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Τρίτη 5 Σεπτεμβρίου 2017

Salad bar selection patterns of elementary school children

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Publication date: 1 January 2018
Source:Appetite, Volume 120
Author(s): Geraldine Moreno-Black, Jean Stockard
From the perspective of child-focused nutrition research, the analysis of the school cafeteria culture and environment is critical. Most children eat at least one meal at school per school day, thus elementary schools are a good setting for influencing the early development of healthy eating habits. The salad bar in particular has gained attention as a means of increasing fruit and vegetable consumption. The purpose of the present study was to provide insight about the types of items children choose or do not choose from the salad bar. Our aims were to document elementary school children's food selection patterns by examining photographs of 2903 cafeteria trays. Our results show students in this study took very few items – and a substantial number did not take any at all. We examined three factors, gender, grade, and item placement, in relation to food selection. Gender was the most significant factor, with girls being more likely to choose both fruits and vegetables. Students in lower grades were more likely to select vegetables and to choose more of them. Finally, item placement did not affect choice. Our findings lead us to suggest the importance of integrating information about fruits and vegetables into the school curriculum and that schools strongly consider which items to offer because our results indicate children consistently do not choose certain items and probably do not conceive of them in the context of the adult concept of a salad. Finally, because a child's choice of food is not always a simple act we suggest ethnographic research on how children perceive and use salad bars would provide important insight into the value of retaining or expanding salad bars in elementary schools.



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Understanding Immunity through the Lens of Disease Ecology

Publication date: Available online 4 September 2017
Source:Trends in Immunology
Author(s): Stephen M. Hedrick
As we describe the immune system in ever more exquisite detail, we might find that no matter how successful, this approach will not be sufficient to understand the spread of infectious agents, their susceptibility to vaccine therapy, and human disease resistance. Compared with the strict reductionism practiced as a means of characterizing most biological processes, I propose that the progression and outcome of disease-causing host–parasite interactions will be more clearly understood through a focus on disease ecology.



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Influence of soil physical properties and vegetation coverage at different slope aspects in a reclaimed dump

Abstract

Vegetation coverage is an important parameter for affecting soil erosion and the physical and chemical properties of soil. To analyze the mutual influence between vegetation coverage and soil quality at different slope aspects in a reclaimed dump, fitting analyses were built between the normalized difference vegetation index and soil physical properties at each slope aspect. Twenty six quadrats were sampled in slope-platform alternate mode. Each quadrat was 10 m × 10 m. Vegetation index and soil physical properties were measured and calculated. Through curve fitting analysis, the results showed that soil bulk density has a negative correlation with the vegetation index on shady and half shady slopes, sunny slopes, and half sunny slopes. Soil porosity has a positive correlation with the vegetation index on shady and half shady slopes, sunny slope, and half sunny slope. The soil mass water content has a concave function relationship with the vegetation index on shady and half shady slopes and has a quadratic function relationship with the vegetation index on sunny and half sunny slopes, with the parabola moving upwards. The soil gravel content has a linear relationship with the vegetation index on shady and half shady slopes, and the image has a negative slope with a quadratic function relationship to the vegetation index on sunny slope and half sunny slope, with the parabola moving downwards. Due to differences among hydrothermal conditions, the relationship between vegetation coverage and soil quality indicators at different slope aspects is different; therefore, reasonable improvement of soil quality indicators on sunny and half sunny slopes could help plants to grow. These findings feed into a reference document that sets out how vegetation and soil quality may be improved in mining areas.



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Ecotoxicity and antibiotic resistance of a mixture of hospital and urban sewage in a wastewater treatment plant

Abstract

Hospital and urban effluents are a source of diverse pollutants such as organic compounds, heavy metals, detergents, disinfectants, pharmaceuticals, and microorganisms resistant to antibiotics. Usually, these two types of effluent are mixed in the sewage network, but a pilot site in France now allows studying them separately or mixed to understand more about their characteristics and the phenomena that occur following their mixing. In this study, their ecotoxicity (Daphnia magna mobility, Pseudokirchneriella subcapitata growth, Brachionus calyciflorus reproduction, and SOS Chromotest) and antibiotic resistance (integron quantification) were assessed during mixing and treatment steps. The main results of this study are (i) the ecotoxicity and antibiotic resistance potentials of hospital wastewater are higher than in urban wastewater and (ii) mixing two different effluents does not lead to global synergistic or antagonistic effects on ecotoxicity and antibiotic resistance potential. The global additivity effect observed in this case must be confirmed by other studies on hospital and urban effluents on other sites to improve knowledge relating to this source of pollution and its management.



