-AP5 and CNQX, respectively) glutamate receptors as well as to metabotropic glutamate receptor (mGLUR; 50 µM MCPG), mGLUR1 (100 µM MPEP) and mGLUR5 (10 µM 4C3HPG) prevented the hyperphosphorylation provoked by QUIN. Also, intra and extracellular Ca{sup 2+} quelators (1 mM EGTA; 10 µM BAPTA-AM, respectively) prevented QUIN-mediated effect, while Ca{sup 2+} influx through voltage-dependent Ca{sup 2+} channel type L (L-VDCC) (blocker: 10 µM verapamil) is not implicated in this effect. Morphological analysis showed dramatically altered actin cytoskeleton with concomitant change of morphology to fusiform and/or flattened cells with retracted cytoplasm and disruption of the GFAP meshwork, supporting misregulation of actin cytoskeleton. Both hyperphosphorylation and cytoskeletal remodeling were reversed 24 h after QUIN removal. Astrocytes are highly plastic cells and the vulnerability of astrocyte cytoskeleton may have important implications for understanding the neurotoxicity of QUIN in neurodegenerative

  2. Individual recognition of social rank and social memory performance depends on a functional circadian system.

    Science.gov (United States)

    Müller, L; Weinert, D

    2016-11-01

    In a natural environment, social abilities of an animal are important for its survival. Particularly, it must recognize its own social rank and the social rank of a conspecific and have a good social memory. While the role of the circadian system for object and spatial recognition and memory is well known, the impact of the social rank and circadian disruptions on social recognition and memory were not investigated so far. In the present study, individual recognition of social rank and social memory performance of Djungarian hamsters revealing different circadian phenotypes were investigated. Wild type (WT) animals show a clear and well-synchronized daily activity rhythm, whereas in arrhythmic (AR) hamsters, the suprachiasmatic nuclei (SCN) do not generate a circadian signal. The aim of the study was to investigate putative consequences of these deteriorations in the circadian system for animalś cognitive abilities. Hamsters were bred and kept under standardized housing conditions with food and water ad libitum and a 14l/10 D lighting regimen. Experimental animals were assigned to different groups (WT and AR) according to their activity pattern obtained by means of infrared motion sensors. Before the experiments, the animals were given to develop a dominant-subordinate relationship in a dyadic encounter. Experiment 1 dealt with individual recognition of social rank. Subordinate and dominant hamsters were tested in an open arena for their behavioral responses towards a familiar (known from the agonistic encounters) or an unfamiliar hamster (from another agonistic encounter) which had the same or an opposite social rank. The investigation time depended on the social rank of the WT subject hamster and its familiarity with the stimulus animal. Both subordinate and dominant WT hamsters preferred an unfamiliar subordinate stimulus animal. In contrast, neither subordinate nor dominant AR hamsters preferred any of the stimulus animals. Thus, disruptions in circadian

  3. Calcium dynamics predict direction of synaptic plasticity in striatal spiny projection neurons.

    Science.gov (United States)

    Jędrzejewska-Szmek, Joanna; Damodaran, Sriraman; Dorman, Daniel B; Blackwell, Kim T

    2017-04-01

    The striatum is a major site of learning and memory formation for sensorimotor and cognitive association. One of the mechanisms used by the brain for memory storage is synaptic plasticity - the long-lasting, activity-dependent change in synaptic strength. All forms of synaptic plasticity require an elevation in intracellular calcium, and a common hypothesis is that the amplitude and duration of calcium transients can determine the direction of synaptic plasticity. The utility of this hypothesis in the striatum is unclear in part because dopamine is required for striatal plasticity and in part because of the diversity in stimulation protocols. To test whether calcium can predict plasticity direction, we developed a calcium-based plasticity rule using a spiny projection neuron model with sophisticated calcium dynamics including calcium diffusion, buffering and pump extrusion. We utilized three spike timing-dependent plasticity (STDP) induction protocols, in which postsynaptic potentials are paired with precisely timed action potentials and the timing of such pairing determines whether potentiation or depression will occur. Results show that despite the variation in calcium dynamics, a single, calcium-based plasticity rule, which explicitly considers duration of calcium elevations, can explain the direction of synaptic weight change for all three STDP protocols. Additional simulations show that the plasticity rule correctly predicts the NMDA receptor dependence of long-term potentiation and the L-type channel dependence of long-term depression. By utilizing realistic calcium dynamics, the model reveals mechanisms controlling synaptic plasticity direction, and shows that the dynamics of calcium, not just calcium amplitude, are crucial for synaptic plasticity. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  4. Detection of changes in hydrologic system memory associated with urbanization in the Great Lakes region

    Science.gov (United States)

    Yang, G.; Bowling, L. C.

    2010-12-01

    The Great Lakes region has experienced large land-cover / land-use change (LCLUC) in the last century, especially the growth of urban areas accompanied with increased human activities. Many hydrologic impacts of urbanization have been documented due to the reduction of the perviousness of urban landscapes, e.g. the reduced infiltration rate and runoff response time, the increased flashiness of daily streamflow and the magnitude of flood peaks. Such changes might be equivalently interpreted as a decrease in hydrologic system memory with urbanization, i.e. the current discharge in a flow time series has less correlation with its prior flows. Based on observed streamflow at several USGS gauge stations in the Great Lakes region, appropriate fractional autoregressive integrated moving average (FARIMA) models are introduced for daily and monthly streamflow respectively. The recently improved Variable Infiltration Capacity (VIC) model with urban representation is applied to simulate the water and energy response in many basins in the region with various degrees of urbanization. The VIC model is driven by different years’ land use/cover maps, including a 1992 base map and a 2030 map predicted by the Land Transformation Model (LTM). A no-urban scenario was also created by removing urban and rescaling other vegetations’ fraction based on the 1992 map. The simulated daily and monthly streamflow from some gauged basins is validated using the above fitted FARIMA models. The difference in the fitted FARIMA model parameters, e.g. AR(1) and Hurst exponent representing short and long memory respectively, between different land use/cover scenarios is mainly induced by differences in urban area. In order to further explore the relationship among urban growth, hydrologic system memory and other hydrologic change, metrics relating to the flow distribution, daily variation in streamflow and frequency of high-flow events are also calculated for selected basins.

  5. Characterization of NiTi Shape Memory Damping Elements designed for Automotive Safety Systems

    Science.gov (United States)

    Strittmatter, Joachim; Clipa, Victor; Gheorghita, Viorel; Gümpel, Paul

    2014-07-01

    Actuator elements made of NiTi shape memory material are more and more known in industry because of their unique properties. Due to the martensitic phase change, they can revert to their original shape by heating when subjected to an appropriate treatment. This thermal shape memory effect (SME) can show a significant shape change combined with a considerable force. Therefore such elements can be used to solve many technical tasks in the field of actuating elements and mechatronics and will play an increasing role in the next years, especially within the automotive technology, energy management, power, and mechanical engineering as well as medical technology. Beside this thermal SME, these materials also show a mechanical SME, characterized by a superelastic plateau with reversible elongations in the range of 8%. This behavior is based on the building of stress-induced martensite of loaded austenite material at constant temperature and facilitates a lot of applications especially in the medical field. Both SMEs are attended by energy dissipation during the martensitic phase change. This paper describes the first results obtained on different actuator and superelastic NiTi wires concerning their use as damping elements in automotive safety systems. In a first step, the damping behavior of small NiTi wires up to 0.5 mm diameter was examined at testing speeds varying between 0.1 and 50 mm/s upon an adapted tensile testing machine. In order to realize higher testing speeds, a drop impact testing machine was designed, which allows testing speeds up to 4000 mm/s. After introducing this new type of testing machine, the first results of vertical-shock tests of superelastic and electrically activated actuator wires are presented. The characterization of these high dynamic phase change parameters represents the basis for new applications for shape memory damping elements, especially in automotive safety systems.

  6. Savoring the past: Positive memories evoke value representations in the striatum

    Science.gov (United States)

    Speer, Megan E.; Bhanji, Jamil P.; Delgado, Mauricio R.

    2014-01-01

    Summary Reminders of happy memories can bring back pleasant feelings tied to the original experience, suggesting an intrinsic value in reminiscing about the positive past. However, the neural circuitry underlying the rewarding aspects of autobiographical memory is poorly understood. Using fMRI, we observed enhanced activity during the recall of positive relative to neutral autobiographical memories in corticostriatal circuits that also responded to monetary rewards. Enhanced activity in the striatum and medial prefrontal cortex was associated with increases in positive emotion during recall and striatal engagement further correlated with individual measures of resiliency. Striatal response to the recall of positive memories was greater in individuals whose mood improved after the task. Notably, participants were willing to sacrifice more tangible monetary rewards in order to reminisce about positive past experiences. Our findings suggest that recalling positive autobiographical memories is intrinsically valuable, which may be adaptive for regulating positive emotion and promoting better well-being. PMID:25451197

  7. Asymmetric Programming: A Highly Reliable Metadata Allocation Strategy for MLC NAND Flash Memory-Based Sensor Systems

    Directory of Open Access Journals (Sweden)

    Min Huang

    2014-10-01

    Full Text Available While the NAND flash memory is widely used as the storage medium in modern sensor systems, the aggressive shrinking of process geometry and an increase in the number of bits stored in each memory cell will inevitably degrade the reliability of NAND flash memory. In particular, it’s critical to enhance metadata reliability, which occupies only a small portion of the storage space, but maintains the critical information of the file system and the address translations of the storage system. Metadata damage will cause the system to crash or a large amount of data to be lost. This paper presents Asymmetric Programming, a highly reliable metadata allocation strategy for MLC NAND flash memory storage systems. Our technique exploits for the first time the property of the multi-page architecture of MLC NAND flash memory to improve the reliability of metadata. The basic idea is to keep metadata in most significant bit (MSB pages which are more reliable than least significant bit (LSB pages. Thus, we can achieve relatively low bit error rates for metadata. Based on this idea, we propose two strategies to optimize address mapping and garbage collection. We have implemented Asymmetric Programming on a real hardware platform. The experimental results show that Asymmetric Programming can achieve a reduction in the number of page errors of up to 99.05% with the baseline error correction scheme.

  8. Asymmetric programming: a highly reliable metadata allocation strategy for MLC NAND flash memory-based sensor systems.

    Science.gov (United States)

    Huang, Min; Liu, Zhaoqing; Qiao, Liyan

    2014-10-10

    While the NAND flash memory is widely used as the storage medium in modern sensor systems, the aggressive shrinking of process geometry and an increase in the number of bits stored in each memory cell will inevitably degrade the reliability of NAND flash memory. In particular, it's critical to enhance metadata reliability, which occupies only a small portion of the storage space, but maintains the critical information of the file system and the address translations of the storage system. Metadata damage will cause the system to crash or a large amount of data to be lost. This paper presents Asymmetric Programming, a highly reliable metadata allocation strategy for MLC NAND flash memory storage systems. Our technique exploits for the first time the property of the multi-page architecture of MLC NAND flash memory to improve the reliability of metadata. The basic idea is to keep metadata in most significant bit (MSB) pages which are more reliable than least significant bit (LSB) pages. Thus, we can achieve relatively low bit error rates for metadata. Based on this idea, we propose two strategies to optimize address mapping and garbage collection. We have implemented Asymmetric Programming on a real hardware platform. The experimental results show that Asymmetric Programming can achieve a reduction in the number of page errors of up to 99.05% with the baseline error correction scheme.

  9. Asymmetric Programming: A Highly Reliable Metadata Allocation Strategy for MLC NAND Flash Memory-Based Sensor Systems

    Science.gov (United States)

    Huang, Min; Liu, Zhaoqing; Qiao, Liyan

    2014-01-01

    While the NAND flash memory is widely used as the storage medium in modern sensor systems, the aggressive shrinking of process geometry and an increase in the number of bits stored in each memory cell will inevitably degrade the reliability of NAND flash memory. In particular, it's critical to enhance metadata reliability, which occupies only a small portion of the storage space, but maintains the critical information of the file system and the address translations of the storage system. Metadata damage will cause the system to crash or a large amount of data to be lost. This paper presents Asymmetric Programming, a highly reliable metadata allocation strategy for MLC NAND flash memory storage systems. Our technique exploits for the first time the property of the multi-page architecture of MLC NAND flash memory to improve the reliability of metadata. The basic idea is to keep metadata in most significant bit (MSB) pages which are more reliable than least significant bit (LSB) pages. Thus, we can achieve relatively low bit error rates for metadata. Based on this idea, we propose two strategies to optimize address mapping and garbage collection. We have implemented Asymmetric Programming on a real hardware platform. The experimental results show that Asymmetric Programming can achieve a reduction in the number of page errors of up to 99.05% with the baseline error correction scheme. PMID:25310473

  10. Accelerated Cyclic Reduction: A Distributed-Memory Fast Solver for Structured Linear Systems

    KAUST Repository

    Chávez, Gustavo

    2017-12-15

    We present Accelerated Cyclic Reduction (ACR), a distributed-memory fast solver for rank-compressible block tridiagonal linear systems arising from the discretization of elliptic operators, developed here for three dimensions. Algorithmic synergies between Cyclic Reduction and hierarchical matrix arithmetic operations result in a solver that has O(kNlogN(logN+k2)) arithmetic complexity and O(k Nlog N) memory footprint, where N is the number of degrees of freedom and k is the rank of a block in the hierarchical approximation, and which exhibits substantial concurrency. We provide a baseline for performance and applicability by comparing with the multifrontal method with and without hierarchical semi-separable matrices, with algebraic multigrid and with the classic cyclic reduction method. Over a set of large-scale elliptic systems with features of nonsymmetry and indefiniteness, the robustness of the direct solvers extends beyond that of the multigrid solver, and relative to the multifrontal approach ACR has lower or comparable execution time and size of the factors, with substantially lower numerical ranks. ACR exhibits good strong and weak scaling in a distributed context and, as with any direct solver, is advantageous for problems that require the solution of multiple right-hand sides. Numerical experiments show that the rank k patterns are of O(1) for the Poisson equation and of O(n) for the indefinite Helmholtz equation. The solver is ideal in situations where low-accuracy solutions are sufficient, or otherwise as a preconditioner within an iterative method.

