Exploring the use of phonological and semantic representations in working memory

In the traditional conception of working memory for word lists, phonological codes are used primarily, and semantic codes are often discarded or ignored. Yet, other evidence indicates an important role for semantic codes. We carried out a preplanned set of four experiments to determine whether phonological and semantic codes are used similarly or differently. In each trial, random lists of one, two, three, four, six, or eight words were followed by a probe to be judged present in the list or absent from it. Sometimes, a probe was absent from the list but rhymed with a list item (in Experiments 1 and 2) or was a synonym of a list item (in Experiments 3 and 4). A probe that was similar to a list item was to be rejected just like other nontarget probes, a reject-similar use (in Experiments 1 and 3), or it was to be placed in the same category as list items, an accept-similar use (in Experiments 2 and 4). The results were comparable in the accept-similar use of both phonological and semantic codes. However, the reject-similar use was interestingly different. Rejecting rhyming items was more difficult than rejecting control words, as expected, whereas rejecting synonyms was easier than rejecting control words, presumably due to a recall-to-reject process. This effect increased with memory load. We discuss theoretically important differences between the use of phonology and semantics in working memory

The proportion of working memory items recoverable from long-term memory remains fixed despite adult aging.

We explored whether long-term memory (LTM) retrieval is constrained by working memory (WM) limitations, in 80 younger and 80 older adults. Participants performed a WM task with images of unique everyday items, presented at varying set sizes. Subsequently, we tested participants’ LTM for items from the WM task and examined the ratio of LTM/WM retention. While older adults’ WM and LTM were generally poorer than that of younger adults, their LTM deficit was no greater than what was predicted from their WM performance. The ability to encode WM information into LTM appeared immune to age-related cognitive decline

A lifespan study of the confidence-accuracy relation in working memory and episodic long-term memory

The relation between an individual’s memory accuracy and reported confidence in their memories can indicate self-awareness of memory strengths and weaknesses. We provide a lifespan perspective on this confidence-accuracy relation, based on two previously published experiments with 320 participants, including children aged 6 to 13, young adults aged 18 to 27, and older adults aged 65 to 77, across tests of working memory (WM) and long-term memory (LTM). Participants studied visual items in arrays of varying set sizes and completed item recognition tests featuring six-point confidence ratings either immediately after studying each array (WM tests) or following a long period of study events (LTM tests). Confidence-accuracy characteristic analyses showed that accuracy improved with increasing confidence for all age groups and in both WM and LTM tests. These findings reflect a universal ability across the lifespan to use awareness of the strengths and limitations of one’s memories to adjust reported confidence. Despite this age invariance in the confidence-accuracy relation, however, young children were more prone to high-confidence memory errors than other groups in tests of WM, whereas older adults were more susceptible to high-confidence false alarms in tests of LTM. Thus, although participants of all ages can assess when their memories are weaker or stronger, individuals with generally weaker memories are less adept at this confidence-accuracy calibration. Findings also speak to potential different sources of high-confidence memory errors for young children and older adults, relative to young adults

Interprofessional team-based placements: The importance of space, place, and facilitation.

Interprofessional education in practice settings typically requires greater resource investment than in the classroom or online. Increased interest in return on investment means research on the outcomes of practice-based interprofessional education is needed. In this article, we report findings from a qualitative study involving a series of focus groups with health sciences' students during their interprofessional placements in three community health settings in Western Australia. An exploratory case study approach was adopted to determine students' perceptions of the placement and their learning. The presage-process-product (3P) model of learning and teaching was employed to illuminate to the nature of this interprofessional education experience. Verbatim transcripts were analysed by two researchers using an inductive approach to derive key themes. Findings illuminate a number of factors that strongly influenced student perceptions of their learning in interprofessional practice-based placements including a dedicated space to collaborate and learn; exposure to a wide range of professions in practice settings; the approach of the facilitators; and students' previous clinical experience, year level and the timing of the placement. Students reported that the placement enhanced their knowledge, professional communication, leadership, understanding of other health professions and collaboration. This study provides contemporary insight into key factors that influence student learning during practice-based interprofessional placements

The pseudophosphatase MK-STYX interacts with G3BP and decreases stress granule formation

MK-STYX [MAPK (mitogen-activated protein kinase) phospho-serine/threonine/tyrosine-binding protein] is a pseudophosphatase member of the dual-specificity phosphatase subfamily of the PTPs (protein tyrosine phosphatases). MK-STYX is catalytically inactive due to the absence of two amino acids from the signature motif that are essential for phosphatase activity. The nucleophilic cysteine residue and the adjacent histidine residue, which are conserved in all active dual-specificity phosphatases, are replaced by serine and phenylalanine residues respectively in MK-STYX. Mutations to introduce histidine and cysteine residues into the active site of MK-STYX generated an active phosphatase. Using MS, we identified G3BP1 [Ras-GAP (GTPase-activating protein) SH3 (Src homology 3) domain-binding protein-1], a regulator of Ras signalling, as a binding partner of MK-STYX. We observed that G3BP1 bound to native MK-STYX; however, binding to the mutant catalytically active form of MK-STYX was dramatically reduced. G3BP1 is also an RNA-binding protein with endoribonuclease activity that is recruited to ‘stress granules’ after stress stimuli. Stress granules are large subcellular structures that serve as sites of mRNA sorting, in which untranslated mRNAs accumulate. We have shown that expression of MK-STYX inhibited stress granule formation induced either by aresenite or expression of G3BP itself; however, the catalytically active mutant MK-STYX was impaired in its ability to inhibit G3BP-induced stress granule assembly. These results reveal a novel facet of the function of a member of the PTP family, illustrating a role for MK-STYX in regulating the ability of G3BP1 to integrate changes in growth-factor stimulation and environmental stress with the regulation of protein synthesis

