[Semantic factors in storing negated sentences].
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Humans↗
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Results for “memory differentiation”
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The differential effects of ecstasy/polydrug use on executive components: shifting, inhibition, updating and access to semantic memory.
RATIONALE/OBJECTIVES: Recent theoretical models suggest that the central executive may not be a unified structure. The present study explored the nature of central executive deficits in ecstasy users. METHODS: In study 1, 27 ecstasy users and 34 non-users were assessed using tasks to tap memory updating (computation span; letter updating) and access to long-term memory (a semantic fluency test and the Chicago Word Fluency Test). In study 2, 51 ecstasy users and 42 non-users completed tasks that assess mental set switching (number/letter and plus/minus) and inhibition (random letter generation). RESULTS: MANOVA revealed that ecstasy users performed worse on both tasks used to assess memory updating and on tasks to assess access to long-term memory (C- and S-letter fluency). However, notwithstanding the significant ecstasy group-related effects, indices of cocaine and cannabis use were also significantly correlated with most of the executive measures. Unexpectedly, in study 2, ecstasy users performed significantly better on the inhibition task, producing more letters than non-users. No group differences were observed on the switching tasks. Correlations between indices of ecstasy use and number of letters produced were significant. CONCLUSIONS: The present study provides further support for ecstasy/polydrug-related deficits in memory updating and in access to long-term memory. The surplus evident on the inhibition task should be treated with some caution, as this was limited to a single measure and has not been supported by our previous work.
Adult↗
Visuospatial memory deficits at different stages of Parkinson's disease.
Groups of patients with idiopathic Parkinson's disease (PD), either medicated or unmedicated, were compared with matched groups of normal controls on a computerised battery of tests designed to investigate spatial working memory, visuospatial recognition memory and learning. The medicated PD patients were subdivided into those with mild and severe clinical disability on the basis of Hoehn and Yahr ratings, thus making three groups of PD patients in all. In a test of spatial recognition memory, a significant impairment was only evident in those PD patients who were medicated and had severe clinical symptoms (Hoehn and Yahr stage III-IV). In contrast, none of the three patient groups were impaired in a complementary test of visual pattern recognition memory. Whilst all three patient groups performed well in a test of simultaneous visual matching to sample, medicated patients (MED PD) with severe clinical symptoms were significantly impaired when a short (0-12 sec) delay was introduced. In a test of paired associates learning requiring both visual pattern and visuospatial memory, deficits in learning and memory were only evident in the severely impaired MED PD group. In contrast, in a test of spatial working memory known to be sensitive to frontal lobe damage, significant impairments were found in both groups of medicated PD patients and particularly in those patients with more severe clinical symptoms. Taken together, the results suggest that there are multiple memory impairments in PD which may differentially depend on the clinical severity of the disease.
Aged↗
Acute effects of caffeine on several operant behaviors in rhesus monkeys.
The acute effects of 1,3-trimethylxanthine (caffeine) were assessed using an operant test battery (OTB) of complex food-reinforced tasks that are thought to depend upon relatively specific brain functions, such as motivation to work for food (progressive ratio, PR), learning (incremental repeated acquisition, IRA), color and position discrimination (conditioned position responding, CPR), time estimation (temporal response differentiation, TRD), and short-term memory and attention (delayed matching-to-sample, DMTS). Endpoints included response rates (RR), accuracies (ACC), and percent task completed (PTC). Caffeine sulfate (0.175-20.0 mg/kg, IV), given 15 min pretesting, produced significant dose-dependent decreases in TRD percent task completed and accuracy at doses > or = 5.6 mg/kg. Caffeine produced no systematic effects on either DMTS or PR responding, but low doses tended to enhance performance in both IRA and CPR tasks. Thus, in monkeys, performance of an operant task designed to model time estimation is more sensitive to the disruptive effects of caffeine than is performance of the other tasks in the OTB.