  11. Method and system for training dynamic nonlinear adaptive filters which have embedded memory

    Science.gov (United States)

    Rabinowitz, Matthew (Inventor)

    2002-01-01

    Described herein is a method and system for training nonlinear adaptive filters (or neural networks) which have embedded memory. Such memory can arise in a multi-layer finite impulse response (FIR) architecture, or an infinite impulse response (IIR) architecture. We focus on filter architectures with separate linear dynamic components and static nonlinear components. Such filters can be structured so as to restrict their degrees of computational freedom based on a priori knowledge about the dynamic operation to be emulated. The method is detailed for an FIR architecture which consists of linear FIR filters together with nonlinear generalized single layer subnets. For the IIR case, we extend the methodology to a general nonlinear architecture which uses feedback. For these dynamic architectures, we describe how one can apply optimization techniques which make updates closer to the Newton direction than those of a steepest descent method, such as backpropagation. We detail a novel adaptive modified Gauss-Newton optimization technique, which uses an adaptive learning rate to determine both the magnitude and direction of update steps. For a wide range of adaptive filtering applications, the new training algorithm converges faster and to a smaller value of cost than both steepest-descent methods such as backpropagation-through-time, and standard quasi-Newton methods. We apply the algorithm to modeling the inverse of a nonlinear dynamic tracking system 5, as well as a nonlinear amplifier 6.

  12. Role of the somatostatin system in contextual fear memory and hippocampal synaptic plasticity.

    Science.gov (United States)

    Kluge, Christian; Stoppel, Christian; Szinyei, Csaba; Stork, Oliver; Pape, Hans-Christian

    2008-04-01

    Somatostatin has been implicated in various cognitive and emotional functions, but its precise role is still poorly understood. Here, we have made use of mice with somatostatin deficiency, based upon genetic invalidation or pharmacologically induced depletion, and Pavlovian fear conditioning in order to address the contribution of the somatostatin system to associative fear memory. The results demonstrate an impairment of foreground and background contextual but not tone fear conditioning in mice with targeted ablation of the somatostatin gene. These deficits were associated with a decrease in long-term potentiation in the CA1 area of the hippocampus. Both the behavioral and the electrophysiological phenotypes were mimicked in wild-type mice through application of the somatostatin-depleting substance cysteamine prior to fear training, whereas no further deficits were observed upon application in the somatostatin null mutants. These results suggest that the somatostatin system plays a critical role in the acquisition of contextual fear memory, but not tone fear learning, and further highlights the role of hippocampal synaptic plasticity for information processing concerning contextual information.

  13. The dynamic nature of systems consolidation: Stress during learning as a switch guiding the rate of the hippocampal dependency and memory quality.

    Science.gov (United States)

    Pedraza, Lizeth K; Sierra, Rodrigo O; Boos, Flávia Z; Haubrich, Josué; Quillfeldt, Jorge A; Alvares, Lucas de Oliveira

    2016-03-01

    Memory fades over time, becoming more schematic or abstract. The loss of contextual detail in memory may reflect a time-dependent change in the brain structures supporting memory. It has been well established that contextual fear memory relies on the hippocampus for expression shortly after learning, but it becomes hippocampus-independent at a later time point, a process called systems consolidation. This time-dependent process correlates with the loss of memory precision. Here, we investigated whether training intensity predicts the gradual decay of hippocampal dependency to retrieve memory, and the quality of the contextual memory representation over time. We have found that training intensity modulates the progressive decay of hippocampal dependency and memory precision. Strong training intensity accelerates systems consolidation and memory generalization in a remarkable timeframe match. The mechanisms underpinning such process are triggered by glucocorticoid and noradrenaline released during training. These results suggest that the stress levels during emotional learning act as a switch, determining the fate of memory quality. Moderate stress will create a detailed memory, whereas a highly stressful training will develop a generic gist-like memory. © 2015 Wiley Periodicals, Inc.

  14. Memory and Energy Optimization Strategies for Multithreaded Operating System on the Resource-Constrained Wireless Sensor Node

    Directory of Open Access Journals (Sweden)

    Xing Liu

    2014-12-01

    Full Text Available Memory and energy optimization strategies are essential for the resource-constrained wireless sensor network (WSN nodes. In this article, a new memory-optimized and energy-optimized multithreaded WSN operating system (OS LiveOS is designed and implemented. Memory cost of LiveOS is optimized by using the stack-shifting hybrid scheduling approach. Different from the traditional multithreaded OS in which thread stacks are allocated statically by the pre-reservation, thread stacks in LiveOS are allocated dynamically by using the stack-shifting technique. As a result, memory waste problems caused by the static pre-reservation can be avoided. In addition to the stack-shifting dynamic allocation approach, the hybrid scheduling mechanism which can decrease both the thread scheduling overhead and the thread stack number is also implemented in LiveOS. With these mechanisms, the stack memory cost of LiveOS can be reduced more than 50% if compared to that of a traditional multithreaded OS. Not is memory cost optimized, but also the energy cost is optimized in LiveOS, and this is achieved by using the multi-core “context aware” and multi-core “power-off/wakeup” energy conservation approaches. By using these approaches, energy cost of LiveOS can be reduced more than 30% when compared to the single-core WSN system. Memory and energy optimization strategies in LiveOS not only prolong the lifetime of WSN nodes, but also make the multithreaded OS feasible to run on the memory-constrained WSN nodes.

  15. Technology for Sustainment of Strategic Systems. Report Memory (MRAM) Product Development

    National Research Council Canada - National Science Library

    Beck, Vicki

    2004-01-01

    ...) Honeywell is developing radiation-hardened Magneto-resistive Random Access Memory (MRAM) non-volatile memory for military and aerospace products where data processing and storage performance is critical utilizing Motorola technology...

  16. Glucocorticoids interact with the hippocampal endocannabinoid system in impairing retrieval of contextual fear memory

    NARCIS (Netherlands)

    Atsak, P.; Hauer, D.; Campolongo, P.; Schelling, G.; McGaugh, J.L.; Roozendaal, B.

    2012-01-01

    There is extensive evidence that glucocorticoid hormones impair the retrieval of memory of emotionally arousing experiences. Although it is known that glucocorticoid effects on memory retrieval impairment depend on rapid interactions with arousal-induced noradrenergic activity, the exact mechanism

  17. An innovative seismic bracing system based on a superelastic shape memory alloy ring

    International Nuclear Information System (INIS)

    Gao, Nan; Jeon, Jong-Su; DesRoches, Reginald; Hodgson, Darel E

    2016-01-01

    Shape memory alloys (SMAs) have great potential in seismic applications because of their remarkable superelasticity. Seismic bracing systems based on SMAs can mitigate the damage caused by earthquakes. The current study investigates a bracing system based on an SMA ring which is capable of both re-centering and energy dissipation. This lateral force resisting system is a cross-braced system consisting of an SMA ring and four tension-only cable assemblies, which can be applied to both new construction and seismic retrofit. The performance of this bracing system is examined through a quasi-static cyclic loading test and finite element (FE) analysis. This paper describes the experimental design in detail, discusses the experimental results, compares the performance with other bracing systems based on SMAs, and presents an Abaqus FE model calibrated on the basis of experimental results to simulate the superelastic behavior of the SMA ring. The experimental results indicate that the seismic performance of this system is promising in terms of damping and re-centering. The FE model can be used in the simulation of building structures using the proposed bracing system. (paper)

  18. Working memory.

    Science.gov (United States)

    Baddeley, A

    1992-01-31

    The term working memory refers to a brain system that provides temporary storage and manipulation of the information necessary for such complex cognitive tasks as language comprehension, learning, and reasoning. This definition has evolved from the concept of a unitary short-term memory system. Working memory has been found to require the simultaneous storage and processing of information. It can be divided into the following three subcomponents: (i) the central executive, which is assumed to be an attentional-controlling system, is important in skills such as chess playing and is particularly susceptible to the effects of Alzheimer's disease; and two slave systems, namely (ii) the visuospatial sketch pad, which manipulates visual images and (iii) the phonological loop, which stores and rehearses speech-based information and is necessary for the acquisition of both native and second-language vocabulary.

  19. Olfactory identification deficits and associated response inhibition in obsessive-compulsive disorder: on the scent of the orbitofronto-striatal model.

    Science.gov (United States)

    Bersani, Giuseppe; Quartini, Adele; Ratti, Flavia; Pagliuca, Giulio; Gallo, Andrea

    2013-11-30

    Olfactory identification ability implicates the integrity of the orbitofrontal cortex (OFC). The fronto-striatal circuits including the OFC have been involved in the neuropathology of Obsessive Compulsive Disorder (OCD). However, only a few studies have examined olfactory function in patients with OCD. The Brief Smell Identification Test (B-SIT) and tests from the Cambridge Neuropsychological Automated Battery (CANTAB) were administered to 25 patients with OCD and to 21 healthy matched controls. OCD patients showed a significant impairment in olfactory identification ability as well as widely distributed cognitive deficits in visual memory, executive functions, attention, and response inhibition. The degree of behavioural impairment on motor impulsivity (prolonged response inhibition Stop-Signal Reaction Time) strongly correlated with the B-SIT score. Our study is the first to indicate a shared OFC pathological neural substrate underlying olfactory identification impairment, impulsivity, and OCD. Deficits in visual memory, executive functions and attention further indicate that regions outside of the orbitofronto-striatal loop may be involved in this disorder. Such results may help delineate the clinical complexity of OCD and support more targeted investigations and interventions. In this regard, research on the potential diagnostic utility of olfactory identification deficits in the assessment of OCD would certainly be useful. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  20. Light-erasable embedded charge-trapping memory based on MoS2 for system-on-panel applications

    Science.gov (United States)

    He, Long-Fei; Zhu, Hao; Xu, Jing; Liu, Hao; Nie, Xin-Ran; Chen, Lin; Sun, Qing-Qing; Xia, Yang; Wei Zhang, David

    2017-11-01

    The continuous scaling and challenges in device integrations in modern portable electronic products have aroused many scientific interests, and a great deal of effort has been made in seeking solutions towards a more microminiaturized package assembled with smaller and more powerful components. In this study, an embedded light-erasable charge-trapping memory with a high-k dielectric stack (Al2O3/HfO2/Al2O3) and an atomically thin MoS2 channel has been fabricated and fully characterized. The memory exhibits a sufficient memory window, fast programming and erasing (P/E) speed, and high On/Off current ratio up to 107. Less than 25% memory window degradation is observed after projected 10-year retention, and the device functions perfectly after 8000 P/E operation cycles. Furthermore, the programmed device can be fully erased by incident light without electrical assistance. Such excellent memory performance originates from the intrinsic properties of two-dimensional (2D) MoS2 and the engineered back-gate dielectric stack. Our integration of 2D semiconductors in the infrastructure of light-erasable charge-trapping memory is very promising for future system-on-panel applications like storage of metadata and flexible imaging arrays.

