Effects of temporal association on recognition memory

The influence of temporal association on the representation and recognition of objects was investigated. Observers were shown sequences of novel faces in which the identity of the face changed as the head rotated. As a result, observers showed a tendency to treat the views as if they were of the same person. Additional experiments revealed that this was only true if the training sequences depicted head rotations rather than jumbled views: in other words, the sequence had to be spatially as well as temporally smooth. Results suggest that we are continuously associating views of objects to support later recognition, and that we do so not only on the basis of the physical similarity, but also the correlated appearance in time of the objects.

A Context Noise Model of Episodic Recognition Memory

Item noise models of recognition assert that interference at retrieval is generated by the words from the study list. Context noise models of recognition assert that interference at retrieval is generated by the contexts in which the test word has appeared. The authors introduce the bind cue decide model of episodic memory, a Bayesian context noise model, and demonstrate how it can account for data from the item noise and dual-processing approaches to recognition memory. From the item noise perspective, list strength and list length effects, the mirror effect for word frequency and concreteness, and the effects of the similarity of other words in a list are considered. From the dual-processing perspective, process dissociation data on the effects of length. temporal separation of lists, strength, and diagnosticity of context are examined. The authors conclude that the context noise approach to recognition is a viable alternative to existing approaches. (PsycINFO Database Record (c) 2008 APA, all rights reserved)

Provision of 4-1BB ligand enhances effector and memory CTL responses generated by immunization with dendritic cells expressing a human tumor-associated antigen

Up-regulation of receptor-ligand pairs during interaction of an MHC-presented epitope on dendritic cells (DCs) with cognate TCR may amplify, sustain, and drive diversity in the ensuing T cell immune response. Members of the TNF ligand superfamily and the TNFR superfamily contribute to this costimulatory molecule signaling. In this study, we used replication deficient adenoviruses to introduce a model tumor-associated Ag (the E7 oncoprotein of human papillomavirus 16) and the T cell costimulatory molecule 4-IBBL into murine DCs, and monitored the ability of these recombinant DO to elicit E7-directed T cell responses following immunization. Splenocytes from mice immunized with DCs expressing E7 alone elicited E7-directed effector and memory CTL responses. Coexpression of 4-1BBL in these E7-expressing DO increased effector and memory CTL responses when they were used for immunization. 4-1BBL expression up-regulated CD80 and CD86 second signaling molecules in DO. We also report an additive effect of 4-IBBL and receptor activator of NF-kappaB/receptor activator of NF-kappaB ligand coexpression in E7-transduced DC inummogens on E7-directed effector and memory CTL responses and on MHC class II and CD80/86 expression in DCs. Additionally, expression of 4-1BBL in E7-transduced DCs reduced nonspecific T cell activation characteristic of adenovirus vector-associated immunization. The results have generic implications for improved or tumor Ag-expressing DC vaccines by incorporation of exogenous 4-1BBL. There are also specific implications for an improved DC-based vaccine for human papillomavirus 16-associated cervical carcinoma.

Is the effect of reading misspellings context dependent?

In 48 university students performing single-item spelling recognition, prior exposure to misspelled words improved slightly the accuracy on correctly spelled words and increased markedly the 'false alarm' rate (classifying a misspelling seen at study as correct). In a group given a dictation test (N = 24) the only effect of exposure to misspellings was a small increment in the number of misspellings that matched the misspelling seen at study. The two test groups showed no advantage of having the same display format at study and test (AA or BB vs AB or BA). Experiment 2 (in progress) investigated a format match at study and test against a condition with a new test context (AA or BB vs AC or BC). The results to date suggest an influence of memory of the study trial rather than simply an updating by the study exposures of abstract lexical representations. [ABSTRACT FROM AUTHOR]

Auditory-visual speech integration by prelinguistic infants: Perception of an emergent consonant in the McGurk effect

The McGurk effect, in which auditory [ba] dubbed onto [go] lip movements is perceived as da or tha, was employed in a real-time task to investigate auditory-visual speech perception in prelingual infants. Experiments 1A and 1B established the validity of real-time dubbing for producing the effect. In Experiment 2, 4(1)/(2)-month-olds were tested in a habituation-test paradigm, in which 2 an auditory-visual stimulus was presented contingent upon visual fixation of a live face. The experimental group was habituated to a McGurk stimulus (auditory [ba] visual [ga]), and the control group to matching auditory-visual [ba]. Each group was then presented with three auditory-only test trials, [ba], [da], and [deltaa] (as in then). Visual-fixation durations in test trials showed that the experimental group treated the emergent percept in the McGurk effect, [da] or [deltaa], as familiar (even though they had not heard these sounds previously) and [ba] as novel. For control group infants [da] and [deltaa] were no more familiar than [ba]. These results are consistent with infants'perception of the McGurk effect, and support the conclusion that prelinguistic infants integrate auditory and visual speech information. (C) 2004 Wiley Periodicals, Inc.

