Enriched housing reverses age-associated impairment of cognitive functions and tPA-dependent maturation of BDNF

Although tissue type plasminogen activator (tPA) and brain derived neurotrophic factor (BDNF) have been extensively described to influence brain outcomes in a number of disorders, their roles during physiological aging are poorly investigated. In the present study, we investigated whether maintenance of mice in different environmental conditions could influence age-associated changes in hippocampal tPA expression and BDNF maturation in relation with modifications of their cognitive performances. Our data indicate that maintenance in enriched housing led to a reversal of age-associated decrease in expression of hippocampal tPA. A subsequent increase in the level of mature BDNF and an improvement in emotional and spatial memories were observed. Taken together, these data suggest that the tPA–BDNF axis could play a critical role in the control of cognitive functions influenced both by the age and housing conditions.     

Formation par alternance : expérience scolaire et rapport à l’apprendre chez des apprentis de niveau V et leurs maîtres d’apprentissage

This qualitative research in line with a socio-constructivist approach of the relation to knowledge aims at studying the conditions of efficiency of apprenticeship (training centre/working place) for wage-earning apprentices with a level V. The thematic analysis of 38 interviews (19 apprentices and 19 apprenticeship masters) reveals that apprentices and apprenticeship masters develop some similar schooling experience and relations to learning based on a massive rejection for any schooling form of transmission. We thus show that an apprenticeship based on work and study can offer young people the opportunity to reinvest their relation to learning but only under the conditions of finding ways to escape the circle of school condemnation. These young people must also be able to find in this system the necessary conditions which will give a meaning to their experience of apprentices.     

A Multicriteria Spatial Decision Support System Development for Siting a Landfill in the Province of Torino (Italy)

The present paper proposes a spatial multicriteria approach for supporting Decision‐Makers in the siting process of a Municipal Solid Waste landfill in the Province of Torino (Italy). In particular, the contribution illustrates the development of a Multicriteria‐Spatial Decision Support System based on the integration of Geographic Information Systems and a specific Multicriteria Decision Analysis technique, named Analytic Network Process (ANP). This technique, which represents the generalization of the more well‐known Analytic Hierarchy Process to dependences and feedbacks, is particularly suitable for dealing with complex decision problems which are characterized by inter‐relationships among the elements at stake. The application allows the dependence relationships among the criteria to be assessed, and the relative importance of all the elements that play an influence on the final choice to be evaluated. The purpose of the study is to generate a suitability map of the area under analysis for locating a waste landfill, paying particular attention to the contribution that the spatial ANP offers to sustainability assessments of undesirable facilities. To this end, the simple network structure has been used and both exclusionary and non‐exclusionary criteria have been identified and grouped into clusters. The results are obtained in the form of suitability maps analysed through ilwis 3.3 software (52North, ITC, Enschede, The Netherlands) and have been further verified through a sensitivity analysis with reference to the clusters priorities in order to test the robustness of the proposed model. The main findings of this research have proved that the spatial ANP is a useful tool to help technicians to make their decision process traceable and reliable. Moreover, this approach helps Decision‐Makers to undertake a sound reflection of the siting problem. Finally, the implementation of the spatial ANP technique gives an originality value to the present research because it represents one of the first applications at both the national and international level. Copyright © 2011 John Wiley & Sons, Ltd.     

Statistical inference and spatial patterns in correlates of IQ

Cross-national comparisons of IQ have become common since the release of a large dataset of international IQ scores. However, these studies have consistently failed to consider the potential lack of independence of these scores based on spatial proximity. To demonstrate the importance of this omission, we present a re-evaluation of several hypotheses put forward to explain variation in mean IQ among nations namely: (i) distance from central Africa, (ii) temperature, (iii) parasites, (iv) nutrition, (v) education, and (vi) GDP. We quantify the strength of spatial autocorrelation (SAC) in the predictors, response variables and the residuals of multiple regression models explaining national mean IQ. We outline a procedure for the control of SAC in such analyses and highlight the differences in the results before and after control for SAC. We find that incorporating additional terms to control for spatial interdependence increases the fit of models with no loss of parsimony. Support is provided for the finding that a national index of parasite burden and national IQ are strongly linked and temperature also features strongly in the models. However, we tentatively recommend a physiological - via impacts on host-parasite interactions - rather than evolutionary explanation for the effect of temperature. We present this study primarily to highlight the danger of ignoring autocorrelation in spatially extended data, and outline an appropriate approach should a spatially explicit analysis be considered necessary.     

Tuning of human vestibulospinal reflexes by leg rotation

Changing the foot position modifies the mechanical action exerted by the ankle extensor and flexor muscles over the body. We verified, in two groups of healthy subjects standing with the heels touching or apart, whether a 90° external rotation of the right leg and foot also changes the pattern of vestibulospinal reflexes elicited by electrical stimulation of the labyrinth. With the head oriented forward, leg rotation did not modify the labyrinthine-driven displacements of the center of pressure (CoP). When the head was rotated in the horizontal plane, either to the right or to the left, the CoP displacement increased along the y axis in all subjects. Changes in the x component in most instances appropriate to preserve unmodified the direction of body sway elicited by the stimulus were observed. Right leg rotation increased the basal EMG activity of ankle extensors and flexors on the left side, while the right side activity was unaffected. The EMG responses to labyrinthine stimulation were modified only on the left side, in a way appropriate to correct the effects of the altered torque pattern exerted on the body by right leg muscles. It appears, therefore, that somatosensory signals related to leg rotation and/or copy of the corresponding voluntary motor commands modify the pattern of vestibulospinal reflexes and maintain the postural response appropriate to counteract a body sway in the direction inferred by labyrinthine signals.     