  1. MSAProbs-MPI: parallel multiple sequence aligner for distributed-memory systems.

    Science.gov (United States)

    González-Domínguez, Jorge; Liu, Yongchao; Touriño, Juan; Schmidt, Bertil

    2016-12-15

    MSAProbs is a state-of-the-art protein multiple sequence alignment tool based on hidden Markov models. It can achieve high alignment accuracy at the expense of relatively long runtimes for large-scale input datasets. In this work we present MSAProbs-MPI, a distributed-memory parallel version of the multithreaded MSAProbs tool that is able to reduce runtimes by exploiting the compute capabilities of common multicore CPU clusters. Our performance evaluation on a cluster with 32 nodes (each containing two Intel Haswell processors) shows reductions in execution time of over one order of magnitude for typical input datasets. Furthermore, MSAProbs-MPI using eight nodes is faster than the GPU-accelerated QuickProbs running on a Tesla K20. Another strong point is that MSAProbs-MPI can deal with large datasets for which MSAProbs and QuickProbs might fail due to time and memory constraints, respectively. Source code in C ++ and MPI running on Linux systems as well as a reference manual are available at http://msaprobs.sourceforge.net CONTACT: jgonzalezd@udc.esSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  2. Striatal dopamine release induced by repetitive transcranial magnetic stimulation over dorsolateral prefrontal cortex: effect of aging

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Seong Ae; Cho, Sang Soo; Yoon, Eun Jin; Kim, Ji Sun; Lee, Byung Chul; Kim, Yu Kyeong; Kim, Sang Eun [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    2007-07-01

    We previously demonstrated dopamine (DA) release in the bilateral striatal regions following prefrontal repetitive transcranial magnetic stimulation (rTMS) in young subjects. Several lines of evidence support substantial age-related changes in human dopaminergic neurotransmission. One possible explanation is alteration of cortico striatal neural connection with aging. Therefore, we investigated how frontal activation by rTMS influences striatal DA release in the elderly with SPECT measurements of striatal binding of [123I]iodobenzamide (lBZM), a DA D2 receptor radioligand that is sensitive to endogenous DA. Five healthy elderly male subjects (age, 64 3 y) were studied with brain [123I]IBZM SPECT under three conditions (resting, sham stimulation, and active rTMS over left dorsolateral prefrontal cortex (DLPFC)), while receiving a bolus plus constant infusion of [123I]IBZM. rTMS session consisted of three blocks. In each block, 15 trains of 2 sec duration were delivered with 10 Hz stimulation frequency and 100% motor threshold. Striatal V3', calculated as (striatal - occipital)/occipital radioactivity, was measured under equilibrium condition at baseline and after sham and active rTMS. Sham stimulation did not affect striatal V3'. rTMS over left DLPFC induced no significant change in V3' in the right striatum compared with baseline condition (0.91 0.25 vs. 0.96 0.25, P = NS). Interestingly, left striatal V3' showed a significant increase after rTMS over left DLPFC compared with sham condition (1.09 0.33 vs. 0.93 0.27, P < 0.05; 17.0 11.1% increase). These results are discrepant from previous ones from young subjects, who showed frontal rTMS-induced reduction of striatal V3', indicating rTMS-induced striatal DA release. We found no significant striatal DA release induced by rTMS over DLPFC in healthy elderly subjects using in vivo binding competition techniques. These results may support an altered cortico striatal circuit in normal aging.

  3. Striatal grafts in a rat model of Huntington's disease

    DEFF Research Database (Denmark)

    Guzman, R; Meyer, M; Lövblad, K O

    1999-01-01

    , which was found unaltered for the first 21 days posttransplantation, whereas a hypointense graft signal was detected at 99 days posttransplantation. At 2 days posttransplantation, T2-weighted images showed the graft region as a hyperintense area surrounded by a rim of low signal intensity but at later...... time-points graft location could not be further verified. Measures for graft size and ventricle size obtained from MR images highly correlated with measures obtained from histologically processed sections (R = 0.8, P ...Survival and integration into the host brain of grafted tissue are crucial factors in neurotransplantation approaches. The present study explored the feasibility of using a clinical MR scanner to study striatal graft development in a rat model of Huntington's disease. Rat fetal lateral ganglionic...

  4. Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology?

    Science.gov (United States)

    Charron, Giselle; Doudnikoff, Evelyne; Canron, Marie-Helene; Li, Qin; Véga, Céline; Marais, Sebastien; Baufreton, Jérôme; Vital, Anne; Oliet, Stéphane H R; Bezard, Erwan

    2014-01-01

    The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e., the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson's disease (PD) remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified "tripartite" synapses in the basal ganglia in general and the striatum in particular, we therefore characterized anatomically the PD-related modifications in astrocytic morphology, the changes in astrocytic network connections and the consequences on the spatial relationship between astrocytic processes and asymmetric synapses in normal and PD-like conditions in experimental and human PD. Our results unravel a dramatic regulation of striatal astrocytosis supporting the hypothesis of a key role in (dys) regulating corticostriatal transmission. Astrocytes and their various properties might thus represent a therapeutic target in PD.

  5. Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology?

    Directory of Open Access Journals (Sweden)

    Giselle eCharron

    2014-09-01

    Full Text Available The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e. the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson’s disease (PD remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified tripartite synapses in the basal ganglia in general and the striatum in particular, we therefore characterized anatomically the PD-related modifications in astrocytic morphology, the changes in astrocytic network connections and the consequences on the spatial relationship between astrocytic processes and asymmetric synapses in normal and PD-like conditions in experimental and human PD. Our results unravel a dramatic regulation of striatal astrocytosis supporting the hypothesis of a key role in (dysregulating corticostriatal transmission. Astrocytes and their various properties might thus represent a therapeutic target in PD.

  6. Speech-induced striatal dopamine release is left lateralized and coupled to functional striatal circuits in healthy humans: A combined PET, fMRI and DTI study

    Science.gov (United States)

    Simonyan, Kristina; Herscovitch, Peter; Horwitz, Barry

    2013-01-01

    Considerable progress has been recently made in understanding the brain mechanisms underlying speech and language control. However, the neurochemical underpinnings of normal speech production remain largely unknown. We investigated the extent of striatal endogenous dopamine release and its influences on the organization of functional striatal speech networks during production of meaningful English sentences using a combination of positron emission tomography (PET) with the dopamine D2/D3 receptor radioligand [11C]raclopride and functional MRI (fMRI). In addition, we used diffusion tensor tractography (DTI) to examine the extent of dopaminergic modulatory influences on striatal structural network organization. We found that, during sentence production, endogenous dopamine was released in the ventromedial portion of the dorsal striatum, in its both associative and sensorimotor functional divisions. In the associative striatum, speech-induced dopamine release established a significant relationship with neural activity and influenced the left-hemispheric lateralization of striatal functional networks. In contrast, there were no significant effects of endogenous dopamine release on the lateralization of striatal structural networks. Our data provide the first evidence for endogenous dopamine release in the dorsal striatum during normal speaking and point to the possible mechanisms behind the modulatory influences of dopamine on the organization of functional brain circuits controlling normal human speech. PMID:23277111

  7. Trehalose rescues glial cell dysfunction in striatal cultures from HD R6/1 mice at early postnatal development.

    Science.gov (United States)

    Perucho, Juan; Gómez, Ana; Muñoz, María Paz; de Yébenes, Justo García; Mena, María Ángeles; Casarejos, María José

    2016-07-01

    The pathological hallmark of Huntington disease (HD) is the intracellular aggregation of mutant huntingtin (mHTT) in striatal neurons and glia associated with the selective loss of striatal medium-sized spiny neurons. Up to the present, the role of glia in HD is poorly understood and has been classically considered secondary to neuronal disorder. Trehalose is a disaccharide known to possess many pharmacological properties, acting as an antioxidant, a chemical chaperone, and an inducer of autophagy. In this study, we analyzed at an early postnatal development stage the abnormalities observed in striatal glial cell cultures of postnatal R6/1 mice (HD glia), under baseline and stressing conditions and the protective effects of trehalose. Our data demonstrate that glial HD alterations already occur at early stages of postnatal development. After 20 postnatal days in vitro, striatal HD glia cultures showed more reactive astrocytes with increased expression of glial fibrillary acidic protein (GFAP) but with less replication capacity, less A2B5(+) glial progenitors and more microglia than wild-type (WT) cultures. HD glia had lower levels of intracellular glutathione (GSH) and was more susceptible to H2O2 and epoxomicin insults. The amount of expressed GDNF and secreted mature-BDNF by HD astrocytes were much lower than by WT astrocytes. In addition, HD glial cultures showed a deregulation of the major proteolytic systems, the ubiquitin-proteasomal system (UPS), and the autophagic pathway. This produces a defective protein quality control, indicated by the elevated levels of ubiquitination and p62 protein. Interestingly, we show that trehalose, through its capacity to induce autophagy, inhibited p62/SQSTM1 accumulation and facilitated the degradation of cytoplasmic aggregates from mHTT and α-synuclein proteins. Trehalose also reduced microglia activation and reversed the disrupted cytoskeleton of astrocytes accompanied with an increase in the replication capacity. In

  8. Malfunctioning DNA damage response (DDR) leads to the degeneration of nigro-striatal pathway in mouse brain.

    Science.gov (United States)

    Kirshner, Michal; Galron, Ronit; Frenkel, Dan; Mandelbaum, Gil; Shiloh, Yosef; Wang, Zhao-Qi; Barzilai, Ari

    2012-03-01

    Pronounced neuropathology is a feature of ataxia-telangiectasia (A-T) and Nijmegen breakage syndrome (NBS), which are both genomic instability syndromes. The Nbs1 protein, which is defective in NBS, is a component of the Mre11/RAD50/NBS1 (MRN) complex. This complex plays a major role in the early phase of the cellular response to double strand breaks (DSBs) in the DNA. Among others, MRN is required for timely activation of the protein kinase ATM (A-T mutated), which is disrupted in patients with A-T. Earlier reports show that Atm-deficient mice exhibit severe degeneration of tyrosine hydroxylase (TH)-positive dopaminergic nigro-striatal neurons and their terminals in the striatum. This cell loss is accompanied by a large reduction in immunoreactivity for the dopamine transporter protein (DAT) in the striatum. To test whether Nbs1 inactivation also affects the integrity of the nigro-striatal pathway, we examined this pathway in a murine model with conditional inactivation of the Nbs1 gene in central nervous system (Nbs1-CNS-Δ). We report that this model has a reduction in TH-positive cells in the substantia nigra. This phenomenon was seen at very early age, while Atm-/- mice showed a progressive age-dependent reduction. Furthermore, we observed an age-dependent increase in the level of TH in the striatum of Atm-/- and Nbs1-CNS-Δ mice. In addition to the altered expression of TH, we also found a reduction of DAT in the striatum of both Atm-/- and Nbs1-CNS-Δ mice at 60 days of age. Finally, microglial recruitment and alterations in the levels of various neurotrophic factors were also observed. These results indicate that malfunctioning DNA damage response severely affects the integrity of the nigro-striatal pathway and suggest a new neurodegenerative pathway in Parkinsonian syndromes.

  9. Design of Cyber Attack Precursor Symptom Detection Algorithm through System Base Behavior Analysis and Memory Monitoring

    Science.gov (United States)

    Jung, Sungmo; Kim, Jong Hyun; Cagalaban, Giovanni; Lim, Ji-Hoon; Kim, Seoksoo

    More recently, botnet-based cyber attacks, including a spam mail or a DDos attack, have sharply increased, which poses a fatal threat to Internet services. At present, antivirus businesses make it top priority to detect malicious code in the shortest time possible (Lv.2), based on the graph showing a relation between spread of malicious code and time, which allows them to detect after malicious code occurs. Despite early detection, however, it is not possible to prevent malicious code from occurring. Thus, we have developed an algorithm that can detect precursor symptoms at Lv.1 to prevent a cyber attack using an evasion method of 'an executing environment aware attack' by analyzing system behaviors and monitoring memory.

  10. Contamination due to memory effects in filtered vacuum arc plasma deposition systems

    International Nuclear Information System (INIS)

    Martins, D.R.; Salvadori, M.C.; Verdonck, P.; Brown, I.G.

    2002-01-01

    Thin film synthesis by filtered vacuum arc plasma deposition is a widely used technique with a number of important emerging technological applications. A characteristic feature of the method is that during the deposition process not only is the substrate coated by the plasma, but the plasma gun itself and the magnetic field coil and/or vacuum vessel section constituting the macroparticle filter are also coated to some extent. If then the plasma gun cathode is changed to a new element, there can be a contamination of the subsequent film deposition by sputtering from various parts of the system of the previous coating species. We have experimentally explored this effect and compared our results with theoretical estimates of sputtering from the stopping and range of ions in matter code. We find film contamination of the order of 10 -4 -10 -3 , and the memory of the prior history of the deposition hardware can be relatively long lasting

  11. Contamination due to memory effects in filtered vacuum arc plasma deposition systems

    CERN Document Server

    Martins, D R; Verdonck, P; Brown, I G

    2002-01-01

    Thin film synthesis by filtered vacuum arc plasma deposition is a widely used technique with a number of important emerging technological applications. A characteristic feature of the method is that during the deposition process not only is the substrate coated by the plasma, but the plasma gun itself and the magnetic field coil and/or vacuum vessel section constituting the macroparticle filter are also coated to some extent. If then the plasma gun cathode is changed to a new element, there can be a contamination of the subsequent film deposition by sputtering from various parts of the system of the previous coating species. We have experimentally explored this effect and compared our results with theoretical estimates of sputtering from the SRIM (Stopping and Range of Ions in Matter) code. We find film contamination of order 10-4 - 10-3, and the memory of the prior history of the deposition hardware can be relatively long-lasting.

  12. A QDWH-Based SVD Software Framework on Distributed-Memory Manycore Systems

    KAUST Repository

    Sukkari, Dalal

    2017-01-01

    This paper presents a high performance software framework for computing a dense SVD on distributed- memory manycore systems. Originally introduced by Nakatsukasa et al. (Nakatsukasa et al. 2010; Nakatsukasa and Higham 2013), the SVD solver relies on the polar decomposition using the QR Dynamically-Weighted Halley algorithm (QDWH). Although the QDWH-based SVD algorithm performs a significant amount of extra floating-point operations compared to the traditional SVD with the one-stage bidiagonal reduction, the inherent high level of concurrency associated with Level 3 BLAS compute-bound kernels ultimately compensates for the arithmetic complexity overhead. Using the ScaLAPACK two-dimensional block cyclic data distribution with a rectangular processor topology, the resulting QDWH-SVD further reduces excessive communications during the panel factorization, while increasing the degree of parallelism during the update of the trailing submatrix, as opposed to relying to the default square processor grid. After detailing the algorithmic complexity and the memory footprint of the algorithm, we conduct a thorough performance analysis and study the impact of the grid topology on the performance by looking at the communication and computation profiling trade-offs. We report performance results against state-of-the-art existing QDWH software implementations (e.g., Elemental) and their SVD extensions on large-scale distributed-memory manycore systems based on commodity Intel x86 Haswell processors and Knights Landing (KNL) architecture. The QDWH-SVD framework achieves up to 3/8-fold on the Haswell/KNL-based platforms, respectively, against ScaLAPACK PDGESVD and turns out to be a competitive alternative for well and ill-conditioned matrices. We finally come up herein with a performance model based on these empirical results. Our QDWH-based polar decomposition and its SVD extension are freely available at https://github.com/ecrc/qdwh.git and https

  13. Brain Events Underlying Episodic Memory Changes in Aging: A Longitudinal Investigation of Structural and Functional Connectivity.