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The effect of substrate/inoculum ratio on the kinetics of methane production in swine wastewater anaerobic digestion

Abstract

Methane production from swine wastewater was evaluated by using sewage sludge as inoculum in three substrate to inoculum ratios (SIRs) named A (1:1), B (3:1) and C (6:1), with the objective to identify the proportion that optimizes the performance of the process. Duplicated batch bioreactors of 1 L capacity under mesophilic conditions were used to carry out the experiment. The highest biogas yield was observed in A treatment (554 ± 75 mL/g volatile solid (VS)). Cumulative methane production decreased from 382 ± 22 to 232 ± 5 mL/g VS when SIR increased from 1:1 to 6:1. The first-order model and the modified Gompertz equation were used to model the experimental cumulative methane yield giving adjustments with coefficients of determination of 96 and 99% respectively. The effect of the SIR was analysed based on the kinetic parameters of the Gompertz equation, which are methane production potential, maximum methane production rate and lag-phase time. The best performance in terms of the kinetic parameters was obtained for treatment A; however, treatment B could still ensure a stable process. The use of higher inoculum concentration generated 463.1% higher methane production rate and required 77.3% shorter adaptation time (lag phase) in the SIR range studied. When higher SIR was used (e.g. 14:1, previous work), it could be observed that the Gompertz equation also adjusted adequately the experimental data (R 2 > 0.99) although the lag-phase time did not remain in a linear relationship with SIR but exponentially above SIR = 6:1. These results demonstrated that when a low amount of inoculum was used, the adaptation time of microorganisms resulted much higher than expected delaying the methane production and extending the time needed to achieve adequate performance of the process.



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Subretinal fibrin absorption after 577-nm subthreshold micropulse laser therapy in a CSC case: a brief report



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How extreme dieting becomes compulsive: a novel hypothesis for the role of anxiety in the development and maintenance of anorexia nervosa

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Publication date: Available online 5 September 2017
Source:Medical Hypotheses
Author(s): E.C. Lloyd, A.M. Haase, B. Verplanken, I. Frampton
The US National Institute of Mental Health's Research Domain Criteria (NIMH RDoC) advocates the study of features common to psychiatric conditions. This transdiagnostic approach has recently been adopted into the study of anorexia nervosa (AN), an illness that can be considered compulsive in nature. This has led to the development of an account of AN that identifies key roles for the heightened reinforcement of starvation, leading to its excessive repetition, and goal-directed system dysfunction. Continuing to consider models of illness in other compulsive disorders, we extend the existing account to explain the emergence of reinforcement and goal-directed system abnormalities in AN, proposing that anxiety is central to both processes. As such we emphasise the particular importance of the anxiolytic effects of starvation, over other reinforcing outcomes, in encouraging the continuation of starvation within a model that proposes a number of mechanisms by which anxiety operates. We suggest the psychopathology of AN mediates the relationship between the anxiolytic effects of starvation and excessive repetition of starvation, and that compulsive starvation has reciprocal effects on other factors of the model. We thus account for the emergence of symptoms of AN other than compulsive starvation, and for the relationship between different features of the disorder. By extending and adapting an existing explanation of AN, we provide a richer aetiological model that invites new research questions and could inform novel approaches to prevention and treatment.



