Chronic stress prior to hippocampal stroke enhances post-stroke spatial deficits in the ziggurat task

Stress is one of the most important variables to determine recovery following stroke. We have previously reported that post-stroke exposure to either stress or corticosterone (CORT) alleviates hippocampal ischemic outcome. The present experiment expands previous findings by investigating the influence of exposure to stress prior to ischemic event. Rats received either daily restraint stress (1h/day; 16 consecutive days) or CORT (0.5mg/kg; 16 consecutive days) prior to focal ischemic stroke in the hippocampus induced by bilateral injection of endothelin-1 (ET-1). All experimental groups were then tested in the ziggurat task, a new task for spatial cognition. The stress+stroke group showed significant deficits in both hippocampal structure and function. No deleterious effect of pre-stroke exposure to CORT was found in the CORT+stroke group. Our results indicate that a history of chronic stress sensitizes hippocampal cells to the damaging consequences of focal ischemia. The opposing effects of CORT-related experiences in this study not only reflect the diversity of glucocorticoid actions in the stress response, but also provide evidence that elevated CORT in the absence of emotional disturbance is not sufficient to produce hippocampal deficit.     

Scaling movement amplitude: adaptation of timing and amplitude control in a bimanual task

Participants traced two circles simultaneously and the diameter of one circle was scaled as the diameter of the other circle remained constant. When the scaled circle was larger, amplitude error shifted from overshooting to undershooting, while shifting from undershooting to overshooting when this circle was smaller. Asymmetric coordination was unstable when the left arm traced a circle larger than the right arm, yet stable when the left arm traced a smaller circle. When producing symmetric coordination and the left arm traced the larger circle, relative phase shifted by 30°, but a right arm lead predominated. When the left arm traced the smaller circle and symmetric coordination was required, a 30° shift in relative phase occurred, but hand lead changed from left to right. The modulation of movement amplitude and relative phase emerged simultaneously as a result of neural crosstalk effects linked to initial amplitude conditions and possibly visual feedback of the hands' motion.     

How to measure post-error slowing: A confound and a simple solution

In many response time tasks, people slow down after they make an error. This phenomenon of post-error slowing (PES) is thought to reflect an increase in response caution, that is, a heightening of response thresholds in order to increase the probability of a correct response at the expense of response speed. In many empirical studies, PES is quantified as the difference in response time (RT) between post-error trials and post-correct trials. Here we demonstrate that this standard measurement method is prone to contamination by global fluctuations in performance over the course of an experiment. Diffusion model simulations show how global fluctuations in performance can cause either spurious detection of PES or masking of PES. Both confounds are highly undesirable and can be eliminated by a simple solution: quantify PES as the difference in RT between post-error trials and the associated pre-error trials. Experimental data are used as an empirical illustration.     

The testing effect as a function of explicit testing instructions and judgments of learning

During study, people monitor their learning; the output of this monitoring is captured in so-called judgments of learning (JOLs). JOLs predict later recall better if they are made after a slight delay, instead of immediately after study (the delayed JOL effect). According to the self-fulfilling prophecy (SFP) hypothesis delayed JOLs are based on covert retrieval attempts from long-term memory, and successful retrieval attempts in themselves enhance learning (the testing effect). We compared memory for 40 Swahili-Swedish paired associates after a week as a function of three different learning conditions, namely study plus (i) explicitly instructed self-testing, (ii) delayed JOLs, or (iii) less self-testing. We showed that repeated delayed JOLs lead to a memory improvement that does not differ significantly from a comparable condition where the participants are explicitly testing memory, and both the latter groups performed reliably better than a group that self-tested less. The results suggest that delayed JOLs improve long-term retention as efficiently as explicit memory testing and lend support to the SFP hypothesis.     

Listening to music and physiological and psychological functioning: the mediating role of emotion regulation and stress reactivity

Music listening has been suggested to have short-term beneficial effects. The aim of this study was to investigate the association and potential mediating mechanisms between various aspects of habitual music-listening behaviour and physiological and psychological functioning. An internet-based survey was conducted in university students, measuring habitual music-listening behaviour, emotion regulation, stress reactivity, as well as physiological and psychological functioning. A total of 1230 individuals (mean?=?24.89?±?5.34 years, 55.3% women) completed the questionnaire. Quantitative aspects of habitual music-listening behaviour, i.e. average duration of music listening and subjective relevance of music, were not associated with physiological and psychological functioning. In contrast, qualitative aspects, i.e. reasons for listening (especially 'reducing loneliness and aggression', and 'arousing or intensifying specific emotions') were significantly related to physiological and psychological functioning (all p?=?0.001). These direct effects were mediated by distress-augmenting emotion regulation and individual stress reactivity. The habitual music-listening behaviour appears to be a multifaceted behaviour that is further influenced by dispositions that are usually not related to music listening. Consequently, habitual music-listening behaviour is not obviously linked to physiological and psychological functioning.     

The Social Representations of the Bali Climate Conference in the French and German Media

Climate change is a major current affair for which recent United Nations climate conferences aim to build consensus and develop international solutions. The objective of this article is to compare, through the theoretical lens of social representations, the way in which French and German media, specifically newspapers, represent the Bali climate conference. We use the triangulation of data analysis to take both the pragmatic and the semantic aspects of media discourse into account. Results show that German media adopt both a local and a global vision of climate change and of the conference. Religious metaphors highlight a moral dimension of the conference, suggesting anchoring in human and political categories. In contrast, in French media, we identify that conflicts between countries render the stakes of climate change concrete by war metaphors. The French discourses examined are shown to be organised through the anchoring of political and financial categories. Results are discussed in relation to the history of green movements in the two countries and in relation to practical implications. Copyright © 2011 John Wiley & Sons, Ltd.     

The effects of delay on neonatal retention of habituated head-turning

Recovery of neonatal head orientation following auditory habituation was used to examine the effects of intertrial delay. One of two words served as stimuli with criterion orienting and habituation established before the delay. Fifty-six full-term neonates were assigned randomly to one of four delay groups: 10 (control), 55, 100, or 145 s. The percentage of head-turns toward the sound source (with one turn per trial) for blocks of three trials served as the principal dependent variable. Recovery of localized head-turning increased as length of delay increased, with the 100- and 145-s groups showing greater recovery than the 10- and 55-s groups. Infants presented with control trials systematically turned away from the sound source following habituation. Selective sensory adaptation, spontaneous recovery, and short-term memory interpretations of these data are considered.     

Trends in attempted suicide in Denmark, 1976-1980

The object of the present study was to estimate proportions and changes in the incidence of suicide attempts in Denmark. Case sheets concerning all admissions in 1976-1979 (total 6,650) at the Department of Psychiatry, Odense University Hospital (the catchment area of which provides a representative sample of the Danish population), were examined with a view to establishing the reasons for admission. Rates of suicide attempts by age and sex in 1976-1979 were calculated, and estimated rates of the suicide attempts in 1980 added. Trend analysis showed an increase in the mean rates from 1976 to 1979 of 48%, followed by a decrease in 1980 of 13%. There were high increases among the adolescents, but the increase was above all due to the fact that more and more men attempted suicide; the study suggests as a new phenomenon more male than female suicide attempters. We stress the fact that incidences calculated on the basis of hospital admissions only underestimate the real proportions of self-destructive behavior.