    Science.gov (United States)

    Fjell, Anders M; Sneve, Markus H; Storsve, Andreas B; Grydeland, Håkon; Yendiki, Anastasia; Walhovd, Kristine B

    2016-03-01

    Episodic memories are established and maintained by close interplay between hippocampus and other cortical regions, but degradation of a fronto-striatal network has been suggested to be a driving force of memory decline in aging. We wanted to directly address how changes in hippocampal-cortical versus striatal-cortical networks over time impact episodic memory with age. We followed 119 healthy participants (20-83 years) for 3.5 years with repeated tests of episodic verbal memory and magnetic resonance imaging for quantification of functional and structural connectivity and regional brain atrophy. While hippocampal-cortical functional connectivity predicted memory change in young, changes in cortico-striatal functional connectivity were related to change in recall in older adults. Within each age group, effects of functional and structural connectivity were anatomically closely aligned. Interestingly, the relationship between functional connectivity and memory was strongest in the age ranges where the rate of reduction of the relevant brain structure was lowest, implying selective impacts of the different brain events on memory. Together, these findings suggest a partly sequential and partly simultaneous model of brain events underlying cognitive changes in aging, where different functional and structural events are more or less important in various time windows, dismissing a simple uni-factorial view on neurocognitive aging. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Stochastic memory: getting memory out of noise

    Science.gov (United States)

    Stotland, Alexander; di Ventra, Massimiliano

    2011-03-01

    Memory circuit elements, namely memristors, memcapacitors and meminductors, can store information without the need of a power source. These systems are generally defined in terms of deterministic equations of motion for the state variables that are responsible for memory. However, in real systems noise sources can never be eliminated completely. One would then expect noise to be detrimental for memory. Here, we show that under specific conditions on the noise intensity memory can actually be enhanced. We illustrate this phenomenon using a physical model of a memristor in which the addition of white noise into the state variable equation improves the memory and helps the operation of the system. We discuss under which conditions this effect can be realized experimentally, discuss its implications on existing memory systems discussed in the literature, and also analyze the effects of colored noise. Work supported in part by NSF.

  15. Frontal, Striatal, and Medial Temporal Sensitivity to Value Distinguishes Risk-Taking from Risk-Aversive Older Adults during Decision Making.

    Science.gov (United States)

    Goh, Joshua O S; Su, Yu-Shiang; Tang, Yong-Jheng; McCarrey, Anna C; Tereshchenko, Alexander; Elkins, Wendy; Resnick, Susan M

    2016-12-07

    Aging compromises the frontal, striatal, and medial temporal areas of the reward system, impeding accurate value representation and feedback processing critical for decision making. However, substantial variability characterizes age-related effects on the brain so that some older individuals evince clear neurocognitive declines whereas others are spared. Moreover, the functional correlates of normative individual differences in older-adult value-based decision making remain unclear. We performed a functional magnetic resonance imaging study in 173 human older adults during a lottery choice task in which costly to more desirable stakes were depicted using low to high expected values (EVs) of points. Across trials that varied in EVs, participants decided to accept or decline the offered stakes to maximize total accumulated points. We found that greater age was associated with less optimal decisions, accepting stakes when losses were likely and declining stakes when gains were likely, and was associated with increased frontal activity for costlier stakes. Critically, risk preferences varied substantially across older adults and neural sensitivity to EVs in the frontal, striatal, and medial temporal areas dissociated risk-aversive from risk-taking individuals. Specifically, risk-averters increased neural responses to increasing EVs as stakes became more desirable, whereas risk-takers increased neural responses with decreasing EV as stakes became more costly. Risk preference also modulated striatal responses during feedback with risk-takers showing more positive responses to gains compared with risk-averters. Our findings highlight the frontal, striatal, and medial temporal areas as key neural loci in which individual differences differentially affect value-based decision-making ability in older adults. Frontal, striatal, and medial temporal functions implicated in value-based decision processing of rewards and costs undergo substantial age-related changes. However, age

  16. Spin-transfer torque magnetic memory as a stochastic memristive synapse for neuromorphic systems.

    Science.gov (United States)

    Vincent, Adrien F; Larroque, Jerome; Locatelli, Nicolas; Ben Romdhane, Nesrine; Bichler, Olivier; Gamrat, Christian; Zhao, Wei Sheng; Klein, Jacques-Olivier; Galdin-Retailleau, Sylvie; Querlioz, Damien

    2015-04-01

    Spin-transfer torque magnetic memory (STT-MRAM) is currently under intense academic and industrial development, since it features non-volatility, high write and read speed and high endurance. In this work, we show that when used in a non-conventional regime, it can additionally act as a stochastic memristive device, appropriate to implement a "synaptic" function. We introduce basic concepts relating to spin-transfer torque magnetic tunnel junction (STT-MTJ, the STT-MRAM cell) behavior and its possible use to implement learning-capable synapses. Three programming regimes (low, intermediate and high current) are identified and compared. System-level simulations on a task of vehicle counting highlight the potential of the technology for learning systems. Monte Carlo simulations show its robustness to device variations. The simulations also allow comparing system operation when the different programming regimes of STT-MTJs are used. In comparison to the high and low current regimes, the intermediate current regime allows minimization of energy consumption, while retaining a high robustness to device variations. These results open the way for unexplored applications of STT-MTJs in robust, low power, cognitive-type systems.

  17. Cortico-Striatal Spike-Timing Dependent Plasticity After Activation of Subcortical Pathways

    OpenAIRE

    Schulz, Jan M.; Redgrave, Peter; Reynolds, John N. J.

    2010-01-01

    Cortico-striatal spike-timing dependent plasticity (STDP) is modulated by dopamine in vitro. The present study investigated STDP in vivo using alternative procedures for modulating dopaminergic inputs. Postsynaptic potentials (PSP) were evoked in intracellularly recorded spiny neurons by electrical stimulation of the contralateral motor cortex. PSPs often consisted of up to three distinct components, likely representing distinct cortico-striatal pathways. After baseline recording, bicucullin...

  18. A negative relationship between ventral striatal loss anticipation response and impulsivity in borderline personality disorder

    OpenAIRE

    Herbort, Maike C.; Soch, Joram; W?stenberg, Torsten; Krauel, Kerstin; Pujara, Maia; Koenigs, Michael; Gallinat, J?rgen; Walter, Henrik; Roepke, Stefan; Schott, Bj?rn H.

    2016-01-01

    Patients with borderline personality disorder (BPD) frequently exhibit impulsive behavior, and self-reported impulsivity is typically higher in BPD patients when compared to healthy controls. Previous functional neuroimaging studies have suggested a link between impulsivity, the ventral striatal response to reward anticipation, and prediction errors. Here we investigated the striatal neural response to monetary gain and loss anticipation and their relationship with impulsivity in 21 female BP...

  19. Opposite Effects of Stimulant and Antipsychotic Drugs on Striatal Fast-Spiking Interneurons

    OpenAIRE

    Wiltschko, Alexander B; Pettibone, Jeffrey R; Berke, Joshua D

    2010-01-01

    Psychomotor stimulants and typical antipsychotic drugs have powerful but opposite effects on mood and behavior, largely through alterations in striatal dopamine signaling. Exactly how these drug actions lead to behavioral change is not well understood, as previous electrophysiological studies have found highly heterogeneous changes in striatal neuron firing. In this study, we examined whether part of this heterogeneity reflects the mixture of distinct cell types present in the striatum, by di...

  20. Effect of propofol on the medial temporal lobe emotional memory system: a functional magnetic resonance imaging study in human subjects.

    Science.gov (United States)

    Pryor, K O; Root, J C; Mehta, M; Stern, E; Pan, H; Veselis, R A; Silbersweig, D A

    2015-07-01

    Subclinical doses of propofol produce anterograde amnesia, characterized by an early failure of memory consolidation. It is unknown how propofol affects the amygdala-dependent emotional memory system, which modulates consolidation in the hippocampus in response to emotional arousal and neurohumoral stress. We present an event-related functional magnetic resonance imaging study of the effects of propofol on the emotional memory system in human subjects. Thirty-five healthy subjects were randomized to receive propofol, at an estimated brain concentration of 0.90 μg ml(-1), or placebo. During drug infusion, emotionally arousing and neutral images were presented in a continuous recognition task, while blood-oxygen-level-dependent activation responses were acquired. After a drug-free interval of 2 h, subsequent memory for successfully encoded items was assessed. Imaging analysis was performed using statistical parametric mapping and behavioural analysis using signal detection models. Propofol had no effect on the stereotypical amygdalar response to emotional arousal, but caused marked suppression of the hippocampal response. Propofol caused memory performance to become uncoupled from amygdalar activation, but it remained correlated with activation in the posterior hippocampus, which decreased in proportion to amnesia. Propofol is relatively ineffective at suppressing amygdalar activation at sedative doses, but abolishes emotional modulation and causes amnesia via mechanisms that commonly involve hyporesponsiveness of the hippocampus. These findings raise the possibility that amygdala-dependent fear systems may remain intact even when a patient has diminished memory of events. This may be of clinical importance in the perioperative development of fear-based psychopathologies, such as post-traumatic stress disorder. NCT00504894. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions

  1. Erasing Fear : Effect of Disrupting Fear Memory Reconsolidation on Central and Peripheral Nervous System Activity

    OpenAIRE

    Ågren, Thomas

    2012-01-01

    Fear memories, here defined as learned associations between a stimulus and a physiological fear reaction, are formed through fear conditioning. In animals, fear memories, present in the lateral amygdala, undergo reconsolidation after recall. Moreover, this reconsolidation process can be disrupted both pharmacologically and behaviourally, resulting in a reduced fear response to the stimulus. This thesis examines the attenuation of fear memories by disrupting reconsolidation in humans, using me...

  2. Whole brain radiation-induced impairments in learning and memory are time-sensitive and reversible by systemic hypoxia.

    Science.gov (United States)

    Warrington, Junie P; Csiszar, Anna; Mitschelen, Matthew; Lee, Yong Woo; Sonntag, William E

    2012-01-01

    Whole brain radiation therapy (WBRT) is commonly used for treatment of primary and metastatic brain tumors; however, cognitive impairment occurs in 40-50% of brain tumor survivors. The etiology of the cognitive impairment following WBRT remains elusive. We recently reported that radiation-induced cerebrovascular rarefaction within hippocampal subregions could be completely reversed by systemic hypoxia. However, the effects of this intervention on learning and memory have not been reported. In this study, we assessed the time-course for WBRT-induced impairments in contextual and spatial learning and the capacity of systemic hypoxia to reverse WBRT-induced deficits in spatial memory. A clinical fractionated series of 4.5Gy WBRT was administered to mice twice weekly for 4 weeks, and after various periods of recovery, behavioral analyses were performed. To study the effects of systemic hypoxia, mice were subjected to 11% (hypoxia) or 21% oxygen (normoxia) for 28 days, initiated 1 month after the completion of WBRT. Our results indicate that WBRT induces a transient deficit in contextual learning, disruption of working memory, and progressive impairment of spatial learning. Additionally, systemic hypoxia completely reversed WBRT-induced impairments in learning and these behavioral effects as well as increased vessel density persisted for at least 2 months following hypoxia treatment. Our results provide critical support for the hypothesis that cerebrovascular rarefaction is a key component of cognitive impairment post-WBRT and indicate that processes of learning and memory, once thought to be permanently impaired after WBRT, can be restored.

  3. Children's and Adults' Memory for Emotional Pictures: Examining Age-Related Patterns Using the Developmental Affective Photo System

    Science.gov (United States)

    Cordon, Ingrid M.; Melinder, Annika M. D.; Goodman, Gail S.; Edelstein, Robin S.

