Item content versus contextual strengthening following retrieval

Includes bibliographical references.2015 Summer.Despite a substantial literature describing the memory benefit resulting from testing (i.e., memory retrieval), relatively few investigations have attempted to detail how retrieval acts as a memory modifier. One core issue concerns the extent to which testing and studying effect fundamentally similar or different processes or components of memories. The present paper introduces two computational models, both based in REM theory (Shiffrin & Steyvers, 1997) and designed to provide a plausible basis for describing the testing effect at a more mechanistic level than existing theories. The two models are derived from the same set of core assumptions about the functioning of the memory system, and differ only in their specifications of the components of memories that are modified as a result of retrieval. The “Item Model” (IM) assumes that retrieval serves primarily to strengthen the target item content representation of information that is retrieved. In contrast, the “Context Model” (CM) assumes that retrieval serves to embed additional contextual information into the target memory trace, facilitating the subsequent ability of the memory system to locate such items. This manuscript provides coverage of relevant areas in the literature that have bearing on the IM and CM, details the implementation of the models and their larger framework, and reports on 4 experiments designed to test contrasting predictions of the IM and CM. Experiment 1 observed a testing effect using a mixed list, but not a pure list design, implying that testing may serve to enhance the search process by strengthening context information in memory. Experiments 2-4 were designed to examine the effects of reinstating contextual information during final testing on the testing effect. Experiments 2 and 3 found that reinstating either perceptual contextual elements (Exp. 2), or semantic context cues (Exp. 3) at the time of final test did not significantly impact the magnitude of the testing effect. However, Experiment 4 found that reinstating the initial learning mental/temporal context at the time of final test mitigated the magnitude of the testing effect. Potential nuanced interactions between testing and context in memory are discussed

Testing effects in context memory

2011 Summer.Includes bibliographical references.Retrieving a previously learned piece of information can have profound positive effects on the later retention of such information. However, it is not clear if test-induced memory benefits are restricted to the specific information which was retrieved, or if they can generalize more completely to the full study episode. Two experiments investigated the role of retrieval practice on memory for both target and non-target contextual information. Experiment 1 used a remember-know task to assess the subjective quality of memory as a function of earlier retrieval practice or study. Additionally, memory for context information (target font color) from the initial study episode was assessed. Experiment 2 used paired associates to investigate the effect of testing on non-tested but associated contextual information. Successful retrieval practice, compared with study, resulted in large benefits in target, target-associated, and context information retention across both experiments. Moreover, successful retrieval practice was associated with a greater contribution of remember responses informing recognition decisions. The results suggest that retrieving information may serve to both boost item memory about a target and strengthen the bind between target and associated contextual information. In sum, the present study adds to an emerging literature that test-induced mnemonic benefits may "spill over" to non-tested information

Experimental hut evaluation of bednets treated with an organophosphate (chlorpyrifos-methyl) or a pyrethroid (lambdacyhalothrin) alone and in combination against insecticide-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes

BACKGROUND: Pyrethroid resistant mosquitoes are becoming increasingly common in parts of Africa. It is important to identify alternative insecticides which, if necessary, could be used to replace or supplement the pyrethroids for use on treated nets. Certain compounds of an earlier generation of insecticides, the organophosphates may have potential as net treatments. METHODS: Comparative studies of chlorpyrifos-methyl (CM), an organophosphate with low mammalian toxicity, and lambdacyhalothrin (L), a pyrethroid, were conducted in experimental huts in Côte d'Ivoire, West Africa. Anopheles gambiae and Culex quinquefasciatus mosquitoes from the area are resistant to pyrethroids and organophosphates (kdr and insensitive acetylcholinesterase Ace.1(R)). Several treatments and application rates on intact or holed nets were evaluated, including single treatments, mixtures, and differential wall/ceiling treatments. RESULTS AND CONCLUSION: All of the treatments were effective in reducing blood feeding from sleepers under the nets and in killing both species of mosquito, despite the presence of the kdr and Ace.1(R )genes at high frequency. In most cases, the effects of the various treatments did not differ significantly. Five washes of the nets in soap solution did not reduce the impact of the insecticides on A. gambiae mortality, but did lead to an increase in blood feeding. The three combinations performed no differently from the single insecticide treatments, but the low dose mixture performed encouragingly well indicating that such combinations might be used for controlling insecticide resistant mosquitoes. Mortality of mosquitoes that carried both Ace.1(R )and Ace.1(S )genes did not differ significantly from mosquitoes that carried only Ace.1(S )genes on any of the treated nets, indicating that the Ace.1(R )allele does not confer effective resistance to chlorpyrifos-methyl under the realistic conditions of an experimental hut

Postexposure Treatment and Animal Rabies, Ontario, 1958-2000

This paper investigates the relationship between animal rabies and postexposure treatment (PET) in Ontario by examining the introduction of human diploid cell vaccine (HDCV) in 1980 and the initiation of an oral rabies vaccination program for wildlife in 1989. Introducing HDCV led to an immediate doubling of treatments. Both animal rabies and human treatments declined rapidly after the vaccination program was introduced, but human treatments have leveled off at approximately 1,000 per year

MR diffusion changes in the perimeter of the lateral ventricles demonstrate periventricular injury in post-hemorrhagic hydrocephalus of prematurity