The effect of silicon content on the microstructure and creep behavior in die-cast magnesium AS alloys

The effect of increasing levels of silicon on the microstructure and creep properties of high-pressure die-cast Mg-Al-Si (AS) alloys has been investigated. The morphology of the Mg2Si phase in die-cast AS alloys was found to be a function of the silicon content. The Mg2Si particles in castings with up to 1.14 wt pct Si have a Chinese script morphology. For AS21 alloys with silicon contents greater than 1.4 wt pet Si (greater than the alpha-Mg2Si binary eutectic point), some Mg2Si particles have a coarse blocky shape. Increasing the silicon content above the eutectic level results in an increase in the number of coarse faceted Mg2Si particles in the microstructure. Creep rates at 100 hours were found to decrease with increasing silicon content in AS-type alloys. The decrease in creep rate was most dramatic for silicon contents up to 1.1 wt pct. Further additions of silicon of up to 2.64 wt pct also resulted in significant decreases in creep rate.

Effect of granule morphology on breakage behaviour during compression

In the area of dry particle breakage, Discrete Element Method (DEM) simulations have been widely used to analyse the sensitivity of various physical parameters to the behaviour of agglomerates during breakage. This paper looks at the effect of agglomerate shape and structure on the mechanisms and extent of breakage of dry agglomerates under compressive load using DEM simulations. In the simulations, a spherical-shaped agglomerate produced within the DEM code is compared with an irregularly shaped agglomerate, whose structure is that of an actual granule that was characterised with X-ray microtomography (muCT). Both agglomerates have identical particle size distribution, coordination number and surface energy values, with only the agglomerate shape and structure differing between the two. The work here details the breakage behaviour with a number of traditional DEM output parameters (i.e., contact/cluster distributions) with showing vastly different behaviour between the two agglomerates. (C) 2004 Elsevier B.V. All rights reserved.

Effect of prolonged inactivity on skeletal motor nerve terminals during aestivation in the burrowing frog, Cyclorana alboguttata

This study examined the effect of prolonged inactivity, associated with aestivation, on neuromuscular transmission in the green-striped burrowing frog, Cyclorana alboguttata. We compared the structure and function of the neuromuscular junctions on the iliofibularis muscle from active C. alboguttata and from C. alboguttata that had been aestivating for 6 months. Despite the prolonged period of immobility, there was no significant difference in the shape of the terminals (primary, secondary or tertiary branches) or the length of primary terminal branches between aestivators and non-aestivators. Furthermore, there was no significant difference in the membrane potentials of muscle fibres or in miniature end plate potential (EPP) frequency and amplitude. However, there was a significant decrease in evoked transmitter release characterised by a 56% decrease in mean EPP amplitude, and a 29% increase in the failure rate of nerve terminal action potentials to evoke transmitter release. The impact of this suite of neuromuscular characteristics on the locomotor performance of emergent frogs is discussed.

Using psilocybin to investigate the relationship between attention, working memory, and the serotonin 1A and 2A receptors

Increasing evidence suggests a link between attention, working memory, serotonin (5-HT), and prefrontal cortex activity. In an attempt to tease out the relationship between these elements, this study tested the effects of the hallucinogenic mixed 5-HT1A/2A receptor agonist psilocybin alone and after pretreatment with the 5-HT2A antagonist ketanserin. Eight healthy human volunteers were rested on a multiple-object tracking task and spatial working memory task under the four conditions: placebo, psilocybin (215 mu g/kg), ketanserin (50 mg), and psilocybin and ketanserin. Psilocybin significantly reduced attentional tracking ability, but had no significant effect on spatial working memory, suggesting a functional dissociation between the two tasks. Pretreatment with ketanserin did not attenuate the effect of psilocybin on attentional performance, suggestinga primary involvement of the 5-HT1A receptor in the observed defecit. Based on physiological and pharmacological data,we speculate that this impaired attentional performance may reflect a reduced ability to suppress or ignore distracting stimuli rather than reduced attentional capacity. The clinical relevance of these results is also discussed.

Effect of curve fitting parameters on quantitative analysis of Fe0.94O and Fe2O3 using XPS

The XPS peaks of Fe 3p for Fe2+ and Fe3+ in FeO and Fe2O3, respectively, have been measured and the effects of curve fitting parameters on interpretation of the data have been analysed. Firstly, the peak fit parameters, i.e. (1) the number of peaks to be deconvoluted, (2) the range of the peak for back ground subtraction, (3) straight line (Li) or the Shirley (Sh) background subtraction method, (4) GL ratio (the ratio of Gaussian and Lorentzian contribution to the peak shape) and (5) asymmetry factor (AS), are manually selected. Secondly, the standard peak fit parameters were systematically investigated. The peak shape was fitted to a Voigt function by changing the peak position, the peak height and the full width at half maximum (FWHM) to minimize the chi(2). The recommended peak positions and peak parameters for Fe2+ and Fe3+ in iron oxides have been determined. (c) 2006 Elsevier B.V. All rights reserved.