    2013-01-01

    Two studies were conducted to examine theoretical questions about children's and adults' memory for emotional visual stimuli. In Study 1, 7- to 9-year-olds and adults (N = 172) participated in the initial creation of the Developmental Affective Photo System (DAPS). Ratings of emotional valence, arousal, and complexity were obtained. In Study 2,…

  4. Evaluation of a Connectionless NoC for a Real-Time Distributed Shared Memory Many-Core System

    NARCIS (Netherlands)

    Rutgers, J.H.; Bekooij, Marco Jan Gerrit; Smit, Gerardus Johannes Maria

    2012-01-01

    Real-time embedded systems like smartphones tend to comprise an ever increasing number of processing cores. For scalability and the need for guaranteed performance, the use of a connection-oriented network-on-chip (NoC) is advocated. Furthermore, a distributed shared memory architecture is preferred

  5. The Impact of Transactive Memory System and Interaction Platform in Collaborative Knowledge Construction on Social Presence and Self-Regulation

    Science.gov (United States)

    Yilmaz, Ramazan; Karaoglan Yilmaz, Fatma Gizem; Kilic Cakmak, Ebru

    2017-01-01

    The purpose of this study is to examine the impacts of transactive memory system (TMS) and interaction platforms in computer-supported collaborative learning (CSCL) on social presence perceptions and self-regulation skills of learners. Within the scope of the study, social presence perceptions and self-regulation skills of students in…

  6. Differential effects of cocaine on histone posttranslational modifications in identified populations of striatal neurons.

    Science.gov (United States)

    Jordi, Emmanuelle; Heiman, Myriam; Marion-Poll, Lucile; Guermonprez, Pierre; Cheng, Shuk Kei; Nairn, Angus C; Greengard, Paul; Girault, Jean-Antoine

    2013-06-04

    Drugs of abuse, such as cocaine, induce changes in gene expression and epigenetic marks including alterations in histone posttranslational modifications in striatal neurons. These changes are thought to participate in physiological memory mechanisms and to be critical for long-term behavioral alterations. However, the striatum is composed of multiple cell types, including two distinct populations of medium-sized spiny neurons, and little is known concerning the cell-type specificity of epigenetic modifications. To address this question we used bacterial artificial chromosome transgenic mice, which express EGFP fused to the N-terminus of the large subunit ribosomal protein L10a driven by the D1 or D2 dopamine receptor (D1R, D2R) promoter, respectively. Fluorescence in nucleoli was used to sort nuclei from D1R- or D2R-expressing neurons and to quantify by flow cytometry the cocaine-induced changes in histone acetylation and methylation specifically in these two types of nuclei. The two populations of medium-sized spiny neurons displayed different patterns of histone modifications 15 min or 24 h after a single injection of cocaine or 24 h after seven daily injections. In particular, acetylation of histone 3 on Lys 14 and of histone 4 on Lys 5 and 12, and methylation of histone 3 on Lys 9 exhibited distinct and persistent changes in the two cell types. Our data provide insights into the differential epigenetic responses to cocaine in D1R- and D2R-positive neurons and their potential regulation, which may participate in the persistent effects of cocaine in these neurons. The method described should have general utility for studying nuclear modifications in different types of neuronal or nonneuronal cell types.

  7. Ductile shape memory alloys of the Cu-Al-Mn system

    International Nuclear Information System (INIS)

    Kainuma, R.; Takahashi, S.; Ishida, K.

    1995-01-01

    Cu-Al-Mn shape memory alloys with enhanced ductility have been developed by decreasing the degree of order in the β parent phase. Cu-Al-Mn alloys with Al contents lower than 18% exhibit good ductility with elongations of about 15% and excellent cold-workability arising from a lower degree of order in the Heusler (L21) β 1 parent phase, without any loss in their shape memory behavior. In this paper the mechanical and shape memory characteristics, such as the cold-workability, the Ms temperatures, the shape memory effect and the pseudo-elasticity of such ductile Cu-Al-Mn alloys are presented. (orig.)

  8. Corticostriatal interactions in the generation of tic-like behaviors after local striatal disinhibition

    Science.gov (United States)

    Pogorelov, Vladimir; Xu, Meiyu; Smith, Haleigh R.; Buchanan, Gordon F.; Pittenger, Christopher

    2015-01-01

    The pathophysiology of the tics that define Gilles de la Tourette syndrome (TS) is not well understood. Local disinhibition within the striatum has been hypothesized to play a pathogenic role. In support of this, experimental disinhibition by local antagonism of GABA-A receptors within the striatum produces tic-like phenomenology in monkey and rat. We replicated this effect in mice via local picrotoxin infusion into the dorsal striatum. Infusion of picrotoxin into sensorimotor cortex produced similar movements, accompanied by signs of behavioral activation; higher-dose picrotoxin in the cortex produced seizures. Striatal inhibition with local muscimol completely abolished tic-like movements after either striatal or cortical picrotoxin, confirming their dependence on the striatal circuitry; in contrast, cortical muscimol attenuated but did not abolish movements produced by striatal picrotoxin. Striatal glutamate blockade eliminated tic-like movements after striatal picrotoxin, indicating that glutamatergic afferents are critical for their generation. These studies replicate and extend previous work in monkey and rat, providing additional validation for the local disinhibition model of tic generation. Our results reveal a key role for corticostriatal glutamatergic afferents in the generation of tic-like movements in this model. PMID:25597650

  9. Serial imaging of bilateral striatal necrosis associated with acidaemia in adults

    International Nuclear Information System (INIS)

    Kamei, S.; Takasu, T.; Mori, N.; Yoshihashi, K.; Shikata, E.

    1996-01-01

    Bilateral striatal necrosis in acute encephalopathy has been reported in a small number of adults with methanol or cyanide intoxication, hypoxic encephalopathy or haemolytic-uraemic syndrome. Acute encephalopathy with bilateral striatal necrosis has been reported in infants and children. However, the pathogenesis of the necrosis remains unclear. This is the first report of serial imaging from the very early yo chronic stage in two acute encephalopathic adults with bilateral striatal necrosis. A clinicoradiological study is presented for clarification of the pathological process and pathogenesis. Striatal lesions were not detected in the very early stages, but only thereafter. Serial studies suggested that the lesions were caused by delayed neuronal death. These patients had severe lactic acidosis, near the limit for survival. There hav ebeen few reports of adults with acute encephalopathy and bilateral striatal necrosis in whom arterial pH was described; all these exhibited marked acidosis. The common pathophysiological condition among these encephalopathies with bilateral striatal necrosis could be lactic acidosis elicited by impairnment of ATP generation through the Krebs cycle. The striatum might represent one of the target areas of Krebs-cycle blockade. (orig.)

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

    Science.gov (United States)

    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

  11. Exploration of perpendicular magnetic anisotropy material system for application in spin transfer torque - Random access memory

    Science.gov (United States)

    Natarajarathinam, Anusha

    Perpendicular magnetic anisotropy (PMA) materials have unique advantages when used in magnetic tunnel junctions (MTJ) which are the most critical part of spin-torque transfer random access memory devices (STT-RAMs) that are being researched intensively as future non-volatile memory technology. They have high magnetoresistance which improves their sensitivity. The STT-RAM has several advantages over competing technologies, for instance, low power consumption, non-volatility, ultra-fast read and write speed and high endurance. In personal computers, it can replace SRAM for high-speed applications, Flash for non-volatility, and PSRAM and DRAM for high-speed program execution. The main aim of this research is to identify and optimize the best perpendicular magnetic anisotropy (PMA) material system for application to STT-RAM technology. Preliminary search for perpendicular magnetic anisotropy (PMA) materials for pinned layer for MTJs started with the exploration and optimization of crystalline alloys such as Co50Pd50 alloy, Mn50Al50 and amorphous alloys such as Tb21Fe72Co7 and are first presented in this work. Further optimization includes the study of Co/[Pd/Pt]x multilayers (ML), and the development of perpendicular synthetic antiferromagnets (SAF) utilizing these multilayers. Focused work on capping and seed layers to evaluate interfacial perpendicular anisotropy in free layers for pMTJs is then discussed. Optimization of the full perpendicular magnetic tunnel junction (pMTJ) includes the CoFeB/MgO/CoFeB trilayer coupled to a pinned/pinning layer with perpendicular Co/[Pd/Pt]x SAF and a thin Ta seeded CoFeB free layer. Magnetometry, simulations, annealing studies, transport measurements and TEM analysis on these samples will then be presented.

  12. Maternal obesity caused by overnutrition exposure leads to reversal learning deficits and striatal disturbance in rats.

    Directory of Open Access Journals (Sweden)

    Ting Wu

    Full Text Available Maternal obesity caused by overnutrition during pregnancy increases susceptibility to metabolic risks in adulthood, such as obesity, insulin resistance, and type 2 diabetes; however, whether and how it affects the cognitive system associated with the brain remains elusive. Here, we report that pregnant obesity induced by exposure to excessive high fatty or highly palatable food specifically impaired reversal learning, a kind of adaptive behavior, while leaving serum metabolic metrics intact in the offspring of rats, suggesting a much earlier functional and structural defects possibly occurred in the central nervous system than in the metabolic system in the offspring born in unfavorable intrauterine nutritional environment. Mechanically, we found that above mentioned cognitive inflexibility might be associated with significant striatal disturbance including impaired dopamine homeostasis and disrupted leptin signaling in the adult offspring. These collective data add a novel perspective of understanding the adverse postnatal sequelae in central nervous system induced by developmental programming and the related molecular mechanism through which priming of risk for developmental disorders may occur during early life.

  13. Set selection dynamical system neural networks with partial memories, with applications to Sudoku and KenKen puzzles.

    Science.gov (United States)

    Boreland, B; Clement, G; Kunze, H

    2015-08-01

    After reviewing set selection and memory model dynamical system neural networks, we introduce a neural network model that combines set selection with partial memories (stored memories on subsets of states in the network). We establish that feasible equilibria with all states equal to ± 1 correspond to answers to a particular set theoretic problem. We show that KenKen puzzles can be formulated as a particular case of this set theoretic problem and use the neural network model to solve them; in addition, we use a similar approach to solve Sudoku. We illustrate the approach in examples. As a heuristic experiment, we use online or print resources to identify the difficulty of the puzzles and compare these difficulties to the number of iterations used by the appropriate neural network solver, finding a strong relationship. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. ParBiBit: Parallel tool for binary biclustering on modern distributed-memory systems.

    Science.gov (United States)

    González-Domínguez, Jorge; Expósito, Roberto R

    2018-01-01

    Biclustering techniques are gaining attention in the analysis of large-scale datasets as they identify two-dimensional submatrices where both rows and columns are correlated. In this work we present ParBiBit, a parallel tool to accelerate the search of interesting biclusters on binary datasets, which are very popular on different fields such as genetics, marketing or text mining. It is based on the state-of-the-art sequential Java tool BiBit, which has been proved accurate by several studies, especially on scenarios that result on many large biclusters. ParBiBit uses the same methodology as BiBit (grouping the binary information into patterns) and provides the same results. Nevertheless, our tool significantly improves performance thanks to an efficient implementation based on C++11 that includes support for threads and MPI processes in order to exploit the compute capabilities of modern distributed-memory systems, which provide several multicore CPU nodes interconnected through a network. Our performance evaluation with 18 representative input datasets on two different eight-node systems shows that our tool is significantly faster than the original BiBit. Source code in C++ and MPI running on Linux systems as well as a reference manual are available at https://sourceforge.net/projects/parbibit/.

  15. Motor system contributions to verbal and non-verbal working memory

    Directory of Open Access Journals (Sweden)

    Diana A Liao

    2014-09-01

    Full Text Available Working memory (WM involves the ability to maintain and manipulate information held in mind. Neuroimaging studies have shown that secondary motor areas activate during WM for verbal content (e.g., words or letters, in the absence of primary motor area activation. This activation pattern may reflect an inner speech mechanism supporting online phonological rehearsal. Here, we examined the causal relationship between motor system activity and WM processing by using transcranial magnetic stimulation (TMS to manipulate motor system activity during WM rehearsal. We tested WM performance for verbalizable (words and pseudowords and non-verbalizable (Chinese characters visual information. We predicted that disruption of motor circuits would specifically affect WM processing of verbalizable information. We found that TMS targeting motor cortex slowed response times on verbal WM trials with high (pseudoword vs. low (real word phonological load. However, non-verbal WM trials were also significantly slowed with motor TMS. WM performance was unaffected by sham stimulation or TMS over visual cortex. Self-reported use of motor strategy predicted the degree of motor stimulation disruption on WM performance. These results provide evidence of the motor system’s contributions to verbal and non-verbal WM processing. We speculate that the motor system supports WM by creating motor traces consistent with the type of information being rehearsed during maintenance.

  16. The Associative Memory Serial Link Processor of the ALTAS Fast TracKer Processing System

    CERN Document Server

    Sotiropoulou, Calliope Louisa; The ATLAS collaboration

    2017-01-01

    The upgraded trigger system of the ATLAS experiment at LHC will improve the capability of the detectors to select the events with the greatest scientific potential. The FastTracker (FTK) is one of the ATLAS trigger upgrade that is presently under commissioning. FTK is a hardware system that feeds the High Level Trigger with charged particle tracks reconstructed from hits in silicon detectors at the rate of 105 events per second. Once a track candidate is found, the track reconstruction proceeds by matching low resolution hits to predefined patterns. Selected hits matching the predefined pattern are used in a second processing step for a more precise track fitting algorithm. The main processing element of FTK is the Associative Memory (AM) system that is used to perform pattern matching with high degree of parallelism. Its implementation is called the AM Board Serial Link Processor (AMBSLP) and it is a very efficient pattern matching machine that handles massively parallel data. The AMB SLP consists of two typ...

  17. Memory consolidation

    NARCIS (Netherlands)

    Takashima, A.; Bakker, I.; Schmid, H.-J.