OBJECTIVES: Injury to the preterm lateral ventricular perimeter (LVP), which contains the neural stem cells responsible for brain development, may contribute to the neurological sequelae of intraventricular hemorrhage (IVH) and post-hemorrhagic hydrocephalus of prematurity (PHH). This study utilizes diffusion MRI (dMRI) to characterize the microstructural effects of IVH/PHH on the LVP and segmented frontal-occipital horn perimeters (FOHP). STUDY DESIGN: Prospective study of 56 full-term infants, 72 very preterm infants without brain injury (VPT), 17 VPT infants with high-grade IVH without hydrocephalus (HG-IVH), and 13 VPT infants with PHH who underwent dMRI at term equivalent. LVP and FOHP dMRI measures and ventricular size-dMRI correlations were assessed. RESULTS: In the LVP, PHH had consistently lower FA and higher MD and RD than FT and VPT (p\u3c.050). However, while PHH FA was lower, and PHH RD was higher than their respective HG-IVH measures (p\u3c.050), the MD and AD values did not differ. In the FOHP, PHH infants had lower FA and higher RD than FT and VPT (p\u3c.010), and a lower FA than the HG-IVH group (p\u3c.001). While the magnitude of AD in both the LVP and FOHP were consistently less in the PHH group on pairwise comparisons to the other groups, the differences were not significant (p\u3e.050). Ventricular size correlated negatively with FA, and positively with MD and RD (p\u3c.001) in both the LVP and FOHP. In the PHH group, FA was lower in the FOHP than in the LVP, which was contrary to the observed findings in the healthy infants (p\u3c.001). Nevertheless, there were no regional differences in AD, MD, and RD in the PHH group. CONCLUSION: HG-IVH and PHH results in aberrant LVP/FOHP microstructure, with prominent abnormalities among the PHH group, most notably in the FOHP. Larger ventricular size was associated with greater magnitude of abnormality. LVP/FOHP dMRI measures may provide valuable biomarkers for future studies directed at improving the management and neurological outcomes of IVH/PHH

A 10-kDa Structural Protein of Porcine Reproductive and Respiratory Syndrome Virus Encoded by ORF2b

AbstractThe major structural proteins of porcine reproductive and respiratory syndrome virus (PRRSV) are derived from ORFs 5, 6, and 7. Western blots of sucrose gradient-purified virions and PRRSV-infected MARC-145 cells, probed with immune pig serum, showed the presence of an additional 10-kDa protein. Nucleotide sequence analysis of North American PRRSV isolate SDSU-23983 revealed a small ORF within ORF2, named ORF2b, which, when translated, produced a 73-amino-acid nonglycosylated protein. Recombinant 2b protein expressed by a baculovirus clone, AcVR2, comigrated with the 10-kDa virus-associated protein. The loss of 10-kDa protein immunoreactivity after absorption of immune sera with lysates from AcVR2-infected insect cells demonstrated that the 2b and 10-kDa proteins are immunologically similar. Immunoblots were also used for the detection of anti-2b activity in serum samples from experimentally infected adult pigs. Antibodies against PRRSV were apparent by 14 days postinfection, followed by anti-2b activity and serum neutralizing activity. The putative ORF2b start codon is only 6 nucleotides downstream of the adenine of the ORF2a start codon. The expression of ORF2a and 2b as enhanced green fluorescent fusion proteins showed that both proteins were translated; however, the ORF2b was preferentially expressed. These results suggest that the 2b protein is virion associated and the principal product of ORF2

An adherent tissue-inspired hydrogel delivery vehicle utilised in primary human glioma models.

A physical hydrogel cross-linked via the host-guest interactions of cucurbit[8]uril and utilised as an implantable drug-delivery vehicle for the brain is described herein. Constructed from hyaluronic acid, this hydrogel is biocompatible and has a high water content of 98%. The mechanical properties have been characterised by rheology and compared with the modulus of human brain tissue demonstrating the production of a soft material that can be moulded into the cavity it is implanted into following surgical resection. Furthermore, effective delivery of therapeutic compounds and antibodies to primary human glioblastoma cell lines is showcased by a variety of in vitro and ex vivo viability and immunocytochemistry based assays.This work was supported by The Brain Tumour Charity (RG89672), the National Institute for Health Research Cambridge Biomedical Research Centre; the Higher Education Funding Council for England. We acknowledge the Human Research Tissue Bank and Biomedical Research Centre for the tissue being accessed through the Human Research Tissue Bank. The Human Research Tissue Bank is supported by the NIHR Cambridge Biomedical Research Centre. MJR thanks the University of Cambridge Chemical Biology and Molecular Medicine PhD Training Programme for funding. CCP is thankful for the support of the EPSRC and the Brain Tumour Charity for funding. JHM acknowledges the support of the Gates Cambridge Scholarship programme. AKK was supported by a studentship from the John and Lucille van Geest Foundation

Results of a Rural Traffic Calming Event to Promote Physical Activity

This article describes how community need was addressed through a traffic calming pop-up event in rural Arkansas. The event was conducted on routes connecting a neighborhood, two schools, and a municipal park. A brief survey assessed safety concerns of parents and/or guardians related to children walking or biking to school. Prior to the event, parents/guardians reported it was not safe for their children to walk or bike to school; however, the majority agreed the event made the area safer. Small-scale traffic calming events can provide evidence to stakeholders that built environment changes are an important childhood obesity prevention strategy in rural Extension work