Stress affects dopaminergic signaling pathways in Drosophila melanogaster

Behaviors modulated by dopamine appear to be conserved across species. In the model system Drosophila melanogaster, as in mammals, dopamine modulates female sexual receptivity, a simple form of learning and responses to drugs of abuse. Synthesis, reuptake and binding of dopamine are also evolutionarily conserved. Since stress has been shown to affect dopaminergic signaling pathways in mammals, we investigated the consequences of exposure to diverse stressors on dopaminergic physiology in the fruit fly, D. melanogaster. Animals were exposed to a metabolic stress (starvation), an oxidative stress (via the superoxide anion generator paraquat) or a mechanical stress (gentle vortexing). Sexual maturity, reproductive status, gender and type of stress differentially affected survival. The stress paradigms also resulted in alterations in the activity of tyrosine hydroxylase, the rate-limiting enzyme in dopamine biosynthesis. Exposure to these stressors perturbed female sexual receptivity and ovarian development, which are modulated by dopamine, suggesting that dopaminergic physiology is affected as a consequence of stress. Transgenic Drosophila with reduced levels of neuronal dopamine displayed an altered response to these stressors, suggesting that, as in mammals, dopamine is a key element in the stress response.     

Perceived stress and physiological dysregulation in older adults

We use a population-based representative sample of older Taiwanese to investigate links between respondents' perceived levels of stress and a broad set of biological measures. These biomarkers were collected at a single time (2000) and reflect sympathetic nervous system (SNS)-activity, hypothalamo-pituitary-adrenal (HPA)-activity, immune function, cardiovascular function, and metabolic pathways. We model the relationship between perceived stress and (1) extreme values for each of 16 individual biological indicators; and (2) a measure of cumulative physiological dysregulation based on the full set of biomarkers. We consider two measures of perceived stress, one derived from the 2000 interview and the second based on data from three interviews (1996-2000). Age and sex-adjusted models reveal significant associations between measures of perceived stress and extreme values of cortisol, triglycerides, interleukin-6 (IL-6), dehydroepiandrosterone sulphate (DHEAS) and fasting glucose. Examined individually, numerous biomarkers, including those pertaining to blood pressure and obesity, are not significantly related to perceived stress. Jointly, however, the measure of cumulative physiological dysregulation is associated with both the level of perceived stress at a given time and to a longitudinal measure of perceived stress. Some results suggest that the relationship between level of perceived stress and physiological response is stronger for women than men.     

Towards an account of argumentation in science

In this article it is argued that a complex model that includes Toulmin's functional account of argument, the pragma-dialectical stage analysis of argumentation offered by the Amsterdam School, and criteria developed in critical thinking theory, can be used to account for the normativity and field-dependence of argumentation in science. A pragma-dialectical interpretation of the four main elements of Toulmin's model, and a revised account of the double role of warrants, illuminates the domain specificity of scientific argumentation and the restrictions to which the confrontation and opening stages of scientific critical discussions are subjected. In regard to the argumentation stage, examples are given to show that a general account of argumentation, as advocated by informal logicians, is not applicable to arguments in science. Furthermore, although patterns of inference differ in various scientific practices, deductive validity is argued to be a crucial notion in the assessment of scientific arguments. Finally, some remarks are made concerning the burden of proof and the concluding stage of scientific argumentation.     

Determinants of Self-Protective Behavior: Home Radon Testing

This field experiment explored the use of informational brochures to encourage home radon testing. Homeowners ( N = 271) received a radon brochure, a questionnaire, and a form for ordering a $20 radon test kit. The brochures differed in their presentations of the magnitude of the threat (varying risk likelihood and severity) and the difficulty of reducing radon levels. Some also included a detailed list of home radon risk factors. Combinations of these three variables yielded a 2 × 2 × 2 factorial design. Although 19.2% of the sample ordered tests, the percentage was constant across brochures. Data from the questionnaire showed that self-reported risk likelihood, risk seriousness, and concern were strongly correlated with intentions to test and with actual test orders. Calculations revealed that although the threat manipulation had a highly significant effect on these risk perceptions, the effect was too small to produce different rates of test orders. Confirming previous radon studies, perceived mitigation difficulty proved unrelated to interest in radon testing.     

A psychometric evaluation of the new NEO-PIR facet scales for agreeableness and conscientiousness

The five-factor model of personality represents one of the more important developments in the area of personality theory and assessment. This empirically derived model consists of the major factors of Neuroticism, Extraversion, Openness to Experience, Agreeableness, and Conscientiousness. Currently there is only one commercially available measure of these dimensions: The NEO Personality Inventory (NEO-PI). The NEO-PI measures each of these global domains as well as more specific facets of Neuroticism, Extraversion, and Openness to Experience. The new revision of the NEO-PI (NEO-PIR) now includes facet scales for Agreeableness and Conscientiousness. The purpose of this article is to provide a psychometric evaluation of these new scales using a sample of working adults and relying on both self-report and observer ratings. The results provide strong support for the reliability and construct validity of these new scales.     

Paradigms of truth detection

Alternative models of idealized scientific inquiry are investigated and compared. Particular attention is devoted to paradigms in which a scientist is required to determine the truth of a given sentence in the structure giving rise to his data.     

Successive teacher expectation effects across the early school years

The capacity for teacher expectation effects to interact and compound across a child's schooling offers a largely untested mechanism for magnifying or minimizing effects. This study examined four types of long-term teacher expectation effects: within-year effects of single teachers, cross-year effects of single teachers, mediated effects of single and multiple teachers, and compounded effects of multiple teachers. Participants were 110 students tracked from preschool through Grade 4 on measures of achievement and teacher expectations. Evidence was found for within-year but not direct cross-year effects. However, path models demonstrated enduring indirect effects of teacher expectations on cross-year achievement. Multiple years of teacher expectation effects were additive in predicting student achievement at fourth grade, with similar effects for teachers' over- and underestimates of student ability. The study extends understanding of longer-term teacher expectation effects.     

White Matter Hyperintensities and Working Memory: An Explorative Study

ABSTRACT

White matter hyperintensities (WMH) are commonly observed in elderly people and may have the most profound effect on executive functions, including working memory. Surprisingly, the Digit Span backward, a frequently employed working memory task, reveals no association with WMH. In the present study, it was investigated whether more detailed analyses of WMH variables and study sample selection are important when establishing a possible relationship between the Digit Span backward and WMH. To accomplish this, the Digit Span backward and additional working memory tests, WMH subscores, and cardiovascular risk factors were examined. The results revealed that performance on the Digit Span backward test is unrelated to WMH, whereas a relationship between other working memory tests and WMH was confirmed. Furthermore, a division between several white matter regions seems important; hyperintensities in the frontal deep white matter regions were the strongest predictor of working memory performance.