Animals↗
Acute behavioral effects of MK-801 in rhesus monkeys: assessment using an operant test battery.
The acute effects of MK-801, a selective, noncompetitive NMDA receptor antagonist, were assessed using an operant test battery (OTB) of complex food-reinforced tasks that are thought to depend upon relatively specific brain functions such as motivation to work for food (progressive ratio, PR), learning (incremental repeated acquisition, IRA), color and position discrimination (conditioned position responding, CPR), time estimation (temporal response differentiation, TRD), and short-term memory and attention (delayed matching-to-sample, DMTS). Endpoints included response rates (RR), accuracies (ACC), and percent task completed (PTC). MK-801 (0.003-0.075 mg/kg, IV), given 15 min pretesting, produced significant dose-dependent decreases in measures of IRA and TRD performance at doses > or = 0.03 mg/kg. In both tasks, MK-801 produced significant decreases in accuracy at doses lower than those required to affect response rate. MK-801 also produced statistically significant decreases in PR, CPR, and DMTS measures, but only at higher doses (> or = 0.056 mg/kg) that caused significant decreases in both response rates and accuracies. These results indicate that, in monkeys, performance of operant tasks designed to model learning and time estimation is more sensitive to the disruptive effects of MK-801 than performance of tasks that model motivation, color, and position discrimination, and short-term memory and attention.
Animals↗
Peptide regulatory factors and optimization of vaccines.
The peptide regulatory factors (PRFs), variously termed cytokines, lymphokines, interleukins, colony stimulating factors, interferons, etc., play a key role in the quantitative and qualitative regulation of protective responses--both in initiating immunological and inflammatory responses and in mediating and controlling the effector mechanisms that protect the body against micro-organisms. The process of immunization--involving antigen-presentation, lymphocyte-activation and clonal proliferation--depends on the action of a variety of PRFs. The function of accessory cells--the dendritic cells, macrophages, etc.--is stimulated by PRFs such as interferon-gamma, IL-1, TNF, GM-CSF and IL-4. The activation and expansion of T-lymphocytes requires IL-1, IL-2, IL-4, interferon-gamma, IL-6 and probably IL-7. Likewise, the activation and expansion of B-lymphocytes is regulated by PRFs such as IL-1, IL-2, IL-4, IL-5, IL-6, IL-7 and interferon-gamma. It is likely, although unproven, that PRFs also regulate the differentiation of B-cells to memory cells. Successful vaccination requires the immune system to be primed in such a way that natural challenge with a micro-organism or its products evokes an immune response that has the qualitative and the quantitative characteristics of both the humoral and cellular responses. Antibody class is critically influenced by particular PRFs, e.g. interferon-gamma regulates IgG2a; IL-4, IgE and IgG1; IL-5 and TGF-beta, IgA. PRFs are both produced by and regulate the T-lymphocytes which have key roles in protective responses--either directly, viz. the cytotoxic T-lymphocytes important in protection against certain viruses, or indirectly through the secretion of PRFs that regulate the speed, magnitude and quality of antibody cellular responses. The recruitment and enhanced production and function of granulocytic and phagocytic cells involves a number of T-lymphocyte PRFs including GM-CSF, IL-3, IL-5, IL-4, and IL-6. We do not have a good understanding of the fine-tuning of cellular responses nor of how infection with different pathogens results in different types of inflammatory responses; it is clear, however, that certain cellular responses are due to the action of specific PRFs, e.g. IL-3 induces a mastocytosis and IL-5 an eosinophilia. There is increasing evidence that the relative levels of different PRFs are important determinants of the effectiveness of responses.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Psychiatric presentation of medical illness.
A 37-year-old woman was seen in the emergency department for symptoms of depression. A careful mental status examination resulted in the discovery of an organic basis for the "psychiatric" presentation. As with any patient demonstrating behavioral abnormalities, this case illustrates the importance of an adequate history, physical, and mental status evaluation in ruling out organic etiology prior to labeling a patient's complaints as functional. Medical illnesses that can present as apparent psychiatric disease and the clinical clues that lead to the diagnosis of such cases are discussed.
