Exposure to dietary mercury alters cognition and behavior of zebra finches

Environmental stressors can negatively affect avian cognitive abilities, potentially reducing fitness, for example by altering response to predators, display to mates, or memory of locations of food. We expand on current knowledge by investigating the effects of dietary mercury, a ubiquitous environmental pollutant and known neurotoxin, on avian cognition. Zebra finches Taeniopygia guttata were dosed for their entire lives with sub-lethal levels of mercury, at the environmentally relevant dose of 1.2 parts per million. In our first study, we compared the dosed birds with controls of the same age using tests of three cognitive abilities: spatial memory, inhibitory control, and color association. In the spatial memory assay, birds were tested on their ability to learn and remember the location of hidden food in their cage. The inhibitory control assay measured their ability to ignore visible but inaccessible food in favor of a learned behavior that provided the same reward. Finally, the color association task tested each bird\u27s ability to associate a specific color with the presence of hidden food. Dietary mercury negatively affected spatial memory ability but not inhibitory control or color association. Our second study focused on three behavioral assays not tied to a specific skill or problem-solving: activity level, neophobia, and social dominance. Zebra finches exposed to dietary mercury throughout their lives were subordinate to, and more active than, control birds. We found no evidence that mercury exposure influenced our metric of neophobia. Together, these results suggest that sub-lethal exposure to environmental mercury selectively harms neurological pathways that control different cognitive abilities, with complex effects on behavior and fitness

Curricular orientations to real-world contexts in mathematics

A common claim about mathematics education is that it should equip students to use mathematics in the ‘real world’. In this paper, we examine how relationships between mathematics education and the real world are materialised in the curriculum across a sample of eleven jurisdictions. In particular, we address the orientation of the curriculum towards application of mathematics, the ways that real-world contexts are positioned within the curriculum content, the ways in which different groups of students are expected to engage with real-world contexts, and the extent to which high-stakes assessments include real-world problem solving. The analysis reveals variation across jurisdictions and some lack of coherence between official orientations towards use of mathematics in the real world and the ways that this is materialised in the organisation of the content for students

An Experimental Analysis Of the Demand For Payday Loans

The payday loan industry is one of the fastest growing segments of the consumer financial services market in the United States. We design an environment similar to the one that payday loan customers face and then conduct a laboratory experiment to examine what effect, if any, the existence of payday loans has on individuals\u27 abilities to manage and to survive financial setbacks. Our primary objective is to examine whether access to payday loans improves or worsens the likelihood of financial survival in our experiment. We also test the degree to which people\u27s use of payday loans affects their ability to survive financially. We find that payday loans help the subjects to absorb expenditure shocks and therefore survive financially. However, subjects whose demand for payday loans exceeds a certain threshold level are at a greater risk than a corresponding subject in the treatment in which payday loans do not exist

Invited commentary: hypertension during pregnancy and offspring microvascular structure—insights from the retinal microcirculation

Human clinical studies as well as laboratory animal studies demonstrate that offspring of pregnancies affected by common complications, such as preeclampsia and preterm birth, display developmental phenotypes that relate distinctly to the pregnancy disorder. Several studies have now found microvascular differences in offspring of hypertensive pregnancies, and there is interest in whether these may underlie epidemiologic associations between gestational hypertension and a higher risk of hypertension and stroke in the offspring. The retinal circulation provides a unique window into microvascular structure, of likely relevance to both the cerebrovasculature and broader cardiovascular risk. Yesil et al. (Am J Epidemiol. 2016;184(9):605-615) report in this issue of the Journal that maternal gestational blood pressure elevation is associated with reduced retinal vascular caliber in offspring at 6 years of age, providing a link between variation in pregnancy characteristics and childhood vascular development. Further work to understand the longitudinal association between pregnancy, emergence of microvascular changes, and cardiovascular risk may identify opportunities for future preventive interventions

Invited commentary: hypertension during pregnancy and offspring microvascular structure—insights from the retinal microcirculation

Human clinical studies as well as laboratory animal studies demonstrate that offspring of pregnancies affected by common complications, such as preeclampsia and preterm birth, display developmental phenotypes that relate distinctly to the pregnancy disorder. Several studies have now found microvascular differences in offspring of hypertensive pregnancies, and there is interest in whether these may underlie epidemiologic associations between gestational hypertension and a higher risk of hypertension and stroke in the offspring. The retinal circulation provides a unique window into microvascular structure, of likely relevance to both the cerebrovasculature and broader cardiovascular risk. Yesil et al. (Am J Epidemiol. 2016;184(9):605-615) report in this issue of the Journal that maternal gestational blood pressure elevation is associated with reduced retinal vascular caliber in offspring at 6 years of age, providing a link between variation in pregnancy characteristics and childhood vascular development. Further work to understand the longitudinal association between pregnancy, emergence of microvascular changes, and cardiovascular risk may identify opportunities for future preventive interventions