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Anti-HIV activity of southern African plants: Current developments, phytochemistry and future research

Publication date: 10 January 2018
Source:Journal of Ethnopharmacology, Volume 210
Author(s): Gerhard Prinsloo, Cynthia K. Marokane, Renée A. Street
Ethnopharmacological relevanceThe African continent is home to a large number of higher plant species used over centuries for many applications, which include treating and managing diseases such as HIV. Due to the overwhelming prevalence and incidence rates of HIV, especially in sub-Saharan Africa, it is necessary to develop new and affordable treatments.Aim of the studyThe article provides an extensive overview of the status on investigation of plants from the southern African region with ethnobotanical use for treating HIV or HIV-related symptoms, or the management of HIV. The review also provide an account of the in vitro assays, anti-viral activity and phytochemistry of these plants.Materials and methodsPeer-reviewed articles investigating plants with ethnobotanical information for the treatment or management of HIV or HIV-related symptoms from the southern African region were acquired from Science Direct, PubMed central and Google Scholar. The selection criteria was that (1) plants should have a record of traditional/popular use for infectious or viral diseases, HIV treatment or symptoms similar to HIV infection, (2) if not traditionally/popularly used, plants should be closely related to plants with popular use and HIV activity identified by means of in vitro assays, (3) plants should have been identified scientifically, (4) should be native to southern African region and (5) anti-HIV activity should be within acceptable ranges.ResultsMany plants in Africa and specifically the southern African region have been used for the treatment of HIV or HIV related symptoms and have been investigated suing various in vitro techniques. In vitro assays using HIV enzymes such as reverse transcriptase (RT), integrase (IN) and protease (PR), proteins or cell-based assays have been employed to validate the use of these plants with occasional indication of the selectivity index (SI) or therapeutic index (TI), with only one study, that progressed to in vivo testing. The compounds identified from plants from southern Africa is similar to compounds identified from other regions of the world, and the compounds have been divided into three groups namely (1) flavonoids and flavonoid glycosides, (2) terpenoids and terpenoid glycosides and (3) phenolic acids and their conjugated forms.ConclusionsAn investigation of the plants from southern Africa with ethnobotanical use for the treatment of HIV, management of HIV or HIV-related symptoms, therefore provide a very good analysis of the major assays employed and the anti-viral compounds and compound groups identified. The similarity in identified anti-viral compounds worldwide should support the progression from in vitro studies to in vivo testing in development of affordable and effective anti-HIV agents for countries with high infection and mortality rates due to HIV/AIDS.

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Extracts of Equisetum giganteum L and Copaifera reticulate Ducke show strong antiviral activity against the sexually transmitted pathogen herpes simplex virus type 2

Publication date: 10 January 2018
Source:Journal of Ethnopharmacology, Volume 210
Author(s): Marianela Patzi Churqui, Liza Lind, Karolina Thörn, Alexandra Svensson, Otto Savolainen, Katty Terrazas Aranda, Kristina Eriksson
Ethnopharmacological relevanceEquisetum giganteum L and Copaifera reticulate Ducke have been traditionally used by women of the Tacana tribe in the Bolivian Amazonas for genital hygiene and for treatment of genital infection/inflammation.Aim of the studyTo assess the ability of extracts from Equisetum giganteum L and Copaifera reticulate Ducke to block genital viral infection by herpes simplex virus type 2.Materials and MethodsEquisetum giganteum L and Copaifera reticulate Ducke were collected from the Amazon region of La Paz, Bolivia. Extracts were prepared and screened for anti-viral activity against herpes simplex virus type 2 (HSV-2) using both in vitro and in in vivo models of infection.ResultsEquisetum giganteum L and Copaifera reticulate Ducke efficiently blocked HSV-2 infection of cell cultures without major cell cytotoxic effects. Extracts of Equisetum giganteum L and Copaifera reticulate Ducke could prevent HSV-2 disease development when administered together with virus in a mouse model of genital HSV-2 infection. In vitro analyses revealed that both plant extracts exerted their anti-HSV-2 effects by interfering with viral cell attachment and entry, but could not block viral replication post entry.ConclusionsThese studies show that extracts of Equisetum giganteum L and Copaifera reticulate Ducke have potent antiviral activities against HSV-2 comparable to those two previously identified plants, Croton lechleri Müll. Arg. and Uncaria tomentosa (Willd. ex Schult.) DC. These studies confirm that plants used by the Tacana tribe could be explored further for the development of novel topical antiviral microbicides.