Adult↗
A low glycaemic index breakfast cereal preferentially prevents children's cognitive performance from declining throughout the morning.
This study investigated whether the glycaemic index (GI) of breakfast cereal differentially affects children's attention and memory. Using a balanced cross-over design, on two consecutive mornings 64 children aged 6-11 years were given a high GI cereal and a low GI cereal in a counterbalanced order. They performed a series of computerised tests of attention and memory, once prior to breakfast and three times following breakfast at hourly intervals. The results indicate that children's performance declines throughout the morning and that this decline can be significantly reduced following the intake of a low GI cereal as compared with a high GI cereal on measures of accuracy of attention (M=-6.742 and -13.510, respectively, p<0.05) and secondary memory (M=-30.675 and -47.183, respectively, p<0.05).
Attention↗
Switching feedback mechanisms realize the dual role of MCIP in the regulation of calcineurin activity.
Calcineurin (CaN) assists T-cell activation, growth and differentiation of skeletal and cardiac myocytes, memory, and apoptosis. It also activates transcription of the nuclear factor of activated T-cells (NFAT) family including hypertrophic target genes. It has been reported that the modulatory calcineurin-interacting protein (MCIP) inhibits the CaN activity and thereby reduces the hypertrophic response. However, it has been shown that MCIP facilitates or permits the hypertrophic response under some stress conditions such as isoproterenol infusion or pressure overload by transverse aortic constriction. As there is no direct experimental evidence that can explain these paradoxical phenomena, there has been a controversy concerning the functional role of MCIP in developing the hypertrophic response. It is therefore crucial to establish a hypothesis that can clearly explain these phenomena. Towards this end, we propose in this paper a hypothesis that is based on available experimental evidence as well as mathematical modeling and computer simulations. We hypothesize that there is a threshold in the nuclear NFAT concentration above which MCIP is switched on. Below this threshold, the inhibition of active CaN by MCIP is negligible, while the activated protein kinase increases the dissociation rate of the CaN/MCIP complex. This leads to an augmentation of active CaN. This mechanism realizes the positive effect (i.e., removing any negative feedback) of MCIP in the hypertrophic response. On the other hand, the over-expression of active CaN increases nuclear NFAT to values above the threshold, while CaN is inhibited through binding of MCIP (expressed by the nuclear NFAT). This mechanism realizes the introduction of a negative feedback mechanism. To unravel this switching feedback mechanism, we have developed a mathematical model for which computer simulations are in agreement with the existing experimental data. The simulations demonstrate how the apparently paradoxical behavior can emerge as a result of cellular conditions.
Animals↗
A possible mechanism linking cigarette smoke to higher incidence of respiratory infection and asthma.
T helper type 1 (Th1) cells are responsible for cell-mediated immunity against invading pathogens, while Th2 cells provide help to B cells and control allergic responses. The polarization of naïve Th cells into Th1 or Th2 subsets is controlled by dendritic cells (DCs) migrating from the periphery to draining lymph nodes. Migrating DCs carry not only antigen-specific 'signal 1' and costimulatory 'signal 2', but also Th-polarizing 'signal 3' that reflects the nature of the pathogen and the character of the infected tissue. Any changes imposed by external factors on the DC lifecycle may result in an inappropriate immune response. Here we show that DCs developed in a nicotinic environment (nicDCs) fail to support the terminal development of effector memory Th1 cells due to their differential expression of costimulatory molecules and lack of IL-12 production. Interestingly, they adopt critical Th1-promoting function necessary to prevent and fight infections only when the total balance of environmental signals strongly favors Th1 immunity. Notably, in a Th2-biased environment, nicDCs provoke stronger than normal Th2 responses which predisposes the development and exacerbation of asthma. These results help explain the two opposing effects of cigarette smoke on respiratory immune defense mechanisms: (a) immunosuppression against infectious agents and (b) exacerbation of asthma.