    2016-01-01

    In order to make use of novel experiences and knowledge to guide our future behavior, we must keep large amounts of information accessible for retrieval. The memory system that stores this information needs to be flexible in order to rapidly incorporate incoming information, but also requires that

  18. Divergent short- and long-term effects of acute stress in object recognition memory are mediated by endogenous opioid system activation.

    Science.gov (United States)

    Nava-Mesa, Mauricio O; Lamprea, Marisol R; Múnera, Alejandro

    2013-11-01

    Acute stress induces short-term object recognition memory impairment and elicits endogenous opioid system activation. The aim of this study was thus to evaluate whether opiate system activation mediates the acute stress-induced object recognition memory changes. Adult male Wistar rats were trained in an object recognition task designed to test both short- and long-term memory. Subjects were randomly assigned to receive an intraperitoneal injection of saline, 1 mg/kg naltrexone or 3 mg/kg naltrexone, four and a half hours before the sample trial. Five minutes after the injection, half the subjects were submitted to movement restraint during four hours while the other half remained in their home cages. Non-stressed subjects receiving saline (control) performed adequately during the short-term memory test, while stressed subjects receiving saline displayed impaired performance. Naltrexone prevented such deleterious effect, in spite of the fact that it had no intrinsic effect on short-term object recognition memory. Stressed subjects receiving saline and non-stressed subjects receiving naltrexone performed adequately during the long-term memory test; however, control subjects as well as stressed subjects receiving a high dose of naltrexone performed poorly. Control subjects' dissociated performance during both memory tests suggests that the short-term memory test induced a retroactive interference effect mediated through light opioid system activation; such effect was prevented either by low dose naltrexone administration or by strongly activating the opioid system through acute stress. Both short-term memory retrieval impairment and long-term memory improvement observed in stressed subjects may have been mediated through strong opioid system activation, since they were prevented by high dose naltrexone administration. Therefore, the activation of the opioid system plays a dual modulating role in object recognition memory. Copyright © 2013 Elsevier Inc. All rights

  19. Effects of psychosocial stress on the goal-directed and habit memory systems during learning and later execution.

    Science.gov (United States)

    Fournier, Marion; d'Arripe-Longueville, Fabienne; Radel, Rémi

    2017-03-01

    Instrumental learning occurs through both goal-directed and habit memory systems, which are supported by anatomically distinct brain systems. Interestingly, stress may promote habits at the expense of goal-directed performance, since stress before training in an instrumental task was found to cause individuals to carry on with the learned association in spite of a devalued outcome. These findings nevertheless left pending questions, and it has been difficult to determine which system is primarily affected by stress (an improved habit system, an impaired goal-directed system, or both) and at what point the stress acts (at the moment of learning by making more resistant habits, or after devaluation by making individuals less sensitive to change in the outcome value). The present study (N=72 participants, 63 males and 9 females) aimed to answer these questions with (i) an instrumental task that dissociates the two memory systems and (ii) three conditions of psychosocial stress exposure (Trier Social Stress Test): stress induced before learning, before devaluation, and not induced for the control group. The study confirms that exposure to psychosocial stress leads to habitual performance. Moreover, it provides new insight into this effect by locating its origin as an impairment in the capacity of the goal-directed system rather than a reinforcement in habit learning. These results are discussed in light of recent neurobiological models of stress and memory. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Feasibility study of shape memory alloy ring spring systems for self-centring seismic resisting devices

    International Nuclear Information System (INIS)

    Fang, Cheng; Yam, Michael C H; Zhang, Yanyang; Lam, Angus C C

    2015-01-01

    Shape memory alloys (SMAs) have recently emerged as promising material candidates for structural seismic resisting purposes. Most of the existing SMA-based strategies, however, are based on the wire or rod form of SMAs, where issues such as gripping complexity and fracture may exist. This paper presents a proof-of-concept study on an innovative type of SMA-based self-centring system, namely, a superelastic SMA ring spring system. The proposed system includes a series of inner high-strength steel (HSS) rings and outer superelastic SMA rings stacked in alternation with mating taper faces, where the resisting load is provided by the wedging action which tends to expand the outer rings and concurrently to squeeze the inner rings. The superelastic effect of the SMA offers energy dissipation and a driving force for recentring, and the frictional effect over the taper face further contributes to the overall resisting load and energy dissipation. The feasibility of the new system is carefully examined via numerical studies considering the parameters of ring thickness, taper angle, and coefficient of friction. The key hysteretic responses, including resisting load, stiffness, stress distributions, source of residual deformation, energy dissipation, and equivalent viscous damping, are discussed in detail. The behaviour of the SMA ring springs is also studied via analytical models, and the analytical predictions are found to agree well with the numerical results. Finally, two practical applications of the new system, namely self-centring HS-SMA ring spring connections, and self-centring SMA ring spring dampers, are discussed via comprehensive numerical studies. (paper)

  1. Striatal disorders dissociate mechanisms of enhanced and impaired response selection — Evidence from cognitive neurophysiology and computational modelling

    Directory of Open Access Journals (Sweden)

    Christian Beste

    2014-01-01

    Full Text Available Paradoxically enhanced cognitive processes in neurological disorders provide vital clues to understanding neural function. However, what determines whether the neurological damage is impairing or enhancing is unclear. Here we use the performance of patients with two disorders of the striatum to dissociate mechanisms underlying cognitive enhancement and impairment resulting from damage to the same system. In a two-choice decision task, Huntington's disease patients were faster and less error prone than controls, yet a patient with the rare condition of benign hereditary chorea (BHC was both slower and more error prone. EEG recordings confirmed significant differences in neural processing between the groups. Analysis of a computational model revealed that the common loss of connectivity between striatal neurons in BHC and Huntington's disease impairs response selection, but the increased sensitivity of NMDA receptors in Huntington's disease potentially enhances response selection. Crucially the model shows that there is a critical threshold for increased sensitivity: below that threshold, impaired response selection results. Our data and model thus predict that specific striatal malfunctions can contribute to either impaired or enhanced selection, and provide clues to solving the paradox of how Huntington's disease can lead to both impaired and enhanced cognitive processes.

  2. Evolutionary games played by multi-agent system with different memory capacity

    Science.gov (United States)

    Zhang, Jianlei; Zhang, Chunyan

    2015-06-01

    The evolution of cooperation is still an enigma. Resolution of cooperative dilemma is a hot topic as a perplexing interdisciplinary project, and has captured wide attention of researchers from many disciplines as a multidisciplinary field. Our main concern is the design of a networked evolutionary game model in which players show difference in memory capability. The idea of different memory capacities has its origin on the pervasive individual heterogeneity of real agents in nature. It is concluded that this proposed multiple memory capacity stimulates cooperation in lattice-structured populations. The networking effect is also investigated via a scale free network which is associated with the heterogeneous populations structure. Interestingly, results suggest that the effectiveness of a heterogeneous network at fostering cooperation is reduced in the presence of individual memory here. A thorough inquiry in the coevolutionary dynamics of individual memory and spatial structure in evolutionary games is planned for the immediate future.

  3. A fast and low-power microelectromechanical system-based non-volatile memory device.

    Science.gov (United States)

    Lee, Sang Wook; Park, Seung Joo; Campbell, Eleanor E B; Park, Yung Woo

    2011-01-01

    Several new generation memory devices have been developed to overcome the low performance of conventional silicon-based flash memory. In this study, we demonstrate a novel non-volatile memory design based on the electromechanical motion of a cantilever to provide fast charging and discharging of a floating-gate electrode. The operation is demonstrated by using an electromechanical metal cantilever to charge a floating gate that controls the charge transport through a carbon nanotube field-effect transistor. The set and reset currents are unchanged after more than 11 h constant operation. Over 500 repeated programming and erasing cycles were demonstrated under atmospheric conditions at room temperature without degradation. Multinary bit programming can be achieved by varying the voltage on the cantilever. The operation speed of the device is faster than a conventional flash memory and the power consumption is lower than other memory devices.

  4. Minimum BER Receiver Filters with Block Memory for Uplink DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Debbah Mérouane

    2008-01-01

    Full Text Available Abstract The problem of synchronous multiuser receiver design in the case of direct-sequence single-antenna code division multiple access (DS-CDMA uplink networks is studied over frequency selective fading channels. An exact expression for the bit error rate (BER is derived in the case of BPSK signaling. Moreover, an algorithm is proposed for finding the finite impulse response (FIR receiver filters with block memory such that the exact BER of the active users is minimized. Several properties of the minimum BER FIR filters with block memory are identified. The algorithm performance is found for scenarios with different channel qualities, spreading code lengths, receiver block memory size, near-far effects, and channel mismatch. For the BPSK constellation, the proposed FIR receiver structure with block memory has significant better BER with respect to and near-far resistance than the corresponding minimum mean square error (MMSE filters with block memory.

  5. Minimum BER Receiver Filters with Block Memory for Uplink DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Mérouane Debbah

    2008-05-01

    Full Text Available The problem of synchronous multiuser receiver design in the case of direct-sequence single-antenna code division multiple access (DS-CDMA uplink networks is studied over frequency selective fading channels. An exact expression for the bit error rate (BER is derived in the case of BPSK signaling. Moreover, an algorithm is proposed for finding the finite impulse response (FIR receiver filters with block memory such that the exact BER of the active users is minimized. Several properties of the minimum BER FIR filters with block memory are identified. The algorithm performance is found for scenarios with different channel qualities, spreading code lengths, receiver block memory size, near-far effects, and channel mismatch. For the BPSK constellation, the proposed FIR receiver structure with block memory has significant better BER with respect to Eb/N0 and near-far resistance than the corresponding minimum mean square error (MMSE filters with block memory.

  6. Optical interconnection network for parallel access to multi-rank memory in future computing systems.

    Science.gov (United States)

    Wang, Kang; Gu, Huaxi; Yang, Yintang; Wang, Kun

    2015-08-10

    With the number of cores increasing, there is an emerging need for a high-bandwidth low-latency interconnection network, serving core-to-memory communication. In this paper, aiming at the goal of simultaneous access to multi-rank memory, we propose an optical interconnection network for core-to-memory communication. In the proposed network, the wavelength usage is delicately arranged so that cores can communicate with different ranks at the same time and broadcast for flow control can be achieved. A distributed memory controller architecture that works in a pipeline mode is also designed for efficient optical communication and transaction address processes. The scaling method and wavelength assignment for the proposed network are investigated. Compared with traditional electronic bus-based core-to-memory communication, the simulation results based on the PARSEC benchmark show that the bandwidth enhancement and latency reduction are apparent.

  7. Multi-Threading and Shared-Memory Pool Techniques for Authorization of Credit Card Systems Using Java

    OpenAIRE

    Hamid, Siti Hafizah AB.; University of Malaya; Nasir, Mohd Hairul Nizam M.; University of Malaya; Ming, Wong Yew; University of Malaya; Hassan, Hazrina; University of Malaya

    2008-01-01

    This research paper presents a framework and solution for improving the efficiency of the authorization processing of credit card transactions using multi-threading and shared-memory pool techniques. Through the use of both techniques, a prototype of a real-time multi-threaded authorization system has been developed with Java platforms to overcome the slow sequential authorization processing of a single threaded model of current credit card authorization systems. Via multi-threading technique...

  8. Attentional and non-attentional systems in the maintenance of verbal information in working memory: the executive and phonological loops

    OpenAIRE

    Camos Valerie; Barrouillet Pierre

    2014-01-01

    Working memory is the structure devoted to the maintenance of information at short term during concurrent processing activities. In this respect, the question regarding the nature of the mechanisms and systems fulfilling this maintenance function is of particular importance and has received various responses in the recent past. In the time-based resource-sharing (TBRS) model, we suggest that only two systems sustain the maintenance of information at the short term, counteracting the deleterio...

  9. Observation of quantum-memory-assisted entropic uncertainty relation under open systems, and its steering

    Science.gov (United States)

    Chen, Peng-Fei; Sun, Wen-Yang; Ming, Fei; Huang, Ai-Jun; Wang, Dong; Ye, Liu

    2018-01-01

    Quantum objects are susceptible to noise from their surrounding environments, interaction with which inevitably gives rise to quantum decoherence or dissipation effects. In this work, we examine how different types of local noise under an open system affect entropic uncertainty relations for two incompatible measurements. Explicitly, we observe the dynamics of the entropic uncertainty in the presence of quantum memory under two canonical categories of noisy environments: unital (phase flip) and nonunital (amplitude damping). Our study shows that the measurement uncertainty exhibits a non-monotonic dynamical behavior—that is, the amount of the uncertainty will first inflate, and subsequently decrease, with the growth of decoherence strengths in the two channels. In contrast, the uncertainty decreases monotonically with the growth of the purity of the initial state shared in prior. In order to reduce the measurement uncertainty in noisy environments, we put forward a remarkably effective strategy to steer the magnitude of uncertainty by means of a local non-unitary operation (i.e. weak measurement) on the qubit of interest. It turns out that this non-unitary operation can greatly reduce the entropic uncertainty, upon tuning the operation strength. Our investigations might thereby offer an insight into the dynamics and steering of entropic uncertainty in open systems.

  10. MLP: A Parallel Programming Alternative to MPI for New Shared Memory Parallel Systems

    Science.gov (United States)

    Taft, James R.