Plasmodium falciparum population dynamics in a cohort of pregnant women in Senegal

<p>Abstract</p> <p>Background</p> <p>Pregnant women acquire protective antibodies that cross-react with geographically diverse placental <it>Plasmodium falciparum </it>isolates, suggesting that surface molecules expressed on infected erythrocytes by pregnancy-associated malaria (PAM) parasites have conserved epitopes and, that designing a PAM vaccine may be envisaged. VAR2CSA is the main candidate for a pregnancy malaria vaccine, but vaccine development may be complicated by its sequence polymorphism.</p> <p>Methods</p> <p>The dynamics of <it>P. falciparum </it>genotypes during pregnancy in 32 women in relation to VAR2CSA polymorphism and immunity was determined. The polymorphism of the <it>msp2 </it>gene and five microsatellites was analysed in consecutive parasite isolates, and the <it>DBL5ε + Interdomain 5 </it>(<it>Id5</it>) part of the <it>var2csa </it>gene of the corresponding samples was cloned and sequenced to measure variation.</p> <p>Results</p> <p>In primigravidae, the multiplicity of infection in the placenta was associated with occurrence of low birth weight babies. Some parasite genotypes were able to persist over several weeks and, still be present in the placenta at delivery particularly when the host anti-VAR2CSA antibody level was low. Comparison of diversity among genotyping markers confirmed that some PAM parasites may harbour more than one <it>var2csa </it>gene copy in their genome.</p> <p>Conclusions</p> <p>Host immunity to VAR2CSA influences the parasite dynamics during pregnancy, suggesting that the acquisition of protective immunity requires pre-exposure to a limited number of parasite variants. Presence of highly conserved residues in surface-exposed areas of the VAR2CSA immunodominant DBL5ε domain, suggest its potential in inducing antibodies with broad reactivity.</p

GM and KM immunoglobulin allotypes in the Galician population: new insights into the peopling of the Iberian Peninsula

<p>Abstract</p> <p>Background</p> <p>The current genetic structure of Iberian populations has presumably been affected by the complex orography of its territory, the different people and civilizations that settled there, its ancient and complex history, the diverse and persistent sociocultural patterns in its different regions, and also by the effects of the Iberian Peninsula representing a refugium area after the last glacial maximum. This paper presents the first data on <it>GM </it>and <it>KM </it>immunoglobulin allotypes in the Galician population and, thus, provides further insights into the extent of genetic diversity in populations settled in the geographic extremes of the Cantabrian region of northern Spain. Furthermore, the genetic relationships of Galicians with other European populations have been investigated.</p> <p>Results</p> <p>Galician population shows a genetic profile for <it>GM </it>haplotypes that is defined by the high presence of the European Mediterranean <it>GM</it>*<it>3 23 5* </it>haplotype, and the relatively high incidence of the African marker <it>GM*1,17 23' 5*</it>. Data based on comparisons between Galician and other Spanish populations (mainly from the north of the peninsula) reveal a poor correlation between geographic and genetic distances (<it>r </it>= 0.30, <it>P </it>= 0.105), a noticeable but variable genetic distances between Galician and Basque subpopulations, and a rather close genetic affinity between Galicia and Valencia, populations which are geographically separated by a long distance and have quite dissimilar cultures and histories. Interestingly, Galicia occupies a central position in the European genetic map, despite being geographically placed at one extreme of the European continent, while displaying a close genetic proximity to Portugal, a finding that is consistent with their shared histories over centuries.</p> <p>Conclusion</p> <p>These findings suggest that the population of Galicia is the result of a relatively balanced mixture of European populations or of the ancestral populations that gave rise to them. This would support the importance of the migratory movements that have taken place in Europe over the course of recent human history and their effects on the European genetic landscape.</p

Lexical access speed and the development of phonological recoding during immediate serial recall

A recent Registered Replication Report (RRR) of the development of verbal rehearsal during serial recall revealed that children verbalized at younger ages than previously thought, but did not identify sources of individual differences. Here, we use mediation analysis to reanalyze data from the 934 children ranging from 5 to 10 years old from the RRR for that purpose. From ages 5 to 7, the time taken for a child to label pictures (i.e. isolated naming speed) predicted the child’s spontaneous use of labels during a visually presented serial reconstruction task, despite no need for spoken responses. For 6- and 7-year-olds, isolated naming speed also predicted recall. The degree to which verbalization mediated the relation between isolated naming speed and recall changed across development. All relations dissipated by age 10. The same general pattern was observed in an exploratory analysis of delayed recall for which greater demands are placed on rehearsal for item maintenance. Overall, our findings suggest that spontaneous phonological recoding during a standard short-term memory task emerges around age 5, increases in efficiency during the early elementary school years, and is sufficiently automatic by age 10 to support immediate serial recall in most children. Moreover, the findings highlight the need to distinguish between phonological recoding and rehearsal in developmental studies of short-term memory