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Antiprotozoal activity of medicinal plants used by Iquitos-Nauta road communities in Loreto (Peru)

Publication date: Available online 5 September 2017
Source:Journal of Ethnopharmacology
Author(s): Pedro Vásquez-Ocmín, Sandrine Cojean, Elsa Rengifo, Soulaf Suyyagh-Albouz, Carlos A. Amasifuen Guerra, Sébastien Pomel, Billy Cabanillas, Kember Mejía, Philippe M. Loiseau, Bruno Figadère, Alexandre Maciuk
Ethnopharmacological relevanceIn the Peruvian Amazon, the use of medicinal plants is a common practice. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point for this work was a set of interviews of people living in rural communities from the Peruvian Amazon about their uses of plants. Protozoan diseases are a public health issue in the Amazonian communities, who partly cope with it by using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help identify new antiprotozoal compounds.Aims of studyto inventory and validate the use of medicinal plants by rural people of Loreto region.Materials and methodsRural mestizos were interviewed about traditional medication of parasite infections with medicinal plants. Ethnopharmacological surveys were undertaken in two villages along Iquitos-Nauta road (Loreto region, Peru), namely 13 de Febrero and El Dorado communities. Forty-six plants were collected according to their traditional use for the treatment of parasitic diseases, 50 ethanolic extracts (different parts for some of the plants) were tested in vitro on Plasmodium falciparum (3D7 sensitive strain and W2 chloroquine resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Cytotoxic assessment (HUVEC cells) of the active extracts was performed. Two of the most active plants were submitted to preliminary bioguided fractionation to ascertain and explore their activities.ResultsFrom the initial plants list, 10 were found to be active on P. falciparum, 15 on L. donovani and 2 on the three parasites. The ethanolic extract from Costus curvibracteatus (Costaceae) leaves and Grias neuberthii (Lecythidaceae) bark showed strong in vitro activity on P. falciparum (sensitive and resistant strain) and L. donovani and moderate activity on T. brucei gambiense.ConclusionsThe Amazonian forest communities in Peru represents a source of knowledge on the use of medicinal plants. In this work, several extracts with antiprotozoal activity were identified. This work contributes to validate some traditional uses and opens subsequent investigations on active compounds isolation and identification.

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Trypanocidal activity of polysaccharide extract from Genipa americana leaves

Publication date: Available online 5 September 2017
Source:Journal of Ethnopharmacology
Author(s): Racquel Oliveira da Silva Souza, Paloma Leão Sousa, Ramon Róseo Paula Pessoa Bezerra de Menezes, Tiago Lima Sampaio, Louise Donadello Tessarolo, Francisca Crislandia Oliveira Silva, Maria Gonçalves Pereira, Alice Maria Costa Martins
Ethnopharmacological relevanceThe parts of the Genipa americana (Rubiaceae) tree, also known as "jenipapo" or "jenipapeiro", has been used in traditional Medicine in parasitic and bacterial infections. Thus, the experimental evolution of the antiparasitic activity of polysaccharide extracts from Genipa americana leaves, and correlation with antiparasitic and popular use is important.Aim of the studyTo evaluate the effect of polysaccharide extract obtained from Genipa americana leaves on all Trypanosoma cruzi (Y strain: benznidazole-resistant) developmental forms, a protozoan that causes Chagas' disease.Materials and MethodsAn extract rich in polysaccharides was obtained from the leaves of Genipa americana (GaEPL) by associating depigmentation in methanol followed by extraction of polysaccharides in NaOH and precipitation with ethanol. Cytotoxicity to mammalian cells (LLC-MK2) was determined using an MTT assay. Antiparasitic activity was evaluated against epimastigote, trypomastigote and amastigote forms of T. cruzi. Cell-death mechanism was determined in epimastigote forms by flow cytometry analysis after FITC-annexin V (Ax), 7-AAD, and H2DCFDA staining. Striking morphological changes were observed by scanning electron microscope.ResultsGaEPL (6.5% yield; 54.6% total carbohydrate; 21.1% uronic acid and 12% protein), inhibited all T. cruzi developmental forms, epimastigotes after periods of 24h (IC50= 740±0.075µg/mL), 48h (IC50= 710±0.053µg/mL) and 72h (IC50= 870±0.052µg/mL) of incubation; trypomastigotes (IC50= 470±0.082µg/mL) after periods of 24h and intracellular amastigotes (IC50/2 = 235 or IC50= 470µg/mL) after periods of 24 and 48h of incubation, with no toxicity on LLC-MK2 cells at the used concentrations. Analysis of the possible action mechanism in the parasites suggested cell death by necrosis with the involvement of reactive oxygen species (ROS). The scanning electron microscopy (SEM) confirmed T. cruzi death by necrosis.ConclusionsGaEPL showed significant activity against the epimastigote, trypomastigote and amastigote forms of T. cruzi, strain Y, suggesting cell death by necrosis with involvement of reactive oxygen species.