    1999-01-01

    Recent developments at the NASA AMES Research Center's NAS Division have demonstrated that the new generation of NUMA based Symmetric Multi-Processing systems (SMPs), such as the Silicon Graphics Origin 2000, can successfully execute legacy vector oriented CFD production codes at sustained rates far exceeding processing rates possible on dedicated 16 CPU Cray C90 systems. This high level of performance is achieved via shared memory based Multi-Level Parallelism (MLP). This programming approach, developed at NAS and outlined below, is distinct from the message passing paradigm of MPI. It offers parallelism at both the fine and coarse grained level, with communication latencies that are approximately 50-100 times lower than typical MPI implementations on the same platform. Such latency reductions offer the promise of performance scaling to very large CPU counts. The method draws on, but is also distinct from, the newly defined OpenMP specification, which uses compiler directives to support a limited subset of multi-level parallel operations. The NAS MLP method is general, and applicable to a large class of NASA CFD codes.

  11. Free radical production induced by methamphetamine in rat striatal synaptosomes.

    Science.gov (United States)

    Pubill, David; Chipana, Carlos; Camins, Antonio; Pallàs, Mercè; Camarasa, Jordi; Escubedo, Elena

    2005-04-01

    The pro-oxidative effect of methamphetamine (METH) in dopamine terminals was studied in rat striatal synaptosomes. Flow cytometry analysis showed increased production of reactive oxygen species (ROS) in METH-treated synaptosomes, without reduction in the density of dopamine transporters. In synaptosomes from dopamine (DA)-depleted animals, METH did not induce ROS production. Reserpine, in vitro, completely inhibited METH-induced ROS production. These results point to endogenous DA as the main source of ROS induced by METH. Antioxidants and inhibitors of neuronal nitric oxide synthase and protein kinase C (PKC) prevented the METH-induced oxidative effect. EGTA and the specific antagonist methyllycaconitine (MLA, 50 microM) prevented METH-induced ROS production, thus implicating calcium and alpha7 nicotinic receptors in such effect. Higher concentrations of MLA (>100 microM) showed nonspecific antioxidant effect. Preincubation of synaptosomes with METH (1 microM) for 30 min reduced [(3)H]DA uptake by 0%. The METH effect was attenuated by MLA and EGTA and potentiated by nicotine, indicating that activation of alpha(7) nicotinic receptors and Ca(2+) entry are necessary and take place before DAT inhibition. From these findings, it can be postulated that, in our model, METH induces DA release from synaptic vesicles to the cytosol. Simultaneously, METH activates alpha(7) nicotinic receptors, probably inducing depolarization and an increase in intrasynaptosomal Ca(2+). This would lead to DAT inhibition and NOS and PKC activation, initiating oxidation of cytosolic DA.

  12. Frontal and striatal alterations associated with psychopathic traits in adolescents

    Science.gov (United States)

    Yang, Yaling; Narr, Katherine L.; Baker, Laura A.; Joshi, Shantanu H.; Jahanshad, Neda; Raine, Adrian; Thompson, Paul M.

    2016-01-01

    Neuroimaging research has demonstrated a range of structural deficits in adults with psychopathy, but little is known about structural correlates of psychopathic tendencies in adolescents. Here we examined structural magnetic resonance imaging (sMRI) data obtained from 14-year-old adolescents (n=108) using tensor-based morphometry (TBM) to isolate global and localized differences in brain tissue volumes associated with psychopathic traits in this otherwise healthy developmental population. We found that greater levels of psychopathic traits were correlated with increased brain tissue volumes in the left putamen, left ansa peduncularis, right superiomedial prefrontal cortex, left inferior frontal cortex, right orbitofrontal cortex, and right medial temporal regions and reduced brain tissues volumes in the right middle frontal cortex, left superior parietal lobule, and left inferior parietal lobule. Post hoc analyses of parcellated regional volumes also showed putamen enlargements to correlate with increased psychopathic traits. Consistent with earlier studies, findings suggest poor decision-making and emotional dysregulation associated with psychopathy may be due, in part, to structural anomalies in frontal and temporal regions whereas striatal structural variations may contribute to sensation-seeking and reward-driven behavior in psychopathic individuals. Future studies will help clarify how disturbances in brain maturational processes might lead to the developmental trajectory from psychopathic tendencies in adolescents to adult psychopathy. PMID:25676553

  13. Modeling fall propensity in Parkinson's disease: deficits in the attentional control of complex movements in rats with cortical-cholinergic and striatal-dopaminergic deafferentation.

    Science.gov (United States)

    Kucinski, Aaron; Paolone, Giovanna; Bradshaw, Marc; Albin, Roger L; Sarter, Martin

    2013-10-16

    Cognitive symptoms, complex movement deficits, and increased propensity for falls are interrelated and levodopa-unresponsive symptoms in patients with Parkinson's disease (PD). We developed a test system for the assessment of fall propensity in rats and tested the hypothesis that interactions between loss of cortical cholinergic and striatal dopaminergic afferents increase fall propensity. Rats were trained to traverse stationary and rotating rods, placed horizontally or at inclines, and while exposed to distractors. Rats also performed an operant Sustained Attention Task (SAT). Partial cortical cholinergic and/or caudate dopaminergic deafferentation were produced by bilateral infusions of 192 IgG-saporin (SAP) into the basal forebrain and/or 6-hydroxydopamine (6-OHDA) into the caudate nucleus, respectively, modeling the lesions seen in early PD. Rats with dual cholinergic-dopaminergic lesions (DL) fell more frequently than SAP or 6-OHDA rats. Falls in DL rats were associated with incomplete rebalancing after slips and low traversal speed. Ladder rung walking and pasta handling performance did not indicate sensorimotor deficits. SAT performance was impaired in DL and SAP rats; however, SAT performance and falls were correlated only in DL rats. Furthermore, in DL rats, but not in rats with only dopaminergic lesions, the placement and size of dopaminergic lesion correlated significantly with fall rates. The results support the hypothesis that after dual cholinergic-dopaminergic lesions, attentional resources can no longer be recruited to compensate for diminished striatal control of complex movement, thereby "unmasking" impaired striatal control of complex movements and yielding falls.

  14. Long-term effects of an acute and systemic administration of LPS on adult neurogenesis and spatial memory

    Directory of Open Access Journals (Sweden)

    Jorge eValero

    2014-04-01

    Full Text Available The cognitive reserve is the capacity of the brain to maintain normal performance while exposed to insults or ageing. Increasing evidences point to a role for the interaction between inflammatory conditions and cognitive reserve status during Alzheimer's disease (AD progression. The production of new neurons along adult life can be considered as one of the components of the cognitive reserve. Interestingly, adult neurogenesis is decreased in mouse models of AD and following inflammatory processes. The aim of this work is to reveal the long-term impact of a systemic inflammatory event on memory and adult neurogenesis in wild type (WT and triple transgenic mouse model of AD (3xTg-AD.4 month-old mice were intraperitoneally injected once with saline or lipopolysaccharide (LPS and their performance on spatial memory analyzed with the Morris water maze (MWM test 7 weeks later. Our data showed that a single intraperitoneal injection with LPS has a long-term impact in the production of hippocampal neurons. Consistently, LPS-treated WT mice showed less doublecortin-positive neurons, less synaptic contacts in newborn neurons, and decreased dendritic volume and complexity. These surprising observations were accompanied with memory deficits. 3xTg-AD mice showed a decrease in new neurons in the dentate gyrus compatible with, although exacerbated, the pattern observed in WT LPS-treated mice. In 3xTg-AD mice, LPS injection did not significantly affected the production of new neurons but reduced their number of synaptic puncta and impaired memory performance, when compared to the observations made in saline-treated 3xTg-AD mice. These data indicate that LPS treatment induces a long-term impairment on hippocampal neurogenesis and memory. Our results show that acute neuroinflammatory events influence the production of new hippocampal neurons, affecting the cognitive reserve and leading to the development of memory deficits associated to Alzheimer's disease

  15. Seeing the Wood for the Trees: Applying the dual-memory system model to investigate expert teachers' observational skills in natural ecological learning environments

    Science.gov (United States)

    Stolpe, Karin; Björklund, Lars

    2012-01-01

    This study aims to investigate two expert ecology teachers' ability to attend to essential details in a complex environment during a field excursion, as well as how they teach this ability to their students. In applying a cognitive dual-memory system model for learning, we also suggest a rationale for their behaviour. The model implies two separate memory systems: the implicit, non-conscious, non-declarative system and the explicit, conscious, declarative system. This model provided the starting point for the research design. However, it was revised from the empirical findings supported by new theoretical insights. The teachers were video and audio recorded during their excursion and interviewed in a stimulated recall setting afterwards. The data were qualitatively analysed using the dual-memory system model. The results show that the teachers used holistic pattern recognition in their own identification of natural objects. However, teachers' main strategy to teach this ability is to give the students explicit rules or specific characteristics. According to the dual-memory system model the holistic pattern recognition is processed in the implicit memory system as a non-conscious match with earlier experienced situations. We suggest that this implicit pattern matching serves as an explanation for teachers' ecological and teaching observational skills. Another function of the implicit memory system is its ability to control automatic behaviour and non-conscious decision-making. The teachers offer the students firsthand sensory experiences which provide a prerequisite for the formation of implicit memories that provides a foundation for expertise.

  16. From brain synapses to systems for learning and memory: Object recognition, spatial navigation, timed conditioning, and movement control.

    Science.gov (United States)

    Grossberg, Stephen

    2015-09-24

    This article provides an overview of neural models of synaptic learning and memory whose expression in adaptive behavior depends critically on the circuits and systems in which the synapses are embedded. It reviews Adaptive Resonance Theory, or ART, models that use excitatory matching and match-based learning to achieve fast category learning and whose learned memories are dynamically stabilized by top-down expectations, attentional focusing, and memory search. ART clarifies mechanistic relationships between consciousness, learning, expectation, attention, resonance, and synchrony. ART models are embedded in ARTSCAN architectures that unify processes of invariant object category learning, recognition, spatial and object attention, predictive remapping, and eye movement search, and that clarify how conscious object vision and recognition may fail during perceptual crowding and parietal neglect. The generality of learned categories depends upon a vigilance process that is regulated by acetylcholine via the nucleus basalis. Vigilance can get stuck at too high or too low values, thereby causing learning problems in autism and medial temporal amnesia. Similar synaptic learning laws support qualitatively different behaviors: Invariant object category learning in the inferotemporal cortex; learning of grid cells and place cells in the entorhinal and hippocampal cortices during spatial navigation; and learning of time cells in the entorhinal-hippocampal system during adaptively timed conditioning, including trace conditioning. Spatial and temporal processes through the medial and lateral entorhinal-hippocampal system seem to be carried out with homologous circuit designs. Variations of a shared laminar neocortical circuit design have modeled 3D vision, speech perception, and cognitive working memory and learning. A complementary kind of inhibitory matching and mismatch learning controls movement. This article is part of a Special Issue entitled SI: Brain and Memory

  17. Striatal dopamine D1 and D2 receptors are differentially regulated following buprenorphine or methadone treatment.

    Science.gov (United States)

    Allouche, Stéphane; Le Marec, Thierry; Coquerel, Antoine; Noble, Florence; Marie, Nicolas

    2015-05-01

    Chronic administration of morphine induces adaptations in neurotransmission system such as the dopamine pathway, and these modifications could be influenced by the drug administration pattern. Methadone and buprenorphine are the two main opioid substitution therapies, and despite their protracted use in humans, no study has investigated their ability to regulate dopamine system after chronic exposure/withdrawal. We evaluated the consequences of two administration patterns of methadone and buprenorphine on striatal dopamine D1 (D1R) and D2 (D2R) receptor levels. Mice were treated with escalating doses of methadone or buprenorphine for 5 days either once daily (binge) or three times a day (TTD). D1R and D2R density in striatum was measured by autoradiography using [(3)H]-SCH23390 and [(3)H]-raclopride, respectively, at 1 (WD1), 14 (WD14), and 35 (WD35) days after the last opioid injection. A downregulation of D1R was observed upon TTD administration of buprenorphine and binge methadone treatment while an increase of those receptor levels was detected both with binge buprenorphine and TTD methadone treatments. Concerning the D2R, we rather measured an early or late downregulation with both agonists and administration patterns. Our results demonstrated that methadone and buprenorphine were able to differentially regulate dopamine receptor density depending on the withdrawal period and the administration pattern.

  18. In-line polarization holographic memory system using PQ doped PMMA photopolymer (Conference Presentation)

    Science.gov (United States)

    Lin, Shiuan-Huei; Lin, Lun Kuang; Marinova, Vera; Hsu, Ken-Yuh

    2016-09-01

    Polarization hologram provides some unique features over classical phase or amplitude hologram. One of the most important features is that the photo-induced anisotropy in those materials leads to the polarization-dependent diffraction from the hologram. This property is useful for many applications, such as optical interconnection, holographic data storage and bio-imaging …etc. Recently, the 9, 10-phenanthrenequinone -doped poly(methyl methacrylate) (PQ/PMMA) photopolymer with cm thickness has attracted intense research interesting for the volume holographic applications because the experiments demonstrated that PQ/PMMA photopolymers possess not only high optical quality but also negligible shrinkage effect under light exposure [3-5]. Additionally, in terms of chemical formula, the PQ/PMMA consists of planar structures PQ molecules dispersed in amorphous PMMA polymer so that it is possible to be oriented if irradiated with polarized light, resulting in a photoinduced birefringence. This phenomenon makes it capable for permanent polarization holographic recording via photochemical reaction. Thus, combining these two properties may make PQ/PMMA photopolymer attractive for volume polarization holographic applications. In this paper, we particularly characterize polarization holographic recording in our materials for high-density data storage. Then, we will demonstrate a in-line polarization holographic memory system using PQ/PMMA photopolymer.