A twin study of spatial and non-spatial delayed response performance in middle age

Delayed alternation and object alternation are classic spatial and non-spatial delayed response tasks. We tested 632 middle-aged male veteran twins on variants of these tasks in order to compare test difficulty, measure their inter-correlation, test order effects, and estimate heritabilities (proportion of observed variance due to genetic influences). Non-spatial alternation (NSA), which may involve greater reliance on processing of subgoals, was significantly more difficult than spatial alternation (SA). Despite their similarities, NSA and SA scores were uncorrelated. NSA performance was worse when administered second; there was no SA order effect. NSA scores were modestly heritable (h(2)=.25; 26); SA was not. There was shared genetic variance between NSA scores and general intellectual ability (r(g)=.55; .67), but this also suggests genetic influences specific to NSA. Compared with findings from small, selected control samples, high "failure" rates in this community-based sample raise concerns about interpretation of brain dysfunction in elderly or patient samples.     

No sex differences in spatial location memory for abstract designs

Previous research has demonstrated a female advantage, albeit imperfectly, on tests of object location memory where object identity information is readily available. However, spatial and visual elements are often confounded in the experimental tasks used. Here spatial and visual memory performance was compared in 30 men and 30 women by presenting 12 abstract designs in a spatial array for recall and recognition (visual memory) and spatial location ("object" location memory). Object location memory was measured via a sensitive absolute displacement score defined as the distance in mms between the position assigned to the object during recall and the actual position it originally occupied. There were no sex differences in either the visual or spatial location tests. Controlling for age and estimated IQ scores made no impact on the results. These data suggest an absence of a sex difference in purely visual and spatial aspects of object location memory.     

Eye movement suppression interferes with construction of object-centered spatial reference frames in working memory

The brain’s frontal eye fields (FEF), responsible for eye movement control, are known to be involved in spatial working memory (WM).In a previous fMRI experiment (Wallentin, Roepstorff & Burgess, Neuropsychologia, 2008) it was found that FEF activation was primarily related to the formation of an object-centered, rather than egocentric, spatial reference frame. In this behavioral experiment we wanted to demonstrate a causal relationship between eye movement control and manipulation of spatial reference frames. Sixty-two participants recalled either spatial (“Was X in front of Y?”) or non-spatial (“Was X darker than Y?”) relations in a previously shown image containing two to four objects, each with an intrinsic orientation and unique luminance. During half of all recall trials a moving visual stimulus was presented, which participants had to ignore, thus suppressing eye movement. Response times were significantly slower for spatial relations with distraction while there was no effect on non-spatial relations. There was no effect on accuracy, i.e. WM maintenance. This is consistent with the hypothesis that in spatial representations the FEFs are involved in WM content manipulation, such as establishing an object-centered spatial frame of reference.     

The GROOP effect: groups mimic group actions

Research on perception–action links has focused on an interpersonal level, demonstrating effects of observing individual actions on performance. The present study investigated perception–action matching at an inter-group level. Pairs of participants responded to hand movements that were performed by two individuals who used one hand each or they responded to hand movements performed by an individual who used both hands. Apart from the difference in the number of observed agents, the observed hand movements were identical. If co-actors form action plans that specify the actions to be performed jointly, then participants should have a stronger tendency to mimic group actions than individual actions. Confirming this prediction, the results showed larger mimicry effects when groups responded to group actions than when groups responded to otherwise identical individual actions. This suggests that representations of joint tasks modulate automatic perception–action links and facilitate mimicry at an inter-group level.     

Does changing the reference frame affect infant categorization of the spatial relation BETWEEN?

Past research has shown that variation in the target objects depicting a given spatial relation disrupts the formation of a category representation for that relation. In the current research, we asked whether changing the orientation of the referent frame depicting the spatial relation would also disrupt the formation of a category representation for that relation. Experiments 1 to 3 provided evidence that 6- and 7-month-olds formed a category representation for BETWEEN when a diamond shape was depicted in different locations between two vertical or horizontal reference bars during familiarization and in a novel location between the same orientation of bars during test. By contrast, in Experiment 4, same-age infants did not form a category representation for BETWEEN when the diamond shape was depicted between two vertical (or horizontal) bars during familiarization and between two horizontal (or vertical) bars during test. Moreover, in Experiment 5, 9- and 10-month-olds did form a category representation for BETWEEN when the orientation of the referent bars depicting the relation changed from familiarization to test. The findings suggest that the formation of category representations for spatial relations by infants is affected by changes to either target (figure) or referent (ground).