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Distribution characteristics of heavy metal(loid)s in aggregates of different size fractions along contaminated paddy soil profile

Abstract

Soil aggregates exert a significant influence on the retention and availability of heavy metal(loid)s in soil. In this study, the concentration distribution and chemical forms of heavy metals (Cu, Zn, Cd, Pb, and Hg) and a metalloid (As) in different aggregate-sized fractions (2–0.25, 0.25–0.05, 0.05–0.002, and < 0.002 mm) along the profile (0–1, 1–5, 5–15, and 15–25 cm) of a contaminated paddy field were investigated. The results showed that the values of pH, free Fe oxides (Fed), bulk density, and catalase activity gradually increased, whereas the soil organic matter (SOM), cation exchange capacity (CEC), electrical conductivity (EC), microbial biomass carbon (MBC), and urease activity decreased with depth. Long-term heavy metal pollution might impact the catalase activity but showed no obvious influence on the urease activity. Additionally, there was a notable difference in physicochemical properties among the soil aggregates of various particle sizes. The 2–0.25-mm fraction aggregates contained more organic matter, whereas the highest values of CEC and Fed were observed in the < 0.002-mm fraction. The concentrations of all six heavy metals/metalloid decreased with depth. In different layers, Cu and Cd showed the highest concentrations in the 2–0.25 mm-fraction, followed by the < 0.002-mm fraction, whereas the highest concentrations of Zn, Pb, and As appeared in the < 0.002-mm fraction. No obvious distribution regularity was observed for Hg among the aggregates. All of the metal(loid)s had lower activity in the deeper soil layers, except for Hg. Furthermore, Cu and Cd displayed more stable forms in the < 0.002-mm fraction aggregates.



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Age and the association of dementia related pathology with trajectories of cognitive decline

Publication date: Available online 5 September 2017
Source:Neurobiology of Aging
Author(s): Willemijn J. Jansen, Robert S. Wilson, Pieter Jelle Visser, Sukriti Nag, Julie A. Schneider, Bryan D. James, Sue E. Leurgans, Ana W. Capuano, David A. Bennett, Patricia A. Boyle
The association of dementia related pathologies with cognition is hypothesized to decrease as age advances. We examined this in 413 persons without cognitive impairment at baseline who completed annual cognitive evaluations during a mean of 10.4 years. After death, neuropathologic examinations quantified beta-amyloid plaque load, neurofibrillary tangles, and TDP-43 pathology, and identified Lewy bodies, hippocampal sclerosis, and gross and microscopic cerebral infarcts. We tested whether age at death modified associations of these neuropathologies with the nonlinear trajectory of cognitive decline using mixed-effects change point models. The rate of global cognitive decline was gradual at first and then increased approximately 10-fold in the last 3 years of life. After adjustment for all other pathologic indices, tangle density, gross infarcts, Lewy bodies, and TDP-43 were associated with global cognitive decline. However, the deleterious association of dementia related pathologies with cognitive decline did not systematically vary by age. This suggests that the neuropathologic mechanisms underlying late-life cognitive decline do not substantially differ across the spectrum of age.