  19. Memory dynamics under stress.

    Science.gov (United States)

    Quaedflieg, Conny W E M; Schwabe, Lars

    2018-03-01

    Stressful events have a major impact on memory. They modulate memory formation in a time-dependent manner, closely linked to the temporal profile of action of major stress mediators, in particular catecholamines and glucocorticoids. Shortly after stressor onset, rapidly acting catecholamines and fast, non-genomic glucocorticoid actions direct cognitive resources to the processing and consolidation of the ongoing threat. In parallel, control of memory is biased towards rather rigid systems, promoting habitual forms of memory allowing efficient processing under stress, at the expense of "cognitive" systems supporting memory flexibility and specificity. In this review, we discuss the implications of this shift in the balance of multiple memory systems for the dynamics of the memory trace. Specifically, stress appears to hinder the incorporation of contextual details into the memory trace, to impede the integration of new information into existing knowledge structures, to impair the flexible generalisation across past experiences, and to hamper the modification of memories in light of new information. Delayed, genomic glucocorticoid actions might reverse the control of memory, thus restoring homeostasis and "cognitive" control of memory again.

  20. ROLE OF THE ENDOCANNABINOID SYSTEM IN REGULATING GLUCOCORTICOID EFFECTS ON MEMORY FOR EMOTIONAL EXPERIENCES

    NARCIS (Netherlands)

    Atsak, P.; Roozendaal, B.; Campolongo, P.

    2012-01-01

    Glucocorticoids, stress hormones released from the adrenal cortex, have potent modulatory effects on emotional memory. Whereas early studies focused mostly on the detrimental effects of chronic stress and glucocorticoid exposure on cognitive performance and the classic genomic pathways that mediate

  1. Role of the endocannabinoid system in regulating glucocorticoid effects on memory for emotional experiences

    NARCIS (Netherlands)

    Atsak, P.; Roozendaal, B.; Campolongo, P.

    2012-01-01

    Glucocorticoids, stress hormones released from the adrenal cortex, have potent modulatory effects on emotional memory. Whereas early studies focused mostly on the detrimental effects of chronic stress and glucocorticoid exposure on cognitive performance and the classic genomic pathways that mediate

  2. Business Case Analysis: Reconfiguration of the Frederick Memorial Healthcare System Courier Service

    National Research Council Canada - National Science Library

    Rauch, Nathan C

    2008-01-01

    This business case projects the likely benefits and costs to Frederick Memorial Hospital that would result from a decision to reconfigure its courier service by way of vehicle diversification and route realignment...

  3. ORELA data acquisition system hardware. Vol. 6. Eight-stage stacking buffer memory (Q-5066)

    International Nuclear Information System (INIS)

    Wintenberg, R.E.; Reynolds, J.W.

    1977-01-01

    A Stacking Buffer Memory for de-randomizing data on high data rate experiments at ORELA is documented by a description of operation, mechanical details of design, and a detailed theory of operation illustrated through six examples of operation

  4. Very Dense High Speed 3u VPX Memory and Processing Space Systems, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — While VPX shows promise as an open standard COTS computing and memory platform, there are several challenges that must be overcome to migrate the technology for a...

  5. Involvement of the amygdala in memory storage: Interaction with other brain systems

    OpenAIRE

    McGaugh, James L.; Cahill, Larry; Roozendaal, Benno

    1996-01-01

    There is extensive evidence that the amygdala is involved in affectively influenced memory. The central hypothesis guiding the research reviewed in this paper is that emotional arousal activates the amygdala and that such activation results in the modulation of memory storage occurring in other brain regions. Several lines of evidence support this view. First, the effects of stress-related hormones (epinephrine and glucocorticoids) are mediated by influences involving ...

  6. Kmerind: A Flexible Parallel Library for K-mer Indexing of Biological Sequences on Distributed Memory Systems.

    Science.gov (United States)

    Pan, Tony; Flick, Patrick; Jain, Chirag; Liu, Yongchao; Aluru, Srinivas

    2017-10-09

    Counting and indexing fixed length substrings, or k-mers, in biological sequences is a key step in many bioinformatics tasks including genome alignment and mapping, genome assembly, and error correction. While advances in next generation sequencing technologies have dramatically reduced the cost and improved latency and throughput, few bioinformatics tools can efficiently process the datasets at the current generation rate of 1.8 terabases every 3 days. We present Kmerind, a high performance parallel k-mer indexing library for distributed memory environments. The Kmerind library provides a set of simple and consistent APIs with sequential semantics and parallel implementations that are designed to be flexible and extensible. Kmerind's k-mer counter performs similarly or better than the best existing k-mer counting tools even on shared memory systems. In a distributed memory environment, Kmerind counts k-mers in a 120 GB sequence read dataset in less than 13 seconds on 1024 Xeon CPU cores, and fully indexes their positions in approximately 17 seconds. Querying for 1% of the k-mers in these indices can be completed in 0.23 seconds and 28 seconds, respectively. Kmerind is the first k-mer indexing library for distributed memory environments, and the first extensible library for general k-mer indexing and counting. Kmerind is available at https://github.com/ParBLiSS/kmerind.

  7. Tracking Real-Time Changes in Working Memory Updating and Gating with the Event-Based Eye-Blink Rate

    NARCIS (Netherlands)

    Rac-Lubashevsky, R.; Slagter, H.A.; Kessler, Y.

    2017-01-01

    Effective working memory (WM) functioning depends on the gating process that regulates the balance between maintenance and updating of WM. The present study used the event-based eye-blink rate (ebEBR), which presumably reflects phasic striatal dopamine activity, to examine how the cognitive

  8. Cortico–Amygdala–Striatal Circuits Are Organized as Hierarchical Subsystems through the Primate Amygdala

    Science.gov (United States)

    Cho, Youngsun T.; Ernst, Monique

    2013-01-01

    The prefrontal and insula cortex, amygdala, and striatum are key regions for emotional processing, yet the amygdala's role as an interface between the cortex and striatum is not well understood. In the nonhuman primate (Macaque fascicularis), we analyzed a collection of bidirectional tracer injections in the amygdala to understand how cortical inputs and striatal outputs are organized to form integrated cortico–amygdala–striatal circuits. Overall, diverse prefrontal and insular cortical regions projected to the basal and accessory basal nuclei of the amygdala. In turn, these amygdala regions projected to widespread striatal domains extending well beyond the classic ventral striatum. Analysis of the cases in aggregate revealed a topographic colocalization of cortical inputs and striatal outputs in the amygdala that was additionally distinguished by cortical cytoarchitecture. Specifically, the degree of cortical laminar differentiation of the cortical inputs predicted amygdalostriatal targets, and distinguished three main cortico–amygdala–striatal circuits. These three circuits were categorized as “primitive,” “intermediate,” and “developed,” respectively, to emphasize the relative phylogenetic and ontogenetic features of the cortical inputs. Within the amygdala, these circuits appeared arranged in a pyramidal-like fashion, with the primitive circuit found in all examined subregions, and subsequent circuits hierarchically layered in discrete amygdala subregions. This arrangement suggests a stepwise integration of the functions of these circuits across amygdala subregions, providing a potential mechanism through which internal emotional states are managed with external social and sensory information toward emotionally informed complex behaviors. PMID:23986238

  9. Altered resting state cortico-striatal connectivity in mild to moderate stage Parkinson’s disease

    Directory of Open Access Journals (Sweden)

    Youngbin Kwak

    2010-09-01

    Full Text Available Parkinson’s disease (PD is a progressive neurodegenerative disorder that is characterized by dopamine depletion in the striatum. One consistent pathophysiological hallmark of PD is an increase in spontaneous oscillatory activity in the basal ganglia thalamocortical networks. We evaluated these effects using resting state functional connectivity MRI (fcMRI in mild to moderate stage Parkinson’s patients on and off L-DOPA and age-matched controls using six different striatal seed regions. We observed an overall increase in the strength of cortico-striatal functional connectivity in PD patients off L-DOPA compared to controls. This enhanced connectivity was down-regulated by L-DOPA as shown by an overall decrease in connectivity strength, particularly within motor cortical regions. We also performed a frequency content analysis of the BOLD signal time course extracted from the six striatal seed regions. PD off L-DOPA exhibited increased power in the frequency band 0.02 – 0.05 Hz compared to controls and to PD on L-DOPA. The L-DOPA associated decrease in the power of this frequency range modulated the L-DOPA associated decrease in connectivity strength between striatal seeds and the thalamus. In addition, the L-DOPA associated decrease in power in this frequency band also correlated with the L-DOPA associated improvement in cognitive performance. Our results demonstrate that PD and L-DOPA modulate striatal resting state BOLD signal oscillations and corticostriatal network coherence.

  10. Altered resting-state functional connectivity of striatal-thalamic circuit in bipolar disorder.

    Directory of Open Access Journals (Sweden)

    Shin Teng

    Full Text Available Bipolar disorder is characterized by internally affective fluctuations. The abnormality of inherently mental state can be assessed using resting-state fMRI data without producing task-induced biases. In this study, we hypothesized that the resting-state connectivity related to the frontal, striatal, and thalamic regions, which were associated with mood regulations and cognitive functions, can be altered for bipolar disorder. We used the Pearson's correlation coefficients to estimate functional connectivity followed by the hierarchical modular analysis to categorize the resting-state functional regions of interest (ROIs. The selected functional connectivities associated with the striatal-thalamic circuit and default mode network (DMN were compared between bipolar patients and healthy controls. Significantly decreased connectivity in the striatal-thalamic circuit and between the striatal regions and the middle and posterior cingulate cortex was observed in the bipolar patients. We also observed that the bipolar patients exhibited significantly increased connectivity between the thalamic regions and the parahippocampus. No significant changes of connectivity related to the frontal regions in the DMN were observed. The changed resting-state connectivity related to the striatal-thalamic circuit might be an inherent basis for the altered emotional and cognitive processing in the bipolar patients.

  11. Striatal lesions produce distinctive impairments in reaction time performance in two different operant chambers.

    Science.gov (United States)

    Brasted, P J; Döbrössy, M D; Robbins, T W; Dunnett, S B

    1998-08-01

    The dorsal striatum plays a crucial role in mediating voluntary movement. Excitotoxic striatal lesions in rats have previously been shown to impair the initiation but not the execution of movement in a choice reaction time task in an automated lateralised nose-poke apparatus (the "nine-hole box"). Conversely, when a conceptually similar reaction time task has been applied in a conventional operant chamber (or "Skinner box"), striatal lesions have been seen to impair the execution rather than the initiation of the lateralised movement. The present study was undertaken to compare directly these two results by training the same group of rats to perform a choice reaction time task in the two chambers and then comparing the effects of a unilateral excitotoxic striatal lesion in both chambers in parallel. Particular attention was paid to adopting similar parameters and contingencies in the control of the task in the two test chambers. After striatal lesions, the rats showed predominantly contralateral impairments in both tasks. However, they showed a deficit in reaction time in the nine-hole box but an apparent deficit in response execution in the Skinner box. This finding confirms the previous studies and indicates that differences in outcome are not simply attributable to procedural differences in the lesions, training conditions or tasks parameters. Rather, the pattern of reaction time deficit after striatal lesions depends critically on the apparatus used and the precise response requirements for each task.

  12. A multiplexed quantum memory.

    Science.gov (United States)

    Lan, S-Y; Radnaev, A G; Collins, O A; Matsukevich, D N; Kennedy, T A; Kuzmich, A

    2009-08-03

    A quantum repeater is a system for long-distance quantum communication that employs quantum memory elements to mitigate optical fiber transmission losses. The multiplexed quantum memory (O. A. Collins, S. D. Jenkins, A. Kuzmich, and T. A. B. Kennedy, Phys. Rev. Lett. 98, 060502 (2007)) has been shown theoretically to reduce quantum memory time requirements. We present an initial implementation of a multiplexed quantum memory element in a cold rubidium gas. We show that it is possible to create atomic excitations in arbitrary memory element pairs and demonstrate the violation of Bell's inequality for light fields generated during the write and read processes.

  13. Validation of a new scoring system for the Weigl Color Form Sorting Test in a memory disorders clinic sample.

    Science.gov (United States)

    Byrne, L M; Bucks, R S; Cuerden, J M

    1998-04-01

    The Bristol Memory Disorders Clinic uses the Weigl Color Form Sorting Test (CFST) to appraise abstraction and the ability to shift set. The original scoring system for the CFST (Grewal & Haward, 1984), developed on the premise that sorting to form is more difficult than sorting to color, had no score for an individual able to sort to form and subsequently unable to shift to color with a cue. Clinical experience suggested that the performance of some individuals required such a score. A new scoring system was developed and validated in a memory-disorders-clinic sample. The validation showed the new score to be necessary and gave support to the original premise that people with organic brain damage show a preference for sorting to color.

  14. Naringenin ameliorates learning and memory impairment following systemic<