HRT and everyday memory at menopause: A comparison of two samples of mid-aged women

Research on the effect of hormone replacement therapy (HRT) on memory in mid-aged women is equivocal although findings indicate that oestrogen may enhance verbal memory. Mood may mediate the relationship between HRT and memory. This study examined the effect of HRT on mood and everyday memory in two samples of women between ages 40 and 60 years. In the cross-sectional comparison (N = 124), HRT users performed significantly better on tests of everyday and verbal memory. A within-woman comparison of 17 women showed that everyday memory, working memory, and delayed verbal memory improved after 3 months of HRT use. The improvement in memory was not mediated by mood. These results suggest that any effect of HRT on mood may be short-term but that some aspects of everyday memory are enhanced, particularly verbal memory. The development of the everyday memory construct and future investigation are discussed.

The effect of auditory and visual distracters on the useful field of view: Implications for the driving task

PURPOSE. The driving environment is becoming increasingly complex, including both visual and auditory distractions within the in- vehicle and external driving environments. This study was designed to investigate the effect of visual and auditory distractions on a performance measure that has been shown to be related to driving safety, the useful field of view. METHODS. A laboratory study recorded the useful field of view in 28 young visually normal adults (mean 22.6 +/- 2.2 years). The useful field of view was measured in the presence and absence of visual distracters (of the same angular subtense as the target) and with three levels of auditory distraction (none, listening only, listening and responding). RESULTS. Central errors increased significantly (P < 0.05) in the presence of auditory but not visual distracters, while peripheral errors increased in the presence of both visual and auditory distracters. Peripheral errors increased with eccentricity and were greatest in the inferior region in the presence of distracters. CONCLUSIONS. Visual and auditory distracters reduce the extent of the useful field of view, and these effects are exacerbated in inferior and peripheral locations. This result has significant ramifications for road safety in an increasingly complex in-vehicle and driving environment.

Sponsorship-linked marketing: The role of articulation in memory

Corporate sponsorship of events contributes significantly to marketing aims, including brand awareness as measured by recall and recognition of sponsor-event pairings. Unfortunately, resultant advantages accrue disproportionately to brands having a natural or congruent fit with the available sponsorship properties. In three cued-recall experiments, the effect of articulation of sponsorship fit on memory for sponsor-event pairings is examined. While congruent sponsors have a natural memory advantage, results demonstrate that memory improvements via articulation are possible for incongruent sponsor-event pairings. These improvements are, however, affected by the presence of competitor brands and the way in which memory is accessed.

The effect of larval age on morphology and gene expression during ascidian metamorphosis

Metamorphosis is both an ecological and a developmental genetic transition that an organism undergoes as a normal part of ontogeny. Many organisms have the ability to delay metamorphosis when conditions are unsuitable. This strategy carries obvious benefits, but may also result in severe consequences for older larvae that run low on energy. In the marine environment, some lecithotrophic larvae that have prolonged periods in the plankton may begin forming postlarval and juvenile structures that normally do not appear until after settlement and the initiation of metamorphosis. This precocious activation of the postlarval developmental program may reflect an adaptation to increase the survival of older, energy-depleted larvae by allowing them to metamorphose more quickly. In the present study, we investigate morphological and genetic consequences of delay of metamorphosis in larvae of Herdmania momus (a solitary stolidobranch ascidian). We observe significant morphological and genetic changes during prolonged larval life, with older larvae displaying significant changes in RNA levels, precocious migration of mesenchyme cells, and changes in larval shape including shortening of the tail. While these observations suggest that the older H. momus larvae are functionally different from younger larvae and possibly becoming more predisposed to undergo metamorphosis, we did not find any significant differences in gene expression levels between postlarvae arising from larvae that metamorphosed as soon as they were competent and postlarvae developing from larvae that postponed metamorphosis. This recalibration, or convergence, of transcript levels in the early postlarva suggests that changes that occur during prolonged larval life of H. momus are not necessarily associated with early activation of adult organ differentiation. Instead, it suggests that an autonomous developmental program is activated in H. momus upon the induction of metamorphosis regardless of the history of the larva.

How lifetimes shape epigenotype within and across generations

Despite our detailed characterization of the human genome at the level of the primary DNA sequence, we are still far from understanding the molecular events underlying phenotypic variation. Epigenetic modifications to the DNA sequence and associated chromatin are known to regulate gene expression and, as such, are a significant contributor to phenotype. Studies of inbred mice and monozygotic twins show that variation in the epigenotype can be seen even between genetically identical individuals and that this, in some cases at least, is associated with phenotypic differences. Moreover, recent evidence suggests that the epigenome can be influenced by the environment and these changes can last a lifetime. However, we also know that epigenetic states in real-time are in continual flux and, as a result, the epigenome exhibits instability both within and across generations. We still do not understand the rules governing the establishment and maintenance of the epigenotype at any particular locus. The underlying DNA sequence itself and the sequence at unlinked loci (modifier loci) are certainly involved. Recent support for the existence of transgenerational epigenetic inheritance in mammals suggests that the epigenetic state of the locus in the previous generation may also play a role. Over the next decade, many of these processes will be better understood, heralding a greater capacity for us to correlate measurable molecular marks with phenotype and providing the opportunity for improved diagnosis and presymptomatic healthcare.