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Altered intertemporal choice with age is only partially mediated by prefrontal cortex Decline of prefrontal cortical-mediated executive functions but attenuated delay discounting in aged Fischer 344 x Brown Norway hybrid rats

Publication date: Available online 5 September 2017
Source:Neurobiology of Aging
Author(s): Caesar M. Hernandez, Lauren M. Vetere, Caitlin A. Orsini, Joseph A. McQuail, Andrew P. Maurer, Sara N. Burke, Barry Setlow, Jennifer L. Bizon
Despite the fact that prefrontal cortex (PFC) function declines with age, aged individuals generally show an enhanced ability to delay gratification, as evident by less discounting of delayed rewards in intertemporal choice tasks. The current study was designed to evaluate relationships between two aspects of PFC-dependent cognition (working memory and cognitive flexibility) and intertemporal choice in young (6 mo.) and aged (24 mo.) Fischer 344 x Brown-Norway F1 hybrid rats. Rats were also evaluated for motivation to earn rewards using a progressive ratio task. As previously reported, aged rats showed attenuated discounting of delayed rewards, impaired working memory, and impaired cognitive flexibility compared to young. Among aged rats, greater choice of delayed reward was associated with preserved working memory, impaired cognitive flexibility, and less motivation to work for food. These relationships suggest that age-related changes in PFC and incentive motivation contribute to variance in intertemporal choice within the aged population. Cognitive impairments mediated by PFC are unlikely, however, to fully account for the enhanced ability to delay gratification that accompanies aging.



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Dynamic range in BOLD modulation: Lifespan aging trajectories and association with performance

Publication date: Available online 5 September 2017
Source:Neurobiology of Aging
Author(s): Kristen M. Kennedy, Maria A. Boylan, Jenny R. Rieck, Chris M. Foster, Karen M. Rodrigue
Alteration of dynamic range of modulation to cognitive difficulty has been proposed as a salient predictor of cognitive aging. Here we examine in 171 adults (aged 20-94 years) the effects of age on dynamic modulation of BOLD activation to difficulty in parametrically increasing working memory load (0-,2-,3-,4-back conditions). First, we examined parametric increases and decreases in activation to increasing WM load (positive modulation effect and negative modulation effect). Second, we examined the effect of age on modulation to difficulty (WM load) to identify regions that differed with age as difficulty increased (age-related positive and negative modulation effects). Weakened modulation to difficulty with age was found in both the positive-modulation (middle frontal, superior/inferior parietal) and negative-modulation effect (deactivated) regions (insula, cingulate, medial superior frontal, fusiform, and parahippocampal gyri, hippocampus, and lateral occipital cortex). Age-related alterations to positive modulation emerged later in the lifespan than negative modulation. Further, these effects were significantly coupled in that greater up-modulation was associated with lesser down-modulation. Importantly, greater frontal-parietal up-modulation to difficulty and greater down-modulation of deactivated regions was associated with better task accuracy and up-modulation with better working memory span measured outside the scanner. These findings suggest that greater dynamic range of modulation of activation to cognitive challenge is in service of current task performance, as well as generalizing to cognitive ability beyond the scanner task, lending support to its utility as a marker of successful cognitive aging.



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Intravenous treatment with human recombinant ApoA-I Milano reduces β-amyloid cerebral deposition in the APP23-transgenic mouse model of Alzheimer’s disease

Publication date: Available online 5 September 2017
Source:Neurobiology of Aging
Author(s): Sofía Fernández-de Retana, Alex Montañola, Paula Marazuela, Maialen De La Cuesta, Aina Batlle, Marc Fatar, Saskia Grudzenski, Joan Montaner, Mar Hernández-Guillamon
Beyond the crucial role of apolipoproteinA-I (ApoA-I) on peripheral cholesterol metabolism, this apolipoprotein has also been implicated in β-amyloid (Aβ)-related neuropathologies. ApoA-I-Milano (M) is a mutated variant, which has been shown to present increased vasoprotective properties compared to ApoA-I-wild type (wt) in models of atherosclerosis and cardiovascular damage. We speculated that ApoA-I-M may also protect Aβ–affected vasculature and reverse some of the pathological features associated with Alzheimer's disease (AD). For this purpose, we produced and characterized human recombinant ApoA-I-wt and ApoA-I-M proteins. Both of them were able to avoid the aggregation of Aβ in vitro, even though rApoA-I-M was significantly more effective in protecting endothelial cells from Aβ(1-42)-toxicity. Next, we determined the effect of chronic intravenous administration of rApoA-I-M in the APP23-transgenic mouse model of AD. We found reduced cerebral levels of Aβ(1-40) and Aβ(1-42) in mice that received rApoA-I-M, which were accompanied by a lower expression of astrocyte and microglia neuroinflammatory markers. Our results suggest an applicability of this molecule as a therapeutic candidate for protecting the brain in AD.