Asthma↗
Electroencephalographic peak alpha frequency correlates of cognitive traits.
EEG peak alpha frequency (PAF) has been shown to differentiate groups of adults with higher memory performance from those of lower performance, groups of children with advanced reading ability from matched controls, and to predict state-dependent working memory. The present study attempted to explore PAF as a predicting variable for verbal and attentional cognitive trait abilities in young adults. Nineteen undergraduate students had their EEG recorded during initial rest, reading, and post-reading rest, and at a different day were evaluated on reading, vocabulary, and attentional performance. Results showed significant correlations of reading vocabulary and response control with PAF during reading and post-reading recordings, but not during initial rest. PAF may reflect some general cognitive ability that is not necessarily memory or reading, possibly response control or the ability to acquire vocabulary. It is suggested that cognitive ability traits may reflect the ability to induce cognitive states.
Adult↗
Sex-related differences in amygdala functional connectivity during resting conditions.
Recent neuroimaging studies have established a sex-related hemispheric lateralization of amygdala involvement in memory for emotionally arousing material. Here, we examine the possibility that sex-related differences in amygdala involvement in memory for emotional material develop from differential patterns of amygdala functional connectivity evident in the resting brain. Seed voxel partial least square analyses of regional cerebral blood flow data revealed significant sex-related differences in amygdala functional connectivity during resting conditions. The right amygdala was associated with greater functional connectivity in men than in women. In contrast, the left amygdala was associated with greater functional connectivity in women than in men. Furthermore, the regions displaying stronger functional connectivity with the right amygdala in males (sensorimotor cortex, striatum, pulvinar) differed from those displaying stronger functional connectivity with the left amygdala in females (subgenual cortex, hypothalamus). These differences in functional connectivity at rest may link to sex-related differences in medical and psychiatric disorders.
Adult↗
Targeting T cell responses by selective chemokine receptor expression.
Immune responses require the orchestrated migration of T cells throughout the body. Conventional CD4+ and CD8+ alphabeta T cells undergo clonal expansion in the secondary lymphoid tissues, during which they are programmed to migrate into specific non-lymphoid tissues and other lymphoid effector sites such as B cell follicles. By contrast, T cell populations expressing receptors with limited diversity (i.e. gammadelta T cells and NK T cells) appear to be preprogrammed to localize in non-lymphoid tissues where they monitor tissue integrity or serve regulatory functions. By promoting chemotaxis and integrin activation, chemokines and their receptors (in conjunction with surface adhesion molecules) control these T cell homing events. Thus, expression of chemokine receptors defines T cells with tropism for particular tissues and/or microenvironments, and identifies T cell subsets with distinct functional properties.
Animals↗
Mechanisms in 'pure retrograde amnesia': functional, physiological or pathophysiological?
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Amnesia, Retrograde↗
Synesthetic colors determined by having colored refrigerator magnets in childhood.
Synesthesia is a condition in which percepts in one modality reliably elicit secondary perceptions in the same or a different modality that are not in the stimulus. In a common manifestation, synesthetes see colors in response to spoken or written letters, words and numbers. In this paper we demonstrate that the particular colors seen by a grapheme-color synesthete AED were learned from a set of refrigerator magnets and that the synesthesia later transferred to Cyrillic in a systematic way, with the colors induced by the Cyrillic letters determined by their visual or phonetic similarity to English letters. Closer examination of the data reveals that letters of either language that are more visually similar to the English capitals in the magnet set are also more saturated. In order to differentiate AED's synesthesia from ordinary memory, we use a novel psychophysical method to show that AED's synesthetic colors are subject to ordinary lightness constancy mechanisms. This suggests that the level of representation at which her synesthesia arises is early in the stream of visual processing.
Adult↗
Differential modulation of the 5-HT(4) receptor agonists and antagonist on rat learning and memory.
Recent data suggest that activation of 5-HT(4) receptors may modulate cognitive processes such as learning and memory. In the present study, the effects of two potent and selective 5-HT(4) agonists, RS 17017 [1-(4-amino-5-chloro-2-methoxyphenyl)-5- (piperidin-1-yl)-1-pentanone hydrochloride] and RS 67333 [1(4-amino-5-chloro-2-methoxyphenyl)-3- (1-n-butyl-4-piperidinyl)-1-propanone], were studied in an olfactory associative discrimination task. The implication of 5-HT(4) receptors in the associative discriminative task was suggested by the following observation. Injection of a selective 5-HT(4) receptor antagonist RS 67532 [1-(4-amino-5-chloro-2-(3, 5-dimethoxybenzyloxyphenyl)-5-(1-piperidinyl)-1-pentanone; 1 mg/kg: i.p.] before the third training session induced a consistent deficit in associative memory during the following training sessions. This deficit was absent when the antagonist was injected together with either a specific hydrophilic 5-HT(4) (RS 17017, 1 mg/kg) or a specific hydrophobic (RS 67333, 1 mg/kg) 5-HT(4) receptor agonist. RS 67333 was more potent than RS 17017. This difference in potency certainly reflects a difference in their capacity to enter into the brain. This is also likely to be the reason why, injected alone, the hydrophobic 5-HT(4) agonist (RS 67333) but not the hydrophilic 5-HT(4) agonist (RS 17017) improved learning and memory performance.
Aniline Compounds↗
An hypothesis about redundancy and reliability in the brains of higher species: analogies with genes, internal organs, and engineering systems.
The phenomena of behavioral resistance to massive brain damage and behavioral recovery from brain damage suggest there is redundancy in neural tissue. This paper uses basic concepts from probability theory and reliability engineering, as a first step toward more rigorously establishing the plausibility of the redundancy hypothesis. Exponential effects in the relevant formulas lead to results that are intuitively surprising. Thus, within a broad range of parametric assumptions related to lifespan and number of neurons or neural subsystems, it appears that the human brain may be at least twice as large as it would have to be for short-term survival. Simple reliability models suggest that redundancies are in parallel connections of smallest subsystems, such as individual neurons. Other implications of the basic formulas concern the relation between backed-up subsystem reliability and lifetime usage frequency for each subsystem, and the evolution of approximately equal allocation of lifetime reliability among components of a system. In addition, the paper briefly reviews more complex reliability engineering approaches. Redundancy as a reason for neural mass action is compared to other theoretical reasons for mass action in sensorimotor function and learning. Relationships of the present hypothesis to other theories of recovery from brain damage and to theories of regressive trophic phenomena in ontogeny are briefly discussed; it is suggested that as stages of ontogeny progress, both redundancy and flexibility in simpler behavioral functions are traded away for a larger, more differentiated repertoire of complex functions and memories.
Animals↗
An electrophysiological study of dyslexic and control adults in a sentence reading task.
Event-related potentials and cued-recall performance were used to compare dyslexic and control adult subjects. Sentences that ended either congruously or incongruously were presented visually, one word at a time, at fast (stimulus-onset-asynchrony (SOA)=100 ms) or slow (SOA=700 ms) rates of presentation. Results revealed (1) a large effect of presentation rate that started with the N1-P2 components and lasted for the entire recording period, (2) larger N400 components for dyslexic than control subjects, at slow presentation rates, to both congruous and incongruous endings and (3) a large ERPs difference related to memory (Dm effect) that did not differentiate controls from dyslexics but was larger at slow than at fast rates of presentation. These findings indicate that the reading impairment observed in the present group of adult dyslexics is more likely to result from difficulties integrating the meaning of words within a sentence context than from pure sensory processing deficits.
Adult↗