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Aging and a genetic KIBRA polymorphism interactively affect feedback- and observation-based probabilistic classification learning

Publication date: Available online 5 September 2017
Source:Neurobiology of Aging
Author(s): Nicolas W. Schuck, Jessica R. Petok, Martijn Meeter, Brit-Maren M. Schjeide, Julia Schröder, Lars Bertram, Mark A. Gluck, Shu-Chen Li
Probabilistic category learning involves complex interactions between the hippocampus and striatum that may depend on whether acquisition occurs via feedback or observation. Little is known about how healthy aging affects these processes. We tested whether age-related behavioral differences in probabilistic category learning from feedback or observation depend on a genetic factor known to influence individual differences in hippocampal function, the KIBRA gene (SNP rs17070145). Results showed comparable age-related performance impairments in observational as well as feedback-based learning. Moreover, genetic analyses indicated an age-related interactive effect of KIBRA on learning: among older adults the beneficial T-allele was positively associated with learning from feedback, but negatively with learning from observation. In younger adults, no effects of KIBRA were found. Our results add behavioral genetic evidence to emerging data showing age-related differences in how neural resources relate to memory functions, namely that hippocampal and striatal contributions to probabilistic category learning may vary with age. Such findings highlight the effects genetic factors can have on relative age-related decline of different memory functions.



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Scholar : These new articles for Atmospheric and Oceanic Science Letters are available online

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Future changes in precipitation extremes over China using the NEX-GDDP high-resolution daily downscaled data-set | Open Access
Huo-Po Chen, Jian-Qi Sun & Hui-Xin Li
Pages: 1-8 | DOI: 10.1080/16742834.2017.1367625


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The evolution of human sleep: Technological and cultural innovation associated with sleep-wake regulation among Hadza hunter-gatherers

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Publication date: December 2017
Source:Journal of Human Evolution, Volume 113
Author(s): David R. Samson, Alyssa N. Crittenden, Ibrahim A. Mabulla, Audax Z.P. Mabulla
Sleep is necessary for the survival of all mammalian life. In humans, recent investigations have generated critical data on the relationship between sleep and ecology in small-scale societies. Here, we report the technological and social strategies used to alter sleep environments and influence sleep duration and quality among a population of hunter-gatherers, the Hadza of Tanzania. Specifically, we investigated the effects that grass huts, sound levels, and fire had on sleep. We quantitatively compared thermal stress in outdoor environments to that found inside grass hut domiciles to test whether the huts function as thermoregulated microhabitats during the rainy season. Using physiological equivalent temperature (PET), we found that the grass huts provide sleep sites with less overall variation in thermal stress relative to outside baseline environments. We also investigated ambient acoustic measures of nighttime environments and found that sound significantly covaried with sleep-wake activity, with greater sound levels associating with less sleep. Finally, after controlling for ecological variables previously shown to influence sleep in this population, fire was shown to neither facilitate nor discourage sleep expression. Insofar as data among contemporary sub-tropical foragers can inform our understanding of past lifeways, we interpret our findings as suggesting that after the transition to full time terrestriality, it is likely that early Homo would have had novel opportunities to manipulate its environments in ways that could have significantly improved sleep quality. We further conclude that control over sleep environment would have been essential for migration to higher latitudes away from equatorial Africa.



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Editorial Board

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Publication date: October 2017
Source:Journal of Human Evolution, Volume 111





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